Method of producing silicon carbide

FIELD: chemistry.

SUBSTANCE: silicon carbide is obtained from a charge comprising nanopowder of silicon-containing (SiO, SiO2, H2SiO3) carbon-containing (a carbohydrate of the general formula Cn(H2O)m, where n ≥12; m=n-1, a polyhydric alcohol of the general formula CnH2n+2On, where n≥2, aldehyde or ketone derivatives of polyhydric alcohols of the general formula (CH2O)n, where n≥3, components, prepared in deionized water, with the subsequent stepwise heating in three stages: up to a temperature of 145-195°C with the maintaining for 1.5-3 hours, up to 800-1000°C, with the maintaining for 0.4-1 h, and up to 1450-1650°C, with the maintaining for 1-1.5 hours.

EFFECT: increasing the purification degree and the yield product of the order of 80-85% 3 etc.

3 ex

 



 

Same patents:

FIELD: chemistry.

SUBSTANCE: invention relates to obtaining raw material for making ceramic articles with a positive temperature coefficient of resistance (PTC ceramics) by injection moulding. Ceramic filler, which is converted to a PTC ceramic after firing, is mixed with a thermoplastic-based matrix. A granular material is obtained, which is used for injection moulding. The matrix and filler are mixed in a roller mill. The method is realised using tools with a low degree of wear such that material containing less than 10 ppm metallic impurities caused by wear is obtained. To this end, the surfaces of tools which might come into contact with the filler have a hard tungsten carbide-based coating. The basic materials used to obtain the ceramic are BaCO3, NiO2, MnSO4 and Y2O3, as well as at least one of the compounds SiO2, CaCO3, SrCO3, Pb3O4.

EFFECT: obtaining raw material with low content of impurities, which enables to preserve the necessary electrical properties in the moulded article.

5 cl, 3 dwg

FIELD: construction.

SUBSTANCE: method of wall ceramic items manufacture includes preparation of raw mixture and introduction of porophore into the raw mixture, plastic formation of items, drying and burning. Solid paraffin is introduced into the raw mixture as porophore at the following ratio of components, wt %: solid paraffin - 5.0-50.0; raw material - the remaining part of mixture.

EFFECT: advanced method of wall ceramic items manufacture to ensure possibility of porophore extraction from moulded and dried item before it is burnt and used in next process cycle.

2 cl, 1 tbl

The invention relates to the technology of the hard magnetic ferrites and can be used in the manufacture of film magnets
The invention relates to the technology of carbon-containing refractory materials based on refractory oxides or silicon carbide and can be used in refractory and metallurgical industries

The invention relates to ceramic homogeneous suspensions of ceramic powder and the method of their preparation

FIELD: process engineering.

SUBSTANCE: invention relates to production of construction materials and can be used for reconstruction and designing of brick soft-mud forming plants. Proposed line comprises extrusion press, open-frame automatic cutter, brick automatic stacker and drier. Note here that, additionally, this line is equipped with drying frames with T-like pillars and automatic stacker to place frames with bricks on drying frames. Automatic stacker consists of transition roll table, step conveyor, grouping conveyor and lifter with arms. Drying frames with bricks are fed into driers by means of stackers over smooth floor. Note here they are arranged in two tiers inside drying chamber over it height onto t-like pillars of said drying frames.

EFFECT: reduced production floor and amount of automatic hardware, lower metal input.

7 dwg

FIELD: construction.

SUBSTANCE: composition of a charge for high-porosity ceramic material with latticed-cellular structure for catalyst carriers comprises an inert filler - electrically molten corundum and disperse phase with a strengthening additive. At the same time to increase material strength, they use a high-aluminous porcelain mass as a disperse phase, and the strengthening additive is a composition MgO+SiC, providing for formation of the phase of eutectic composition in the system MgO-SiO2 when baked in the temperature range of 1250-1300°C with the following ratio of components: electrically molten corundum - 5-20 wt %, high-aluminous porcelain mass - 76.5-90 wt %, strengthening additive MgO+SiC - 3.5-5 wt %.

EFFECT: usage of the specified composition makes it possible to manufacture high-porosity strong ceramic materials with latticed-cellular structure with higher mechanical compression strength with preservation of total volume open porosity.

3 ex

Ceramic material // 2515757

FIELD: chemistry.

SUBSTANCE: ceramic material of the chemical formula AgBaPb3Oz, where z=(4.5-6) depending on synthesis conditions, is produced. The ceramic material has stable strength and electrical properties with respect to cooling to liquid nitrogen temperature and subsequent heating to room temperature. Initial resistance of samples depends on the pressure of pressing articles and high-temperature sintering process.

EFFECT: enabling use of the material when making nanoelectronic elements, active elements of cryoelectronic circuits operating in space vacuum and cold conditions and using novel conducting ceramic materials with a very low temperature coefficient of change in resistance.

6 dwg

FIELD: machine building.

SUBSTANCE: proposed method comprises making ceramic plate work pieces and their grinding. Prior to grinding, said plates are arranged between grinding wheels to allow their differential rotation relative to the latter, their relative rpm being defined by the following relationship: NL=n1/n2, where n1 is ceramic plate rpm, min-1, n2 is grinding wheel rpm, min-1. Aster grinding, wear-resistant coat is applied on functional surface of the plate by vacuum-plasma deposition of the following composition in wt %: titanium - 40, niobium - 40, aluminium - 20.

EFFECT: higher bending strength and crack-resistance, higher reliability.

2 dwg

FIELD: chemistry.

SUBSTANCE: method involves (a) making a first grid structure from a plurality of solid particles, wherein the structure is made such that it includes one or more voids between particles and the voids are at least partially filled with material of a first fluid medium; (b) partial displacement of the material of the first fluid medium by a material which fills the fluid medium such that the material which fills the fluid medium partially enters the voids in the grid structure; (c) at least partial hardening of the material which fills the fluid medium entering the voids of the grid structure to form a composite material; and (d) removing at least a portion of solid particles from the composite material to form one or more pores in the hardened filling material where said portion is removed.

EFFECT: designing a method of producing and the obtained porous composite material with improved properties.

42 cl, 1 tbl, 44 dwg, 29 ex

FIELD: chemistry.

SUBSTANCE: invention relates to production of boron suboxide composite material which can be used as an abrasive. The composite material contains crushed or granulated boron suboxide, AlxByOz distributed in a binding phase, where x ranges from 4 to 8, y ranges from 2 to 4 and z ranges from 9 to 33. The amount of the binding phase is less than 30% of the mass of the composite material, preferably 3-15 wt %. In order to obtain the composite material, a coating of aluminium or aluminium compound is applied on the boron suboxide particles and then sintered at temperature higher than 1600°C and pressure lower than 300 MPa.

EFFECT: high impact viscosity of the material.

9 cl, 4 ex, 1 tbl

FIELD: chemistry.

SUBSTANCE: invention relates to the technology of ceramic materials, particularly to zirconium dioxide based materials, and can be used in making articles with a complex shape, particularly parts of friction bearings and other friction pairs. The method of increasing crack resistance of zirconium dioxide based materials involves laser treatment of the surface of the zirconium dioxide crystal, carried out in pulsed mode of the laser with pulse duration of 1.5-4 ms, pulse-repetition frequency of 20 Hz, radiation energy of the laser pulses equal to 3-5 J and laser beam scanning rate of the surface of the crystal equal to 150 mm/min. Laser treatment of the surface of the crystal leads to local heating accompanied by phase conversion, which provides the required crystallographic structure.

EFFECT: high crack and wear resistance of zirconium dioxide based materials with possibility of obtaining given mechanical properties on separate areas of the ceramic specimen.

FIELD: chemistry.

SUBSTANCE: invention relates to production of high-temperature superconducting materials used in making solenoids, high-speed counter devices, medical equipment, as well as in cryogenic engineering. The technical result is achieved due to that the mixture for making superconducting ceramic material contains powdered yttrium oxide, copper and barium peroxide, a transition metal oxide selected from chromium (VI) oxide; iron (III) oxide; cobalt oxide; manganese (III) oxide; nickel (II) oxide or zinc (II) oxide, as well as in hyperstoichiometric ratio - potassium or sodium perchlorate, with the following ratio of components, wt %: yttrium oxide 17.29-17.58, barium peroxide 51.85-52.73, copper 26.27-29.69, sodium perchlorate 2.74-6.67 or potassium perchlorate 3.08-7.48; chromium oxide CrO3 1.55-4.59 or cobalt oxide Co3O4 1.23-3.72, or manganese oxide Mn2O3 1.22-3.66, or iron oxide Fe2O3 1.24-3.70, or nickel oxide NiO 1.16-3.47, or zinc oxide ZnO 1.26-3.77.

EFFECT: obtaining end product in a Y-Ba-Cu-O system, which contains a transition metal (Fe; Co; Ni; Mn; Cr or Zn) due to shortage of copper while simultaneously simplifying the process of producing high-temperature superconducting material in combustion mode.

1 ex, 1 tbl

FIELD: medicine.

SUBSTANCE: hereby is described new method of obtaining highly densified and at least partly but preferably completely or almost completely hydrated ceramic material designed for use in pharmaceutical composition manufacture, in particular for controlled release of one or more therapeutic, prophylactic and/or diagnostic compound. Method includes concomitant hydration and densification stage of biologically resolving and hydrating ceramic material such as calcium sulfate.

EFFECT: invention also belongs to compositions containing such ceramic highly densified material pharmaceutical composition can be used for targeted and controlled prolonged local release of active compounds, eg anticancer remedies, thus minimising side effects' range and gravity due to local concentration's temporally optimised dynamics profile.

77 cl, 8 dwg, 9 ex, 5 tbl

FIELD: chemistry.

SUBSTANCE: invention relates to production of ceramic proppants designed for use in oil industry when extracting oil through hydraulic fracturing. The polymer-coated proppant is in form of ceramic granules with a polymer coating consisting of a hardened epoxy resin (ER) with polyethylene polyamine (PEPA) in which a mixture of particles of hexamethylenetetramine (HMTA) and phenol formaldehyde novolac resin (PFNR) is embedded, where the said mixture has particle size of 100-120 mcm and also contains solid particles of phenolformaldehyde resol resin (PFRR) with size of 5 mcm or less, taken in the following ratio in wt %: said PFNR 50-70, said PFRR 30-50, with ratio of ER with PEPA and mixture of PFNR with HMTA and with PFRR (per dry substances) between 1.5:1 and 1.5:3. The invention is developed in subclaims.

EFFECT: increased adhesion strength of polymer-coated proppants used at temperature above 80°C.

4 cl, 2 ex, 2 tbl

FIELD: chemistry.

SUBSTANCE: method of making articles from ceramic-matrix composite material includes forming a frame from carbon or silicon carbide fibres, partial packing of the frame with a carbon-ceramic matrix material using corresponding precursors and siliconising the obtained workpiece. The frame is first soaked with a ceramic-forming polymer, which is a silicon nitride and/or carbide precursor; a plastic workpiece is formed at the curing temperature of the binder, heat treated at final temperature of 1300-1600°C, after which carbon is fed into the pores of the material, for example by partial packing with pyrocarbon and/or soaking with a coke-forming polymer and carbonisation, and/or by carbonisation of the pores with catalytic carbon. Siliconising is carried out via a vapour-liquid phase method by heating, holding at 1600-1700°C for 1-3 hours and cooling in silicon vapour. Before soaking the frame with the ceramic-forming polymer, a gas-phase coating is formed on refractory fibres, the coating being selected from pyrocarbon, silicon carbide and boron nitride.

EFFECT: higher performance of articles made from ceramic-matrix composite material under thermal and mechanical load in an oxidative medium.

7 cl, 1 tbl

FIELD: chemistry.

SUBSTANCE: method includes forming a frame of silicon carbide fibres having in their structure free carbon and oxygen bonded with silicon atoms; packing the frame with a coke-pyrocarbon matrix until its content is 0.9-1.5 times the content of oxygen in the silicon carbide fibres with respect to the density of a plastic workpiece; siliconising the obtained workpiece in a vacuum using a vapour-liquid phase method by heating and cooling in silicon vapour, alternating with additional partial packing of the porous workpiece with the coke-pyrocarbon matrix. The feeding of silicon into the pores of the workpiece material during siliconisation and the coke-pyrocarbon matrix during partial packing of the material is carried out in portions in at least two steps. At the first step of feeding silicon into the pores of the material, the workpiece is heated to 1300-1500°C and to 1600-1700°C the next steps. Siliconisation at least the first step is carried out by capillary condensation of silicon vapour. The next feeding of the coke-pyrocarbon matrix into the pores of the material, wherein content of the coke-pyrocarbon matrix before the first siliconisation step is 0.9-1.2 times the content of oxygen in the silicon carbide fibres, is carried out via partial packing with pyrocarbon before saturation with coke-forming binder, followed by carbonisation.

EFFECT: longer service life of articles in oxidative media and thermal and mechanical loads at high temperatures.

3 cl, 22 ex, 1 tbl

FIELD: chemistry.

SUBSTANCE: invention relates to composite materials with the composition SiC/C-SiC-Si, which are designed to operate in oxidative media and under mechanical load at high temperatures. The method includes forming a frame of silicon carbide fibres having in their structure free carbon and oxygen bonded to silicon; packing the frame with a coke-pyrocarbon matrix until its content is 0.9-1.7 times the content of oxygen in the silicon carbide fibres with respect to the density of a plastic workpiece. The obtained workpiece is the heat treated at 1300-1500°C. In the preferred version of the method, heat treatment is carried out at atmospheric pressure in a medium of argon and/or especially pure nitrogen or in silicon monoxide vapour. Before siliconisation, the workpiece is partially packed with pyrocarbon and/or impregnated with coke-forming binder followed by carbonisation to obtain material with open porosity of 20-30% and density higher than 1.5 g/cm3, if said characteristics are not satisfied. Siliconisation is carried out using a vapour-liquid-phase method by impregnating the material with silicon vapour condensate.

EFFECT: longer service life of articles in oxidative media and mechanical loads at high temperatures.

7 cl, 1 tbl, 26 ex

FIELD: process engineering.

SUBSTANCE: invention relates to silicon carbide-based structural materials used in oil production and processing industries (end seals, oil pumps, downhole pumps, bearings, etc). Proposed process comprises forming of the billet based on fine filler as the powder of cubic boron nitride or boron carbide and temporary binder. Formed billet is annealed at final temperature corresponding to that of complete removal of volatile products from temporary binder, and siliconizing. This compound uses the mix of said powders with carbon of silicon-active variety with particle size of not over 20 mcm (ash or colloidal graphite) as aforesaid fine filler. Siliconizing after annealing is performed by vapour-liquid-phase process at capillary condensation of silicon vapours at billet heating to 1300-1500°C. Cubic boron nitride or boron carbide and carbon in the mix are taken in the amount of 70-80 and 20-30 wt %.

EFFECT: higher hardness and strength of composite.

2 cl, 1 tbl

FIELD: construction.

SUBSTANCE: method comprises the manufacture of frame made of heat-resistant fiber, filling it with dispersed filler, treatment of frame with coke-forming binder, forming and siliconising of the obtained porous workpiece. Nitrides of high-melting metals (such as silicon and titanium) are used as the dispersed filler, at chemical interaction with carbon of which, high-melting carbides and / or carbonitrides of metals are formed. Siliconising of workpiece is carried out by vapour-liquid-phase method via the capillary condensation of vapours of silicon at a temperature of workpiece not more than 1500°C with the subsequent heating up to 1700-1850°C, maintenance in the mentioned interval of temperatures during 1-3 hours and cooling. Prior to conduct the siliconising process, heat treatment of plastic workpiece is carried out when the temperature of formation of carbides or carbonitrides of metals is of 1300-1400°C.

EFFECT: providing the possibility of manufacturing the large-sized thin-walled products without the use of mechanical processing, as well as improving the reliability of their work in oxidising mediums at high temperatures.

3 cl, 1 tbl, 10 ex

FIELD: chemistry.

SUBSTANCE: matrix from thermostable fibres is made, filled with disperse filler and impregnated with coke-forming binding agent. As dispersive filler applied are refractory metals such as B, Si, Ti, Zr, Hf, in capsule from respective nitride or without one. Then, moulding of plastic workpiece and its thermal processing in nitrogen medium at temperature of carbide and/or carbonitrides of respective metals is realised. Obtained porous workpiece is siliconised by steam-liquid phase method by capillary condensation of silicon vapour, heated to 1700-1850°C and kept in the said interval of temperatures for 1-3 hours.

EFFECT: invention provides possibility of manufacturing bulky thin-walled products without application of mechanical processing, increased reliability of their work in oxidising media at high temperatures.

3 cl, 13 ex, 1 tbl

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