(a) providing an aqueous solution of ammonium paratungstate(APT);

(b) adding aqueous potassium hydroxide solution to the aqueous solution of APT as a doping substance, wherein the mole ratio of potassium to ammonium is 0.1 to 10, thereby forming an ammonium potassium paratungstate;

(c) converting the ammonium potassium paratungstate to potassium-doped tungsten blue oxide;

(d) reducing the doped tungsten blue oxide to doped tungsten powder; and

(e) compacting the doped tungsten powder and drawing doped tungsten wire from the compacted powder.

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When cutting tungsten carbide cutting tools, tungsten carbide cutting tools for cutting the amount of wear has a significant impact, especially in cutting speed. Different cutting speed on the wear of tungsten carbide cutting tools have different variations. In general, the greater the cutting speed, the greater the amount of flank wear, the more severe tools wear. Uncoated tungsten carbide tools in high-speed cutting, the rapid rise in the amount of flank wear, cutting the distance is very short, but the amount is much larger than the amount of wear and wear low-speed cutting. When the cutting speed reaches 100m / min or more, the coating due to friction during cutting off, the substrate is exposed to participate in a cutting tool. Lead to increased wear of tungsten carbide cutting tools, and ultimately failure.

Different grades of tungsten carbide cutting tools wear is as cutting speed increases. Low speed cutting with adhesive wear as the main wear mechanism, high-speed cutting wear and diffusion wear oxide as the main wear mechanism. This is because with the increase in cutting speed and tools - chip contact surface temperature with increasing pressure, knife - contact debris from sliding contact between the adhesive into contact. Under the adhesion force in the tools and workpiece contact surface friction generated by the process, the tools material fine particles from peeling or cutting. When the cutting temperature reaches 800 ~ 900 ℃, decomposition occurs between the workpiece and the tools element and the diffusion element to each other, the strength of the tools is reduced, resulting in tungsten carbide cutting tools wear or breakage failure.




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A process for producing APT from a heavy metal alloy containing tungsten comprising introducing the heavy metal alloy into an electrolytic cell as an anode, said cell comprising an inert cathode and an aqueous electrolyte solution comprising ammonium hydroxide and ammonium nitrate, passing a direct electric current through said cell, said ammonium hydroxide and ammonium nitrate being maintained at a suitable concentration for oxidizing tungsten and forming ammonium paratungstate. After the desired concentration of ammonium paratungstate is reached in the electrolyte solution, the reaction may be stopped and the electrolyte withdrawn. The resulting ammonium paratungstate may be purified by conventional methods known in the art.

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Tungsten carbide tools wear process is divided into early wear, normal wear and severe wear of three phases.

1. Wear the early stages
Tungsten carbide cutting tools and the workpiece during the fourth year, as the new tools sharpening surface roughness and micro-cracks, defects such as oxidation or decarbonization layer, so that the actual contact area is small, the contact point bonding serious, so the tools wear faster. As the cutting proceeds, the tools surface micro peak peak gradually rubbed off, the surface roughness values decrease, the actual contact area increases, increased number of contact points, so tungsten carbide tools wear rate decreased. Coated tungsten carbide cutting tools at low speed, the wear more evenly. When the speed increases, the wear and tear is beginning to show a parabolic band.

2. Normal wear stage
After the initial worn, rough surfaces and polished tungsten carbide cutting tools gradually phase into the normal wear and tear. This stage is relatively slow uniform wear, with the growth of the amount of wear and the cutting time is approximately proportional to the increase. This stage is the stage of effective working tool. When the tools wear stage into the normal wear and tear, wear, Deputy Regional flank wear was uniform phenomenon. Especially coated tungsten carbide cutting tools, wear range presents a uniform wear strip. Compared with uncoated tungsten carbide cutting tools, wear it more slowly into the normal wear stage.

3. Severe wear stage
When the amount of wear tungsten carbide cutting force reaches a certain value will increase sharply, cutting temperature rises rapidly, the flank wear values will increase significantly decreased mechanical efficiency, precision loss, abnormal vibration and noise, the final result cutting tools fall, resulting in the loss of tungsten carbide cutting ability.

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