| 摘要 |
PROBLEM TO BE SOLVED: To improve the chipping resistance and the abrasion resistance by quantitatively specifying a space between cracks in a coating layer of the cemented carbide alloy and position of a tip and a rear end of these cracks. SOLUTION: Tips of 50% or more of cracks formed in a coating film at a surface side thereof do not pass through the coating film surface. Tips of 50% or more of cracks formed in the coating film of a ridge of a blade tip and/or a cutting face exist in the titanium nitride of the most inside layer, or in an upper layer than the titanium nitride, or in an interface between these layers. The mean length of the cracks in the coating film of the ridge of the blade tip and/or the cutting face is shorter than the mean value of the coating film thickness in a flank. The mean value of the space between the cracks in the film of the titanium nitride in the ridge of blade tip and/or the cutting face is 10μm or less, and the mean space between the cracks in the alumina film of the ridge of the blade tip and/or the cutting face is larger than the mean space between the cracks in the titanium carbide film, and desirably set at a value twice larger, especially set at a value 2-50 times larger.
|
