6results about How to "Improve densification efficiency" patented technology

The invention relates to a variable-thickness integral control surface prefabricated body forming method and a mold, belongs to the technical field of control surface prefabricated body forming, and solves the technical problems of long forming preparation period and local layering of a control surface prefabricated body. Cutting cloth according to the size of the prefabricated body division area; preparing a lower layer-by-layer staggered triangular filling area prefabricated body, and preparing an upper layer-by-layer staggered triangular filling area prefabricated body; fixing the prefabricated body, and sewing; the upper die assembly and the lower die assembly are used for replacing the lower sewing tool and the upper sewing tool; and the upper mold assembly and the lower mold assembly are closed through a pressing strip, and the thickness-variable overall control surface prefabricated body is fixed. The method is used for forming the variable-thickness integral control surface preform.

The invention relates to a high-performance carbon-carbon composite material and a preparation method thereof, and the preparation method comprises the following steps: (1) carrying out controlled deposition shaping on a carbon fiber woven body by adopting a CVD (Chemical Vapor Deposition) method to obtain a preformed body; (2) carrying out impregnation-carbonization densification cycle treatment on the preformed body by adopting an impregnant containing a carbon nano tube to obtain a compact carbon-carbon composite material; and (3) depositing the carbon-carbon composite material by adopting the CVD method again to obtain the high-performance carbon-carbon composite material. According to the invention, the CVD and impregnation-carbonization combined process is adopted, so that the manufacturing time can be greatly shortened, and the defect of long time of a pure CVD process is overcome; the density of the initial CVD preform is optimized, so that the proportion of an impregnant entering a matrix in the impregnation process is increased; the carbon residue rate of the impregnant is increased by further adding the carbon nanotubes into the impregnant, the defect of low carbon residue rate of the currently used impregnant is overcome, the cycle index of the impregnation-carbonization process is reduced, the time is saved, and the cost is reduced.

The invention discloses a method for preparing an ultra-long and ultra-thick plate-shaped carbon / carbon composite material on a large scale at low cost, which comprises the following steps: carrying out primary graphitization treatment on a carbon fiber preform to obtain a carbon fiber blank, loading the carbon fiber blank into a chemical vapor deposition furnace to carry out chemical vapor deposition treatment, and then carrying out secondary graphitization treatment to obtain the ultra-long and ultra-thick plate-shaped carbon / carbon composite material. A carbon / carbon green body is obtained, and the carbon / carbon green body is subjected to resin carbon densification treatment; according to the chemical vapor deposition, in the CVI deposition process, the flowing direction of gas in the deposition process is effectively controlled through the arrangement of an original chemical vapor deposition device, the freshness of carbon source gas in a deposition chamber is made to be consistent, an independent gas channel area is formed around each product, gas makes full contact with all parts of a blank, densification is uniform, the microstructure of the product is controllable, and the product quality is improved. After the product is subjected to high-temperature heat treatment at 2000-2500 DEG C, the graphitization degree range is 40-70%.

The invention belongs to the technical field of preparation of carbon-carbon composite materials, and particularly relates to a tool for a chemical vapor infiltration process and a preparation method and application of a carbon-carbon composite material. The tool for the chemical vapor infiltration process comprises a to-be-treated prefabricated body group, wherein a through hole penetrating through the to-be-treated prefabricated body group is formed in the center of the to-be-treated prefabricated body group; the to-be-treated prefabricated body group comprises prefabricated body layers and flow guide layers which are alternately stacked; the prefabricated body layer comprises a prefabricated body to be treated; the flow guide layer comprises a plurality of flow guide gaskets which are uniformly arranged between the adjacent prefabricated body layers, and an airflow channel is formed between the adjacent flow guide gaskets; the carbon source gas release device comprises a gas outlet end, and the gas outlet end is located at the bottom of the through hole of the to-be-treated preform group; and the gas path spoiler covers the top of the to-be-treated prefabricated body group. When the tool is used for preparing the carbon-carbon composite material, the densification efficiency of the material can be improved, the preparation period is shortened, meanwhile, the utilization rate of a carbon source can be increased, and defects in the carbon-carbon composite material are reduced.

The invention relates to a C-CNTF / HfC-SiC ceramic matrix composite material and a preparation method thereof. The preparation method comprises the following steps: carrying out shearing dispersion treatment on HfC powder and optional graphene in a solvent to prepare a slurry dispersion liquid; impregnating fiber cloth by using the slurry dispersion liquid, drying and curing; laminating the fiber cloth, and sewing the fiber cloth in the Z direction by using continuous carbon nanotube fibers; dipping with HfC slurry, drying and curing; and dipping by using a polycarbosilane precursor, and then curing and cracking to obtain the ceramic-based composite material. The invention also relates to the composite material prepared by the method. According to the method, solid slurry with stable dispersibility is obtained by graphene-assisted shearing dispersion; uniform impregnation of the slurry is realized by adopting a multi-stage vacuum-pressure impregnation mode; directional regulation and control of the heat conductivity are realized through Z-direction sewing of the carbon nanotube fibers; finally, the composite material with excellent mechanical property and thermal protection property is obtained.

The application relates to the field of magnetic core materials, and particularly discloses a low-temperature sintering NiZn magnetic core material and a preparation method thereof. The low-temperature sintering NiZn magnetic core material comprises the following raw materials in percentage by mass: NiO 10-20%, ZnO 20-35%, Fe2O3 45-55%, and a sintering aid 2-5%, wherein the sintering aid comprises at least two of Bi2O3, V2O5 and MnO. By optimizing the component proportion of each raw material and the sintering aid, the application realizes low-temperature sintering below 950 DEG C, can reduce energy consumption by more than 30% compared with the traditional process which needs to be sintered above 1200 DEG C, and solves the problems of easy decline of magnetic performance, insufficient sintering density and increased loss caused by low-temperature sintering, so that the prepared magnetic core material has low loss, a density greater than or equal to 94%, and a magnetic permeability greater than or equal to 85 (1MHz), meets the demand of high-frequency electronic devices, and has high compatibility with low-temperature packaging materials.