Liquid Form Synthesis Tungsten Carbide

Tungsten carbide is the main raw material for the production of hard alloy. The basic process of producing alloy powder in tungsten production and processing enterprises is that the tungsten carbide powder and cobalt powder are mixed through mechanical mixing. The uniformity of the alloy powder is not ideal, and it has a great influence on the subsequent hard alloy pressing. Some scholars try to pre allot alloy powder in liquid state, and then to reduce the alloy powder:

(1) 270 ~ 330g/L ammonium tungstate solution, 800 ~ 850g/L cobalt nitrate solution and 100 ~ 130g/L chromium nitrate solution are prepared in advance.

(2) The ammonia concentration in ammonium tungstate solution is controlled, the ammonia concentration in ammonium tungstate solution is between 50 and 70g/L, and ammonium tungstate solution after ammonia modulation is added into the heat reaction kettle, and the mixed cobalt solution is slowly added at the side stirring edge, and the evaporation is heated to reduce the ammonia to the value of pH to 8.5~9, and then the above preparation is added. The chromium nitrate solution will continue to heat and stop heating when the pH value is reduced to 7~7.5.

(3) A tungsten cobalt chromium coprecipitation crystal was obtained by vacuum filtration and the co precipitation crystal was obtained by vacuum filtration after cooling. The co precipitation crystal was dried in a infrared oven and then burned at 700~750°C in a high temperature furnace to obtain tungsten cobalt chromium compound metal oxide.

(4) The tungsten cobalt chromium composite metal oxide is reduced at low temperature range of 710~840°C with a flow rate of 80 cubic meters / hour and the dew point < -80°C as a reducing agent. The reduction time is 4~5 hours, and it is reduced to a tungsten cobalt chromium single homogeneous tungsten cobalt chromium metal reduction powder.

(5) The reduced tungsten cobalt chromium metal reducing powder is isolated from the air with carbon dioxide gas and is cooled at low temperature for 7~9 hours at the temperature of 20~24°C. The surface of the tungsten cobalt chromium metal reducing powder will be passivated in the process of cooling, which ensures that the tungsten cobalt chromium metal reducing powder is not oxidized during the transfer and carbon distribution; then the tungsten cobalt chromium gold after cooling is made. The required carbon is added to the reduction powder, and then milled and milled for 3~5 hours. The tungsten cobalt chromium metal reduction powder is fully mixed with carbon.

(6) Tungsten cobalt chromium metal reduction powder after carbon distribution was placed on a high temperature continuous automatic molybdenum wire furnace. The tungsten carbide cobalt chromium metal composite powder was prepared at the temperature of 1100~1150 °C at the furnace temperature for 3~4 hours, and the mixture of tungsten carbide, cobalt carbide and chromium carbide was obtained.

(7) The composite powder after the carbonization is sifted 80 mesh after ball milling, then the gas flow is broken to screen 40 mesh again, and the finished product is obtained. This step is used to remove the coarse particles and aggregate in the compound powder, so that the final product has high purity, high carbon content, uniform distribution, and finishes of grain size.

Compared with the production of conventional alloy powder, the production methods and technological ideas are different. The prepared tungsten carbide cobalt chromium metal composite powder has high purity, high carbon content, good uniformity, positive distribution, complete grain size, good composition of chemical main content and excellent performance.

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