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:
In order to provide a rare earth oxide-alumina type sintered body having no defect such as void and pore, and high strength, toughness and reliability, silica is added to a mixture of rare earth oxide and alumina to control a crystal grain size of the sintered body to not more than 30 .mu.m, whereby abnormal grain growth and occurrence of pore are restrained to produce a practically usable rare earth oxide-alumina-silica sintered body having excellent strength and toughness and uniform structure. According to this production method, rare earth oxide-alumina-silica sintered bodies having no defect such as void and pore, and high strength, toughness and reliability can easily be obtained.
摘要:
In order to provide a mixed oxide ceramic sintered body having no defect such as void and pore, and high strength, toughness and reliability, a mixed oxide of rare earth oxide-alumina oxide added with silica is fired with a non-oxide mixture of SiC and/or Si.sub.3 N.sub.4. In the production method, the crystal grain size of the sintered body is controlled to not more than 30 .mu.m, and abnormal grain growth and occurrence of pore can be restrained to easily produce a practically usable mixed oxide ceramic sintered body having excellent toughness inherent to oxide sintered body and excellent high-temperature strength inherent to SiC and Si.sub.3 N.sub.4 and uniform structure.
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.
摘要:
A zirconia film formed on a substrate and having substantially one or two kinds of particular planes such as (200), (111) or (111) planes only oriented in parallel to the surface of the substrate, and a process for preparing it. This zirconia film is dense, and improved in the thermal resistance, thermal insulation properties and corrosion resistance.
摘要:
The present invention relates to a method of producing a functionally grant material whose components and structure are continuously adjusted by the coating, plating and powder metallurgy techniques to change its function in turn and provide a method of producing a functionally gradient material superior in heat-resistance, corrosion-resistance and resistance to thermal fatigue by distributing a third component having a lower Young's modulus or formed of high-strength material sufficiently durable to the fracture strength among ceramics as a first component and metals or other ceramics as a second component to change the function.
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:
The present invention provides pitch conversion processing technology capable of minimizing the distortion of speech sound naturalness. A speech waveform in a pitch-unit is considered to be divided into two segments: 1) the segment of β, that starts from the minus peak, where the waveform depending on the shape of vocal tracts appears, and 2) the segment of γ where the waveform depending on the vocal tract shape is attenuating and converging on the next minus peak. In addition, α is the point where a minus peak appears along with the glottal closure. Based on characteristics of speech waveforms, the present invention processes waveform for converting pitch in the segment of γ just before the next minus peak, which is least affected by the minus peak associated with the glottal closure. As such, waveform processing can be performed by keeping the complete contour of waveform at around the peak, and thereby reducing the effects of pitch conversion.
摘要:
A crystalline sialon comprising crystals containing aluminum, silicon, nitrogen and oxygen, in which the crystal structure has a hexagonal system wurtzite structure identical with that of AlN crystals, and the volume of the unit cell thereof has a value smaller than that of the AlN crystals. The crystalline sialon can be synthesized by mixing a silicon-containing gas, an aluminum halide, a nitrogen atom-containing gas and an oxygen atom-containing gas, converting the gas mixture into plasmas by microwave discharging and depositing a film on the surface of a substrate, in which the temperature of the substrate, while controlling a flow rate of the silicon-containing gas and a flow rate of the oxygen-containing gas. The crystalline sialon of the present invention has high hardness, is excellent in oxidation resistance, as well as excellent in heat conductivity and adhesion with a superhard 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.