Nano-cemented Carbide Powder Synthesis

Before preparing nano-cemented carbide, the first thing is to synthesize the finer nano powder, which includes mechanical alloying (MA), spray conversion, senate situ carbon reduction and co-precipitation.

1. Mechanical Alloying (MA)

Mechanical alloying method is mainly through the use of mechanical driving force of high energy synthetic materials at low temperatures, high energy ball mill machine is one of the most commonly used tools. The research of nano-cemented carbide powder by MA has two main directions: one is use tungsten (W) and carbon (C) synthesizes to nano tungsten carbide (WC) powder by MA; another one is mixed tungsten carbide (WC) and cobalt (Co) powder, to meet the requirements of nano composite material by high-energy ball milling. Chinese scholars successfully W, C, Co mixed after milling synthesized nano scale WC-Co composite powder. It uses mechanical chemical method, which uses tungsten trioxide (WO₃) and magnesium (Mg) and carbon (C) in nitrogen (N₂) or hydrogen (H₂) - Under an inert gas such as argon (Ar) atmosphere such as ball milling mixing occurs explosive reaction (after generation W and MgO, W and C diffusion reaction occurs, generating W₂C and WC) prepared nano carbides WC, grain size is about 4-20nm. This method has simple operation, easy process and high efficiency, but the small granularity will be polluted by the friction between ball and the wall.

2. Spray conversion

Spray conversion process is also known as thermo-chemical method or fluidized bed process. Some scholars in related fields of the United States developed the method by metatungstate and cobalt chloride (CoCl₂ • nH₂O) solution or Co (en) 3WO₄ and sulfuric acid (H₂WO4) aqueous spray-drying and fluidized-bed reduction (flow bed reduction is a direct reduction process technology production of raw materials to produce tissue composition uniform nano powder (about 20-50nm) restore the furnace refractory composition structure) and carbonization reaction by constructing a fluidized bed reduction of iron ore.

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