摘要:
The preset invention provides a ceramic adjusting shim capable of minimizing the abrasion of parts contacting the adjusting shim, for example, a cam and a tappet. The ceramic adjusting shim is produced from a ceramic material and has a surface roughness of 0.05 to 0.2 .mu.m in ten-point average roughness Rz.
摘要:
The present invention provides an improved adjusting shim used in a valve train for an internal combustion engine for an automobile. The adjusting shim produced from a base material consisting of a ceramic material containing 80 to 98 wt. % of silicon nitride and/or sialon and has a porosity of not more than 3%, a bending strength of not less than 1.0 GPa and an impact compressive elastic limit (Hugoniot elastic limit) of not less than 15 GPa, wherein the base material is provided on the surface thereof which contacts a cam with a ceramic surface layer having a composition different from that of the base material and a hardness lower than that of the base material. The adjusting shim of the present invention enables a power loss of a valve train to be minimized; the abrasion resistance thereof to be improved; and the fuel economy, the performance and durability of an internal combustion engine to be improved.
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:
A combination of an adjusting shim and a cam used in a valve train in an internal combustion engine for automobiles, the adjusting shim composed of a ceramic material which sets the surface roughness of a sliding surface of the adjusting shim with respect to a cam to not more than 0.1 .mu.m in ten-point mean roughness Rz, and which contains not less than 60 vol. % of silicon nitride or sialon, and the cam composed of cast iron a surface of which is chill hardened and then provided with a phosphate film thereon. The combination of an adjusting shim and a cam is capable of smoothing a sliding surface of the cam by the break-in of the part even if the cam is not subjected to a super-precision finishing process; preventing the seizure and abnormal abrasion of sliding surfaces; stabilizing a smoothed condition of the sliding surfaces of the cam and shim for a long period of time; and providing excellent sliding characteristics of the sliding surfaces owing to a decrease in the friction coefficient thereof.
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:
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.
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.
摘要:
A silicon nitride sintered body characterized by comprising crystal grains having a linear density of 60 to 120 per 50 .mu.m length as measured in an arbitrary two-dimensional section of the sintered body. The silicon nitride sintered body has a shock compressive elasticity limit (Hugoniot-elastic limit) of 15 GPa or more and is substantially composed of crystal phases of .alpha.-silicon nitride and .beta.'-sialon. The percentages of the .alpha.-silicon nitride and .beta.'-sialon are not more than 30% and not less than 70%, respectively. The silicon nitride sintered body is particularly excellent in mechanical strengths at room temperature as well as in productivity and cost efficiency and is useful for applications as the material of parts where a particularly high impact strength is required, such as a valve train mechanism for automobile parts.
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.