CUTTING TOOL MADE OF AL2O3-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 Al12O3, having an average crystalline particle diameter of not more than 1.mu.m in an amount of from not less than 1.0% to less than 10% by volume. The Al12O3, layer has a thickness (d) of from 0.5 .mu.m to 50 .mu.m. The average crystalline particle diameter (s) of A12O3 is from 0.01 .mu.m to 4 .mu.m if the thickness (d) of the Al2O3 layer is from 0.5 .mu.m to 25 .mu.m or from not less than 0.01 .mu.m to not more than 10 .mu.m if the thickness (d) of the Al2O3 layer is from more than 25 .mu.m to 50 .mu.m .