Types and properties of powder prepared by vacuum atomization

Thermal spray alloy powder

Thermal spraying is a surface strengthening technology. It uses a heat source in the form of electric arc, plasma arc, gas-oxygen, etc. to heat metal or non-metallic materials to a molten or semi-melted state, and atomize them into fine droplets or high-temperature particles under the action of high-speed airflow. The high-flying speed is sprayed onto the surface of the processed workpiece to form a firm covering layer, so that the surface of the workpiece can obtain various special physical and chemical properties such as different hardness, wear resistance, corrosion resistance, heat insulation, and insulation. Thermal spray alloy powders include nickel-based, iron-based, copper-based and diamond-based alloy powders, which are used for the repair and protection of mechanical parts according to different coating hardness.

Thermal spray powders are mostly alloy powders, which are generally produced by the atomization method. Ordinary intermediate frequency smelting is easy to cause the oxidation and burning of alloy elements. With the burning of alloy elements, its chemical composition will also change. As a result, the metal powder produced has a color difference, the total oxygen content increases, and sometimes the composition will deviate. Therefore, in order to reduce the oxidation and burning loss of alloy elements, vacuum smelting and inert gas atomization are generally used to make powder. The coating formed after spraying with this powder has good resistance to high temperature oxidation and thermal corrosion, which can meet the requirements of modern aeroengines with high thrust ratio.

High temperature alloy powder

As one of the key components of high-performance engines, turbine disk materials and their manufacturing technology have always received special attention from the aerospace engineering community. As the degree of alloying increases, the macrostructure segregation of the alloy becomes more serious and the process performance deteriorates. The application of high-temperature alloys manufactured by traditional processes in high thrust ratio engines is restricted. Compared with traditional cast and forged superalloys, powdered superalloys have the advantages of uniform structure, no macrosegregation, fine grains, high yield strength, and good fatigue performance. The use of them to manufacture turbine disks and other key components can meet the requirements of advanced high thrust ratio engines. The requirements have been widely used.

Electrical contact material

Alumina dispersion-strengthened copper alloy (alumina copper or dispersed copper) is a new type of structural functional material developed in recent years. It has high strength and good resistance to high temperature softening, as well as excellent electrical and thermal conductivity. The copper and aluminum are vacuum smelted according to the appropriate ratio, and the powder is made by high-pressure gas atomization. The powder is quantitatively aerated in an oxygen distribution furnace at low temperature, and the powder after the oxygen distribution is put into a rubber sleeve for cold isostatic pressing, Preparation of powder ingots. The ingot is internally oxidized to oxidize all the aluminum in the alloy to alumina, and then reduced by hydrogen to remove excess oxygen. The ingot is prepared into a dispersed copper material of appropriate specifications through subsequent thermal processing. Dispersed copper has been applied in some industrial sectors.

For example, it is used as an electrode for resistance welding in the automobile industry; it is used as a lead wire in the electronic and electrical industry instead of expensive key wires for commutators, relay copper sheets and contact supports.

Stainless steel powder, aluminum alloy powder, etc.

Almost all stainless-steel powders are produced by the atomization method. The stainless-steel powder atomized with nitrogen or hydrogen has a spherical shape, high loose packing density, good fluidity, and low oxygen content. Adopt special consolidation methods, such as hot isostatic pressing or hot injection extrusion process to obtain fully dense products. It is also used in injection molding and thermal spraying processes.

Because metal aluminum is extremely easy to oxidize, ordinary gas atomized powder spraying can easily cause the impurity content in the aluminum alloy powder to exceed the standard. Moreover, the aluminum powder has high activity and is very easy to ignite or explode. Therefore, vacuum smelting is generally used, and inert gas is used to protect powder.

Solder

Brazing is a method of joining metals. Brazing technology is widely used in machinery manufacturing, electronics industry, instrument manufacturing, national defense and cutting-edge technology. In the brazing and soldering industries, metal powder is widely used as filler metal, that is, solder. The solder includes tin-lead alloy, lead-based alloy, tin-based alloy, zinc-based alloy, etc. Brazing materials include copper alloys, silver alloys, nickel-based alloys, etc. Most of the brazing materials are prepared by atomization with high-pressure nitrogen or hydrogen.