Nano Tungsten Carbide Processes

There are some common used nano tungsten carbide powder processes as follow:

1. MA (Metal Alloying): It is a by high energy ball milling the powder is subjected to repeated deformation, cold welding, broken, so as to achieve inter-atomic level alloying element complex physical and chemical process. It has simple operation, high efficiency and the granularity of grains can meet the requirements, but the powder pollution often caused by the friction between tank and balls;

2. SCP (Spraying Conversion Process): It is a new kind of process by American scholars. It uses ammonium paratungstate (CH4) 6 (H2W12040) and an aqueous solution of cobalt chloride CoCl2 • nH2O or Co (en) 3WO4 and H2WO4 tungstate solution by spray drying and fluidized-bed reduction and carbonization reaction homogeneous grain powder (20-50nm);

3. In-situ carburization: It combines in-situ synthesis and carburizing process. In situ synthesis is the use of different elements or compounds react under certain conditions, and in the metal matrix to generate one or more ceramic phase particles have reached the improvement of a single metal alloy. American scholars used polyacrylonitrile as carbon source in situ, without vapor carbide, tungsten and cobalt salts are dissolved in acid polyacrylonitrile solution, low-temperature drying after move 90% Ar-10% argon, hydrogen H2 reduction of direct reduction furnace was cemented carbide powder, the grain size of about 50-80nm;

4. Co-precipitation: Mix different chemical composition and add in solution in a mixture of appropriate preparation precipitating agent precursor precipitate and then the precipitate is dried or calcined, to thereby obtain the corresponding powder particles, which is an important method for preparing a composite oxide containing two or more kinds of ultra-fine powders of metal elements. The researchers use the sodium tungstate or tungsten and cobalt ammonium acetate co-precipitation WC-Co precursor powder through hydrogen reduction and carbonization reaction made cemented carbide powder (about 50nm). However, this method is only applicable to the W / Co atomic ratio close to 5.5. While the use of ammonium tungstate and cobalt hydroxide precipitate will be able to co-atomic ratio of the high-side W / Co, access to a broader range of composite powder.

In addition, there are some other synthesis methods, such as vapor evaporation, high-frequency plasma synthesis, high-frequency induction heating synthesis, ARC. But they all still in the research step, which did not put into practical production. Nano carbide fine and uniform microstructure, mechanical properties have been significantly enhanced. The mean free path of cobalt binder phase is shortened, crack propagation resistance will be improved, the better the toughness of cemented carbide. As tungsten carbide micro drills, nano tungsten carbide micro drill has higher efficiency, lower wear consumption, longer service life.