65results about How to "Improve densification efficiency" patented technology

The invention relates to a rapid preparation method of a low-cost carbon/carbon composite material, and belongs to the field of composite materials. The method is mainly used for reducing the preparation cycle and the cost of the high-density carbon/carbon composite material. A low-density carbon/carbon composite material is formed through compounding fixed carbon fiber fabric in fiber bundles, the carbon fiber bundles are filled with carbon particles to make macro-pores become micro-pores, and low-pressure liquid impregnation carbonization or chemical vapor infiltration and high temperature thermal treatment are carried out to obtain the high-density carbon/carbon composite material. Compared with traditional methods, the preparation method of the carbon/carbon composite material, disclosed in the invention, has the advantages of greatly shortened preparation cycle and greatly reduced preparation cost.

The invention relates to a method for enhancing density of a SiC/SiC ceramic matrix composite. The method comprises the following steps: (1) a SiC/SiC ceramic matrix composite with a certain densification degree is immersed in slurry, in which an organic precursor and SiC powder are uniformly dispersed, and impregnation is carried out in an environment of 5-10 KPa vacuum degree for 20-50 min; (2) a material which has undergone vacuum impregnation is dried and the dried material undergoes cross-linking and curing; (3) the cross-linked and cured material undergoes pyrolysis treatment; and (4) the material which has undergone pyrolysis treatment further undergoes densification process in the atmosphere of a gaseous precursor containing Si and C elements by a chemical vapor infiltration technology while infiltration temperature is 850-1100 DEG C, pressure intensity is 10-20 KPa and infiltration time is 4-30 h. The method provided by the invention has advantages of simple operation, short densification time, good repeatability and high densification efficiency and has obvious advantages in the aspect of filling material voids. The method is a method with operability and development prospect.

The invention provides a preparation method of a carbon/carbon composite material. The preparation method comprises the following steps of: a, preparing a carbon fiber preform; b, performing graphitization treatment on the carbon fiber preform to obtain a carbon fiber green body; c, carrying out CVD (Chemical Vapor Deposition) densification treatment on the carbon fiber green body, punching the carbon fiber green body after carrying out at least one CVD densification treatment to obtain a first intermediate, and repeatedly carrying out CVD densification treatment on the first intermediate until the density of the first intermediate reaches a first preset value to obtain a second intermediate; d, carrying out dipping curing-high-temperature heat treatment on the second intermediate until the density of the second intermediate reaches a target value, and obtaining a semi-finished product; and e, carrying out finish machining on the semi-finished product to obtain a finished product withthe target shape and size. The method is simple in process, low in production cost and high in product percent of pass, and large-batch preparation of the small-size carbon/carbon composite material can be realized.

The invention discloses a multi-deposition-chamber CVI (chemical vapor infiltration) device for compacting a carbon/carbon crucible and a method using the same. The device comprises a chemical vapor deposition furnace consisting of an outer furnace tank and an inner furnace tank and also comprises multiple layers of graphite partition plates which are distributed in the inner furnace tank from bottom to top and multiple intake tubes which are inserted in the inner furnace tank from bottom to top; adjacent two layers of graphite partition plates are isolated by multiple graphite shores; the upper part of the graphite partition plate arranged on the most-top layer is provided with a gas-sealing plate; dependant deposition chambers are respectively formed between adjacent two layers of graphite partition plates and between the gas-sealing plate and the graphite partition plate arranged on the most-top layer; multiple deposition chambers are distributed from top to bottom; and the multiple intake tubes are respectively inserted into the multiple deposition chambers from bottom to top. The compacting method comprises the following steps: 1, charging of a crucible prefabricated body; and 2, compacting treatment. The device disclosed by the invention has simple structure, reasonable design, good use effect, good compacting effect, good density uniformity, large charging amount and the like, is convenient for assembling and easy to use and operate.

The invention discloses a preparation method of a carbon fiber enhanced carbon-silicon carbide friction material, belonging to the preparation field of carbon fiber enhanced carbon-silicon carbide composite materials. The preparation method comprises the following steps: (1) weaving a carbon fiber preform for formation; (2) carrying out high-temperature thermal treatment on the carbon fiber preform; (3) preparing an asphalt-resin mixed impregnant; (4) carrying out dipping, curing and carbonization on the asphalt-resin mixed impregnant; (5) preparing resin/carbon powder dipping precursor; (6) carrying out dipping, curing and carbonization on the resin/carbon powder dipping precursor; (7) carrying out high-temperature thermal treatment on a porous carbon/carbon blank; and (8) carrying out fusion siliconing on the porous carbon/carbon blank, so as to obtain the carbon fiber enhanced carbon-silicon carbide friction material. The preparation method is simple and controllable in process, short in preparation period and strong material structure designability, and the prepared friction material can be applied to automobile brake discs (pieces), high-speed train brake shoes and magnetically levitated train runners.

The invention discloses a rapid densification method of a carbon/carbon composite material. The rapid densification method comprises the following steps: (1) densifying a carbon fiber full-mesh felt with an initial density of 0.15-0.20 g/cm<3> to 0.8-1.5 g/cm<3>, and controlling the pyrolytic carbon microstructure of a matrix as a rough layer structure pyrolytic carbon; (2) vacuumizing to 10<-2> Pa by adopting an SPS furnace, rapidly heating the carbon/carbon composite material to 1600-2200 DEG C, slowly pressurizing to 30-40 MPa, controlling the heating speed within 100-200 DEG C/min and controlling the pressurizing speed within 0.5-1 MPa/min; (3) preserving the heat and the pressure for 10-30 min, cooling, releasing the pressure, controlling the cooling speed within 80-100 DEG C/min and controlling the pressure releasing speed within 1-2 MPa/min so as to finish the densification process of the carbon/carbon composite material and prepare a pyrolytic carbon-based carbon/carbon composite material with a density of 1.6-1.8 g/cm<3>.

The invention discloses a fabrication method of an automobile brake disc. An automobile brake pair pre-fabricated body is fabricated with carbon fiber prepreg through integrated molding pressing, anda polysilazane solution and a polycarbosilane solution are used as a ceramic precursor; the automobile brake pair pre-fabricated body is fabricated through an integrated molding pressing process, andthe density of the pre-fabricated body is larger than 1.4 g/cm3; a carbon fiber automobile brake pair pre-fabricated part is impregnated through the liquid ceramic precursor; the liquid precursor is subjected to high-temperature pyrolyzing after cross-linking and solidifying are finished and then is converted into a ceramic substrate; and then the impregnation-pyrolysis process is repeated, and finally a carbon fiber reinforced carbon-based/ceramic-based composite material is obtained. The production period is shortened greatly, the production cost is reduced, the densification efficiency is improved, and through adjustment of the impregnation proportion of polycarbosilane and polysilazane, the friction property and mechanical strength of an automobile brake pair can be optimized at the same time.

The present invention relates to a production method of high-performance carbon/carbon frictional resistance material which can be used in brake system of high-speed train, magnetic suspension train and racing automobile, etc. It is characterized by that said invention adopts laminated knitted carbon cloth as reinforced skeleton, and uses rough type pyrolytic carbon and wear-resistant high temperature resistant resin pyrolytic carbon to fill and compact the carbon-reinforced skeleton to form high-density wear-resistant carbon/carbon material, and adopts high-temperature reaction silconing method to add antioxidant SiC base body so as to raise high temperature frictional performance and surface frictional resistance performance of said carbon/carbon material.

The invention discloses a preparation method of a three-dimensional silicon carbide fiber-reinforced silicon dioxide-zirconium dioxide multiphase ceramic composite material. The preparation method ofthe three-dimensional silicon carbide fiber-reinforced silicon dioxide-zirconium dioxide multiphase ceramic composite material comprises the following steps of (1) stabilizing SiO2-ZrO2 composite sol;(2) impregnating three-dimensional silicon carbide fiber prefabricated members into the stabilized SiO2-ZrO2 composite sol; (3) drying the impregnated three-dimensional silicon carbide fiber prefabricated members; (4) performing thermal treatment; (5) repeating the impregnation-drying-thermal treatment process in the steps of (2) to (4) until the weight gain rate of a three-dimensional silicon carbide fiber-reinforced silicon dioxide-zirconium dioxide multiphase ceramic composite material intermediate in a current impregnation-drying-thermal treatment process relative to a previous impregnation-drying-thermal treatment process is smaller than 1% to obtain the three-dimensional silicon carbide fiber-reinforced silicon dioxide-zirconium dioxide multiphase ceramic composite material. The prepared three-dimensional silicon carbide fiber-reinforced silicon dioxide-zirconium dioxide multiphase ceramic composite material has the advantages of being high in high-temperature resistance and antioxidant and mechanical performance and the like.

The invention discloses a wet needling process for preparing a carbon/carbon composite material, and relates to the technical field of preparation of carbon/carbon composite materials. The process comprises the following steps: dipping a carbon fiber web in slurry to obtain a carbon fiber web preform; laminating the carbon fiber web preform and carbon fiber cloth to obtain a slurry-containing carbon fiber fabric; needling the slurry-containing carbon fiber fabric to obtain a slurry-containing needled fabric; sequentially carrying out heating, curing and carbonization treatment on the slurry-containing needle-punched fabric to obtain a low-density carbon/carbon composite material blank; the low-density carbon/carbon composite material green body is repeatedly subjected to the treatment processes of dipping, heating, curing and carbonizing, and a high-density carbon/carbon composite material green body is obtained; performing high-temperature heat treatment on the high-density carbon/carbon composite material green body to obtain a carbon/carbon composite material; the slurry is an ethanol suspension of asphalt and graphite powder. According to the process method, the preparation period of the carbon/carbon composite material prepared by a needling method is shortened.

The invention discloses a high-density flat carbon fiber gradient stitching preform and a preparation method thereof, and belongs to the field of equipment materials. According to the method, the flat carbon fiber bundles are adopted and woven into the light and thin single-layer flat carbon fiber plane prefabricated body, and then the flat carbon fiber gradient stitching prefabricated body is prepared through gradient lamination and stitching, so that the requirements of high layer density, high bearing capacity, strong interlayer and low stitching damage are met; and the problems of high porosity, high cost, long period, frequent processing and low mechanical property retention rate of the subsequent carbon/carbon composite material are thoroughly solved.

The invention discloses a preparation method of a three-dimensional carbon fiber-reinforced silicon dioxide-zirconium dioxide multiphase ceramic composite material. The preparation method of the three-dimensional carbon fiber-reinforced silicon dioxide-zirconium dioxide multiphase ceramic composite material comprises the following steps of (1) stabilizing SiO2-ZrO2 composite sol; (2) impregnatingthree-dimensional carbon fiber prefabricated members into the stabilized SiO2-ZrO2 composite sol; (3) drying the impregnated three-dimensional carbon fiber prefabricated members; (4) performing thermal treatment; (5) repeating the impregnation-drying-thermal treatment process in the steps of (2) to (4) until the weight gain rate of a three-dimensional carbon fiber-reinforced silicon dioxide-zirconium dioxide multiphase ceramic composite material intermediate in a current impregnation-drying-thermal treatment process relative to a previous impregnation-drying-thermal treatment process is smaller than 1% to obtain the three-dimensional carbon fiber-reinforced silicon dioxide-zirconium dioxide multiphase ceramic composite material. The prepared three-dimensional carbon fiber-reinforced silicon dioxide-zirconium dioxide multiphase ceramic composite material has the advantages of being high in high-temperature resistance and antioxidant and mechanical performance and the like.

The invention discloses a three-dimensional carbon fiber preform enhanced yttrium oxide-aluminum oxide complex-phase ceramic composite material and a preparation method thereof. The composite materialcomprises a three-dimensional carbon fiber preform and yttrium oxide-aluminum oxide complex-phase ceramic, in the yttrium oxide-aluminum oxide complex-phase ceramic, the molar content of Al2O3 is 5%-95%, pores of a three-dimensional carbon fiber preform are uniformly filled with the yttrium oxide-aluminum oxide complex-phase ceramic, and the porosity of the three-dimensional carbon fiber preformenhanced yttrium oxide-aluminum oxide complex-phase ceramic composite material is 10%-15%. The preparation method comprises the following steps; (1) preparing yttrium oxide-aluminum oxide composite sol; (2) carrying out dipping; (3) drying; (4) carrying out heat treatment; and (5) repeating a dipping-drying-heat treatment process in the step (2)-step (4). The composite material has the advantagesof low porosity, high compactness, high temperature resistance, oxidation resistance, excellent mechanical property and the like. The preparation method is high in preparation efficiency, and the compactness and mechanical property of the prepared composite material are improved remarkably.

The invention discloses a densification tool mold and densification method for ceramic matrix composite matrix, and the densification tool mold comprises a sealing end cover, a shape-preserving frame and a material storage base which are sequentially connected in a sealed mode; a flat-plate-shaped fiber prefabricated body is arranged between the shape-preserving frame and the sealing end cover, and a filling port and an air inlet are formed in the upper surface of the sealing end cover; the filling port is used for being communicated with a slurry feeding pipe, and the air inlet is used for being connected with an air pump. The upper surface of the sealing end cover is provided with an exhaust port and a connecting port used for connecting a pressure gauge and a safety valve, and the exhaust port is used for being connected with a vacuum pump. The flat-plate-shaped fiber prefabricated body is clamped through the shape-preserving frame, the size stability of the prefabricated body can be maintained, material deformation caused by external pressurization in the densification process can be effectively avoided, closed holes formed in the material in the impregnation process are effectively reduced, the repeated densification frequency can be reduced through pressurization of the air pump; therefore, the densification efficiency of the material is improved, and near-net forming of the ceramic-based composite material is realized.