Production Volumes and Use Pattern

Tungsten carbide is manufactured by direct carburization of tungsten with carbon (Roempp, 2003).Mixtures ot metal and carbon DiaCK or grapmte are tieated ai a iemperarure of 140u - L v-vacuum or under hydrogen (Tulhoff, 2000):vv+c．)WC.When heating a mixture of tungsten and carbon in a car'oon tube or high-frequency furnace to ca.800 0C, cast tungsten carbide is o'otained (Gmelin, 1993), However, most tungsten carbide is so'I"das powders with distinct ranges of grain sizes (Tulhoff, 2000),
Purity and gYain size determine the physical properties and the technical applicability of tungstencarbide. Since milling changes the chemical composition and the shape of the grains, coarsepowders of tungsten carbide can not be milled to obtain fine-~ained powders.

Instead, to obtain theiesired industr'ie'al' product, the particle size of the raw materials is carefully selected. The grain sizeof the product is also irrfluenc'ed by manufacturing parameters like temperature, reaction tiffie,resence of humidity and hydrogen.'Typica/ production lines start from tungsten ore (W, Nb, Fe-oxides), tungsten scrap, scheelite (Ca\V04), tungstic acid (H2W04), and ammonium paratungstate《NH'4)10W'1'2S04" X 5 H:O). Typica/ intermediates are yellow~(W03), blue (appro}cimatciY  W4Ullj,a'nd brown tungsten oxide '(W02).

There are several m~t'hods for the manufacturin9 0f the technicaltungsten carbide powders (Tu/hoff, 2000): Tungstic acid powder is reduced to tungsten by hydrogenat 750 0C. The metal particles are carburized at 1400 0C. This method is applied for fine powderswith an average grain size of l llm.

Tungsten Manufacturer & Supplier: Chinatungsten Online - http://www.chinatungsten.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

 

• < Prev
• Next >