| 摘要 |
A silicon nitride member, a method for manufacturing the silicon nitride member and a cutting tool are disclosed. A cutting tool 1 includes a substrate 3 formed through sintering of a silicon nitride material, and a hard film 5 composed of a plurality of hard-component layers. The cutting tool 1 is characterized in that: when the amount of a grain boundary phase as measured at a central portion (for example, the barycenter) of the substrate 3 is taken as 100% by volume, the amount of the grain boundary phase at a depth of 300 mum from the surface of the substrate 3 is 50% to 70% by volume; when the strength of the substrate 3 as measured before coating with the hard film 5 is taken as 100%, the hardness as measured after coating with the hard film 5 is 70% to 95%; and a change in weight of the substrate 3 associated with sintering is 1.5% to 3.5% by weight.
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