Showing papers on "Silicon carbide published in 1976"
TL;DR: Sialons as mentioned in this paper are phases in the Si-Al-O-N and related systems and are comparable in variety and diversity with the mineral silicates, and are built up of one-, two-, and threedimensional arrangements of (Si, Al) (O, N)4 tetrahedra.
Abstract: Although silicon nitride is at present a leading contender for gas turbines and other hightemperature engineering applications, it is only the first of a wide field of nitrogen ceramics, other members of which offer better prospects for technological exploitation. “Sialons” are phases in the Si-Al-O-N and related systems and are comparable in variety and diversity with the mineral silicates. They are built up of one-, two-, and threedimensional arrangements of (Si, Al) (O, N)4 tetrahedra in the same way that the fundamental structural unit in the silicates is the SiO4 tetrahedron. These new oxynitrides include structure types based uponα andΒ silicon nitrides, silicon oxynitride, aluminium nitride and silicon carbide, eucryptite, spinel, melilite and apatite. They are being explored for their thermal, mechanical, chemical and electrical properties.
838 citations
TL;DR: In this article, the synthesis of continuous β-SiC fibres by a new process: the conversion of organometallic polymers to inorganic substances was studied, and the transformation process and the structure and mechanical properties of these fibres were studied.
Abstract: MUCH work has been done on preparing heat-resistant silicon carbide materials in fibrous form, since plastics or metals can be reinforced with them to obtain very heat-resistant material of great mechanical strength. SiC whiskers1 are, however, impractical because of their shortness (several mm), their non-uniform diameter and high cost of production. SiC-on-W (ref. 2) and SiC-on-C (ref. 3) filaments have been produced by chemical vapour methods. These coated filaments are more expensive, and the treatment for making such composite materials requires careful control. We report here on the synthesis of continuous β-SiC fibres by a new process: the conversion of organometallic polymers to inorganic substances. We have studied the transformation process and the structure and mechanical properties of these fibres.
464 citations
TL;DR: In this article, the authors showed that the oxidation of silicon carbide, hot-pressed with ∼ 4 wt % Al2O3, in 1 atm dry oxygen follows classical parabolic behaviour with an activation energy of 481 kJ mol−1 in the temperature range 1200 to 1400° C.
Abstract: The oxidation of silicon carbide, hot-pressed with ∼ 4 wt % Al2O3, in 1 atm dry oxygen follows classical parabolic behaviour with an activation energy of 481 kJ mol−1 in the temperature range 1200 to 1400° C. The oxide film consists predominantly of cristobalite and a glassy phase in which additive (Al) and various impurity elements (Fe, Na, K, etc) concentrate. The desorption of CO(g) from the SiC/SiO2 interface appears to be oxidation rate controlling.
147 citations
TL;DR: A thermodynamic analysis of the stability of Si3N4 and SiC is presented in this article, which can be employed to assess their suitability for use at high temperatures in various environments.
134 citations
Patent•
22 Apr 1976TL;DR: In this article, a method of making a dense silicon carbide ceramic is disclosed involving the steps of homogeneously dispersing silicon carbides with a sufficient amount of a boron containing additive and a carbonaceous additive, forming the powder mixture into a shaped green body and then sintering the body in a controlled atmosphere and in the absence of external pressure at a temperature of about 1900°-2100° C.
Abstract: A method of making a dense silicon carbide ceramic is disclosed involving the steps of homogeneously dispersing silicon carbide with a sufficient amount of a boron containing additive and a carbonaceous additive, forming the powder mixture into a shaped green body and then sintering the body in a controlled atmosphere and in the absence of external pressure at a temperature of about 1900°-2100° C. such that density of the body is at least 85% of the theoretical density of silicon carbide. The complex shaped silicon carbide product formed thereby is also disclosed.
114 citations
TL;DR: In this paper, the authors investigated the erosion of pyrolytic graphite and silicon carbide due to the bombardment with monoenergetic hydrogen ions with energies of 600 to 7500 eV in the temperature range of near room temperature to 750°C.
106 citations
101 citations
TL;DR: In this paper, the corrosion behavior of sintered SiC in gaseous environments and alkaline melts was investigated at 900°C, where SiC formed a dense coherent surface film of SiO2 which was not corroded by thin layers of condensed sodium sulfate.
Abstract: The corrosion behavior of sintered SiC in gaseous environments and alkaline melts was investigated at 900°C. In oxidizing atmospheres such as normally exist in a gas turbine, SiC forms a dense coherent surface film of SiO2 which is not corroded by thin layers of condensed sodium sulfate. However, under some conditions, especially when very low oxygen pressures are maintained at the SiC surface or when basic salt melts or slags containing carbonaceous material are present, rapid corrosion of the ceramic can occur. On the other hand, SiC is inert in pure N2, H2, or H2-H2S mixtures at 900°C. These different modes of behavior are discussed in the context of possible high- temperature applications of SiC ceramics.
83 citations
TL;DR: In this article, the authors describe the deposition of cubic and 6 H silicon carbide onto 6 H substrates, and the influence of the deposition parameters (e.g. temperature, gas composition and flow rate) are discussed.
79 citations
Patent•
13 Dec 1976
TL;DR: In this paper, continuous silicon carbide fibers composed of aluminum, aluminum alloy or magnesium alloy matrix were used to construct a light metal composite materials reinforced with continuous silicon carbonide fibers.
Abstract: Light metal composite materials reinforced with novel continuous silicon carbide fibers composed of aluminum, aluminum alloy or magnesium alloy matrix and the continuous silicon carbide fibers containing 0.01-40% by weight of free carbon, in which the free carbon is reacted with aluminum or added metal elements in the aluminum alloy or magnesium alloy to form carbides. When the silicon carbide fibers are coated with a metal or ceramics, the wettability of the silicon carbide fibers to said matrix is more improved.
66 citations
Patent•
21 Jun 1976TL;DR: In this article, a silicon carbide sintered body characterized by its microstructural stability at high temperatures is produced by forming a mixture of β-silicon carbide powder, α-sensor carbide seeding powder, boron additive and a carbonaceous additive into a green body.
Abstract: A silicon carbide sintered body characterized by its microstructural stability at high temperatures is produced by forming a mixture of β-silicon carbide powder, α-silicon carbide seeding powder, boron additive and a carbonaceous additive into a green body and sintering it to produce a sintered body with a density of at least 80% wherein at least 70% by weight of the silicon carbide is α-silicon carbide.
Patent•
19 Apr 1976
TL;DR: In this article, the authors show that silicon carbide fibers having high tensile strength are produced by dissolving at least one of organosilicon high molecular weight compounds having a softening point of higher than 50°C, in which silicon and carbon are the main skeleton components.
Abstract: Silicon carbide fibers having a high tensile strength are produced by (1) dissolving at least one of organosilicon high molecular weight compounds having a softening point of higher than 50° C, in which silicon and carbon are the main skeleton components, in a solvent for the organosilicon high molecular weight compounds or heating and melting said organosilicon high molecular weight compounds to prepare a spinning solution and spinning said spinning solution into filaments, (2) preliminarily heating the spun filaments at a temperature of 350°-800° C under vacuum to volatilize low molecular weight compounds contained in the high molecular weight compounds, and (3) baking the thus treated filaments at a temperature of 800°-2,000° C under vacuum or at least one non-oxidizing atmosphere selected from the group consisting of an inert gas, CO gas and hydrogen gas, to form silicon carbide fibers.
TL;DR: In this article, the migrational behaviour of a number of metallic fission products in the coated UO2 particle fuel, proposed for High-Temperature Reactors, is described and the derivation of parameters enabling calculations to be made of the release of selected important isotopes is also discussed, particularly with reference to Trisco coated particles in which the silicon carbide layer is either defective or absent.
TL;DR: In this article, the electrical effects of included silicon carbide (SiC) particles in edge-defined film-fed grown silicon ribbons have been examined by employing a scanning electron microscope operated in the electron-beam-induced current mode.
Abstract: The electrical effects of included silicon carbide (SiC) particles in edge‐defined film‐fed grown silicon ribbons have been examined. By employing a scanning electron microscope operated in the electron‐beam‐induced current mode, as well as observing the effects of SiC particles on solar‐cell characteristics, the electrical activity of particles and particle‐generated defects were studied. The influence of SiC particles largely appears to be a result of impurity accumulation around them rather than a direct effect of the inclusions.
TL;DR: The Schottky barrier heights for Au, Al, and Ba on diamond are reported in this article, and the variation of the barrier energy with metals is found to be small.
Patent•
Avco1
TL;DR: In this article, a silicon carbide filament containing an inner and outer surface layer of carbon rich silicon carbides, together with a method of making the same, is described, and a method to make the same is described.
Abstract: A refractory substrate, which generally is graphite or carbon is overcoated with silicon carbide by chemical vapor deposition from gaseous sources of silicon and carbon. The deposition generally takes place in combination with hydrogen and the coating on the substrate generally has a thickness at least equal to the diameter of the substrate itself. A silicon carbide filament containing an inner and outer surface layer of carbon rich silicon carbide, together with a method of making the same, is described.
Patent•
03 Aug 1976TL;DR: In this paper, a molding surface formed of silicon carbide (SiC) or silicon nitride (Si3N4) is used to mold glass elements to finish surfaces.
Abstract: METHOD OF MOLDING GLASS ELEMENTS ABSTRACT OF THE DISCLOSURE Molding of finished surfaces on glass elements is achieved by conforming the glass to a molding surface formed of silicon carbide (SiC) or silicon nitride (Si3N4). Preparation of glass elements by this method of molding eliminates the necessity for any conventional grinding or polishing operations.
Patent•
18 Oct 1976
TL;DR: In this article, a heat-resistant composite material reinforced with continuous silicon carbide fibers is produced by forming a powdery ceramics matrix and the fibers into a composite, and pressing and heating the composite into a sintered composite.
Abstract: A heat-resistant composite material reinforced with continuous silicon carbide fibers is produced by forming a powdery ceramics matrix and the fibers into a composite, and pressing and heating the composite into a sintered composite. The composite material is excellent in the mechanical strength at a high temperature, heat resistance, oxidation resistance and corrosion resistance.
TL;DR: In this paper, the possibility that such calibrations are neutron flux dependent is discussed and the need for a fast reactor calibration experiment is identified, and the possibility of a fast reaction time experiment is discussed.
Patent•
22 Nov 1976
TL;DR: In this article, a high-density, high-strength silicon carbide ceramic material that is produced using a silicon carbides powder containing boron or boroni-containing compound as a densification additive by the utilization of BORON in the sintering atmosphere is described.
Abstract: Disclosure is made of a high-density, high-strength silicon carbide ceramic material that is produced using a silicon carbide powder containing boron or boron-containing compound as a densification additive by the utilization of boron in the sintering atmosphere.
TL;DR: In this article, the authors discuss the properties of the refractory coating materials and the ways in which they can be modified for special applications, e.g. isotropic pyrocarbon coatings for bioengineering purposes.
Patent•
21 Jun 1976
TL;DR: In this article, the Disclosure Silicon carbide sintered moldings having a high flexural strength and various excellent properties are produced by mixing SiC powders or SiC fibers with a binder of organosilicon low molecular weight compounds or organo-silicon high molecular weight compound, molding the mixture into a desired shape and heating the molded mixture at a high temperature.
Abstract: of the Disclosure Silicon carbide sintered moldings having a high flexural strength and various excellent properties are produced by mixing SiC powders or SiC fibers with a binder of organosilicon low molecular weight compounds or organo-silicon high molecular weight compounds, molding the mixture into a desired shape and heating the molded mixture at a high temperature.
Patent•
04 Aug 1976TL;DR: In this paper, a mixture of β-silicon carbide, boron carbide and a carbonaceous additive is formed into a green body and sintered producing a sintering body with a density of at least about 85% containing borone carbide in an amount ranging from about 10% to about 30% by weight of the total amount of silicon carbide.
Abstract: A particulate mixture of β-silicon carbide, boron carbide and a carbonaceous additive is formed into a green body and sintered producing a sintered body with a density of at least about 85% containing boron carbide in an amount ranging from about 10% to about 30% by weight of the total amount of silicon carbide and boron carbide present.
TL;DR: In this article, the fabrication methods for diodes with emission in the blue region of the spectrum are described, and emission spectra and efficiency data are presented for several types of Diodes.
Abstract: Silicon carbide light-emitting diodes have been produced by vapour growth techniques and liquid-phase epitaxy. The fabrication methods for diodes with emission in the blue region of the spectrum are described. Emission spectra and efficiency data are presented for several types of diodes.
Patent•
13 Feb 1976
TL;DR: In this paper, an improved sintered tungsten carbide insert and surface conditioning method was used to improve retention within an interferringly sized hole and to decrease the frequency of fracture of the inserts.
Abstract: In an earth boring tool an improved sintered tungsten carbide insert and surface conditioning method to improve retention within an interferringly sized hole and to decrease the frequency of fracture of the inserts. The insert has a randomly varied surface finish that is obtained from abrasive treatment with particles having hardness greater than 9.0 on Mohs' Scale. The particles are selected from the class consisting of silicon carbide, boron carbide, boron, and diamond. The resulting surface has asperities varying from a maximum value, smaller than that formed by grinding, to a minimum value, larger than the mat finish obtained by abrading with aluminum oxide.
TL;DR: In this article, the synthesis of high purity SiC mouldings with high mechanical strength by low temperature (1,000−1,400 °C) sintering of SiC powders bond with three-dimensional polycarbosilanes is described.
Abstract: As is well known, silicon carbide is a practical heat-resisting material, because it has high strength and excellent oxidation, corrosion and thermal shock resistance. It is, however, difficult to obtain it as a sintered body because of its poor sintering characteristics. The usual method1 for obtaining SiC with high flexural strength are to add a sintering promoter to fine SiC powder followed by hot pressing. The process is complicated and not suitable for obtaining large products. We here report the synthesis of high purity SiC mouldings with high mechanical strength by low temperature (1,000−1,400 °C) sintering of SiC powders bond with three-dimensional polycarbosilanes. The method is based on the conversion of an organosilicon polymer to the inorganic compound by heat treatment2–5.
TL;DR: In this article, a thermodynamic analysis of the equilibrium in the SiC-H2 system has been carried out at various constant pressures (1, 5 × 10-1, and 10-2 atm) over the 1500-3000 K temperature range.
Patent•
17 Mar 1976
TL;DR: A metal processing furnace of the indirect arc type having opposed electrodes projected into and establishing an ionized atmosphere in the furnace crucible is provided with apparatus that introduces a finely divided charge mixture consisting essentially of silica and coke into the system for free-fall into and through the ionised atmosphere as discussed by the authors.
Abstract: A metal processing furnace of the indirect arc type having opposed electrodes projected into and establishing an ionized atmosphere in the furnace crucible is provided with apparatus that introduces a finely divided charge mixture consisting essentially of silica and coke into the system for free-fall into and through the ionized atmosphere. Following reaction of the mixture's ingredients in the ionized atmosphere, silicon carbide crystals are deposited at the bottom of the furnace interior below the ionized atmosphere for subsequent collection and removal from within the furnace system. By control of charge composition and process parameters, silicon carbide crystals having predominantly either alpha or beta crystalline structures and with crystal sizes predominantly in the range of 250 to 3,000 microns are produced.
Patent•
09 Apr 1976TL;DR: A silicon carbide body with a density of at least 85% is machined to required specification and then fired at a temperature ranging from 1400°C to 2100°C in a firing atmosphere ranging in pressure from 10-3 torr to 25 torr as discussed by the authors.
Abstract: STRENGTH IMPROVEMENT IN MACHINED SiC BODIES Abstract of the Disclosure A silicon carbide body with a density of at least 85% is machined to required specification and then fired at a temperature ranging from 1400°C to 2100°C in a firing atmosphere ranging in pressure from 10-3 torr to 25 torr to increase its fracture strength by at least 10%.