Cutting tool made of A12O3-coated cBN-based sintered material

摘要

A cutting tool according to the present invention is coated with one or more Al2O3 layers on at least a part of the surface of a cBN-based sintered material substrate taking part in cutting. The sintered material substrate is made of cBN in an amount of from 20% to 99% by volume and Al2O3 having an average crystalline particle diameter of not more than 1 mum in an amount of from not less than 1.0% to less than 10% by volume. The Al2O3 layer has a thickness (d) of from 0.5 mum to 50 mum. The average crystalline particle diameter (s) of Al2O3 is from 0.01 mum to 4 mum if the thickness (d) of the Al2O3 layer is from 0.5 mum to 25 mum or from not less than 0.01 mum to not more than 10 mum if the thickness (d) of the Al2O3 layer is from more than 25 mum to 50 mum.