Nanocrystalline Nickel-tungsten Alloy Powder

As a traditional material, nickel-tungsten alloy has attracted much attention because of its many superior properties and some potential applications. Tungsten-nickel alloy electroplating has compact structure, high heat resistance, comparable to ceramics, wear resistance and oxidation resistance at high temperature, and good self-lubrication and corrosion resistance.

At present, the preparation methods of nickel-tungsten alloys mainly include electrodeposition, laser forming, powder metallurgy and so on. In addition, there is a new method to prepare nanocrystalline Ni-W alloy powder. This method directly uses ammonium tungstate metatungstate, nickel nitrate and auxiliary agent as raw materials for precursor mixing and sintering reduction. The process includes:

1.Raw materials: ammonium metatungstate ((NH₄)₆H₂W₁₂O₄₀), nickel nitrate (Ni(NO₃)₂) and auxiliary agents are used.

2.Solution preparation: dissolve the selected raw materials in water according to a certain proportion and mix evenly;

3.Precursor preparation: The water solution obtained in step (2) is heated and stirred. With the volatilization of the water solution, the solution bubbles after concentration, releases a large amount of gas, and undergoes violent redox reaction instantaneously to form powder precursor.

4.Preparation of nickel-tungsten alloy powders: The precursors obtained in step (3) were reduced in H₂ atmosphere at 600-700 ℃ for 1-2 hours to obtain pure nickel-tungsten alloy powders with fine grains.

The nanocrystalline nickel-tungsten alloy powder has fine particle size and high surface activity, which can optimize the subsequent processing of the powder. It can reduce the heat treatment temperature and increase the heat treatment speed. It is advantageous to obtain the alloy with high density, uniform structure distribution and fine grain. The above method uses tungstate and nickel nitrate as raw materials, controls the reaction process of precursor preparation by controlling the type and proportion of raw materials, and controls the particle size, pore size and alloy powder composition of precursor. It has the advantages of short process, low preparation cost, simple and fast process, and is suitable for large-scale production.

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