Why Spherical Tungsten Powder is The First Choice for Thermal Spraying Materials

Tungsten is an important thermal spraying material. Thermal spraying technology uses heat source to heat the spray material to melt or semi dissolve state, and spray at certain speed to deposit the coating on the pretreated substrate surface. The thermal spraying technology makes a special working surface on the surface of the ordinary material. 

It can achieve many functions, such as anticorrosion, wear resistance, friction reduction, high temperature resistance, oxidation resistance, heat insulation, insulation, conductive and microwave protection, so as to save materials and save energy.

In order to achieve the above effect, the requirements for tungsten powder are more stringent in the application of thermal spraying, so as to ensure a stable and uniform thermal spraying coating. Therefore, with the basic characteristics of shape, size and size distribution, bulk density, fluidity and surface quality of powder of thermal spraying is an important part of the thermal spraying powder material performance in general, large size and high purity spherical tungsten powder is the best material for the application of thermal spraying.

The preparation method of high purity spherical tungsten powder includes the following steps:

(1)The spherical APT (ammonium partrunate) was calcined for 6~12 hours at the temperature of 1000℃ ~1250℃ , and the tungsten oxide was prepared. The shape and morphology of the spherical tungsten oxide particles reached the spherical reduction quality requirement of the tungsten particles (particle size 0.1 to 2mm, purity greater than 99.95%, and sphericity rate greater than 97%).

(2)Under the premise of meeting the requirement of spherical shape of tungsten oxide, the reduction temperature is 1250℃ ~1450℃, and the reduction time is 10~12 hours. The hydrogen is reduced at 99.99% purity, dew point -83 degree and boat size.

(3)Ball milling is carried out after reduction to eliminate agglomeration and caking produced during the reduction process, so as to obtain uniformly dispersed spherical tungsten particles.

(4)The spherical tungsten particles after ball milling are then sieved and the spherical tungsten particles with high purity are obtained. The particle size of the spherical tungsten particles is 0.1 to 2mm, the purity is more than 99.95wt%, and the spherical rate is more than 97%.

The advantage of high purity spherical tungsten powder is not only to meet the functional requirements of coating, but also to meet the needs of spray technology, that is, it can deliver uniformly, smoothly and steadily to the jet flame, so as to ensure stable and uniform thermal spraying coating.

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