89results about How to "Short sintering cycle" patented technology

The invention relates to a method for preparing a medical porous NiTi shape memory alloy by microwave sintering. The method comprises the following steps of: (1) compounding powder: compounding titanium powder, nickel powder and pore-forming agent powder according to certain mass percentage; (2) performing ball milling: putting the compounded powder body into a stainless steel ball milling pot for ball milling; (3) pressing billets: performing mold pressing on the powder materials after the ball milling at the pressure of between 50 and 500 MPa into pressed billets; (4) charging in a furnace:putting the obtained pressed billets and a microwave auxiliary heating material into a polycrystalline mullite fiber heat insulation barrel, and putting the heat insulation barrel into a microwave sintering furnace; and (5) performing microwave sintering. The method has the advantages that: the preparation method is simple and convenient, the sintering cycle is short, the energy consumption is low, the method is suitable for industrialized production, the porous NiTi shape memory alloy obtained by sintering has good mechanical properties, a pore structure is in three-dimensional communication, the pore ratio is controllable between 20 and 80 percent, the pore sizes are uniform and are controllable between 30 and 600 mu m, and the medical porous NiTi shape memory alloy can be used as materials for repairing and replacing hard tissues such as bones, joints, artificial tooth roots and the like.

The invention belongs to the field of hard alloy preparation, and in particular relates to an ultra-fine crystal gradient alloy with a rich-cobalt surface and a preparation method of the alloy. According to the ultra-fine crystal gradient alloy with the rich-cobalt surface, a gradient layer with the rich-cobalt surface, which is 10-40mu m thick, is formed by taking WC (Wolfram Carbide) and cubic phase carbonitride as a core part hard phase and cobalt as the binding phase, wherein the average size of the crystal particles of WC in the hard phase and the gradient layer is 0.2-0.4mu m, the content of cobalt in the gradient layer with the rich-cobalt surface is 1.2-2 times of the standard content of cobalt of hard alloys, and the gradient layer with the rich-cobalt surface is free of the cubic phase carbonitride. The preparation method comprises the following steps: firstly, preparing the materials, wet-grinding and pressing into a material blank, and supplying an inert gas with the pressure of 5-10MPa before reaching a liquid phase sintering temperature, wherein the liquid phase sintering temperature is 1,350-1,500 DEG C. By charging the gas with certain pressure in the liquid phase sintering period, the ultra-fine crystal gradient alloy with the rich-cobalt surface is prepared, the WC crystal grains are refined, a rich-cobalt surface layer of certain thickness is obtained, the sintering period is shortened, and the production cost is lowered.

The invention relates to a preparation method of an in-situ synthesized Cu-graphene heteropolymer reinforced aluminum matrix composite. The preparation method of the in-situ synthesized Cu-graphene hybrid polymer reinforced aluminum matrix composite comprises the following steps of preparation of a Cu-graphene heteropolymer: uniformly mixing copper nitrate trihydrate, glucose and sodium chloride in deionized water; placing uniformly mixed solution in an environment with temperature of -20 degrees centigrade for 48 h; using a freezing and drying technology to obtain a precursor powder; using achemical vapor deposition method to calcine and reduce the precursor powder; and finally, using the deionized water to wash off sodium chloride template to obtain the Cu-graphene heteropolymer; and mixing of the Cu-graphene / aluminum matrix composite powder: placing the obtained composite powder under a condition of 500 MPa to be formed through cold pressing; sintering a cold-pressed block body material in a tube furnace for 1 h through argon shielding, and finally hotly extruding the sintered block body material under an environment condition of 600 MPa according to an extrusion ratio of 1:40so as to obtain a Cu-graphene / aluminum block body composite.

The invention relates to a preparation method of a high-strength / toughness super-high manganese steel-based TiC / TiN steel bonded hard alloy. The preparation method is characterized by mixing one of TiO2 powder, TiH2 powder or Ti powder with colloidal graphite according to a C / Ti atomic proportion of 0.7 to 1.1, thus preparing in-situ synthetic TiC powder; mixing one of the TiO2 powder, the TiH2 powder or the Ti powder with urea ((NH2)2CO) according to an N / Ti atomic proportion of 0.4 to 1.1, thus preparing in-situ synthetic TiN mixed powder; preparing Mo-Fe powder, V-Fe powder, Cr-Fe powder, Mn-Fe powder, Si-Fe powder, Fe powder, Ni powder, the colloidal graphite and a rare-earth raw material according to proportions required by adhesive-phase metal chemical component mass proportions, filling and ball-milling in a steel ball, adding absolute ethyl alcohol as a medium and PVA (Polyvinyl Acetate) in the steel ball, drying slurry after ball milling, pressing, forming and sintering, thus obtaining steel bonded alloy. According to the preparation method disclosed by the invention, an in-situ reaction synthesis technology and a liquid-phase sintering technology are combined, the particle size is small, the surface has no sharp corner, a matrix interface is better in bonding, and the interface is clear. The preparation method of the steel bonded alloy is capable of increasing the comprehensive mechanical property of the alloy, the cost is low, and the technology is simple and convenient.

The invention relates to a method for preparing SiC whiskers through an interface reaction, and the SiC whiskers, and belongs to the technical field of preparation of high-performance ceramic materials. The method for preparing the SiC whiskers through the interface reaction comprises the following steps: (1) according to the situation that the molar ratio of carbon to silicon is (1.5 to 3):1, a silicon source and a carbon source are taken to be mixed with boric acid to prepare a silicon dioxide-carbon-boric acid precursor, wherein the silicon source is silicate ester or silicon dioxide, and the carbon source is activated carbon or coal; and (2) the obtained silicon dioxide-carbon-boric acid precursor is pressed into a sheet and then buried in quartz sand to be subjected to microwave sintering, then the surface wrapped quartz sand is removed, then washing is conducted through hydrofluoric acid, and the SiC whiskers are obtained. According to the method, the adsorption property of the activated carbon can be fully utilized to form a good nuclear shell structure, the boric acid is adopted to adjust the pH of the precursor, a reaction can be accelerated through B2O3, and the couplingheat effect of microwave sintering can be fully utilized through the microwave effect to achieve rapid synthesis of the SiC whiskers.