摘要:
A glass-aluminum nitride composite comprising a sintered body is produced by adding glass powder to aluminum nitride grains having an oxygen content of less than 2% and a mean grain diameter of 1.0 .mu.m or more and subjecting the mixture to molding and sintering. A suitable glass is one based on borosilicate and the addition of an AlN whisker serves to improve the strength. The composite material of the present invention has a high heat conductivity, a low permittivity and a high strength and is suitable as a semiconductor packaging material.
摘要:
A novel thin film magnetic head is provided characterized by the use of a new substrate material excellent in mechanical property as well as machinability. This substrate is composed of a ceramic compact comprising 4 to 45% by volume of Component A, 55 to 96% by volume of Component B and at most 3% by volume of unavoidable impurities:Component A: at least one member selected from the group consisting of carbides, nitrides, carbonitrides, carboxides, oxynitrides and carboxynitrides of Group IVa, Va and VIa elements of Periodic Table and mixtures or solid solutions thereof.Component B: ZrO.sub.2 consisting of at least 70% by weight of tetragonal and/or cubic system and the balance of monoclinic system, in which at least one member selected from the group consisting of oxides of Group IIIa elements of Periodic Table, CaO and MgO, and mixtures thereof is dissolved to form a solid solution.
摘要:
A ceramic sintered body with a high density and high surface smoothness is obtained by sintering a ceramic composition comprising oxides as a substantial or partial component in an atmosphere of CO gas or in a mixture of CO gas and an inert gas.
摘要:
A wet molding method in which a ceramic slurry is charged into a cavity and uniaxially pressed by a punch to remove excess liquid from a portion of the slurry facing the punch to effect molding, the method being improved by maintaining at least one of the following conditions; (a) the pressing of the slurry is stopped at a time between T and 1.5 T, T being defined as the pressing time necessary to remove sufficient excess liquid from the slurry in the mold to produce a molded mass; or (b) the punch displacement position at a time at which sufficient excess liquid is removed from the slurry in the mold to produce a molded mass is less than 17% of the total mold length.
摘要:
A high thermal conductive silicon nitride base sintered body which comprises a phase comprising crystal grains of silicon nitride and a grain boundary phase containing a compound of at least one element selected from the group consisting of yttrium and the lanthanide elements in an amount of 1 to 20% by weight in terms of oxide amount, and contains free silicon dispersed therein in an amount of 0.01 to 10% by weight based on the whole. This high thermal conductive silicon nitride base sintered body has high strength coupled with high thermal conductivity and thus is useful not only as various parts for semiconductor devices, such as radiating insulating substrates, but as various structural parts for machines, OA apparatuses, etc.
摘要:
The present invention is intended to provide a sliding member that can prevent abnormal wear and partial wear of the mating metal sliding component even when an oil contaminated with exhaust gas components is used. A ceramic sliding component is manufactured as followed. A silicon nitride-based material for the sliding face member is joined to a metal body having a higher thermal expansion coefficient than the sliding face member. A crowned portion is formed on the sliding face of the sliding face member in such a way that the difference between the amounts of crowning (da, db) at two arbitrary points axially symmetric with respect to the center line of the crowned portion is 10% or more and 50% or less of the average of the crowning amounts at the two points.
摘要:
There are provided a process for forming a silicon nitride sintered body, encompassing a sialon sintered body, by making much of the superplasticity of the sintered body intact as a simple material without formation thereof into a composite material, and a formed sintered body produced by the foregoing process. A silicon nitride sintered body (encompassing a sialon sintered body) having a relative density of at least 95% and a linear density of 120 to 250 in terms of the number of grains per 50 .mu.m in length in a two-dimensional cross section of the sintered body is formed through plastic deformation thereof at a strain rate of at most 10.sup.-1 /sec under a tensile or compressive pressure at a temperature of 1,300 to 1,700.degree. C. The formed sintered body has a degree of orientation of 5 to 80% as examined according to a method specified by Saltykov, a linear density of 80 to 200, and excellent mechanical properties especially at ordinary temperatures.
摘要:
Provided herein is a me silicon nitride based sintered body composed only of uniform, fine crystal grains, and improved in both strength and fracture toughness in the middle and low temperature ranges. The crystalline silicon nitride powder thus produced is composed of crystal grains whose longer-axis diameter is not more than 200 nm or an amorphous silicon nitride powder is used as material powder. According to the disclosed method, the silicon nitride powder is sintered at a temperature of 1200.degree. C. to 1400.degree. C. or sintered with a product of sintering temperature (.degree. C.) and sintering time (sec) below 600000 (.degree. C. sec) at a temperature of 1400.degree. C. to 1900.degree. C. By this method, a silicon nitride based sintered body in which the longer-axis diameter of silicon nitride and/or sialon crystals is not more than 200 nm is obtained.
摘要:
An industrially feasible method of grinding silicon nitride ceramics is disclosed and provides a sufficiently smooth surface. Namely, the surface has a maximum height-roughness Rmax of 0.1 microns or less and a ten-point mean roughness Rz of 0.05 micron. Further, with this method, surface damage can be repaired while grinding. The vertical cutting feed rate of a grinding wheel into a workpiece should be within the range of 0.005-0.1 micron for each rotation of the working surface of the wheel and change linearly or stepwise. The cutting speed of the grinding wheel in a horizontal (rotational) direction should be within the range of 25 to 75 m/sec. With this arrangement, the contact pressure and grinding heat that is generated between the workpiece and the hard abrasive grains during grinding are combined. In other words, mechanical and thermal actions are combined.
摘要:
An industrially feasible method of grinding silicon nitride ceramics is disclosed and provides a sufficiently smooth surface. Namely, the surface has a maximum height-roughness Rmax of 0.1 microns or less and a ten-point mean roughness Rz of 0.05 microns. Further, with this method, surface damage can be repaired while grinding. The vertical cutting feed rate of a grinding wheel into a work piece should be within the range of 0.005-0.1 micron for each rotation of the working surface of the wheel and change linearly or stepwise. The cutting speed of the grinding wheel in a horizontal (rotational) direction should be within the range of 25 to 75 m/sec. With this arrangement, the contact pressure and grinding heat that is generated between the work piece and the hard abrasive grains during grinding are combined. In other words, mechanical and thermal actions are combined.