How to make 100 ppm copper solutions

Copulation at home

Copper is one of the ancient metals: people started it in the 4th millennium BC. To be used to create tools of labor. Such a broad copper distribution can be explained by the fact that the substance is found in nature in a metallic native state. And today copper is used everywhere - in metallurgy, the automotive industry, electrical engineering and construction.

Content:

  1. Composition of copper
  2. Physical properties of copper
  3. Process of copper plating
  4. Use of copper
  5. Types of copper
    • With immersion in electrolyte
    • Without immersion in electrolyte
  6. Copper baths

Contents

Composition of copper

Metallic copper is a heavy metal pink-red color, malleable and soft, which melts at a temperature of more than 1080 degrees Celsius, is a very good conductor of heat and the electrical current: the electrical conductivity of copper is 1.7 times higher than Aluminum and more than 6 times higher than iron, and only slightly inferior to silver conductivity.

The specific properties of copper are determined by the content of specific impurities in the metal, the amount of which can vary about 10 to 50 times. The following classification of copper is accepted for oxygen content:

  • anoxic copper with an oxygen content of less than 0.001%;
  • Copper refined with an oxygen content of 0.001-0.01%, but with an increased presence of phosphorus;
  • High purity copper with an oxygen content of about 0.03-0.05%;
  • a general purpose metal with an oxygen content of 0.05-0.08%.

In copper, in addition to oxygen, hydrogen may be present, which enters the process of electrolysis in the metal or when annealing takes place in an atmosphere containing water vapor. At high temperatures, water vapor decomposes to form hydrogen, which easily diffuses into copper.

Hydrogen atoms in oxygen-free copper are located in the interstices of the crystal lattice and do not particularly affect the properties of the metal. In oxygen-containing copper, hydrogen can react with copper oxide at high temperatures, while water vapor is generated in the copper column, which is at high pressure, which leads to swelling, cracks and fractures. This phenomenon is called "hydrogen sickness".

Iron, bismuth, antimony and lead affect the plasticity of copper. Impurities that are easily soluble in copper (lead, oxygen, sulfur, bismuth) cause brittleness at high temperatures, which hinders the process of hot pressure treatment.

Physical properties of copper

The main property of copper, its intended use, is high electrical conductivity or low electrical resistance. Impurities such as iron, phosphorus, arsenic, tin and antimony significantly impair electrical conductivity. The electrical conductivity is strongly influenced by the mechanical condition of copper.

The second important property of copper is its significant thermal conductivity. Alloy additives and properties reduce the thermal conductivity of copper, so that copper-based copper alloys are clearly inferior in this indicator.

Copper at normal temperatures is korrozitsionno stable in environments such as fresh water, dry air, sea water with a low rate of water movement, non-oxidizing acid and salt solutions in the absence of oxygen, dry halogen gas, alkaline solutions with the exception of ammonia and ammonium salts, organic acid phenolic resins and alcohols.

Copper is not stable in ammonia, ammonium chloride, oxidative mineral acids and solutions of acid salts. Its caustic properties are also significantly worse in some environments with levels of contaminants increasing. Copper is allowed to contact with its alloys, tin, lead, in a humid atmosphere, sea and fresh water. At the same time, copper contact with zinc and aluminum is not allowed due to their rapid destruction.

Copper, its alloys and compounds have found wide use in various industries. Copper in electrical engineering is used in its pure form in the tires of contact and bare wires, cable products, power generators, telephones and radios. Vacuum devices, heat exchangers and pipes are made of copper.

Copper alloys with various metals are used in the automotive industry and in the manufacture of chemical devices. Red copper wire that makes all kinds of cords and bends the most complex elements. The high properties of copper make it indispensable for the production of filigree parts.

Process of copper plating

Copper plating is the method of electroplating copper whose thickness is 1 to 300 µm or more. Copper Plating Steel is one of the most important plating operations, applied as a pre-process in the manufacture of metal surfaces for coating other metals - with chrome plating, nickel plating and silver plating, as well as a completely independent process.

The use of copper plating as a preliminary manipulation is due to the fact that this metal is able to hold steel very firmly in order to smooth out the surface defects. Other materials will precipitate well on copper, but on pure steel - not very much.

Copper coatings are characterized by high adhesion to various metals, high electrical conductivity and ductility. They are usually placed on steel, zinc and aluminum parts.

The newly applied copper coating has a bright pink, matt or glossy color, depending on the application technology. Copper coatings in atmospheric conditions can easily be oxidized and coated with a coating of oxides, giving stains of various shades and iridescent spots.

Use of copper

Galvanic copper plating is mostly used in such cases:

  1. For decorative purposes. Vintage copper products are very popular now. Copper plating allows copper layers to be applied to the metal which, after a special treatment, "get old", so to speak, and look as if they had long been manufactured.
  2. In the electrotype. Used electroplating for making metal copies of products of various shapes and sizes. A plastic or wax base is created, which is coated with an electrically conductive paint and a copper layer. Such a technology of copper plating is widely used in the manufacture of jewelry, souvenirs, bas-reliefs, matrices and waveguides.
  3. For technical purposes. Copper plating is of great importance in the electrical field. Because of the low cost of copper plating compared to gold or silver plating, copper plating has found application in the manufacture of electrotechnical tires, electrodes, contacts and other elements that operate under voltage. Copper is often used as a solder coating.

Copper plating is used in combination with other galvanic coatings:

  • When applying a multi-layer protective and decorative coating. Typically, copper is used in combination with chrome and nickel, (3-layer protective and decorative coating) and other metals as an intermediate layer, which increase the adhesion with the base metal and the durable and shiny coating.
  • To protect the spot during carburization. The copper coating can protect parts of steel products from carburization. Only cover the areas with copper that are to be machined. A hard carburized surface layer is not suitable for similar treatments, and copper can protect the coated areas from the process of carbon diffusion within them.
  • When restoring and repairing parts. Copper plating is an important process for restoration work and for the restoration of chrome-plated parts of theme and automotive equipment. A sizeable layer of copper is applied - about 100-250 μm or more, which covers the defects of metal and pores and serves as a new base for subsequent coatings.

Types of copper

The procedure of copper plating with your own hands is also available to beginners. To do this, you just need to know its basic intricacies. There are two methods of home copper plating: with immersion in the electrolyte and without immersion.

With immersion in electrolyte

The metal product is treated with a sandpaper to remove the oxide film, wiped with a brush, washed with water as follows, degreased in hot soda solution and washed again. After that, it is customary to drop two copper plates, which are anodes, into a jar or jar on copper wires.

A piece of wire is suspended between the plates. The wires coming from the copper plates are tied together and connected to the positive of the power source and the part with the negative. Then the rheostat for current control and the milliammeter are connected to the circuit. Requires a DC power source with a voltage not exceeding 6 V.

For home copper plating, you need to prepare the next electrolyte solution. Take 20 grams of copper sulfate and 2-3 milliliters of sulfuric acid per 100 milliliters of water and pour into the dishes. Make sure this solution completely covers the electrodes.

If you are using a rheostat, you will need to set a current between 10-15 mA for every inch of the square surface of the part. Somewhere in 20 minutes it is necessary to turn off the electricity and remove the product, it has already been covered with a thin layer of copper. The longer the process takes, the more copper becomes thicker.

Without immersion in electrolyte

This procedure is carried out for steel, aluminum and zinc. From one end of the insulation core wire is removed, and then thin copper wires must be rasterebit to make a copper brush. For convenience, you will need to tie it on a copper brush or a wooden stick and the other end of the cable will need to be connected to the positive power supply.

Next, you should prepare an electrolyte - a solution of copper sulfate, preferably slightly acidified, and pour it into a wide bottle, in which the brush will be conveniently immersed. Prepare a metal plate or other small object with a flat surface. It must be wiped with a fine emery cloth and degreased by boiling in a detergent solution.

Then it is necessary to put the plate in a cuvette or bath and connect it to the negative power source with a wire. After the circuit is assembled, you should only enter the electrolyte. Dip into the solution of copper sulfate "brush", which should be worn along the plate, do not touch the surface.

It is recommended to work in such a way that the electrolyte layer is always between the brush and the plate. All the operation of the wiring should be moistened with a solution. The plate on the eyes will be covered with a layer of red copper metal. It will take a few minutes to machine a small part.

When you have coated, you need to air dry the part and shine the matte layer of copper with a cloth or woolen cloth. The process of copper plating aluminum becomes when the product is not lowered into the electrolytic bath, but is processed in small areas from the outside, adding an electrolyte when the product is so large that it is impossible to find a suitable bath for it to choose.

Copper baths

Plants for copper plating from ordinary electroplating baths are no different. Electrolytes for copper plating are pretty easy to come by when you have the ingredients you need. There are two types of copper solutions: alkaline and acidic.

In acidic solutions, copper coatings with good adhesion cannot be obtained on zinc and steel products, since in this case zinc and iron dissolve with copper and the adhesion to the protective layer is impaired.

To eliminate this feature, it is recommended to make the first thin copper layer (2-3 µm) in an alkaline solution for copper plating and, in the future, to increase the coating to a certain thickness in the acidic electrolyte, which is more economical. Zinc products that are complex in shape are best plated in alkaline electrolytes.

The most common acidic electrolytes are boron fluoride and sulfuric acid. The greatest use has been found for sulfate electrolytes, which differ in the simplicity of the composition, the high current efficiency and the considerable stability.

Before copper-plating steel parts in acidic electrolytes, it is advisable to first suspend them in a cyanide electrolyte or to precipitate them with a thin layer of nickel. These electrolytes have several disadvantages.

One of these is the inability to directly cover zinc and steel parts due to the contact separation of copper, which has poor adhesion to the base metal. Compared to other electrolytes, electrolytes have a low stray capacitance and a coarser precipitate structure.

Among the alkaline electrolytes for copper plating, pyrophosphate and cyanide electrolytes are known.
Cyanide electrolytes made of copper are characterized by their high throwing power, the possibility of copper processing of carpentry products and a fine crystalline precipitate structure.

The disadvantages of alkaline electrolytes include low current density and instability of the solution due to carbonization from exposure to free carbon dioxide from carbon dioxide. In addition, cyanide electrolytes are characterized by a reduced current output of no more than 60-70%.

So copper is a metal that is used everywhere: in the automotive industry, in electrical engineering and in construction. And in electroplating, it is known that copper plating technology prepares a metal surface for coating with other metals or as an independent process.