摘要:
A high-strength silicon nitride sintered body having a flexural strength of 100 kg/mm.sup.2 or higher and a process for producing the same are disclosed, the sintered body comprising not less than 90% by weight of a single crystalline phase of silicon aluminum oxynitride (Si.sub.6-z Al.sub.2 O.sub.z N.sub.8-z, wherein z is a number of from 0 to 4.2) having an average longer diameter of not more than 5 .mu.m and an aspect ratio of not less than 5, the crystal phase constituting a network structure in the sintered body, the balance being a crystalline or amorphous (glassy) phase comprising one or more of oxides or oxynitrides of a rare earth metal, a group 3A metal, a group 2A metal or Si, and the process comprising mixing silicon nitride powder, an organic metal salt as a first sintering aid, and at least one of a metal oxide, a metal nitride, and a metal oxynitride as a second sintering aid, either separately or as a mixture of two or more thereof, with a solvent and a surface active agent, subjecting the mixture or mixtures to ultrasonic dispersion, mixing the mixtures together followed by drying to obtain a mixed powder, molding the mixed powder, and sintering the molded article at a temperature of from 1,600.degree. to 2,200.degree. C. in a non-oxidative atmosphere.
摘要:
A high-strength silicon nitride sintered body having a flexural strength of 100 kg/mm.sup.2 or higher and a process for producing the same are disclosed, the sintered body comprising not less than 90% by weight of a single crystalline phase of silicon aluminum oxynitride (Si.sub.6-z Al.sub.2 O.sub.z N.sub.8-z, wherein z is a number of from 0 to 4.2) having an average longer diameter of not more than 5 .mu.m and an aspect ratio of not less than 5, the crystal phase constituting a network structure in the sintered body, the balance being a crystalline or amorphous (glassy) phase comprising one or more of oxides or oxynitrides of a rare earth metal, a group 3A metal, a group 2A metal or Si, and the process comprising mixing silicon nitride powder, an organic metal salt as a first sintering aid, and at least one of a metal oxide, a metal nitride, and a metal oxynitride as a second sintering aid, either separately or as a mixture of two or more thereof, with a solvent and a surface active agent, subjecting the mixture or mixtures to ultrasonic dispersion, mixing the mixtures together followed by drying to obtain a mixed powder, molding the mixed powder, and sintering the molded article at a temperature of from 1,600.degree. C. to 2,200.degree. C. in a non-oxidative atmosphere.
摘要翻译:公开了一种弯曲强度为100kg / mm 2以上的高强度氮化硅烧结体及其制造方法,所述烧结体包含不小于90重量%的氮化硅铝的单晶相( Si6-zAl2OzN8-z,其中z为0-4.2的数),平均长度不大于5μm,纵横比不小于5,构成烧结体网状结构的晶相 余量为包含稀土金属,3A族金属,2A族金属或Si族的氧化物或氮氧化物中的一种或多种的结晶或无定形(玻璃质)相,并且该方法包括将氮化硅粉末,有机金属 盐作为第一烧结助剂,以及作为第二烧结助剂的金属氧化物,金属氮化物和金属氮氧化物中的至少一种,分别地或作为其两种或多种的混合物与溶剂和表面活性剂 对混合物进行处理 或与超声分散体的混合物,将混合物混合在一起,然后干燥以获得混合粉末,模塑混合粉末,并在非氧化性气氛中在1600℃至2200℃的温度下烧结该模制品。
摘要:
There is provided a process for the production of a sintered article which comprises steps ofshaping a raw material powder comprising silicon nitride,thermally treating a shaped article in a non-oxidizing atmosphere at a temperature of 1300.degree. to 1650.degree. C. for at least 2 hours to form .beta.-silicon nitride of not less than 85% calculated from X-ray diffraction patterns and to increase a relative density of the article to not less than 80%, preferably to 80 to 85 %, andsintering the thermally treated article at a temperature of 1700.degree. to 2000.degree. C.
摘要:
The present invention relates to a silicon nitride sintered body [wherein the composition of Si.sub.3 N.sub.4 -first aid (Y.sub.2 O.sub.3 +MgO)-second aid (at least one of Al.sub.2 O.sub.3 and AlN)] falls within a range defined by lines joining points A, B, C and D in FIG. 1, the crystal phase of the sintered body contains both .alpha.-Si.sub.3 N.sub.4 and .beta.'-sialon, and the relative density is 98% or more. This sintered body is produced by subjecting a green compact of the above-described source to primary sintering in a nitrogen gas atmosphere at 1300 to 1700.degree. C. so that the relative density reaches 96% or more, and the precipitation ratio of the .alpha.-Si.sub.3 N.sub.4 crystal phases to the .beta.'-sialon crystal phase in the sintered body is in the range of from 40:60 to 80:20; and then subjecting the primary sintered body to secondary sintering in a nitrogen gas atmosphere at 1300 to 1700.degree. C. so that the relative density reaches 98% or more. The sintered body has superior strength properties, especially at ordinary temperatures, and can be produced with a high productivity in a high yield at a low cost.
摘要翻译:本发明涉及一种氮化硅烧结体[其中,Si 3 N 4 - 急救(Y 2 O 3 + MgO) - 辅助剂(Al 2 O 3和AlN中的至少一种)的组成]落在由连接点A,B, C和D。 如图1所示,烧结体的结晶相含有α-Si 3 N 4和β'-Sialon,相对密度为98%以上。 该烧结体是通过使上述源的生坯在1300〜1700℃的氮气气氛中进行一次烧结而制成的,使得相对密度达到96%以上, Si3N4晶相与烧结体中的β' - 赛隆结晶相的比例范围为40:60至80:20; 然后在1300〜1700℃的氮气气氛中使一次烧结体进行二次烧结,使得相对密度达到98%以上。 该烧结体具有优异的强度特性,特别是在普通温度下,可以低成本高产率地以高生产率生产。
摘要:
Described are sintered silicon nitride bodies useful as materials for parts required to have strength, especially excellent impact strength for items such as automobile parts and machine parts. The sintered Si.sub.3 N.sub.4 bodies contain 80-98 wt. % of silicon nitride and have a porosity not higher than 3% and an shock compressive elasticity limit of at least 15 GPa.
摘要翻译:描述了可用作对于诸如汽车部件和机器部件的物品具有强度,特别优异的冲击强度的部件的材料的烧结氮化硅体。 烧结的Si 3 N 4体含有80-98wt。 %的氮化硅,并且具有不高于3%的孔隙率和至少15GPa的冲击压缩弹性极限值。
摘要:
The present invention relates to a silicon nitride sintered body [wherein the composition of Si.sub.3 N.sub.4 -first aid (Y.sub.2 O.sub.3 +MgO)-second aid (at least one of Al.sub.2 O.sub.3 and AlN)] falls within a range defined by lines joining points A, B, C and D in FIG. 1, the crystal phase of the sintered body contains both .alpha.-Si.sub.3 N.sub.4 and .beta.'-sialon, and the relative density is 98% or more. This sintered body is produced by subjecting a green compact of the above-described source to primary sintering in a nitrogen gas atmosphere at 1300.degree. to 1700.degree. C. so that the relative density reaches 96% or more, and the precipitation ratio of the .alpha.-Si.sub.3 N.sub.4 crystal phases to the .beta.'-sialon crystal phase in the sintered body is in the range of from 40:60 to 80:20; and then subjecting the primary sintered body to secondary sintering in a nitrogen gas atmosphere at 1300.degree. to 1700.degree. C. so that the relative density reaches 98% or more. The sintered body has superior strength properties, especially at ordinary temperatures, and can be produced with a high productivity in a high yield at a low cost.
摘要:
Disclosed is a silicon nitride sintered body produced by subjecting a green compact of a mixed powder composed of 1) a silicon nitride powder having a percentage .alpha. crystallization of 93% or more and a mean grain diameter of 0.7 .mu.m or less and 2) 5 to 15% by weight in total of a first sintering aid selected from among rare earth element, yttrium oxide and lanthanide oxides and a second sintering aid consisting of aluminum oxide or nitride and at least one selected from among oxides and nitrides of Mg, Ca and Li, to primary sintering in a nitrogen gas atmosphere under a pressure of 1.1 atm or less at 1500.degree. to 1700.degree. C.; and subjecting the sintered body to secondary sintering in a nitrogen gas atmosphere under a pressure of 10 atm or more at the primary sintering temperature or below, thereby giving a sintered body wherein the relative density of the sintered body is 99% or more and the precipitation ratio of an .alpha.-Si.sub.3 N.sub.4 (including .beta.'-sialon) crystal phase ranges from 1:3 to 1:8 in terms of the peak intensity ratio in X-ray diffraction.
摘要:
To lighten the weight of an electromagnetic actuator and a valve-open-close mechanism by forming the stems from a lighter material than conventional. A pair of electromagnets formed of stators and coils are opposed to each other with a gap therebetween. An armature is disposed in the gap so as to be reciprocable between one electromagnet and the other electromagnet by the electromagnets. A first stem for transmitting the movement of the armature from one electromagnet toward the other electromagnet to a valve of the internal combustion engine is inserted in a guide hole formed in the stator of one electromagnet. The first stem is formed of a lighter material than the armature to lighten the weight of the electromagnetic actuator and a valve-open-close mechanism of an internal combustion engine.
摘要:
A valve-open-close mechanism is proposed which has parts designed to reduce friction during sliding. The electromagnetic actuator comprises a pair of electromagnets each having a stator and a coil opposed to each other with a gap therebetween, an armature disposed in the gap, and a first stem for transmitting to external the movement of said armature. A retainer and a first return spring are provided on the valve. A second stem is provided at other side of the armature and another retainer and a second return spring are provided for the second stem. A coating film is formed on at least one of the surface or end face of the stem portion of the valve, end faces of the first return spring or second return spring, spring bearing end faces of the retainers, surface or end face of the second stem, and the surface of the armature.
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 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.