摘要:
A super hard-highly pure silicon nitride includes a preferentially oriented crystalline silicon nitride having a grain size of 1-50 .mu.m and a micro Vickers hardness of 3,000 kg/mm.sup.2 under a load of 100 g, a finely grained crystalline silicon nitride having an average grain size of less than 1 .mu.m and a micro Vickers hardness of 3,500 kg/mm.sup.2 under a load of 100 g, and an amorphous silicon nitride having a micro Vickers hardness of 2,200 kg/mm.sup.2 under a load of 100 g, and is produced by blowing a nitrogen depositing source and a silicon depositing source on a substrate heated at 500.degree.-1,900.degree. C. with a blowpipe composed of a pipe assembly wherein a first pipe for the nitrogen depositing source is surrounded with the second pipe for silicon depositing source and the distance from an opening end of the first pipe to the substrate is shorter than a distance from an opening end of the second pipe to the substrate.
摘要:
An Si.sub.3 N.sub.4 -Al.sub.2 O.sub.3 composite sintered body suitable for use in high-temperature structural materials consists of .alpha.-Al.sub.2 O.sub.3 and at least one crystal phase of Si.sub.3 N.sub.4 and sialon and is produced by sintering a shaped body of a particular Si.sub.3 N.sub.4 -Al.sub.2 O.sub.3 mixed powder at 1,500.degree.-1,900.degree. C.
摘要:
A super hard-highly pure silicon nitride includes a preferentially oriented crystalline silicon nitride having a grain size of 1-50 .mu.m and a micro Vickers hardness of 3,000 kg/mm.sup.2 under a load of 100 g, a finely grained crystalline silicon nitride having an average grain size of less than 1 .mu.m and a micro Vickers hardness of 3,500 kg/mm.sup.2 under a load of 100 g, and an amorphous silicon nitride having a micro Vickers hardness of 2,200 kg/mm.sup.2 under a load of 100 g, and is produced by blowing a nitrogen depositing source and a silicon depositing source on a substrate heated at 500.degree.-1,900.degree. C. with a blowpipe composed of a pipe assembly wherein a first pipe for the nitrogen depositing source is surrounded with a second pipe for the silicon depositing source and the distance from an opening end of the first pipe to the substrate is shorter than the distance from an opening end of the second pipe to the substrate.
摘要:
A super hard-highly pure silicon nitride includes a preferentially oriented crystalline silicon nitride having a grain size of 1-50 .mu.m and a micro Vickers hardness of 3,000 kg/mm.sup.2 under a load of 100 g, a finely grained crystalline silicon nitride having an average grain size of less than 1 .mu.m and a micro Vickers hardness of 3,500 kg/mm.sup.2 under a load of 100 g, and an amorphous silicon nitride having a micro Vickers hardness of 2,200 kg/mm.sup.2 under a load of 100 g, and is produced by blowing a nitrogen depositing source and a silicon depositing source on a substrate heated at 500.degree.-1,900.degree. C. with a blowpipe composed of a pipe assembly wherein a first pipe for the nitrogen depositing source is surrounded with a second pipe for the silicon depositing source and the distance from an opening end of the first pipe to the substrate is shorter than the distance from an opening end of the second pipe to the substrate.
摘要:
A super hard-highly pure silicon nitride includes a preferentially oriented crystalline silicon nitride having a grain size of 1-50 .mu.m and a micro Vickers hardness of 3,000 kg/mm.sup.2 under a load of 100 g, a finely grained crystalline silicon nitride having an average grain size of less than 1 .mu.m and a micro Vickers hardness of 3,500 kg/mm.sup.2 under a load of 100 g, and an amorphous silicon nitride having a micro Vickers hardness of 2,200 kg/mm.sup.2 under a load of 100 g, and is produced by blowing a nitrogen depositing source and a silicon depositing source on a substrate heated at 500.degree.-1,900.degree. C with a blowpipe composed of a pipe assembly wherein a first pipe for the nitrogen depositing source is surrounded with a second pipe for the silicon depositing source and the distance from an opening end of the first pipe to the substrate is shorter than the distance from an opening end of the second pipe to the substrate.
摘要:
A super hard-highly pure silicon nitride includes a preferentially oriented crystalline silicon nitride having a grain size of 1-50 .mu.m and a micro Vickers hardness of 5,000 kg/mm.sup.2 under a load of 100 g, a finely grained crystalline silicon nitride having an average grain size of less than 1 .mu.m and a micro Vickers hardness of 3,500 kg/mm.sup.2 under a load of 100 g, and an amorphous silicon nitride having a micro Vickers hardness of 2,200 kg/mm.sup.2 under a load of 100 g, and is produced by blowing a nitrogen depositing source and a silicon depositing source on a substrate heated at 500.degree.-1,900.degree. C. with a blowpipe composed of a pipe assembly wherein a first pipe for the nitrogen depositing source is surrounded with a second pipe for the silicon depositing source and the distance from an opening end of the first pipe to the substrate is shorter than the distance from an opening end of the second pipe to the substrate.
摘要:
An alumina-zirconia-silicon carbide sintered ceramic composite having high strength and high hardness is composed of 5 to 50 volume percent of partially stabilized zirconia powder of mean particle size between 0.1 and 1.0 .mu.m, 3 to 40 volume percent of silicon carbide powder of mean particle size smaller than 1 .mu.m or silicon carbide whiskers of 1 .mu.m or less in diameter with an aspect ratio between 3 and 200 or combination of said silicon carbide powder and said silicon carbide whiskers, the balance being substantially alumina powder, wherein zirconia plus silicon carbide accounts for 55 volume percent at most of the total.The sintered ceramic composite is manufactured by making a mixed powder composed of 5 to 50 volume percent of partially stabilized zirconia powder of mean particle size between 0.1 and 1.0 .mu.m, 3 to 40 volume percent of silicon carbide powder of mean particle size smaller than 1 .mu.m or silicon carbide whiskers of 1 .mu.m or less in diameter with an aspect ratio between 3 and 200 or combination of said silicon carbide powder, and said silicon carbide whiskers, the balance being substantially alumina powder, wherein zirconia plus silicon carbide accounts for 55 volume percent at most of the total, and then sintering the molded mixed powder at a temperature between 1400.degree. and 1800.degree. C.Further, the mixed powder to be molded and sintered is made on a ball mill equipped with a pot made of one or more of the ceramic materials of which such sintered ceramic is composed.
摘要:
A super hard-highly pure silicon nitride includes a preferentially oriented crystalline silicon nitride having a grain size of 1-50 .mu.m and a micro Vickers hardness of 3,000 kg/mm.sup.2 under a load of 100 g, a finely grained crystalline silicon nitride having an average grain size of less than 1 .mu.m and a micro Vickers hardness of 3,500 kg/mm.sup.2 under a load of 100 g, and an amorphous silicon nitride having a micro Vickers hardness of 2,200 kg/mm.sup.2 under a load of 100 g, and is produced by blowing a nitrogen depositing source and a silicon depositing source on a substrate heated at 500.degree.-1,900.degree. C. with a blowpipe composed of a pipe assembly wherein a first pipe for the nitrogen depositing source is surrounded with a second pipe for the silicon depositing source and the distance from an opening end of the first pipe to the substrate is shorter than the distance from an opening end of the second pipe to the substrate.
摘要:
A method for advantageously producing sintered eutectic ceramics having a homogenous and dense structure, in particular, a eutectic containing a rare earth aluminate compound. The method allows eutectic powder of alumina and a rare earth aluminate compound to stand at a temperature of 1300-1700° C. for 1-120 minutes under vacuum or in an non-oxidative atmosphere under a pressure of 5-100 MPa using a spark plasma sintering apparatus, thereby causing crystal growth to occur to obtain a rare earth aluminate eutectic structure crystal.
摘要:
A drawing device 4 is mounted in a drawing shaft 3, and pipe replacement device A connected with new pipes is arranged on the side of starting shaft 2, wherein the drawing device 4 and the pipe replacement device A is connected through pull-rods 5 inserted into existing pipes with each other. The pipe replacement device A is comprised of a cutting part 11 including cutter bodies 14 (shanks 14a to 14i) arranged in the axial direction and at angular intervals in the circumferential direction, an expanding part 12 having expanding rollers 18a to 18f, and a connecting part 13. Each cutter body 14 has a plurality of cutting edges, wherein distances between the respective cutting edges and the center of the circle become larger in order from the forward side toward the backward side. While the pipe replacement device A is traveled in the inside of cast iron pipes, the inner wall of cast iron pipes is cut by the cutter bodies 14 to form grooves. Splitting of existing pipes into arc-shaped pieces 1a is made starting from the grooves. Arc-shaped pieces 1a are pressed into the ground, by which a tunnel 7 surrounded by arc-shaped pieces 1a and portions of consolidated earth is formed, while new pipes 6 are introduced into the tunnel 7, and besides the new pipes 6 are protected by protective armors formed of arc-shaped pieces 1a.