3.2 Arc spraying materials
Arc spraying materials mainly include non-ferrous metal wires (metals such as aluminum, zinc, copper, nickel and their alloys) and black metal wires (carbon steel, stainless steel). At present, 2-3mm powder core wire is tried at home and abroad, and the required alloy powder is filled therein to obtain an alloy sprayed layer.
(1) Zinc and zinc alloys
Zinc is a silver-white metal with good corrosion resistance in the atmosphere or water, and also has an electrochemical protection effect on steel substrates. It is not resistant to corrosion in acids, alkalis and salts. When the water contains sulfur dioxide, its corrosion resistance is very poor. The addition of aluminum to zinc improves the corrosion resistance after spraying, so Zn-A1 alloy spray materials are currently used in large quantities. Zinc spray coatings have been widely used in outdoor open-air steel components such as water gates, bridges, towers and containers.
(2) Aluminum and aluminum alloy
When aluminum is used as an anti-corrosion coating, its effect is similar to that of zinc. Compared with zinc, it has a light specific gravity and a low price, and has a good corrosion resistance in an atmosphere containing sulfur dioxide. The addition of rare earth elements to aluminum and aluminum alloys not only improves the bonding strength of the coating but also reduces the porosity. Aluminum can also be used as a heat resistant spray coating. Under the action of high temperature, aluminum can diffuse on the iron matrix and react with iron to form Fe3A1 which is resistant to high temperature oxidation, thereby improving the heat resistance of the steel. Aluminum coatings have been widely used in water storage containers, steel components surrounded by sulfur gas, food storage, combustion chambers, hulls and gates.
(3) Copper and copper alloys
Pure copper is mainly used as a conductive spray coating for electrical switches and electronic components, and as a decorative spray coating for building surfaces such as portraits, crafts, and cement. The brass spray coating is widely used to repair worn and over-machined parts, to repair brass parts with cast blisters and air holes, and as a decorative spray coating. The aluminum bronze coating has high bonding strength, strong resistance to seawater corrosion, and good corrosion fatigue and wear resistance. Mainly used for spraying water pump blades, air lock valves, pistons, bearing surfaces.
(4) Nickel and nickel-chromium alloys
Nickel-chromium alloys are mainly used as coating materials in nickel alloys. These alloys have excellent high-temperature oxidation resistance and can be used at high temperatures of 800 ° C. They are widely used as heat-resistance materials. Nickel-chromium coatings are resistant to corrosion by water vapor, carbon dioxide, carbon monoxide, ammonia, acetic acid, and alkali. Therefore, nickel-chromium alloys are used in large quantities as corrosion-resistant and high-temperature spray coatings. For example, in the United States, 45CT (45% Cr, 4% Ti, and the balance of Ni) wire arc spraying boiler tubes have achieved good results.
(5) Carbon steel and low alloy steel
Carbon steel and low alloy steel are widely used arc spray materials. It has the characteristics of high strength, good wear resistance and low price. During the arc spraying process, carbon and alloy elements are easily burned, which tends to cause porous coating and oxide slag inclusion, which degrades the performance of the coating. Therefore, carbon steel with higher carbon content is used to compensate for the burning of carbon.
(6) Powder core wire
At home and abroad, powder core wire has been used as the arc spraying material. China has applied 3Crl3, 4Crl3, 7Crl3 and other wires as wear-resistant spraying materials, and has good high temperature stability.
Fourth, the application of arc spraying process in mold manufacturing
4.1 Metal spraying molding is a new technology for rapid mold manufacturing
The application of arc spraying in mold manufacturing is mainly reflected in the rapid manufacturing of molds and also in the repair of molds. In 2003, Xi'an Jiaotong University passed the appraisal of “metal spraying rapid mold manufacturing technology and equipmentâ€, and through technology research, formed a rapid manufacturing integrated system with rapid prototyping technology and metal arc spraying technology as the core, and successfully realized in the enterprise. The result is transformed. The result combines rapid prototyping, metal spraying and brush plating technologies to form a rapid mold manufacturing integration technology. The process includes: spray master preparation, substrate processing, metal arc spraying, filling backing materials, brush plating, etc. Link.
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