All-purpose Tungsten Carbide Thermal Spraying Material Preparation

Thermal spray welding (coating) of cemented carbide powder is a technology for hardening and strengthening mechanical surface developed since 1950s. This technology may effectively prolong the service life of machinery. Tungsten carbide is the most common raw material for thermal spray welding (coating).

Some scholars have developed a kind of tungsten carbide thermal spraying material which is not only suitable for oxygen-acetylene flame spraying, but also suitable for supersonic flame spraying, plasma spraying, explosive spraying and other thermal spraying methods to harden and strengthen the mechanical surface, and has stable chemical composition. Its production process is as follows:

The WC powder with 6.14% ℃ content and 4 micron average fineness is 860g, the cobalt powder with 2 micron average fineness is 120g, the total carbon content is 6.2% and the average fineness is 30 micron is 20g, TaC is 20g, milling for 16 hours, pressing into lumps or flakes, such as 60 x8mm, sintering at vacuum of 20 Pa and temperature of 1420 ℃ for 1 hour, crushing and/or airflow. The physical properties of the cemented carbide are as follows: density 14.21 g/cm³, hardness HRA 87.2, coercive magnetic force 7.4 KA/m and flexural strength 1948 N/mm 2.

The above process is to weigh more than one of the hard phase tungsten carbide, binder phase iron series elements Fe, Co, Ni (including one kind of metal and additive) in proportion, mix them for 1-72 hours by dry mixing or ball milling, so as to achieve uniform dispersion of the material, press the mixture into sheets, blocks or pellets, and then carry out high temperature. Sintering, sintered products are crushed into powder by mechanical or gas, screened and classified into products. Its characteristics are that high temperature sintering can be carried out in vacuum and in specific gases, which are one of inert gases, hydrogen, ammonia and other reducing gases. The sintering temperature is 1250-1500 ℃, and the sintering time is 30-60 minutes. By using crusher to crush and classify the powder, the fineness of the produced powder can be less than 100 microns, and the particle size of the powder is uniform.

The tungsten carbide-based cemented carbide spraying powder has narrow fine distribution, stable chemical composition, good fluidity and high deposition rate, which is suitable for oxygen-acetylene flame spraying and supersonic flame spraying, plasma spraying and explosive spraying. The coatings are uniform in thickness, fine in density and high in hardness. The coatings are wear resistant and corrosion resistant.

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