CEMENTED CARBIDE IMPROVED IN HIGH TEMPERATURE AND THERMODYNAMIC PROPERTY

摘要

PROBLEM TO BE SOLVED: To provide a cemented carbide useful for the fields in which extreme periodic load and frictional force, causing high temp. and thermodynamic fatigue, are brought about. SOLUTION: The cemented carbide for use in development drilling of rocks and stones has, together with a binding phase consisting of Co alone or Co and Ni, 96-88wt.%, preferably 95-91wt.% of WC and has a binder containing Ni by 25% at the maximum, and further, trace amounts of rare earth elements, such as Ce and Y, are arbitrarily added by up to 2% at the maximum based on the total amount of the cemented carbide. For the purpose of coating WC with Co, WC grains have spherical shape and do not recrystallize or do not show grain growth or are not composed of very sharp and angular grains like those of the conventional milled WC, that is, the body has an extremely high thermal conductivity. The average grain diameter is regulated to 8-30m, preferably 12-20m. The maximum grain diameter does not exceed a value twice the average value, and grains having a grain diameter smaller than a value one-half the average grain diameter in the structure do not exceed 2%.