Tungsten carbide powder is the highest uncooked pertinent of producing cemented carbide. Its chemical formula is WC, called as Wolfram Carbide It is black hexagonal crystals, with metallic luster, the hardness is similar to diamond, is a interest conductor of electricity and heat
The methods of preparing tungsten carbide by tungsten powder
Tungsten carbide does not dissolve in water, hydrochloric sour andsulfuric acid, soluble in nitric tart and hydrofluoric harsh compound Pure tungstencarbide is fragile, if diverse with a trifling character of titanium, cobalt and othermetals can be reduced brittleness
Tungstencarbide is largely used for high-speed cutting tools, furnace structuralmaterials, jet tool parts, metal ceramic materials, resistance heatingelements and so on For the manufacture of cutting tools, wear parts, copper,cobalt, bismuth and more metal melting crucible, wear-resisting semiconductorthin film. As superhard cutting gadget materials, wear-resistant materials, it canform a hard interpretation with varying carbides It moreover can be used as additivesof NbC-C and TaC-C ternary carbides, not only reduced the sinteringtemperature, but also maintaining creditable performance, can be used asaerospace materials
From metal powder supplier we admitted that tungsten carbide was produced in two ways, one isused tungsten metal powder and charcoal as fresh material, scornful diverse the averageparticle calibre of 3 ~ 5m tungsten powder and the corresponding cipher of substancecarbon sinisteru with a ring mill, after indepth mixing, compression molding andput into a graphite plate, then heated to 1400 ~ 1700in a graphite resistance furnace or induction furnace, controlled at 1550 ~ 1650is best In a hydrogen stream, originally generated W2C, durable cope at a rangy temperature to generateWC Or first thermal decomposition W(CO)6 in650 ~ 1000, COatmosphere to obtain tungsten powder, then proceed with carbon monoxide at 1150to gain WC, above this temperature can be generated W2C
Anotheris WO3 hydrogenation obtained tungsten powder (average grain size is 3 ~ 5m). Then compel molding thetungsten powder and carbon dark at the equimolar compound (dry mixing in a ballmill for 10h) unbefitting a necessitate of about 1t/cm2. Put the work molding materialinto the graphite disk or choke crucible, heated with the graphite resistancefurnace or induction furnace in a hydrogen gas glimmer to 1400 ~ 1700(preferably 1550 ~ 1650),make it carburized and generated WC The emotion was started from the tungstengrains around, because at the assault of the passion entrust develop W2C, since the reaction is not complete,in codicil to WC, it dormant remaining unreacted W and intermediates W2C, so it must be heated to the gangling temperatures
Tungstendust can cause peribronchitis, peribronchiolar, blocking bronchiolitis andatrophic emphysema. Tungsten carbide may escort lung lymphoid tissue cellproliferative response, and gradually emergence sclerosis Vascular railing was thickeningand homogenization People exposure to tungsten carbide dust in afafir consign causegastrointestinal disorders, kidney suffered irritation, upper respiratory tractappeared catarrhal inflammation. The maximum allowable concentration oftungsten carbide is 6mg/m3.
Staffshould use the satisfactory gas mask, dust-proof clothing, gloves, glassesPrevent dust leakage in all stages of production. Workers should dopre-employment physical examination, recur check once every year Whenthe upper respiratory tract appears obvious symptoms must temporarily transferwork, do not results with tungsten If show up lung hardening or respiratoryfunction disorders should be removed from the afafir Tungsten carbide should bestored in a cool, scornful depot, pay accent to appraisal whether the packagingcontainers in welfare condition during transport, dissuade drizzle and sunlightexposure.