High Temperature Synthesis Method Producing Tungsten Disulfide

Tungsten disulfide is newly developed material which can reduce friction and save power, its property is better than graphite and molybdenum disulfide. The friction coefficient is 0.03, dry friction property is better than any other material, can be used under high temperature and pressure.

At present, tungsten disulfide producing methods mainly includes traditional high temperature synthesis method, chemical vapor sedimentation method, high temperature thermal decomposition method, hydrothermal method. The above produced tungsten disulfide has low output, can not realize continuous production, emission of SOX, H2S and NH3 will pollute environment. H2 is explosive gas, the transmission rate is very low. The produced WS2 has low purity.

Researchers have discovered high temperature synthesis method which is easy to operate with short process, low cost, and environmental friendly. Steps are as follows:

1. Mixing and activating of tungsten and disulfide.

Mix tungsten powder, disulfide powder and tungsten disulfide at certain ratio. Then put mixing powder into ball milling machine. Tungsten power, disulfide powder and tungsten disulfide more ratio is 1000：（2000～6000）：（1～50）, mixing time is 5~40min, grinding time is 5~200min.

2. High Temperature Reaction

Loading the active mixing powder from step 1. Under protection of argon, conduct high temperature reaction in the reacting area, temperature is 230～850℃, time is 1~24h.

3. Sulfide Recovery

Under motivation of argon, steam from step 2 enters different reacting stage of low temperature zone. Sulfur vapor is formed in a low temperature region, and a sulfur-containing lump sulfur solution is installed. A vacuum device of tungsten disulfide is connected with the wall of the low-temperature zone to add tungsten disulfide to the lower wall, so that the mass fraction of tungsten disulfide in the sulfur solution is 0.05% -10 %. Under the action of anti-friction lubrication of tungsten disulfide, the sulfur solution enters the sulfur recovery device through the liquid discharge port on the lower side of the low temperature zone of the reaction tube, and the sulfur block containing tungsten disulfide is recovered to be mixed with the tungsten powder for reuse.

4. Tungsten Disulfide Powder Post Treatment

Tungsten disulfide made from step 2 push through the reaction zone of the low temperature zone and the cooling zone down to room temperature, sieving machine and abrasive machine to obtain the desired size tungsten disulfide powder.

The low temperature zone of the segmented reaction tube is located at the back end of the reaction tube, accounting for 1/5 to 1/3 of the length of the reaction tube and having a temperature of 112 to 445 ° C.

Raw materials added to the process simple composition of tungsten and sulfur elements, mixing and activation process to add tungsten disulfide as a dispersant and activator, reducing tungsten and sulfur powder activation time, under inert atmosphere in the segmented reaction tube without side reactions and by-products, achieve the clean and efficient production of tungsten disulfide, help maximize the use of resources to meet the needs of industrial development.

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