Ngk Spark Plug Company, Limited

Ryoji Toyoda

Fumihiro Kikkawa

Atsushi Komura

Yuki Hatano

Hiroko Nakayama

Shota Nozaki

Yusuke Suzuki

A surface-coated cutting tool including a tool substrate containing WC crystal grains and insulating grains, and a coating layer composed of a multiple nitride of Ti, Al, and V and disposed on the surface of the tool substrate. The multiple nitride is represented by a compositional formula: TiAlVN satisfying the following relations:0.25&#x2264;0.35,0.64&#x2264;0.74,0&#x3c;&#x2264;0.06, and1wherein each of a, b, and c represents an atomic proportion. The coating layer is characterized by exhibiting a peak attributed to a hexagonal crystal phase and a peak attributed to a cubic crystal phase as observed through X-ray diffractometry.

Surface-coated cutting tool

A sialon sintered body and a cutting insert each having thermal shock resistance and VB wear resistance. The sialon sintered body and the cutting insert contain &#x3b2;-sialon and 21R-sialon and exhibit an X-ray diffraction peak intensity ratio [(I/I)&#xd7;100] of 5% or greater and smaller than 30%, wherein Irepresents the sum of the peak intensities of the sialon species, and Irepresents the peak intensity of 21R-sialon, the ratio being calculated from the peak intensities of the sialon species obtained by using X-ray diffractometry.

Sialon sintered body and cutting insert

A sialon sintered body includes a &#x3b2;-sialon (SiAlON) and at least one polytype sialon, wherein a Z value is 0.4 or greater and 1.0 or less, a proportion of a total of peak intensities of each polytype sialon to a total of peak intensities of each sialon, is 10% or greater and 50% or less, at least one rare earth element B selected from a group consisting of La and Ce and at least one rare earth element C selected from a group consisting of Y, Nd, Sm, Eu, Gd, Dy, Er, Yb, and Lu is included, a molar ratio of the rare earth element B and the rare earth element C is 1.0:0.06 to 1.0:3.5 in terms of an oxide, and a total content of the rare earth elements B and C is 0.8 mol % or greater and 4.0 mol % or less in terms of an oxide.

The present invention provides a technique of improving wear resistance of a Sialon sintered body. The Sialon sintered body has a Sialon phase including at least a &#x3b2;-Sialon and a 12H-Sialon among an &#x3b1;-Sialon, the &#x3b2;-Sialon and the 12H-Sialon. A ratio of a second Sialon total content, which is a sum of the contents of the &#x3b1;-Sialon and the 12H-Sialon, to a first Sialon total content, which is a sum of contents of the &#x3b1;-Sialon, the &#x3b2;-Sialon and the 12H-Sialon, is greater than 20% and not greater than 55%, and a ratio of the content of the 12H-Sialon to the first Sialon total content is not less than 2% and not greater than 55%.

An insert includes a silicon nitride sintered body including &#x3b2;-SiNas a main component, Mg, and a rare-earth element Re (Y, La, Ce, Er, Dy, Yb). A content of Mg in terms of MgO is 1.0-7.0 mol %, a content of Re in terms of an oxide thereof is 0.4-1.0 mol %, and a total content of Mg and Re is from 1.7 to less than 7.5 mol %. The insert has a graded composition in which oxygen content increases from a surface of the sintered body toward an inside thereof such that 0.8-1.5 mass % of oxygen is contained in a region of less than 0.5 mm inside from the surface, 1.1-2.3 mass % of oxygen is contained in a region of 0.5 mm or more inside from the surface, and a difference in oxygen content between the regions is 0.1-1.0 mass %.

Growing community of inventors

Kakamigahara, Japan

Ryoji Toyoda