Simple Analysis of Technical Status for Metal Powder Metallurgy

Powder injection molding is still one of the hot spots of current research. Powder injection molding material have been developed from such early systems as the iron based alloy, hard alloy and ceramics which are insensitive to impurities and have low requirements to performance to the nickel based high temperature alloy, titanium alloy and niobium material. Material application area is also developing from the structural material to the functional material such as heat sink material, magnetic material and shape memory alloy. Material structure is also developing from the single homogeneous structure to the composite structure. Forming different composition of powder at the same time can be realized by metal powder injection molding technology, so it will be able to get a sandwich — like composite structure. For example, continuous adjustment of mechanical properties can be achieved by composition of 316L stainless steel and 17-4 PH alloy. One of the important development directions of powder injection molding is closely related to the micro system technology. In the field that is closely related to the micro system technology such as electronic information, micro chemical, medical equipment, etc., device is becoming more miniaturized while the function is becoming more compound. The powder injection molding technology has provided the possibility of implementation.

Micro injection molding technology is the improvement to the traditional injection molding technology. Directed at the small component sized up to 1 um, it is a forming technology with the basic process of which consistent with the traditional injection molding while the particle size of the raw material powder is smaller. With the micro injection molding technology, it has developed a micro fluidic device with the surface microstructure precision of 10 um and stainless steel parts with the size of 350 um to 900 um to realize the common sintering or connection of different material components and composite structure, and get the magnetic or non-magnetic, conductive or non-conductive micro composite parts.

Powder atomization has been always the preparation technology of high-performance powder. Thermal spray technology can extend the period of metal droplets in the liquid state so that the powder can be secondary crushed (atomized), thus the efficiency of atomization is greatly improved and the resulting powder particles are smaller. Research shows that if the gas temperature is increased to 330 °C and the needed gas consumption of powder for the preparation of the same particle size is reduced by 30%, the economic analysis and engineering studies of them show that the technology is completely feasible. Powder atomization technology has been greatly improved. For example, using a new free naked type gas atomization can get finer tool steel power, carbide distribution of which is more uniform and less defective. American, who put the advanced steelmaking technology into use of powder production, combined with electric arc furnace smelting technology, the argon oxygen decarburization technology, high-performance atomizing technology, and hydrogen annealing technology, have greatly improved the quality, compact density and strength of the power.

In terms of reactive powder atomization, in order to reduce reaction of the melt and the crucible during smelting process, Germany developed electrode inductive aerosol melting technology which can prepare high active titanium powder, zirconium and TiAl intermetallic compound powder. Mechanical alloying is still a hot research, but most of them are the lab work. Remarkably in Germany with his development of high-energy ball mill grinding device for the slag grinding of electric arc furnace and recovery metal by hydrometallurgy, this technology not only improved the environment, but also opened up a huge market.

As a new rapid sintering technology, microwave sintering is fully applicable to metal powder materials, such as powder steel, hard alloy, non-ferrous metal, etc. Industrialization of microwave sintering maybe is just around the corner, for no matter the maturity of equipment and technology or the mass production ability is not a big problem. The major obstacle is the degree of acceptance and risk for the producer.