Uniform coarse tungsten carbide powder and cemented tungsten carbide

Abstract

A tungsten carbide powder and cemented tungsten carbide article made from the powder are disclosed. The powder has a particle size of greater than 20 micrometers in diameter and no particles less than one-half the average particle size or greater than two and one-half times the average particle size. A process is disclosed for producing the powder which comprises deagglomerating and classifying the tungsten powder to produce a powder wherein the Fisher Subseive Size is greater than 20 micrometers in diameter and wherein essentially no particles are greater than two and one-half times larger than the average Fisher Subsieve Size, forming a first mixture of the tungsten powder and carbon, carburizing, and deagglomerating and classifying the resulting tungsten carbide powder to eliminate particles greater than two and one-half times the average Fisher Subseive Size value and produce a tungsten carbide powder wherein the particle size is greater than 20 micrometers in diameter and wherein there are no particles less than one-half of the average particle size and no particles greater than two and one-half times the average particle size of the tungsten carbide powder. To produce the article a uniform second mixture is formed of the daeagglomerated and classified tungsten carbide powder and cobalt powder wherein the cobalt content is about 3% to 20% by weight, a third mixture is formed of the second mixture and a wax binder, a green article is formed from the third mixture, and sintered at about 1380.degree. C. to 1550.degree. C.