In the diamond tool industry, mechanical mixture of powders which consists of one kind of element was used as traditional binder material. The traditional material is prepared at high temperature and its composition is not homogeneous. What is more, it is difficult to attain perfect alloying. In order to overcome such disadvantages and increase the physical ability of binder material for diamond tools, many researchers started to study alloying of binder material powder. At present, considerable amount of prealloyed powder in addition to pure cobalt metal is used for manufacturing diamond crowns, natural stone material and tools for building material processing. Because all the particles of prealloyed powder contain various kinds of composition of alloy, it has good homogeneity. In addition, its melting point is lower than that of its major elements.
Now, prealloyed powder is mainly prepared by atomization. The powder prepared in this method has low sintering temperature and high alloying level. Also, it has good fluidity and wear resistance and high ability of binding with diamond. However, because alloy must be refined in advance, the demand for equipment is considerably high and it is difficult to control the composition of binder material. What is more, its particles are rough and it has high content of oxygen. It is also very expensive.
Recently, mechanochemical synthesis has become a method of preparing nano- and micrometer scale materials. This is simple and highly productive, so it is especially convenient for mass production of nano and superfine particles.
Ri Hyok Chol, a researcher at the Faculty of Chemistry, has proposed a method of preparing Fe-Cu-Co prealloyed powder for diamond binder material by reducing precursor powder prepared through the reaction of sulfate and sodium hydrate by mechanochemical synthesis, and compared it with the traditional binder material prepared by mechanical mixing.
The results showed that the binder material prepared from the prealloyed powder that underwent mechanochemical and reducing processes has the following characteristics. First, its particles are fine and the grain size distribution is uniform. Second, the alloy prepared with the use of binder material reaches the relative density of about 98%, the bending strength of about 1 120MPa and the hardness of about HRB110. Third, its mechanical property is superior to the materials prepared by mechanical mixing.
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