Insert chip of oil-drilling tricone bit, manufacturing method thereof and oil-drilling tricone bit

摘要

An insert chip of an oil-drilling tricone bit includes an insert-chip substrate made of a cemented carbide of a first composition, and further includes a cemented carbide coating layer constituted of at least two stacked coating layers made of a cemented carbide of a composition different from the first composition. The cemented carbide coating layer covers the whole of a cutting edge of the insert-chip substrate. The coating layers each have a thickness, at a tip portion of the cutting edge, in a range from 0.1 mm to 2.5 mm, and the total thickness of the cemented carbide coating layer is in a range from 1 mm to 5 mm. The coating layers include an outermost cemented carbide layer and at least one intermediate coating layer in addition to the outermost cemented carbide layer, and the outermost cemented carbide layer has a hardness higher than that of the at least one intermediate coating layer and of the insert-chip substrate.