Manufacturing of copper products to order. Copper-based sintered material for electrical contacts and method for its manufacture

Copper is one of the first metals mastered by mankind.

Thanks to its low and high plasticity, it has not lost its popularity for the fifth millennium. Red metal is widely used both in industry and at home to make jewelry, crafts and parts by casting copper.

In industrial settings, technologies such as

Casting copper into molds
Powder metallurgy
Electroplating
Hot and cold rolled
Sheet stamping
Wire drawing
Mechanical restoration

They require complex and expensive professional equipment, highly qualified personnel and are accompanied by high energy costs.

At home, in a small workshop, simple technologies are used, largely repeating the work techniques of the Copper Age masters. This includes copper casting and wire drawing, as well as forging and embossing. Despite the simplicity and antiquity of technological techniques, home craftsmen achieve high quality products. Sufficient casting accuracy is ensured by careful production of the mold.

Characteristics of copper

Copper is a metal with a relatively low melting point (1083C), a density of 8 g/cm3 and high ductility. It occurs in nature in the form of nuggets. Thanks to these qualities, it became the first metal mastered by mankind. Archaeologists have found tools and weapons in burials dating back to the 3rd millennium BC. Most likely, humanity mastered copper casting even earlier, at the end of the Stone Age.

The Latin name of the metal, Cuprum, is associated with the name of the island of Cyprus, a famous ancient center for the production of bronze products. Copper-based alloys - bronze and brass - have high strength and are less susceptible to oxidation. Bronze was widely used as the main metal of mankind until the development of mass steel production technologies.

Copper has excellent electrical and thermal conductivity. This leads to its widespread use in electrical and thermal engineering.

In addition, copper has pronounced bactericidal properties.

Copper smelting and casting equipment

Casting copper at home does not require particularly complex or expensive equipment. Buying it or making it yourself is quite within the capabilities of a home craftsman.

Required

Crucibles are cylindrical open vessels.

Steel tongs for removing and placing the crucible in the furnace.
Muffle furnace or gas burner.
Steel hook for removing oxide crust from the surface of the melt.
Casting mold.

First of all, you need to melt the copper. The better the feedstock is crushed, the faster the melting will occur. Melting will occur in a crucible made of ceramic or refractory clay. The muffle furnace must be equipped with a thermometer and a glass window for visual inspection. Electronic temperature control and maintenance system will make copper casting easier and provide better casting quality.

Molds for copper casting are made based on the model. Depending on the chosen technology, the molds can be disposable (from a mixture specially molded in the formwork) or reusable - steel molds. Recently, molds made from high-temperature silicone have become widespread.

At home, disposable forms are more often used. The model is made from wax or special types of plasticine. The model completely repeats the spatial configuration of the future product. When a hot melt is poured into a mold, the wax melts and is replaced by metal, which takes its place and repeats all the details of the mold's relief. This form is called lost wax.

There are also burnt forms. They use a model made of flammable material, such as papier-mâché. In this case, the model burns when a high-temperature melt is poured, the combustion products in the form of gases exit through the filling hole.

Application of copper casting

Copper casting is used to manufacture a wide range of products. In jewelry, the legendary metal is often used as part of alloys. It is added in small quantities to gold items to increase their strength and abrasion resistance. Bronze, which is an alloy of copper and tin, is used to create designer pendants, chains, rings and earrings.

Copper casting is also used to make fishing lures of unique shapes. Another area of application is the creation of original scale models of equipment - ships, cars, tanks, airplanes, etc. Here, in addition to bronze, brass is used - an alloy with zinc.

Brass and bronze are also used for casting decorative elements of rooms, linings and designer door handles. Here, in addition to the structural advantages - strength, durability and appearance, the bactericidal properties of copper and its alloys are also used.

The process of melting copper at home

The process of casting copper at home is not difficult, but requires careful preparation, planning and strict adherence to time and temperature parameters.

It begins with grinding wire or scrap and placing it in a crucible. At the same time, turn on the muffle furnace to warm up. The better the metal is crushed, the faster and more efficiently both the melt and the casting will proceed. It is important to monitor the melt temperature. When the temperature is exceeded, the melt begins to actively absorb oxygen from the air and oxidize, which leads to a decrease in the quality of the castings. To reduce the influence of atmospheric oxygen, the surface of the melt is sprinkled with crushed activated carbon.

If a muffle furnace is not available, the crucible can be placed on a welded tripod and heated with a gas burner with the nozzle turned upward.

Important! The burner must be securely fastened

You can also make a stove out of fireclay bricks and a steel grate on which coal will be scattered. Such a stove must be blown with a powerful fan or vacuum cleaner.

After the metal has melted, you need to securely grab the crucible with tongs and remove it from the furnace, placing it on a refractory base.

Using a steel hook, you need to move the film of oxides formed on the surface of the melt towards the wall, and, without allowing it to cool, pour it in a thin stream into the hole of the mold. If a lost wax mold is used, ensure that the stream of metal being poured allows the model material to escape.

Be sure to allow the casting to cool completely before disassembling the mold, cleaning and finishing the product.

Important! The use of safety glasses and gloves with gaiter is mandatory. Do not forget to check the availability and functionality of a fire extinguisher suitable for extinguishing live electrical installations.

Let your casting be successful, and the copper casting made at home will delight you and your customers!

The invention relates to the field of powder metallurgy. The purpose of the invention is to improve the technological properties of the charge, as well as to increase the commutation wear resistance of the sintered material made from it. This goal is achieved by the fact that the copper-based sintered material contains at least one component selected from the group: cadmium, nickel, tin, zinc, graphite, and additionally contains vanadium in the following component ratio (wt.%): (5.0- 15.0) vanadium, (0.3-3.0) at least one component selected from the group: cadmium, nickel, tin, zinc or graphite, copper - the rest. The proposed material has commutation wear (9.4-19.7)10 -6 g/cycle. This goal is also achieved by the fact that when producing a sintered material based on copper containing nickel, anhydrous nickel acetate is used as a binder, and the charge is moistened before granulation. In this case, the charge has a fluidity of 5.0-6.8 g/s. 2 sp. files, 1 table.

The invention relates to the field of powder metallurgy, in particular to copper-based sintered materials for electrical contacts used in low-voltage switching devices, for example, in contactors, circuit breakers, etc. Copper-based sintered material for electrical contacts is known, containing (wt.) : (14.9-19.4) Ni, (20.2-29.4) Zn, (0.5-10) Nb and/or Ba, Cu rest. The disadvantage of this material is that it does not have high enough commutation wear resistance. The closest to the claimed technical solution is a copper-based sintered material containing 1 to 30 wt. graphite, up to 20 wt. at least one metal selected from the group nickel, tin, zinc or cadmium, copper and the rest. This material has a low and stable contact resistance. Its disadvantage is that it has low switching wear resistance. There is a known method for producing a mixture for sintered contacts, according to which a solution of polyvinyl alcohol is introduced into the mixture of powders as a binder, and then the mixture is granulated by rubbing through a sieve and the resulting granules are calcined in air. The disadvantage of this method is that polyvinyl alcohol can be used to granulate only such mixtures, the components of which allow them to be heat treated in air, for example, silver and cadmium oxide. When the charge is heat treated in a protective atmosphere, thermal decomposition of polyvinyl alcohol occurs with the release of finely dispersed carbon on the surface of the particles of the charge components, which prevents them from sintering, the formation of dense products and introduces an additional impurity (carbon) into the finished product. The purpose of the invention is to improve the technological properties of the charge, as well as to increase the switching wear resistance of the sintered material for electrical contacts. This goal is achieved by introducing nickel acetate into the charge as a binder, moistening the charge, granulating by rubbing through a sieve, heat treating the granules, pressing them and sintering them in a protective atmosphere. A technical solution according to which a binder, for example polyvinyl alcohol, is introduced into the powder mixture is known. However, when sintering compacts from such a charge in a protective atmosphere, an additional impurity (carbon) is introduced into the finished product. This drawback is eliminated in the claimed technical solution through the use of nickel acetate. When compacts are sintered in a protective atmosphere, nickel acetate decomposes to release the only non-volatile product, nickel powder. Since nickel is part of the sintered material, no additional impurities are introduced into it in this case. In addition, the use of nickel acetate as a binder, as a private solution, given the known use of various binders to increase the fluidity of the charge, leads to an additional effect, namely: an increase in the density of the material during sintering of compacts and, as a consequence, an increase in its wear resistance. The possibility of achieving this effect does not follow from the disclosure of the content of the general solution, which allows us to conclude that the claimed solution meets the “inventive step” criterion. This goal is also achieved by the fact that the copper-based sintered material containing at least one component selected from the group: cadmium, nickel, tin, zinc, graphite additionally contains vanadium in the following component ratio (wt.): (5.0- 15.0) vanadium, (0.3-3.0) at least one component selected from the group: cadmium, nickel, tin, zinc or graphite, copper the rest. Vanadium forms a heterogeneous structure of the composition, increases its hardness and electrical erosion resistance. Cadmium and zinc evaporate under the influence of an electric arc and provide an ablative effect that reduces overheating of the contact surface and their erosive wear. Tin reduces contact resistance. Nickel and graphite accelerate the movement of the arc reference spot along the surface of the contacts, accelerate the jump of the spot over inclusion particles and reduce overheating of the contacts. In addition, graphite particles, when exposed to high temperatures, form carbon monoxide (CO), which, having reducing abilities, protects the contact surface from oxidation and stabilizes the contact resistance. A comparative analysis of the proposed solution with the prototype allows us to conclude that the claimed composition of the copper-based sintered material for electrical contacts differs from the known one in that it contains a new component vanadium and a different ratio of known components (cadmium, nickel, tin, zinc and graphite). The claimed solution thus meets the “novelty” criterion. Analysis of the compositions of copper-based materials for electrical contacts has shown that copper-based alloys containing zinc and nickel are known. The use of previously unused vanadium in the claimed technical solution together with at least one of the known components of copper-based alloys (nickel or zinc) leads to an increase in the switching wear resistance of the contacts. Such a behavior of the sintered material in an electric arc could not be predicted on the basis of known concepts. Thus, the claimed composition imparts new properties to the material for electrical contacts that are not clearly derived from the prior art, which allows us to conclude that the claimed solution meets the “inventive step” criterion. Example 1. Mix 88.00 g of PMS-1 grade copper powder; 10.50 g of vanadium powder with a particle size of 56 microns, 0.57 g of cadmium oxide (qualification "4", GOST 11120-75, 0.5 g of cadmium by weight), 3.01 g of nickel (II) acetate (qualification "4" , TU 6-09-3848-87; 1.00 g of nickel by weight), previously dehydrated at a temperature of 150-200 o C, moistened with a water-alcohol mixture (1:1 by volume) at the rate of 11.5 ml per 100 g of charge, granulated by rubbing through a sieve No. 063, dried in a drying oven, contacts are pressed from the resulting mixture, sintered in a hydrogen atmosphere and calibrated. The manufactured contacts have a diameter of 8.0 mm, a height of 2.0 mm and comply with GOST 3884-77 (standard size PP0820 and SP 0820). Electroerosive wear is determined at the U-1 stand, on which the contacts switch an alternating current circuit with the parameters: 380 V, 32 A, 50 Hz, co=0.8. The contacts are separated by an electromagnet at a distance of 7.0 mm with an average speed of 0.3 m/s, and brought together by a spring, which provides a contact pressure of 5 N. The duration of testing for each contact pair of the same composition is 10 thousand on/off cycles. Electrical erosion wear (switching wear resistance) is determined by the decrease in the total mass of a pair of contacts during testing and is measured in g/cycle. The results of determining commutation wear are given in the table. Examples 2-5. In a similar way (example 1), contacts containing 4.0 are made and tested; 5.0; 15.0 and 16.0 wt. vanadium Example 6. Mix 89.2 g of copper powder, 10.5 g of vanadium powder and 0.90 g of anhydrous nickel acetate (0.3 g of nickel), moisten the mixture with a water-alcohol mixture, granulate by rubbing through a sieve, dry, press from contacts of the resulting charge are sintered in a hydrogen atmosphere, calibrated and tested at the U-1 stand. The test results are shown in the table. Examples 7, 8. In a similar way (example 6), contacts containing 10.5 wt. vanadium and 1.5 or 3.0 wt. nickel Example 9. 89.2 g of copper powder, 10.5 g of vanadium powder and 0.34 g of cadmium oxide powder (0.3 g of cadmium) are mixed, contacts are pressed from the resulting charge, they are sintered in a hydrogen atmosphere, calibrated and tested on a bench U-1. The test results are shown in the table. Examples 10-20. Contacts are manufactured and tested in a similar way (example 9), the compositions and test results of which are given in the table. The fluidity of the mixture prepared in accordance with examples 1-20 is determined by a method based on recording the time of expiration of a sample of powder from a conical glass funnel with an angle of 60 o and an outlet diameter of 5.0 mm. The tail of the funnel is cut at a distance of 3 mm from the top of its conical part. The results of determining the fluidity of the charge are given in the table. As follows from the table, the contact materials of the proposed composition (examples 1, 3, 4, 6-20) have increased switching wear resistance (reduced switching wear). When the vanadium content is beyond the declared lower (clause 2) and upper (clause 5) limits, switching wear increases to the level of wear of the prototype material (clauses 21-24). Thus, materials containing 5.0 to 15.0 wt. have low commutation wear (high commutation wear resistance). vanadium and 0.3 - 3.0 wt. at least one component selected from the group: cadmium, nickel, tin, zinc or graphite, copper the rest. As follows from the data given in the table, the charge prepared in accordance with the claimed method (items 1-8) has high fluidity, which increases its technological properties. Thus, the use of the proposed technical solution makes it possible to improve the technological properties of the charge, in particular, to improve the filling of molds with a volumetric dosage of the charge, to automate the process of pressing contacts from it; increase the service life of the NVA by increasing the switching wear resistance of the contacts.

Claim

1. Copper-based sintered material for electrical contacts, containing at least one component selected from the group: cadmium, nickel, tin, zinc, graphite, characterized in that it additionally contains vanadium in the following component ratio, wt. Vanadium 5 15 At least one component selected from the group: cadmium, nickel, tin, zinc, graphite 0.3 3.0 Copper Rest 2. A method for producing copper-based sintered material for electrical contacts containing nickel, including introducing a binder into powder, granulation by rubbing through a sieve, heat treatment, pressing and sintering in a protective atmosphere, characterized in that before granulation the mixture is moistened, and anhydrous nickel (II) acetate is used as a binder in an amount of 0.3 to 3.0 wt. in terms of nickel.

In the Ancient East, copper products date back to the 4th millennium BC, in Europe - to the 3rd. 5000 years - this was the shelf life of copper water pipes in the Cheops pyramid. Many things that people need are made from a beautiful and durable honey and pinkish-red metal (Cuprum - Cu).

Copper is occasionally found in nature in the form of nuggets. That is why in ancient times man first came across this particular metal. He turned out to be amazing. It was easy to process, was not afraid of water and did not rust. When copper began to be extracted from copper ore in huge volumes and smelting workshops began operating, it turned out that the metal melts relatively easily at 1083 ° C and has high ductility. Copper can be rolled into the thinnest foil with a thickness of only 0.03 mm, and the wire can be pulled out much thinner than a human hair.

Current industrial copper has several grades. Each of them is used to produce different parts that require their own draw ratio, stamping force and rolling resistance. The metal has high electrical and thermal conductivity. If we take the thermal conductivity of granite as one, then for steel it will be 21 times higher, and for copper it will be 177 times higher. That is why pure copper is widely used in the manufacture of many parts in refrigerators and heating devices, in a variety of electronics, radio and electrical equipment, to microwave ovens.

Copper is easy to solder and is therefore indispensable in production. The metal is widely used in the manufacture of car radiators, heat exchangers, heating systems and solar panels. The unique ability of the metal to resist corrosion makes copper and its alloys indispensable in shipbuilding, in the production of pipelines and shut-off valves in water pressure systems. It is important that these parts are safe when transporting drinking water.

An amazing fact: bacteria do not grow on the surface of copper, and therefore it is purposefully used in the manufacture of equipment for hospitals. Copper also finds the most adequate place for its properties in the parts of air conditioners. Copper cookware is still in price all over the world. It attracts chefs with its high heat output and ability to heat evenly. Due to the fact that this beautiful and easy-to-work metal metal can be easily polished to a given texture and desired shine, it is used with pleasure by jewelers and interior designers.

Copper is a component of many alloys. Phosphorous copper is especially in demand, from which all kinds of springy electrical wires and contacts are made, which easily restore their shape with slight bends.

The familiar “copper” coins are minted from an alloy of copper and aluminum. Our “silver” wallet change also contains copper - as an additive to the base metal, nickel. The famous monument to Peter I in St. Petersburg, which is called “Copper,” is not made of copper, but of bronze. Bronzes are alloys of copper with tin, aluminum, manganese, cadmium, beryllium, lead and other metals. Any bronze must contain at least 50% copper. With other proportions, it will be a different alloy: babbitt, manganin, etc. Alloys of copper and nickel are used not only at the mint, but also in large-scale projects - in the design of aircraft and spacecraft.

Video on the topic

Sources:

Use of aluminum

Some adults remember the delicious aroma of boiling jam that grandmothers prepared in a copper basin on the stove in the summer. It is associated with childhood, hot summer days and sweet foam, furtively stolen from a bowl full of boiling berry jam. But why was it always cooked in copper basins and continues to be cooked today?

Benefits of Copper

Copper basins have always been widely used in the industry, since copper has very good thermal conductivity. Jam prepared in a copper basin does not burn during the cooking process and is evenly heated throughout the entire volume of the container. Such thermal conductivity is observed only in silver utensils, but a copper basin is a cheaper analogue that is well suited for certain purposes.

Pots or basins made of aluminum, brass or stainless steel are also equally suitable for making jam.

However, a copper basin has one unpleasant feature - when cooking jam in them, oxide deposits can form on the surface of the container, so you need to take care of copper utensils. Before and after cooking, the copper basin must be thoroughly washed and rinsed with hot water, and then dried until moisture is completely removed. If oxide appears on its walls or bottom, it should be wiped well with sand, washed with hot soapy water, rinsed, dried and only then used for making jam.

And besides, finding and buying this type of kitchen utensils made of copper or copper-plated is currently not so easy.

Rules for cooking jam in a copper basin

Fruits or berries for jam are placed in a copper basin, poured with boiling sugar syrup and left to infuse for 3-4 hours, during which the fruits are soaked in the sweet mass and saturated with sugar. As a result, the berries will not shrink when cooked and will retain their original shape.

During the process of cooking jam, the fruit foam that forms on its surface must be removed.

To get high-quality jam, you need to be able to correctly determine the end of its cooking. To do this, there are certain signs that the delicacy is ready - for example, at the end of cooking, the foam does not spread around the edges, but collects in the center of the basin. Berries and fruits stop floating and are evenly distributed throughout the entire volume of jam. When you try the syrup, its consistency is thick and viscous, and when cooled it does not spread across the saucer. Well-made jam is distinguished by berries that are translucent and completely soaked in syrup - but it should not be overcooked or caramelized.

To prevent jam from sour berries and fruits, you can add citric acid to it and not sterilize it, but immediately seal it in jars, turn them over and cool them upside down. Also, high-quality jam does not require additional pasteurization or hermetically sealed packaging.

Copper cookware has been valued by chefs and lovers of tasty and healthy food for many centuries. Why exactly did copper dishes deserve such high praise?

Copper cookware has a whole range of useful properties:

High thermal conductivity. This property allows copper cookware to heat evenly, avoiding food burning. At the same time, cooking time is reduced by approximately 30%, and this in turn allows you to retain more vitamins and nutrients in the finished dish.
High antibacterial properties. Copper is able to enter into an oxidation reaction with oxygen molecules, having a detrimental effect on E. coli, salmonella and Staphylococcus aureus, even without the use of high temperatures. Thus, if you use a board to cut vegetables, copper will exhibit its disinfecting properties. This quality was noticed by people many years ago and was especially valued in hot countries - food left in copper dishes could remain at room temperature all day and not spoil. Therefore, using copper cookware can reduce the risk of intestinal infections.
Copper does not emit harmful substances, does not corrode, is durable with proper care and can be inherited. When using copper cookware, remember that some types of vegetables oxidize when cooked; for these, choose copper cookware with a tin or stainless steel interior. They are safe for health and do not react with products. Uncoated copper is indispensable for preparing cold dishes and boiling water.
Copper dishes are very beautiful and will become a worthy interior decoration.

How to care for copper cookware?

In order for copper cookware to last a long time and retain its unique properties, you need to remember some rules:

Do not heat the dishes in a dry state; before heating, first fill the container with water, vegetables or oil;

Do not pour boiling water into an empty container;

Add salt at the end of cooking;

When cooking, use low heat and avoid overheating;

Use only wooden or silicone spatulas and spoons, not metal ones, so as not to scratch the surface, copper is a very soft material;

For washing, use a mixture of salt and flour or special products without abrasives and chlorine;

To prevent stains from appearing on the dishes after washing, wipe them with a towel;

Do not wash copper cookware in the dishwasher.