Patent ID: 6749930
Filing Date: 2004-06-15
Classification: B82Y,C04B,C23C,Y10S,Y10T

Abstract:
A corrosion-resistive member having a corrosion-resistive face which is exposed to a corrosive gas causing ion bombardment, wherein at least a part of said corrosion-resistive member comprises a sintered silicon nitride body having an open porosity of not more than 5%, wherein the total content of elements in Group Ia and Groups 4a-3b of the Periodic Table present in said sintered silicon nitride body is not more than 50 ppm by weight, and wherein said sintered silicon nitride body constitutes said corrosion-resistive face;wherein if two auxiliary planes are formed by cutting said corrosion-resistive member to intersect vertically with said corrosion-resistive face and to be located vertically with respect to each other, an orientation index between said two auxiliary planes is in a range of 0.8 to 1.2, and an orientation index between said corrosion-resistive face and each of said auxiliary faces is not less than 1.5; wherein said orientation index between the two auxiliary planes satisfies the following formula: [Is1(320)/(Is1(320)+Is1(002))]/[Is2(320)/(Is2(320)+Is2(002))]; wherein Is1(320) denotes an intensity of X-ray diffraction at a 320 face of &bgr;-type silicon nitride in one â€œIs1â€  of the auxiliary planes; Is1(002) denotes an intensity of X-ray diffraction at a 002 face of &bgr;-type silicon nitride in the auxiliary planes â€œIs1â€ ; Is2(320) denotes an intensity of X-ray diffraction at a 320 face of &bgr;-type silicon nitride in the other auxiliary plane â€œIs2â€ ; and Is2(002) denotes an intensity of X-ray diffraction at a 002 face of &bgr;-type silicon nitride in the auxiliary planes â€œIs2â€ ; and wherein said orientation index between said corrosion-resistive face and each of said auxiliary planes satisfies the following formula: [Im(320)/(Im(320)+Im(002))]/[Is(320)/(Is(320)+Is(002))]; wherein Im(320) denotes an intensity of X-ray diffraction at a 320 face of &bgr;-type silicon nitride in the corrosion-resistive face â€œmâ€ ; Im(002) denotes an intensity of X-ray diffraction at a 002 face of &bgr;-type silicon nitride in the corrosion-resistive face â€œmâ€ ; Is(320) denotes an intensity of X-ray diffraction at a 320 face of &bgr;-type silicon nitride in the auxiliary plane â€œIsâ€ ; and Is(002) denotes an intensity of X-ray diffraction at a 002 face of &bgr;-type silicon nitride in the auxiliary planes â€œIsâ€ .