Abstract: A silicon nitride cutting tool comprising a sintered product is disclosed. The sintered product comprises silicon nitride, at least one rare earth element compound, and a magnesium compound. The silicon nitride cutting tool further comprises a surface region and an inside region comprising the sintered product with varying content ratios of component compounds to provide enhanced wear and fracture resistance.

Abstract: An object of embodiments according to the invention is to provide a cutting tool having good wear resistance, good sliding property and good fracture resistance. A cutting tool 1 comprising a substrate 2 and a coating layer 6 or a coating layer 9 which covers a surface of the substrate 2. The coating layer 6 or the coating layer 9 comprising a first layer 7 and a second layer 8. The first layer 7 comprises Ti1-a-b-c-dAlaWbSicMd(C1-xNx) when M is at least one selected from Nb, Mo, Hf and Y, 0.45?a?0.55, 0.01?b?0.1, 0?c?0.05, 0.01?d?0.1, 0?x?1). The second layer 8 comprises Ti1-e-f-gAleSifM?g(C1-yNy) when M? is at least one selected from Nb, Mo, Ta, Hf and Y, 0.50?e?0.60, 0?f?0.1, 0.05?g?0.15, 0?y?1).

Abstract: A cutting tool having a substrate and a coating layer for coating the surface of the substrate, the coating layer being composed of Ti1?a?b?c?dAlaWbSicMd(CxN1?x), where M is at least one selected from Nb, Mo, Ta, Hf and Y, 0.45?a?0.55, 0.01?b?0.1, 0.01?c?0.05, 0.01?d?0.1, and 0?x?1. The cutting tool has excellent wear resistance and fracture resistance. The cutting tool may be further provided with a layer composed of at least one selected from carbides, nitrides and carbonitrides of Al and the elements of the groups 4, 5 and 6 of the periodic table.

Abstract: A sintered product of silicon nitride includes a crystal phase mainly having silicon nitride crystal grains and an amorphous grain-boundary phase located on the grain boundaries of the silicon nitride crystal grains. The grain-boundary phase contains lanthanum, aluminum, magnesium, silicon, and oxygen. The sintered product described above contains 0.1% by mass or more of lanthanum on an oxide basis, 0.05 to 0.6% by mass of aluminum on an oxide basis, 0.3% by mass or more of magnesium on an oxide basis, and 2.5% by mass or less of oxygen. The total amount of lanthanum on an oxide basis, aluminum on an oxide basis, and magnesium on an oxide basis is 3.5% by mass or less.

Abstract: An object of embodiments according to the invention is to provide a cutting tool having good wear resistance, good sliding property and good fracture resistance. A cutting tool 1 comprising a substrate 2 and a coating layer 6 or a coating layer 9 which covers a surface of the substrate 2. The coating layer 6 or the coating layer 9 comprising a first layer 7 and a second layer 8. The first layer 7 comprises Ti1-a-b-c-dAlaWbSicMd(C1-xNx) when M is at least one selected from Nb, Mo, Hf and Y, 0.45?a?0.55, 0.01?b?0.1, 0?c?0.05, 0.01?d?0.1, 0?x?1). The second layer 8 comprises Ti1-e-f-gAleSifM?g(C1-yNy) when M? is at least one selected from Nb, Mo, Ta, Hf and Y, 0.50?e?0.60, 0?f?0.1, 0.05?g?0.15, 0?y?1).

Abstract: A silicon nitride cutting tool comprising a sintered product is disclosed. The sintered product comprises silicon nitride, at least one rare earth element compound, and a magnesium compound. The silicon nitride cutting tool further comprises a surface region and an inside region comprising the sintered product with varying content ratios of component compounds to provide enhanced wear and fracture resistance.

Abstract: A sintered product of silicon nitride includes a crystal phase mainly having silicon nitride crystal grains and an amorphous grain-boundary phase located on the grain boundaries of the silicon nitride crystal grains. The grain-boundary phase contains lanthanum, aluminum, magnesium, silicon, and oxygen. The sintered product described above contains 0.1% by mass or more of lanthanum on an oxide basis, 0.05 to 0.6% by mass of aluminum on an oxide basis, 0.3% by mass or more of magnesium on an oxide basis, and 2.5% by mass or less of oxygen. The total amount of lanthanum on an oxide basis, aluminum on an oxide basis, and magnesium on an oxide basis is 3.5% by mass or less.

Abstract: A cutting tool having a substrate and a coating layer for coating the surface of the substrate, the coating layer being composed of Ti1-a-b-c-dAlaWbSicMd(CxN1-x) where M is at least one selected from Nb, Mo, Ta, Hf and Y, 0.45?a?0.55, 0.01?b?0.1, 0.01?c?0.05, 0.01?d?0.1, and 0?x?1. The cutting tool has excellent wear resistance and fracture resistance. The cutting tool may be further provided with a layer composed of at least one selected from carbides, nitrides and carbonitrides of Al and the elements of the groups 4, 5 and 6 of the periodic table.

Abstract: A composite construction 1 is obtained by coating the outer periphery of a core material 2 with a shell layer 3. The core material 2 is composed of a first sintered body that is obtained by bonding, with a binder metal, a first hard particle composed of one or more of carbides, nitrides and carbonitrides of metals of Groups 4a, 5a and 6a of the Periodic Table, or a first ceramics obtained by bonding, with a sintering additive, a first ceramic particle composed of at least one of oxides, carbides, nitrides and carbonitrides selected from the group consisting of metals of Groups 4a, 5a and 6a of the Periodic Table, Al, Si and Zn. The shell layer 3 is composed of a second hard sintered body or second ceramics having a different composition from the first hard sintered body. The ratio of the residual free carbon amount Cin in the core material 2 to the residual free carbon amount Cout in the shell layer 3, Cin/Cout, is 0.5 to 2.

Abstract: A composite construction 1 is obtained by coating the outer periphery of a core material 2 with a shell layer 3. The core material 2 is composed of a first sintered body that is obtained by bonding, with a binder metal, a first hard particle composed of one or more of carbides, nitrides and carbonitrides of metals of Groups 4a, 5a and 6a of the Periodic Table, or a first ceramics obtained by bonding, with a sintering additive, a first ceramic particle composed of at least one of oxides, carbides, nitrides and carbonitrides selected from the group consisting of metals of Groups 4a, 5a and 6a of the Periodic Table, Al, Si and Zn. The shell layer 3 is composed of a second hard sintered body or second ceramics having a different composition from the first hard sintered body. The ratio of the residual free carbon amount Cin in the core material 2 to the residual free carbon amount Cout in the shell layer 3, Cin/Cout, is 0.5 to 2.

Abstract: A composite construction 1 is obtained by coating the outer periphery of a core material 2 with a shell layer 3. The core material 2 is composed of a first sintered body that is obtained by bonding, with a binder metal, a first hard particle composed of one or more of carbides, nitrides and carbonitrides of metals of Groups 4a, 5a and 6a of the Periodic Table, or a first ceramics obtained by bonding, with a sintering additive, a first ceramic particle composed of at least one of oxides, carbides, nitrides and carbonitrides selected from the group consisting of metals of Groups 4a, 5a and 6a of the Periodic Table, Al, Si and Zn. The shell layer 3 is composed of a second hard sintered body or second ceramics having a different composition from the first hard sintered body. The ratio of the residual free carbon amount Cin in the core material 2 to the residual free carbon amount Cout in the shell layer 3, Cin/Cout, is 0.5 to 2.

Abstract: A composite construction 1 is obtained by coating the outer periphery of a core material 2 with a shell layer 3. The core material 2 is composed of a first sintered body that is obtained by bonding, with a binder metal, a first hard particle composed of one or more of carbides, nitrides and carbonitrides of metals of Groups 4a, 5a and 6a of the Periodic Table, or a first ceramics obtained by bonding, with a sintering additive, a first ceramic particle composed of at least one of oxides, carbides, nitrides and carbonitrides selected from the group consisting of metals of Groups 4a, 5a and 6a of the Periodic Table, Al, Si and Zn. The shell layer 3 is composed of a second hard sintered body or second ceramics having a different composition from the first hard sintered body. The ratio of the residual free carbon amount Cin in the core material 2 to the residual free carbon amount Cout in the shell layer 3, Cin/Cout, is 0.5 to 2.