In recent years, the structure of copper base powder variety that produce by the main copper base metal powder companies in China is mainly as follows: electrolytic copper powder occupies 65 percent of the total output of copper base powder, atomized copper alloyed powder occupies 30 percent as well as the rest are redox copper powder, slight sintering copper alloy powder, chemical reduction copper powder and so on.
As iron base metal powder industrialized production technology has become mature in China, it has become the main task of expanding iron base metal powder variety and improving product quality. The traditional copper base metal powder production technology including electrolytic process and atomization method have gradually become mature in China, besides, redox technology, slight sintering technology and copper coated iron powder technology all have walked out pilot plant test and have been listed on the market.
The product structure of iron base metal powder is also being changed. Powder metallurgy products have developed towards high density, high strength and complex shape. Requirements on the performance of iron base powder have also become more and more strict, for example, it requires that iron powder should have high apparent density, good compactibility and high purity. The medium and high density powder metallurgy parts will generally be produced by using water atomized iron powder. However, as reduced iron powder has low apparent density and low compactibility, it will be used as medium and low density powder metallurgy parts and oil bearing. In North America, the proportion between water atomized iron powder output and reduced iron powder output will be 10:1. While in China, the proportion between water atomized iron powder output and reduced iron powder output is 1:3.5. With the development of powder metallurgy product in China, it has become one of the important tasks of promoting the application of water atomized iron powder in powder metallurgy industry.
There has been a beneficial change of reducing iron powder with iron scale and hyperpure iron concentrate powder. With the improvement of continuous casting and steel rolling technology, the quantity of iron scale that can be used in producing iron powder is on the decrease. As the roll steel product variety has increased and product batch has reduced, the chemical composition of iron scale has become impure as well as Si, Mn and other elements will increase, thus it will directly influence the quality of reduced iron powder. while the reduced iron powder that produced by using hyperpure iron concentrate powder as raw materials will have high purity as well as will have stable composition and performance in volume production. Reduced iron powder that produced by hypepure iron concentrate powder had reached 27,800 tons in 2005 in China. Besides, hyperpure iron concentrate powder that produced in Zuoquan County, Beipiao City, Licheng County, Lincheng County and Huoqiu County has also increased. Therefore, it will become the production mainstream of producing reduced iron powder with hyperpure iron concentrate powder. In recent years, with the improvement of reduced iron powder, the performance has gradually become close to world standard and can partially replace water atomized iron powder in producing powder metallurgy structural parts.
When producing copper base metal powder, we should mainly consider product performance, such as powder particle size, particle shape, apparent density, mobility and so on. Besides, we should also consider production environmental protection, production cost and other factors. According to different national conditions, it can be found that among 22,000 tons of copper base powders that produced in North America every year, about 88 percent are made by water atomization + redox technology, in addition, most of copper base metal powders are produced by electrolytic process in China and Japan. With the intensified environmental protection efforts, the pressure of producing copper base metal powder by using electrolytic process will increase. Therefore, we should not blindly expand the production capacity of electrolytic copper powder. In the future, it will become the development trend of producing copper powder with water atomization + redox technology in copper base metal powder industry.
Except for output difference, the variety and quality of iron base and copper base metal powders that produced in China still have a long distance from foreign famous iron powder and copper powder.
a. The stability of iron base metal powder, especially the powder stability in every batch will directly influence the quality of products that produced by powder metallurgy factories. The quality of iron powder in single batch can be comparable with powders that produced in Quebec, Canada and Hoganas, Sweden. However, by continuously producing more than two batches of powders, the powder performance will vary in different batches. While powders that produced in dozens of batches in Quebec and Hoganas will almost have same performance. The reason may be as follows: except for controlling the chemical composition of iron powder (especially oxygen content, carbon content and acid non-soluble substance), particle size and particle composition, we should further study powder mixing process before iron powder leaving factory as well as make final regulation on powder performance so as to make sure powder performance of different batches can keep the same.
b. World famous iron powder factories (Quebec and Hoganas) have moved material mixing process of powder metallurgy factory to iron powder manufacturing plant as well as have produced remixed iron powder with premix technology. This kind of iron powder can be used immediately in powder metallurgy factory when it is unpacked. As C, Ni, Cu and other elements will be evenly distributed in this kind of powder, the performance of powder metallurgy parts will be greatly improved. Currently, among the iron powders that imported from aboard every year in China, premixed iron powder occupies 90 percent. At present, LaiGang Group Powder Metallurgy Company and Ansteel Group Metallurgical Powder Material Factory both are studying on premix technology as well as batches of products have went public and a small amount of products have been exported to Korea. This kind of technology is one of the key methods that are urgently needed to be improved in iron powder industry in China.
c. Regarding iron powder variety, we should pay attention to the development trend of world iron powder new products. For example, warm pressing powder, sinter hardening powder, chromium alloy powder and powders that mixed with special adhesive (the green strength can reach 40MPa and can be used in machining) are still insufficient in China. Therefore, we should combine production, learning and studying so as to develop more new type iron base metal powders.
d. Based on copper and copper alloy powder variety, we should stably develop the production scale of water atomization + redox iron powder, expand variety (such as copper coated iron powder) as well as strengthen research efforts on product performance and stability for powder metallurgy oil bearing and carbon brush industry. Regarding expanding the application field of copper powder, we should pay attention to study deep processing technology of copper powder, such as powder grinding, polishing, oxidation resistance and so on.
In recent years, iron base and copper base metal powder output in China has constantly increased, the variety has expanded, product quality has improved and market has well developed. However, with the rising price of iron scale, concentrate powder, electrolytic copper, coal, electricity and other raw materials, drawback has been cancelled as well as 10 percent of export tax has been charged for iron powder export, thus it will greatly increase the operating pressure of metal powder manufacturing industry. As result, metal powder manufacturers should intensify technological reformation, optimize production technology, reduce production cost, expand the application field of copper base and iron base powder so as to ensure steady and fast development of metal powder manufacturing industry in China and satisfy national economic development needs.
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