Burnishing metal at home with citric acid
Blueing or etching the metal gives the material a beautiful black tint and also protects it from rust and oxidation. Burnishing is used solely to protect steel and can be used on almost any item: knives, bolts, axes and other steel products.
At home, etching can be done in several ways, but one of the most effective is bluing with citric acid. Burnishing metal at home with citric acid does not require special skills, so it can be done by anyone.
Features of bluing with citric acid
It is worth noting that bluing with citric acid is not very durable, so you should not use it for etching handles and knives that are regularly used in cooking. When the procedure is performed correctly, the color of the finished product is even and free of various stains, streaks and other imperfections. It is worth noting that when carrying out bluing it is necessary to pay special attention to several points:
- Steel quality. High carbon steel lends itself best to bluing. Other types of steel may be painted in a lighter shade or have an uneven color.
- When performing the procedure, it is necessary to have good ventilation, as harmful gases are released during the process. If bluing is done in the kitchen, be sure to turn on the hood or open the window.
- The entire bluing process must be carried out under constant supervision, as it is recommended to turn the metal over every few minutes to ensure uniform etching.
If the bluing technology has not been violated, then after just half an hour or an hour you can get high-quality processed metal.
How does bluing occur?
First of all, you need to properly prepare for the bluing process. Preparation includes purchasing citric acid, washing dishes for metal weed, and boiling water.
Most often, bluing occurs in a half-liter jar, since this vessel is most convenient for small blades. If the steel is large, then you should think about using other cookware.
If the blade has a size comparable to a liter or two-liter jar, then you should think about using these containers.
Citric acid must be diluted in water in a ratio of 1 to 10. That is, 50 g of citric acid is needed for a half-liter jar. It is important to use only hot water. The optimal water temperature will be liquid in the range of 80-100 degrees. Be very careful when pouring hot water into a glass container, as the jar may burst in the process. After stirring citric acid in water, the bluing process itself begins.
Important! Before bluing, the steel must be additionally cleaned. For these purposes, you can use alcohol - it will remove dirt and grease.
The bluing process consists of several stages:
- Immersion of steel in a previously prepared container with solution. The product must be completely submerged in water. Within 1-2, a reaction will begin, which is accompanied by the formation of a large number of bubbles.
- Every 2-3 minutes it is necessary to rotate the steel product in the solution to release large bubbles of formed gas. This is necessary to evenly distribute the coating and prevent the appearance of various stains on the steel.
- Every 10 minutes you need to take out the steel product and wipe it with a paper or cloth napkin. During the wiping process, black deposits are removed from the surface, so no need to worry if the fabric or napkin has a different shade.
- Depending on the desired effect and the size of the product itself, the bluing process takes 30-60 minutes.
- If the desired result has been achieved, then it is necessary to remove the steel product from the solution, wipe it with a napkin and machine or sunflower oil. This action stops the reaction and also helps preserve the color of the coating and makes it stronger.
It is worth considering that if the water cools too much, the bluing process may be interrupted, so if it is noticeable that the solution has cooled down, then it is worth warming it up slightly in the microwave or on the stove. The working temperature of the solution is 80 degrees, so the container can additionally be wrapped in a towel to retain heat.
There are many examples of bluing with various materials on the Internet, but citric acid is the most affordable solution. Even if small stains appear after bluing, they will disappear after several cleanings of the item. If you plan to sharpen the steel product in the future, you must do this extremely carefully to prevent abrasions from appearing on the blade itself. If you plan to blue the knife, then it is better to sharpen it in advance before the weeding procedure.
conclusions
- Burnishing occurs quite quickly and can be done at home.
- It is important to follow the technology, as the quality of the metal weed depends on it.
- You should not increase the amount of citric acid in the solution, as this may lead to a deterioration in the bluing result.
- Burnishing with citric acid is optimal for items that have a decorative function and are not used daily for various tasks.
Source: https://leydi-prelest.ru/semya/voronenie-metalla.html
Artistic metal etching at home - Metalist's Handbook
Etching is carried out using special solutions of sulfur or hydrochloric acid. To conduct chemical experiments, you will need a metal container, a protective suit consisting of rubber gloves, goggles and sleeves, tongs and dry wipes. At home, experiments are best carried out outdoors or in rooms with good ventilation.
Etching with blackening on copper sheet
With the right approach to etching, you will achieve a characteristic shine and surface uniformity from copper for a long period of time. Be careful not to get the chemical solution on your hands or eyes. You can neutralize the effect of acids with water - the affected area is washed generously.
If the product gets into your eyes, you should immediately contact your local doctor and undergo a vision test.
Ferric chloride etching
This process is probably known to every teenager who has repeatedly experimented with a found copper twig in the yard.
Ferric chloride solution before and after etching
Advantages:
- Relatively stable speed of chemical processes;
- To carry out the experiment, one element is needed - ferric chloride;
- Proportions are done by eye. That is, the reaction rate does not depend on the amount of ferric chloride;
- Ambient temperature may not be taken into account.
Flaws:
- The rate of interaction between metals gradually decreases and etching turns into flour;
- Not everyone can get the key element. Ferric chloride is often very expensive on the black market;
- The key element stains everything it touches. This way you can irreversibly damage your clothes and interior items.
Copper sulfate and salt
Advantages:
Copper sulfate: preparation of solution, “before” and “after” view
- It is not difficult to obtain copper sulfate, since it is actively used in agriculture to control plant pests;
- Bluish stains can be easily removed from clothing and home furnishings with vinegar.
Flaws:
- Copper sulfate can change not only the properties of copper, but also harm human health;
- The cost of a key element is rapidly rising for inexplicable reasons. In just a few years, its value has literally tripled;
- The reaction rate is highly dependent on the temperature of the liquid. It is worth noting that copper sulfate is very sensitive to minor temperature fluctuations and even heating by 3-5 degrees can increase the etching rate several times.
Persulfate etching
Advantages:
Ammonium persulfate
- To maintain a full chemical reaction, one key element is enough - persulfate;
- The element is absolutely harmless to clothing and interior items, does not leave marks or stains;
- High rate of chemical reaction.
Flaws:
- If it comes into contact with clothing in large quantities, it can burn through the fabric and make holes in it;
- To maintain the process, the key element must be constantly added and heated;
- After weed, a lot of ballast remains - sulfate.
Hydrogen peroxide and hydrochloric acid
Advantages:
Copper beads in a solution of hydrogen peroxide and hydrochloric acid
- It is distinguished by the highest speed of the chemical process of all those discussed above;
- Upon contact with skin or fabric, it does not leave noticeable marks;
- Does not require heating and can be performed at room temperature;
- Availability: Hydrogen peroxide is freely available in pharmacies, and battery electrolyte is suitable instead of hydrochloric acid.
Flaws:
- A strong concentration of hydrochloric acid in a solution can harm not only things, but also human health. Etching copper in this way requires great care and additional protective equipment - gloves, goggles and sleeves. Experiments at home are best carried out in old clothes;
Hydrogen peroxide and citric acid
Advantages:
Etching kit with hydrogen peroxide and citric acid
- Sufficiently high speed of chemical processes;
- When it comes into contact with interior items and fabrics, it does not leave stains on their surface;
- Does not require additional heating, flows easily at room temperature;
- Availability of materials: hydrogen peroxide can be bought at any pharmacy, and citric acid can be obtained at every supermarket or local store;
- The etching solution is completely safe for humans and their clothing. It is worth noting that in case of contact, it is advisable to rinse the eyes and skin with plenty of water;
- Low price of key elements. Conducting a chemical experiment requires at most 15-30 rubles.
Flaws:
- If the concentration of citric acid in the container is exceeded, precipitation may form - etching and copper residues. The resulting precipitates impede the reaction and can leave dark spots on the metal.
Preparation of solutions
Etching copper at home for jewelry purposes
Ammonium persulfate solution before and after copper etching
After carefully weighing all the pros and cons of each method, you can choose the optimal one for conducting experiments at home.
So, etching copper with ferric chloride requires an empty container into which the key ingredient is placed in an even layer. The entire process is done with gloves. Copper is carefully placed on the iron. The container is closed with a plastic bag or lid and left anywhere, preferably away from the table or food.
Scrap metal category how to determine
When etching copper parts using vitriol and salt, you will need: salt, copper sulfate, any container and water. Salt and vitriol are mixed in a 1:1 consistency and dissolved in a cup of water. Copper is placed in an open vessel, since air also takes part in the chemical reaction.
Etching metal at home with persulfate is quite simple.
Kit for preparing a solution of hydrogen peroxide with hydrochloric acid
Take a shallow vessel, pour the powder into it and fill it with a small amount of water. Wait for it to completely dissolve and place the copper product, covering it with a lid.
To clean the surface of a copper product at home using hydrogen peroxide and hydrochloric acid, you will need a small vessel. 100 g is poured into it. peroxide and add 2 tablets of acid. After the acid has completely dissolved, copper is added to the container.
Hydrogen peroxide + citric acid is the easiest way to clean metal and give its surface a smooth shape. To carry out the experiments, you will need a small vessel in the form of a metal saucepan or tray. 200 ml of hydrogen peroxide is poured into the container and 5 g of citric acid is poured. The contents of the tray are stirred using a metal object or a wooden stick, after which the copper product is added.
The chemical reaction in such a solution proceeds very quickly, so do not move away from the tray and get ready to remove the copper immediately after it begins to brighten.
Decorative copper etching
To achieve our goals, we will need: a copper blank, a drawing printed on a laser printer, ferric chloride (you can get this ingredient at any amateur radio store), plastic containers, nail polish remover, an iron, protective equipment and a hammer with nails.
Source: https://ssk2121.com/hudozhestvennoe-travlenie-metalla-v-domashnih-usloviyah/
Deep etching of metal at home
Agree, metal products (knives, blades, amulets) look much more beautiful if they are decorated with patterns and ornaments. But how to apply a pattern to a metal surface? Engraving? This method is also possible, but there are several more.
One of them is called artistic electrochemical etching of metal .
In this article you will learn how to decorate a knife blade.
Below is the entire process from drawing a sketch to the process of etching metal at home.
Development and drawing
Sketch
A subject drawing, a floral ornament, a logo or just a phrase - this is just a small list of design ideas that will be beautifully imprinted on the blade. Choose what pattern you want to see on the blade and start creating a sketch. You can draw it yourself or ask a professional.
Then you need to transfer the design to the blade. To do this, we place the blade in the scanner, transfer the image to the CorelDraw program, where we outline the contours of the blade. Next, apply a suitable ornament. The result should be duplicated in a mirror image and sent for printing.
Blade varnishing and pattern transfer
The blade must be varnished in advance. You can use matte varnish for plastic replica models. The varnish needs to be diluted with a nitro thinner to dry faster, and applied with an airbrush (you can also use a brush). The varnish is used because it retains its plasticity throughout the day and does not crumble under the scrubber.
We cut out the sketch to make it easier to fit to the blade, “black out” the reverse side with a pencil, and attach it to the blade with masking tape. Afterwards we draw the ornament with a thin pen. The result is a drawing on the varnish.
Scratching a drawing
We scratch the pattern on the surface of the varnish using scrubbers with different sharpenings. It is important that the metal of the scrubber is not harder than the metal of the blade, otherwise there will be scratches.
Features of the drawing
In our example, a “field” is etched (this is the most difficult option, since it is more difficult to scratch the design), although a more accessible option is also possible, when only the contours of the design are etched.
Metal etching
You can use a variable transformer, for example, from a toy railroad.
It will be an adapter for a mini-drill, which is indispensable for delicate work. The maximum voltage is 12V, which is more than enough. Heat shrink casing serves as insulation. Flannel: Copper/brass plate – approximately 100\7 mm.
We begin electrochemical etching of metal by placing the fabric on a plate and soaking it all in a saline solution (do not skimp on salt). Then we start etching - with quick touches, you shouldn’t hold it for long, because... the varnish may overheat.
Result
The described method of etching metal at home is good because it is easier to control the process, unlike etching in a “entire” vessel.
You just need to go over the drawing several times (we recommend that you practice on rough blanks first so as not to spoil the blade). When the drawing is finished, turn off the unit and wipe the blade with solvent.
Actually, this is the method of artistic metal etching.
: namuradan-k.se-ua.net
Source: https://steelfactoryrus.com/glubokoe-travlenie-metalla-v-domashnih-usloviyah/
How to etch metal at home
Etching is a method of reproducing designs, ornaments, inscriptions, etc. using chemical means. on the surface of metal objects.
Etching is done in two ways : you can cover all the lines and surfaces of the drawing with a substance that is affected by the mordant.
Or, on the contrary, you can protect all spaces from the action of acids, leaving the lines and surfaces of the drawing free.
If you then cover the entire surface with acid, then in the first case the pattern will turn out to be slightly embossed, in the second case the pattern will appear in-depth.
No matter how simple the etching operation may seem at first glance, beginners often fail, especially when etching thin and complex designs.
Surface cleaning
Before applying the protective coating, the surface to be treated should be thoroughly cleaned of any thin deposits of rust, grease and other dirt. Fat adhering to the surface can be removed by washing in alcohol or gasoline, calcining or, finally, boiling in a solution of soda or sodium hydroxide.
The object, cleaned of dirt and grease, is immersed in a 10% solution of sulfuric acid and left in it until the dark coating of rust disappears.
After this, the surface to be treated can be polished if the shape of the object allows and its purpose does not contradict this operation. But such pre-polishing is not necessary.
The cleaned surface should not be touched with bare fingers, as there is always a greater or lesser amount of fatty substance on them, and the mordant has no effect on fat.
When the surface to be etched has been cleaned enough to have a fresh metallic sheen, begin applying the protective coating.
Protective covering
A good coating can be prepared as follows: melt 1 part asphalt and 2 parts mastic, mix the mixture and add 2 parts white wax to it.
Once cooled, this composition is formed into balls and cones, which are first wrapped in a cloth made of thin dense linen, and on top in dry taffeta.
The composition is applied to the surface as follows: the object to be treated is heated and, gently pressing on the surface, the mass wrapped in taffeta is passed over it evenly; in this case, the composition melts and seeps through the rag, covering the rubbed surface with a thin layer.
When this coating has hardened, it is covered with a thin layer of white lead, finely ground and dissolved in a solution of gum arabic.
Transferring a drawing
Then, using blue paper, the required design or inscription is transferred to a white surface. All places that need to be etched are scraped to the surface of the metal. With a thin and sharp engraving needle you can reproduce even the finest shading of a design.
If you want to etch a simple figure or inscription, then the protective coating can be diluted with some liquid, for example turpentine, to the consistency of thick oil paint. Using this coating, you can reproduce the desired design by hand with a needle or even a steel pen.
When applying a protective coating, you must ensure that the metal surface is completely dry, otherwise the coating will not adhere well in some places, and the acid can then penetrate the metal and etch areas that should remain untouched.
Mordant recipe
as a mordant for copper, brass, bronze and silver items : 3 parts of a saturated aqueous solution of copper nitrate and 1 part of a saturated vinegar solution of ammonia.
For iron and steel, the following mixture is recommended: 400 parts of water, 2-3 drops of nitric acid, 15 parts of calome (mercury dichloride) and 1 part of tartaric acid.
Etching
The object to be etched is lowered into a glazed clay cuvette (bath), into which the appropriate solvent is poured.
If the surface to be treated is flat, then you can set it in a horizontal position, sculpt a finger-thick rim of wax around the edges, and pour the appropriate acid into the resulting flat cuvette.
When the etching is considered complete, the object is rinsed in clean water, and the protective coating is removed by heating or washed off with turpentine.
If a certain amount of etching remains in the recesses, then over time it will corrode the metal surface in places deeper than required. To avoid this, place the washed item in lime water for a few minutes, which neutralizes the remaining acid.
One of the methods of producing a convex or depressed pattern on metal products, which appeared relatively recently, is called etching. The operating principle of this method is based on the use of electrochemical processes in a liquid electrolyte. If you have artistic abilities, even at home you can get a high-quality pattern with a minimum of required materials and equipment.
When doing etching yourself at home, you will need the following consumables and equipment:
- a product intended for decoration - various cutlery, hunting or camping knives, or simple soap dishes on which simple patterns can be made;
- a container of sufficient volume and convenient shape made of non-metallic materials, suitable for placing the entire product being processed or its part to be decorated. It is most convenient to use glass containers for this purpose, which allow visual control of the processing process.
- a sufficient amount of ordinary table salt;
- nail polish of any color;
- nail polish remover intended for cleaning the treated product;
- source of direct electric current of low voltage. In this capacity, a charger can be used to charge car or telephone batteries.
Source: https://MyTooling.ru/instrumenty/kak-travit-metall-v-domashnih-uslovijah
Translation of flat steel heald from Russian into French
Russian-French dictionary of normative and technical terminology > galvanization
24 hot-formed seamless steel pipe
Russian-French dictionary of normative and technical terminology > hot-deformed seamless steel pipe
25 hot-formed straight-seam electric welded steel pipe
Russian-French dictionary of normative and technical terminology > hot-deformed straight-seam electric-welded steel pipe
26 hot rolled seamless steel pipe
Russian-French dictionary of normative and technical terminology > hot-rolled seamless steel pipe
27 hot forged seamless steel pipe
Russian-French dictionary of normative and technical terminology > hot-forged seamless steel pipe
28 hot pressed seamless steel pipe
Russian-French dictionary of normative and technical terminology > hot-pressed seamless steel pipe
29 freight car
Russian-French dictionary of normative and technical terminology > truck
30 heddle carrier holder
Russian-French dictionary of normative and technical terminology > heddle carrier holder
31 flat drainage
Russian-French dictionary of normative and technical terminology > flat drainage
32 electric arc furnace
electric arc furnace An electric furnace in which metal is melted due to the heat from an electric arc burning between the electrodes and the metal or between the electrodes.
[GOST 18111-93]
electric arc furnace (electrothermal device)
An electric furnace (electrothermal device), in which the electrothermal process is carried out by arc heating
[GOST 16382-87]
arc furnace
An electric furnace in which heat is generated by an electric arc of direct or alternating current. Arc furnaces are used for smelting steel (DS type), cast iron (DC type), non-ferrous metals (DM type), ferroalloys (ferroalloy furnaces) and other materials. An arc steel furnace has a number of advantages compared to an open-hearth furnace. In an arc furnace it is possible to obtain a higher temperature than in open hearths, which is what is required to produce alloy steels. This makes it possible to obtain refractory alloys. There is no oxidizing flame in an arc furnace, which makes it possible to create a reducing atmosphere in the furnaces (gas environment of the furnace), and also provides less waste of alloying elements compared to an open-hearth furnace. In electric arc furnaces it is possible to smelt steel with a varied carbon content and any number of alloying elements, and also to obtain metal with a very low sulfur content from an ordinary charge. In this regard, arc furnaces were ideally suited to the production of high-quality and alloy steels. The first laboratory arc furnaces were built in the second half of the 19th century. (French physicist Depres, chemist Pichon, German engineer V. Siemens, Russian engineer N. G. Slavyanov, etc.). The first industrial arc furnaces were built in 1898. Eng. E. Stassano for smelting cast iron with a capacity of 800 kg and in 1899 fr. Eng. P. Eru for melting steel with a capacity of up to 3000 kg and a power of up to 450 kW. Arc furnaces are heat exchanger furnaces with a radiation mode of thermal operation. Depending on the burning conditions of the electric arc, the following are distinguished: - direct-action arc furnace, in which the electric arc burns between a vertical electrode and the metal (with a dependent arc). Such furnaces are used in ferrous metallurgy; - an indirect arc furnace, in which an electric arc burns between two horizontal electrodes above the metal (with an independent arc). Such furnaces are sometimes used in non-ferrous metallurgy; - an arc furnace with a closed (immersed) arc, in which electric arcs burn under a layer of solid charge or liquid slag, into which vertical electrodes are immersed. Such furnaces are used for the production of metals and alloys from ores (ore-thermal furnaces). Arc furnaces operate at atm. pressure (0.1 MPa), in rarefied vapors of melted metals with a pressure of up to 1 Pa (vacuum arc furnaces) or in plasma-forming gases (plasma furnaces). Depending on the type of electric current, an arc furnace can be of direct or alternating current, either single-phase or three-phase (with three or six vertical electrodes).
[http://www.manual-steel.ru/eng-a.html]
Topics
- metallurgy in general
- casting equipment
- electrothermal equipment
General terms
- equipment for melting and pouring metal
FR
Russian-French dictionary of normative and technical terminology > electric arc furnace
33 European Communities
Russian-French dictionary of normative and technical terminology > European Communities
34 jacquard face
Russian-French dictionary of normative and technical terminology > jacquard face
35 Heavy Duty Rigid Steel Tube
- conduit rigide en acier à haute resistance
Heavy Duty Rigid Steel Tube —
[IEV number 442-02-15]
EN
extra-heavy duty rigid steel conduit
EHDRS (abbreviation) a part of a closed wiring system of circular cross-section made of steel of welded construction capable of providing extra-heavy mechanical protection to conductors or cables in electrical installations and allowing them to be drawn in and/or replaced
NOTE – Extra-heavy mechanical protection is provided by using steel of the grade and thickness specified in the appropriate standard.
[IEV number 442-02-15]
FR
conduit rigide en acier à haute resistance
Source: https://translate.academic.ru/flat%20steel%20heald/ru/fr/2/
How to make steel blueing at home. In saltpeter, oil, “Clover” agent
Burnishing or oxidation is a method of surface coating (finishing) of metal products in blue, black, blue-black or tarnished colors by exposing them to chemical and thermal methods.
It is used for the purpose of corrosion protection of metal products, and also gives the surface an attractive tint. There are many ways to surface tint metals. The main one is the creation of an oxide film.
The most common are chemical (alkaline and acidic) and thermal effects on the surface. As a result of this treatment, the chemical composition and structure of the surface layer changes. Externally, this is manifested by the formation of a film in the form of metal oxide.
You can carry out the coating yourself using simpler technologies.
Methods for bluing metals at home and requirements for their implementation
Common home methods for protecting and decorating metal surfaces include:
- boiling parts in special chemical compositions that you can prepare yourself;
- oil coating followed by heat treatment;
- applying the finished product to the surface using a brush.
Carrying out work during chemical bluing involves chemical etching and cleaning operations, as well as mechanical grinding and wiping of the surface.
In order to use bluing at home using chemical reagents, you need to create certain conditions:
- provide the work area with ventilation or exhaust;
- prepare a container from a neutral material that is not destroyed by chemicals. A vessel made of heat-resistant glass, earthenware or porcelain is best suited. If long-term boiling of the solution is required, you can use a stainless steel container;
- the container must have sufficient volume so that the part is completely covered with the composition;
- stock up on protective equipment: gloves, protective mask or goggles, aprons.
Features of chemical bluing and recipes for some compositions
Before performing work, the surface of the metal product is subjected to treatment: removing the old oxide layer by sanding and degreasing with a solvent.
The durable blued finish is primarily produced by boiling solution throughout the entire paint cycle. To obtain a durable film, the process should last from 30 minutes to an hour and a half, so the boiling solution is periodically topped up to ensure complete coverage of the part.
After the process is completed, the part is thoroughly washed using detergents and then lubricated with oil.
For household work, the alkaline oxidation method is mainly used. Let's consider some options for the chemical oxidation of metals in an alkaline environment.
Method number 1:
- Water is poured into a container (porcelain) of the appropriate size and sodium nitrate (sodium nitrate) and caustic soda (sodium hydroxide) are dissolved in it in the ratio: per 100 ml 30 g of sodium and 100 g of soda.
- The mixture is heated to 140 - 160 ° C, and the workpiece is placed in it, which remains there for at least 30 minutes.
If the process is carried out correctly, the result will be a deep black coating, sometimes with a bluish tint.
Method number 2:
A bluish tint to the film can be obtained using a boiling saturated alkaline solution in which potassium or sodium hydroxide is dissolved in high concentration. At least 700 grams of a chemical substance dissolves in 1 liter of water.
These recipes are provided as an example. There are many other chemical formulations using nitrites and nitrates.
Oxidation in an acidic environment is carried out at lower temperatures. For example, when using an acid solution consisting of:
- calcium nitrate – 30 hours,
- orthophosphoric acid – 1 hour,
- manganese dioxide – 1 tsp.
Oxidation is carried out by keeping the workpiece in the solution for at least 30-45 minutes at 100°C.
Means for bluing metals
Simple coating methods that can be used at home include technologies for surface application of oil, saltpeter and ready-made Clover.
These bluing products are easy to use and allow you to carry out work at home without special preparation.
Let's look at ways to create film using each of them.
Oil coating
The technology of creating a protective film using oil is the most common for home use.
It is done like this:
- the sanded and degreased product is coated with machine or sunflower oil;
- then it is placed in the oven and heated to 350 - 400 ° C;
- after cooling, the surface of the part becomes brown or black;
- Remaining oil from the part must be removed with a rag;
- To obtain a more saturated color, the process should be repeated several times.
You can use different oils, for example, gun, linseed or olive. It can be applied with a brush or by dipping the part into an oil composition.
If you need to blacken any part of the part, then it is better to use a blowtorch to do this. During this firing process, the color change in the surface of the workpiece is clearly visible. When a rich brown-black color is achieved, the heat treatment can be stopped.
Use of saltpeter
A good result of chemical bluing is obtained by a classic solution using saltpeter in addition to those given earlier. As a result of boiling the part in a solution of sodium nitrate at a temperature of 130 - 150 ° C, a durable oxide coating of a shiny black-blue hue is obtained.
Recipe for composition with saltpeter:
- Distilled water – 1 liter;
- Sodium nitrate (NaNO3) – 500 g;
- Caustic soda (NaOH) – 500 g.
Ready-made kits with saltpeter for oxidation are available for sale.
You can watch the process of bluing in saltpeter in the video:
The surface with this treatment looks smooth and does not require additional polishing.
Surface treatment with Clover
You can treat metal surfaces with the ready-made “Clover” product. It has a gel-like consistency and is sold in small 50 ml containers.
It is used for minor corrosion damage to metal. To obtain maximum coloring of the product, you need to treat it with Clover two to three times. Before applying it, the part must be sanded and degreased.
Apply the product with a brush and leave for 2 minutes. If a whitish-yellow coating appears, it should be washed off with warm water and the surface wiped dry with a cloth.
The advantage of this product is its ease of use, which is why it is often used to coat weapons. It has no effect on steel containing more than 3% Cr.
Cold bluing at home
The use of the “Clover” product does not require additional heating of the workpiece, therefore this method of processing is classified as cold. In addition to this, other means are used for cold bluing at home, which are also applied to the treated surface with a brush.
For example, they use the domestic drug “Voron-3M”.
When applied to a metal surface, a dense black film is formed. Therefore, this coating is called metal blackening.
The imported product “Paris oxide”, which contains selenium, is also popular.
The drug includes three bottles. One composition is intended for pre-treatment of the surface, the second is the active composition, and the third provides protection for the formed coating.
The solution is also applied to the product using a brush; after obtaining the color, the residue is washed off the surface with warm water.
Cold processing is used for small parts. This method is especially good for bluing a gun, since the method of hot boiling in chemical solutions cannot be used on it.
Burnishing steel at home
The question of how to blue steel at home interests many.
Most of the parts that are blued are steel products. Therefore, the methods described above for treating the metal surface by oxidation and coating with an oil film are mainly used for steel alloys.
Many brands of steel are susceptible to rust. The coating for steel products primarily serves as protection against corrosion and at the same time gives them an attractive appearance. The degree of protection and color of the oxide film depends on the thickness of the layer and the reagents used. The thickness can vary from 1 to 10 microns.
When bluing steel products using a chemical method, the choice of solution components when using heating to high temperatures should be approached with caution. For example, there is a ban on such processing of hardened parts, as well as steels that cannot be heated to high temperatures. This can lead to a deterioration in their technological properties.
It is for this reason that when high heat treatment is necessary, it is recommended to use alkaline solutions. They are more gentle.
Oxidation in acidic compounds is carried out at lower temperatures. For example, when using an acid composition consisting of:
- calcium nitrate – 30 hours,
- orthophosphoric acid – 1 hour,
- manganese dioxide – 1 hour,
- oxidation is carried out at a temperature of 100°C, keeping the part in the solution for at least 30-45 minutes.
Metal blackening
When heating steel blanks in an acidic or alkaline environment, a film of different shades may form on the surface. Bluing includes all colors inherent in tarnish. They change as the film thickness increases from yellow, brown, violet, then to gray, blue and black.
Therefore, bluing is not the same as blackening. You can obtain the desired surface shade by using different heat treatment modes for steel blanks and using different chemical components of the solution.
For example, you can achieve the desired shade by using copper nitrate, which is a salt, in an amount of 70 g and 30 g of alcoholic denatured alcohol. The salt is heated until melted and denatured alcohol is added. The mixture is applied to the steel part and heated with a burner. Stop the heating process after reaching the desired shade.
Blackening of steel blanks can be done using oil. It is enough to coat the product with oil, wax or animal fat and heat it thoroughly over the fire. As a result, a permanent black coating will appear on the surface.
Source: https://plavitmetall.ru/obrabotka/voronenie-v-domashnix-usloviyax.html
Etching - Chemistry
A series of technologies for controlling the removal of the surface layer of a metal part using specially selected chemical reagents is called metal etching. It allows you to remove scale, rust and oxides from products under the influence of acids, salts and alkalis in solutions.
In this way, additional preparation of metal products is carried out for joining or coating, which improves the adhesion of the parts or the applied layer to the base.
The most commonly used method is chemical etching of metal, carried out by immersing the workpiece in a bath of dissolved chemical reagents.
Methods of chemical etching of metal
There are also types of it that provide for additional activation of toxic substances using physical factors.
This is metal etching electrochemical (or galvanic) under the influence of an electric field or ion-plasma through the ionization of reagent particles.
If the word “etching” is used without indicating its type, then we are talking about chemical etching in an aqueous electrolyte. It is also called “liquid”, in contrast to “dry” ion-plasma.
When etching metal with an acid, usually sulfuric or hydrochloric, the workpiece is immersed in its solution. In this case, both the oxides existing on the surface of the part and the base metal enter into an acid reaction. As the acid content increases, the dissolution operations are accelerated simultaneously for the oxides and the base metal.
In addition to the acid concentration, the speed of the metal etching process is also influenced by its temperature regime, as well as the chemical composition of the oxides. The most optimal combination of these factors allows etching to be carried out so that, with the fastest possible dissolution of the oxides, it affects the base metal as little as possible.
In addition, in artistic etching, when it is necessary to keep part of the surface of the product intact, it is covered with a special protective layer.
To clean iron from surface oxides, the optimal solution is 10% hydrochloric acid at a temperature of 40 °C (for using sulfuric acid - 60 °C). As this temperature increases, the speed of the process also increases. The salts obtained during metal etching can also affect the speed of the process. Some of them, for example FeCl2, increase it, while others, such as FeSO4, decrease it.
The etching of metal with ferric chloride is complicated by the production of hydrogen during reactions of iron and acids.
It interacts with the top layer of metal, forming “etching bubbles” in it and making the product more fragile.
In order to prevent this effect, special additives are added to the bath with the etching solution to slow down the reactions. By creating a special shell, they protect the metal from the negative effects of hydrogen.
Tanks made of concrete or wood, coated inside with acid-resistant materials, serve as the main equipment for pickling metal. For the convenience of immersing small workpieces in baths with etching solution, special trays with baskets are used.
When it is necessary to clean not the entire surface, but only part of it, for example, a soldered seam, then a brush is used to apply etching solutions to its surface. The part is then carefully washed with water. Etching pastes are necessary for cleaning rusty metal parts.
The area affected by rust is covered in two stages with different layers of pastes, followed by rinsing.
To treat the surface of a part made of copper or its alloy, metal etching with nitric, hydrochloric or sulfuric acids is used. Aluminum parts should be etched with alkaline solutions. Nickel and alloys must be cleaned with sulfuric acid solutions with the addition of chromic anhydride. Cupronickel parts are also cleaned with a solution of sulfuric acid, adding chromium to it.
In this case, they need to be washed after the etching procedure with warm water, dissolving a little cream of tartar in it. In the form of etching of iron or steel products, ammonia solutions or iron sulfate are used; bronze and brass parts require etching of the metal with copper sulfate, and zinc products - with zinc sulfate, as well as a solution of zinc chloride oxide.
Features of the electrolytic etching process
Electrolytic or galvanic etching of metal is used to speed up the cleaning of parts by immersion in a bath of solution, which usually takes a lot of time. This process is much faster if metal parts are placed in an electrolytic bath in the form of cathodes or anodes. Hence the division of electrolytic etching into cathodic and anodic.
For the anodic method of metal etching, alkaline solutions of metal salts and acids are used as an electrolyte. The cathode is usually lead or, less commonly, iron as materials that do not dissolve in the electrolyte.
Given the speed of the process of metal etching by electrolysis, when cleaning products using this method, it is necessary to strictly follow a certain regime so as not to expose the metal to the risk of excessive electrolytic dissolution.
The characteristics of the anode current are selected based on the state of the surface layer of the product, as well as the required speed of the process. Etching is carried out at room temperature. The duration of the operation is determined empirically.
The cathodic method of metal etching involves the use of lead or its alloy with antimony as an anode. When mixed with acid solutions, alkali metal salts act as an electrolyte. This technology is based on the action of hydrogen produced at the cathode.
It promotes the reduction of metals from oxides located on the part, and hydrogen in the form of gas separates them from the surface of the metal. This etching option is not suitable for workpieces made of hardened steel due to the possible hydrogenation of the surface layer of the metal part.
It can be reduced when using this metal etching technology by introducing tin and lead salts into the electrolyte bath.
Galvanic etching is more economical than chemical etching. This applies not only to the time spent, but also to the amount of chemicals used. In addition, the chemical composition of the poisons for such etching does not include caustic acids, so during it no gases are released that have a negative effect on health.
Upon completion of etching, possible residues of solutions after cleaning on the products are neutralized. If this is not done, particles of salts or acids can contribute to the onset of metal corrosion.
In order to remove these residues, the products are briefly placed in a solution with soda ash. After this, the parts are washed with cold and then hot water and dried.
Storing products treated in this way does not cause corrosion, but in order to avoid possible oxidation, it is better to immediately solder them.
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Metal etching at home - stages of metal engraving
Pickling is a metal processing process in which a layer of a certain thickness is removed from the surface under the influence of active chemicals (acids or salts with an acidic reaction), as well as direct current in an electrolyte bath.
Metal etching can serve various purposes and be used in industry and at home.
The surface of an item subjected to etching receives a number of technological and decorative properties and allows one to examine its microstructure in a metallographic microscope, remove scale and other non-metallic inclusions from the surface, obtain the necessary jewelry ornament or prepare it for soldering.
Etching, also called electrochemical engraving, is most often used at home or in the garage to obtain relief images on various objects with decorative functions.
Most often, it is used on steels with high hardness, the processing of which with conventional engraving tools requires great effort.
This process is not very difficult even in the absence of artistic skills, if you follow its technology.
Metal surface preparation
In order for the etching process to proceed at a high speed and the thickness of the removed layer to be the same, all dirt and traces of oils should be removed from the surface of the product.
For this purpose, ordinary detergents and cleaning products used for washing dishes and warm water are suitable.
After washing and drying, the surface should be wiped with fiber soaked in a solvent, which, in addition to degreasing, helps remove residual moisture.
Separately, it is worth mentioning the quality of surface treatment. Mirror polishing is subsequently guaranteed to give a good contrasting pattern even with a small etching depth. But if its implementation is impossible for some reason, the surface can be treated with sandpaper so that the risks from it go in one direction. This will also give a good optical effect.
Drawing
To apply a design to metal, you can use a lot of different methods that work according to the same mechanism: areas that are not subject to etching are protected from exposure to an aggressive environment or electrolyte.
Method No. 1
The most affordable way is to apply regular nail polish to the protected areas. However, it has a number of significant disadvantages:
- The viscosity of the varnish does not allow the lines to be thin enough to obtain highly complex patterns;
- Good ability in visual arts required;
- Correcting inaccurate lines is difficult.
Method No. 2
First you need to apply a protective layer to the entire surface of the product. To do this, you can use primers GF-021, XV-062 or bitumen varnish, available in auto parts and household goods stores. After the coating has completely dried, you can use a gel pen or a thin marker to draw the contours of the future image. An experienced artist can be hired for this task.
Next, from a copper (or brass) wire or rod, the diameter of which is selected based on the ease of holding in the hand, you need to make a needle with a pointed end and scratch the primer along the image lines to the metal. Harder needle material may damage the polish on the surface of the product.
Already at this stage you can evaluate the relief of the future ornament. To obtain areas with different depths of metal etching, for example, contours and penumbra, this process can be carried out in two or more cycles.
Important! The primer should not chip off during the process. Before applying the design, you should experiment and make sure that it is suitable for the job.
Method No. 3
Source: https://himya.ru/travlenie.html
Surface etching. Part 1
During manufacturing and storage, metal products are exposed to the environment, as a result their surface becomes covered with corrosion products or thermal scale . This layer not only worsens the appearance of the products, but also complicates subsequent technological operations.
Before deposition of galvanic coatings on products, their surface must be cleaned of all contaminants and oxides. Contaminants are removed during the degreasing process (see “Degreasing the surface.”). The surface is cleared of oxides and thermal scale during the etching process .
Etching can be carried out in solutions chemically or electrochemically
Electroplating line for surface etching
Chemical etching is carried out by immersing products in an etching solution without exposure to electric current.
The largest percentage of parts coated in the galvanic shop are made of low-carbon steel, which have an oxide layer on the surface that is uneven in thickness. The scale layer is porous, therefore, when etching in acid solutions, partial dissolution of the metal occurs along with oxides.
For etching ferrous oxide, solutions of sulfuric and hydrochloric acids are mainly used. It is necessary to carry out the etching process in such a way that etching in the base metal solution is minimal. This depends on the composition of the solution, the concentration of acids and temperature.
In a solution of hydrochloric acid, unlike sulfuric acid, etching of scale occurs due to its chemical dissolution. In practice, 10–20% solutions of hydrochloric acid are used at room temperature. When etching in a sulfuric acid solution, the optimal concentration is 20 - 25%, temperature 50 - 600C. Considering the different nature of the effect of acids on iron and its oxides, mixtures of solutions are used for etching: sulfuric acid - 5%, hydrochloric acid - 15% or sulfuric acid 10%, hydrochloric acid - 10%.
The etching process , in addition to removing scale, is accompanied by the release of hydrogen, and hydrogenation of the surface , leading to embrittlement. To prevent the sorption of hydrogen by the metal, inhibitors are introduced into the etching solutions: catapine K-I-1, syntanol, urotropine, etc. in an amount of 3 - 5 g/l.
When etching alloy steels in solutions , due to the presence of thermal scale, the use of more active solutions is required. It is advisable to carry out etching in solutions in two stages: loosen the main layer of scale in a solution of 20% hydrochloric or sulfuric acid, and finish the etching in a solution of 20–40% nitric acid.
To speed up the surface cleaning process, an electrochemical etching method is used, which can be carried out both on the anode and on the cathode
In anodic etching, the oxide film is first etched in a solution, and then a passive film is formed. The etching process is intense, so it is important not to overetch the surface of the part, which is the anode. Anodic etching is used for simple-shaped parts made of carbon and alloy steel.
Compositions of electrolyte solutions for anodic etching of carbon steels, g/l:
Solution 1:
Sulfuric acid 200 – 250 Iron sulfate 7-aqueous 1 – 2 Sodium chloride 20 – 25
Solution temperature 40 – 500C, DA= 5 – 10 A/dm2, time 10 – 20 minutes
Solution 2:
Hydrochloric acid 8 – 10 Sodium chloride 40 – 50 Iron chloride 6-aqueous 140 – 150
Solution temperature 18 – 350C, DA= 5 – 10 A/dm2, time 5 – 10 minutes
The anodic current density is selected depending on the state of the surface during etching in an electrolyte solution and the required speed of the process.
Compositions of electrolyte solutions for cathodic etching of carbon steels, g/l:
Solution 1:
Sulfuric acid 100 – 150
Solution temperature 40 – 500C, DC = 3 – 10 A/dm2, time 10 – 15 minutes.
Solution 2:
Sulfuric acid 50 – 60 Hydrochloric acid 25 – 30 Sodium chloride 15 – 20
Solution temperature 60 – 700C, DA= 10 – 15 A/dm2, time 10 – 15 minutes
Cathodic etching in an electrolyte solution is used primarily to remove oxides from the surface of parts subjected to heat treatment and oil quenching. Lead is used as an anode.
If you have difficulty cleaning the surface, contact us for services.
Attention! Electroplating training course! Find out more
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Source: http://blog.tep-nn.ru/?p=1644
Etching metal at home using electricity and salt
Before you begin metalworking, you should remove any dirt, defects, or traces of rust from the surface. In this article we will talk about electrochemical etching of metal at home using electricity and ferric chloride.
What is the procedure for and where is it used?
The processing method is used both in industry and for private purposes. The main task is to increase the adhesion of the material, that is, adhesion to another substance. Often used before painting surfaces, for example in the automotive industry.
At home, you can use the method for household purposes. In this way, for example, you can actually make a new one out of an old steel bucket. But? Before we understand the technology, we will highlight what types of methods there are and where they are used.
Metal etching: what is it?
This is a method for removing part of the surface layer (to microns) of a metal product using a controlled chemical reaction, often under the influence of a current. Substances of different acidity and salts react with the workpiece. The most common option for metalworking at home is to immerse the sample in a pre-prepared container with reagents.
Industrial Applications
- Cleaning from oxide film.
- Before painting or treating with special protective compounds.
- Before the galvanizing operation.
- To detect corrosion in stainless steel.
- Applying a pattern to small parts of microcircuits that facilitates the conduction of electrical charge.
This is an incomplete list of tasks that the procedure allows you to solve.
Types of etching
Let's present common methods. Most of them can be implemented at home. But you must adhere to safety rules - you will need to deal with chemicals.
Electrolytic
The second name is galvanic processing. The easiest way to use this technology is on small parts when it is necessary to urgently clean the surface. The essence of the procedure is as follows: a saline or acid electrolytic solution is introduced, and the workpiece is placed in it. Then a shock is given. Depending on how it is charged, etching is distinguished:
- Cathode. In an environment with the addition of chemical elements, hydrogen is formed at the cathode in the form of a gas; a reaction occurs with its release. It saturates the liquid and reacts with the alloys, removing scale. It should be taken into account that the strength of the surface suffers and it becomes more fragile, so it is better not to treat thin steel sheets this way. Suitable materials are high carbon steel, heat treated samples.
- Anode. Used more often. At the anode, the oxide film comes off with the release of oxygen. All “extra” particles melt in the solution. The top layer becomes slightly rough. There is a possibility of losing an excessively large amount of metal; it is important not to overexpose the product in a container under voltage.
Chemical
If the previous option was great for steel, especially carbon steel, then this procedure has the same goals, but a completely different audience. You can start processing if you have in your hands:
Suitable: H2SO4, HCl, HNO3. The duration of immersion in the bath depends on the concentration of the composition and the degree of contamination of the workpiece. The interval is quite large - cosmetic cleaning of a thin-walled product may take only 1 minute, and for a thick cast-iron part - up to 2 hours.
The technology is simple. There is metal. An oxide film has formed on it, which needs to be removed. Acids penetrate through the pores under oxidation and interact with the steel surface. During a chemical reaction with iron, hydrogen is released. It repels pollution. But the metal surface can also be damaged. This can be avoided if you pre-treat the part with special rust inhibitors.
Plasma
The procedure also takes place in a chemical environment. But the chemical reaction is excited by a plasma flow generated on the basis of inert gases (containing fluorine). When they interact with corrosion (or silicon), they do not affect the iron itself. This is a very accurate method, but it requires special equipment. The degree of accuracy is up to 10 nanomicrons.
Let's watch a video on this topic:
Galvanic
This is a very fast method, which is why it has gained popularity, especially among those who do it at home. Speed isn't the only advantage. Other advantages:
- fairly clear boundaries and contours;
- no acids are required, so it is a more environmentally friendly method for humans.
First, let's determine the composition of the liquid for immersion; it depends on the material of the workpiece:
A mixture of ammonia and iron sulfate
Copper, bronze, brass
Copper sulfate solution
The immersion bath must be made of dielectric. For example, a glass jar for small parts.
Place the element in a container and pour in a product with good conductive properties. We attach the anode to the product. You will definitely need a source of energy. The procedure takes no more than 2 minutes, then rinse the sample under water.
Artistic
The procedure is suitable for etching a knife at home. The process is very common among restorers and weapon connoisseurs. It can be used to engrave, write the owner’s initials, or add picturesque patterns.
The operation is very simple. You can use any of the above methods, but the fastest and safest is galvanic. A stencil of tape should be left on the surface of the metal. It's easy to do with a good inkjet printer. When the necessary areas are protected (make sure that there are no traces of air under the tape), classic etching can be carried out.
Let's look at the photo:
Surface preparation
In order for the operation to proceed at a fast pace and the surface layer to be removed evenly, it is necessary to make sure in advance that the product has gone through the preparatory stage.
- Using fine sandpaper, polish all defects and remove imperfections.
- Apply soapy water. Dishwashing detergent diluted in water until foamy is suitable.
- Carefully remove all dirt using a brush.
- Let it dry completely, you can use a hair dryer.
- Soak a rag in degreaser and wipe the surface thoroughly.
Source: https://crast.ru/instrumenty/travlenie-metalla-v-domashnih-uslovijah
Electrochemical etching of metal at home - Machine tools, welding, metalworking
Pickling is a metal processing process in which a layer of a certain thickness is removed from the surface under the influence of active chemicals (acids or salts with an acidic reaction), as well as direct current in an electrolyte bath.
Metal etching can serve various purposes and be used in industry and at home. The surface of an item subjected to etching receives a number of technological and decorative properties and allows one to examine its microstructure in a metallographic microscope, remove scale and other non-metallic inclusions from the surface, obtain the necessary jewelry ornament or prepare it for soldering.
Etching, also called electrochemical engraving, is most often used at home or in the garage to obtain relief images on various objects with decorative functions.
Most often, it is used on steels with high hardness, the processing of which with conventional engraving tools requires great effort.
This process is not very difficult even in the absence of artistic skills, if you follow its technology.
: Copper etching
Source: http://ooo-asteko.ru/kak-travit-metall-v-domashnih-usloviyah/
