219results about How to "Achieve near net shape" patented technology

The invention discloses a method for producing a silicon-based ceramic core for an aircraft engine blade. The method comprises the steps of: producing the complex ceramic core through hot injection molding by utilizing three high-purity silica powders with different particle sizes as raw materials, the high-purity silica powder in large particle size as a framework, the high-purity silica powder in small particle size as sintering additives, paraffin and beewax as plasticizers, and oleic acid as a surface active agent, carrying out low-temperature dewaxing and high-temperature roasting to themolded bisque ceramic core in a padding alumina to finally obtain the silicon-based ceramic core for the aircraft engine blade.

The invention discloses a near-net forming method of the 3D braided fiber reinforced metal-based composite material, and belongs to the technical field of advanced composite materials. The method is characterized in that a vacuum air pressure infiltration preparation technology based on a liquid binder is adopted to assist in accurately controlling the shape and the size of a 3D braided fiber preform structure; in the 3D weaving process of the fiber preform, a liquid binder is adopted to accurately fix and shape the 3D braided fiber preform, then the size precision of the 3D braided fiber reinforced metal-based composite material is accurately controlled through the impregnated graphite mold of the embedded fiber preform, and deformation and local fiber polarization of the 3D braided fiberpreform in the infiltration process are prevented. The prepared 3D braided fiber reinforced metal-based composite material has high dimensional accuracy and excellent mechanical properties, the near-net forming of the 3D braided fiber reinforced metal-based composite material is realized, batch industrial production can be realized, the near-net forming method has a wide application prospect in the fields of aerospace, national defense, military and the like.

The invention discloses a method for preparing a diamond/silicon carbide ceramic matrix composite material, and belongs to the field of ceramic materials. The diamond/silicon carbide ceramic matrix composite material is characterized by being prepared from the following raw materials in percentage by weight: 5 to 15 percent of adhesive, 15 to 45 percent of silicon carbide powder, and 40 to 80 percent of diamond particle. The method comprises the following steps of: wet-mixing the raw materials for 8 to 24 hours, performing die forming under the pressure of 75 to 250MPa to obtain a blank of the composite material, oxidizing the blank in the air at the temperature of 200DEG C for 6 to 10 hours, sintering under the protection of nitrogen at the temperature of between 800 and 1,200DEG C for 8 to 15 hours, and cooling together with a furnace; and performing vacuum impregnation, oxidation, sintering and cooling, and circulating for 3 to 7 times to obtain the compact diamond/silicon carbide ceramic matrix composite material, wherein the oxidation temperature is 200DEG C, the oxidation time is 6 to 10 hours, the sintering is performed at the temperature of between 800 and 1,200DEG C for 8 to 15 hours under the protection of nitrogen, and the product is cooled together with the furnace. The method has low equipment requirement, is low in cost and can prepare the complicated-shaped compact diamond/silicon carbide ceramic matrix composite material.

The invention relates to an electroslag smelting casting method of fixed blades of a water turbine. Consumable electrodes are prepared by adopting a voltaic arc furnace refining method and the fixed blades are prepared by adopting an electroslag smelting casting process through a mould. The chemical components of the consumable electrodes are controlled as follows: C is 0.14-0.19 percent, Si is less than or equal to 0.6 percent, Mn is 1.5-1.9 percent, P is less than or equal to 0.035 percent, S is less than or equal to 0.035 percent, V is 0.02-0.15 percent, Nb is 0.015-0.06 percent, Ti is 0.15-0.25 percent, Al is more than or equal to 0.015 percent, O is less than or equal to 0.0040 percent, N is less than or equal to 0.0080 percent, H is less than or equal to 0.00035 percent, and the balance is Fe. The electroslag smelting casting system and the electroslag guide are controlled as follows: CaF2 is 60-80 percent, Al2O3 is 40-20 percent, or less MgO and CaO (the total is less than or equal to 20 percent); and the electroslag amount is usually 1.5-5 percent of the weight of a casting. The invention has less amount of oxide and sulfide, small size, even distribution, clean casting base body, high cooling speed, large crystallization temperature gradient at the front of solid and fluid, compact casting texture, high size precision and little distortion, and can greatly improve the product property of the refined casting.

The invention discloses a preparation method of a diamond/metal-based composite material with a high volume fraction. The preparation method comprises preparation of hydrolysate, preparation of a sizing agent, roasting of a prefabricated member, and vacuum low-pressure infiltration; and the process for each unit is as follows: firstly, preparing tetraethylortho silicate hydrolysate by taking tetraethylortho silicate as a precursor, taking absolute ethyl alcohol as a reaction solvent and taking acid as a catalyst; preparing a prefabricated blank by taking tetraethylortho silicate hydrolysate as an adhesive through a grouting and forming way, and roasting at a high temperature to obtain a diamond porous prefabricated member; and infiltrating a molten liquid into the diamond porous prefabricated member by adopting a vacuum low-pressure infiltration way to realize near net shape forming of the diamond/metal-based composite material. The prepared diamond/metal-based composite material has the advantages of being high in heat conduction, low in expansion, high in gas tightness, and the like, is simple in preparation process, low in cost and suitable for mass production.

The invention belongs to the technical field of particle-reinforced aluminum-based in-situ composite materials and discloses an aluminum-based in-situ composite material formed based on laser 3D printing and a preparation method of the aluminum-based in-situ composite material. The preparation method includes the steps that a mixture of Al-Si-Mg alloy powder and Al2O3 powder is prepared; the mixture is ball-milled through an intermittent ball-milling process; a three-dimensional CAD model established through a workpiece is subjected to layered slicing treatment; laser beams are adopted for scanning the laid powder line by line to form a two-dimensional section of the workpiece; and the steps are repeated till the workpiece is machined, and the aluminum-based in-situ composite material with an Al2Si4O10 reinforced element scattered on an Al matrix is formed. The operation method is easy and convenient to carry out, Al-Si-Mg alloy and Al2O3 generate the Al2Si4O10 reinforced phase in situ under the effect of high-energy lasers in the laser forming process, the interface wettability is improved, and then the interface strength of the composite material is enhanced.

The invention relates to a method for preparing high-thermal-conductivity silicon nitride ceramics. The method comprises the steps that firstly, thermal treatment and acid pickling treatment are carried out on Si3N4 powder, and then Si3N4 slurry is prepared; an Si3N4 thin layer is prepared through a casting process technology, and porous silicon nitride powder prefabricated bodies are obtained after the thin layer is cut and overlapped; the prefabricated bodies are subjected to liquid silicon penetration through high-purity silicon powder, and compact Si3N4/Si is obtained; nitrogen treatment is carried out on Si3N4/Si in a nitrogenation oven, so that Si in the material is subjected to a nitriding reaction to generate Si3N4. Compared with frequently-used processes for preparing the high-thermal-conductivity silicon nitride ceramics, such as isostatic pressing sintering and hot pressed sintering, a tape casting method is combined with liquid silicon penetration forming and nitriding sintering processes, no or little machining is needed, preparation temperature is low, no sintering additive needs to be added, and the influence of a grain boundary on the thermal conductivity of the material is avoided. The thermal conductivity of the prepared silicon nitride ceramics can reach 80-120 Wm<-1>K<-1>.

The invention is concerned with forming mould and its method for rolling cross wedge rolling worm axis roughcast, belonging to metal plastic metal forming technology field. Set mould on the rolling cross wedge rolling and send the heated stick stuff into the cross wedge roller through feeding equipment. The upper mould and down mould with model cavity on their surface to the roller move to same direction and the heated metal round stick stuff moves to the different direction with the action of mould. This realizes continuous radial condensation and extending distortion along axis to form the each step including the shape of worm tooth. The part of spiral tooth shape of the worm axis roughcast is finished through the spiral groove tooth shape of the mould, and the part of step axis is finished through the wedge part of mould. The roller moves around to produce a roughcast of worm axis. The invention has high single machine productivity and availability with low cost, less machining process and excellent quality of production.

The invention relates to the field of ceramic materials and in particular relates to a preparation method of a high-performance ceramic. The preparation method of the high-performance ceramic comprises the following steps: a) preparing a ceramic part biscuit; b) dumping; c) carrying out isostatic cool pressing treatment; d) presintering; e) preparing a hot isostatic pressing sheath, concretely carrying out synchronous powder feeding and laser cladding treatment, and coating the ceramic part biscuit with the hot istostic pressing sheath; f) hot isostatic pressing sintering; and g) removing the hot isostatic pressing sheath, and precisely processing a ceramic part. The preparation method of the high-performance ceramic has the advantages that multiple technologies are combined, so that a complex ceramic part biscuit can be prepared through selective laser sintering, near-net forming of a complex ceramic part is realized, and compactness of the part biscuit subject to aftertreatment is improved; meanwhile, no vacuumizing or encapsulating needs to be carried out, and production processes are reduced; besides, technique is simple, period is short, efficiency is high, cost is low, and the obtained ceramic part is high in strength and good in performance.

The invention relates to the technical field of additive manufacturing (AM), commonly known as 3D printing, in particular to a method for realizing additive manufacturing through cold gas dynamic spray. A cold gas dynamic spray process is adopted to be combined with computer aided manufacturing, so that a 3D printing technology is realized; different from other conventional thermal 3D printing technologies, the technology is a non-thermal input type (non-smelting) 3D printing technology. Based on the cold gas dynamic spray process, the technology enables particles to impact at a high speed under a solid state, and 3D printing additive manufacturing is realized through strong plastic deformation of the particles and deposition. Meanwhile, an advanced computer aided manufacturing technology is combined, so that complex workpieces with relatively high precision can be manufactured; and in the process, powder does not generate phenomena such as oxidization, burning loss, phase change and structural change. Therefore, the method solves the problem that materials such as alloys, amorphous materials, quasi-crystal materials and nano-crystal materials, which are liable to have phase change and are liable to volatilize at a high temperature, cannot apply the conventional thermal input type (smelting type) 3D printing technology to manufacture workpieces.

The invention belongs to the technical field of high-entropy alloys and discloses a high-melting-point high-entropy alloy NbMoTaWVTi and a preparation method of the high-melting-point high-entropy alloy NbMoTaWVTi. According to the method, a forming method that a mechanical alloying technology and a spark plasma sintering technology are combined is adopted. Compared with a traditional vacuum arc furnace casting method, by the adoption of the preparation method, operation is easier and more convenient, the temperature required in forming is lowered greatly, sintering time is short, a block material which is uniform in composition and near-total dense can be obtained through one-time sintering, and near-net forming is achieved; and the microscopic structure of the obtained alloy is characterized in that granular second phases are diffused and distributed in an isometric crystal matrix. By the adoption of the preparation method, the prepared alloy is uniform in structure and tiny in grain size and has higher strength and plasticity, and the optimum mechanical performance meets the conditions that compression yield strength is 2,709.2 MPa, the maximum compressive strength is 3,114.9 MPa, and the plasticity dependent variable generated in fracture is 7.5%.

The invention discloses high-speed steel strengthened and hardened through the combination of the Laves phase and the mu phase and a preparation method of the high-speed steel. The high-speed steel comprises a steel substrate and the strengthening and hardening phases which are dispersed in the steel substrate. The strengthening and hardening phases include the Laves phase and the mu phase. The Laves phase comprises Fe2Nb, Fe2Ti and Fe2W, and the mu phase comprises Fe7Mo6, Co7Mo6, Fe7W6 and Co7W6. According to the high-speed steel, strengthening and hardening operation is conducted through theLaves phase and the mu phase generated in an in-situ mode in the sintering process, the fine mu phase strengthens the substrate so that the substrate can have the higher hardness at high temperature,and the Laves phase with the high hardness and large particles enables the material to have the higher wear resistance. The intermetallic compound strengthening phases generated in an in-situ mode have the good interface relationship with the substrate, and are low in diffusion speed at high temperature, and therefore the material still keeps the high strength, the high toughness and the high heat conductivity coefficient as a large number of alloy elements are added to the material to achieve the high hardness, and the material has the excellent tempering resistance, the excellent high-temperature hardness and the excellent high-temperature strength and has the more excellent performance compared with traditional high-speed steel in the high-temperature and high-speed cutting operation.

The invention provides a FeCoCrNi series high-entropy alloy selective laser melting in-situ additive manufacturing method. The method comprises the following steps: step 1, mixing mixed elemental metal powder with M-X alloy powder and/or N-Y alloy powder, wherein the mixed elemental metal powder at least comprises two of Fe, Co and Ni metal elemental powder, the M element in the M-X alloy powder is the metal element with the highest melting point in a high-entropy alloy, the N metal element in the N-Y alloy powder is the metal element with the lowest melting point in the high-entropy alloy, Xand Y are at least one metal element in the mixed elemental metal powder, and the molar number of each metal element in the mixed metal powder is the same; and step 2, carrying out laser additive manufacturing through laser 3D printing equipment to obtain the FeCoCrNi series high-entropy alloy. The product is good in forming effect and free of air holes and macroscopic cracks.

The invention overcomes the defect of the prior art and provides a high-entropy alloy in-situ preparation method and product by laser additives, FeCoCrNiTi high-entropy alloy powder preparation and in-situ laser additive fabrication are realized, microphase composition of an original sample is changed, and the hardness of the original sample is successfully improved. The method comprises the stepsof raw material mixing, additive preparing and aging treating. Materials prepared adopting the method are high in shaping efficiency and can be used for preparing parts in complex shapes. By means ofthe high-entropy alloy in-situ preparation method and product by the laser additives, near-net shaping of the materials can be realized, and the production cost of the parts is greatly lowered; the sample shaping effect is good, no pore and macroscopic cracking exist, the sample has no micropore and microcrack and has good density and relatively uniform tissue, and three phase structures coexist;and after high-temperature aging treatment is performed, precipitates are all converted from net shapes to plate strip shapes, obviously, just because of this conversion, the hardness of the sample is improved after the high-temperature aging treatment is performed, and the hardness of the sample cooled by quenching is higher than that of the sample cooled along with a furnace.

The invention discloses an isothermal forging method of a straight bevel gear. A blank and a mold are heated to roughly consistent temperatures respectively, then the blank is placed into the mold and is subjected to forging molding in the mold at the relatively low strain rate, and the straight bevel gear is obtained through aftertreatment, wherein the relatively low strain rate is lower than 0.1 mm/s, and the mold adopts a closed mold forging structure. According to the method, firstly, the blank and the mold are heated to the equal temperature or basically equal temperatures, so that the chilling effect produced when the temperature of the mold is lower than that of the blank is avoided, and the plastic flow of the blank is improved; secondly, the mold adopts the closed mold forging structure, the blank bears three-dimensional compressive stress in the forging process, and thus molding of the blank is facilitated; thirdly, the strain rate is lower than 0.1 mm/s, accordingly, the deformation amount of the blank in unit time is small, deformation is sufficient, and molding of the blank is more facilitated.

The invention discloses a preparation method of covered metal spare parts, comprising the steps of: mixing iron powder, nickel powder and chromium powder evenly for pelletization with adhesive; using powder co-injection formation process to form a housing layer part and a core layer part in turn by injection, wherein the feeding materials for two times of injection forming are different; and defatting and sintering the blank formed by injection to obtain the product. The invention provides the basic determination standard of the compatibility of co-sintering by measuring the difference of strain rate of sintering and provides the basic determination standard of the compatibility of co-injection by measuring the difference of viscosity of feeding materials to determine the compatibility determination standard of the covered metal spare part preparation process.

The invention provides a device and a method for hydraulic injection filled type extrusion cast forming of a molten aluminum magnesium alloy, and relates to a device and a method for extrusion cast forming of an aluminum magnesium alloy, which aim to solve the problems that the conventional extrusion casting device cannot realize near net forming and liquid metal is easily oxidized in the extrusion casting process. In the device, a material pushing barrel is provided with a stepped hole; a smelting furnace and a female die are arranged in parallel on the material pushing barrel; and a first charging ram and a second charging ram are arranged in the large-diameter section of the stepped hole and are connected with a piston rod of a double piston rod hydraulic cylinder respectively. The method comprises the following steps of: arranging the smelting furnace and the female die on the material pushing barrel, forming a cavity between a male die and the female die, and introducing protective gas into the smelting furnace and the material pushing barrel; adjusting the distance between the first charging ram and the second charging ram to realize quantitative pouring; filling the liquid metal; pressurizing the male die to realize the near net forming of workpieces; and making the male die in return stroke, and taking the workpieces out. The device and the method are used for a production process of aluminum magnesium alloy workpieces.

The invention discloses an iron-based gradient structure gear and a manufacturing method thereof; to realized high surface layer hardness and high core/shell layer bonding strength, Fe2Ni is adopted as a core layer and the Fe2Ni added with an alloying element Cr is adopted as a shell layer; through strengthening effect of Cr, sintering/heat treatment is adopted to facilitate surface layer hardness to exceed 40 HRC and realize the metallurgical bonding of the core layer and the shell layer; sintering time is adjusted to realized homogeneous diffusion of Cr outside the interface and core/shell layer bonding strength is higher than 280 MPa.

The invention provides a method for preparing diamond/copper composite material parts with high volume fraction. The method comprises the following steps: plating the surface of diamond with a uniform Mo2C layer by using a salt-bath plating technology to improve wettability of the diamond and copper; and then continuing copperizing the surface of the Mo2C layer by using a chemical plating method, and controlling the thickness of a copperizing layer by controlling the content of Cu2+ in a plating solution so as to prepare copper-containing double-plating-layer Cu-Mo2C-Diamond powder with the volume fraction of 30-50 vol.%. The Cu-Mo2C-Diamond powder is formed by an ultra-high-pressure cold pressing method, and Diamond/Cu composite material parts are prepared by a vacuum pressureless sintering method. The method has the advantages that the Diamond/Cu composite material parts with complicated shapes and high volume fractions of (50-70 vol. %) can be directly prepared, meanwhile, composite materials are uniform in structure and high in compactness, the Diamond/Cu composite material parts can be produced in batches, and the production cost is low.

Disclosed is an overall manufacturing method for a large-size thin-walled annular belt type oxygen-enhancing frame. The overall manufacturing method comprises the following steps that a special substrate for laser melting deposition is designed; up-and-down segmentation is carried out along the wall thickness sudden changing portion of the oxygen-enhancing frame; a lower-segment part is formed byselecting a large-power large-scanning-speed laser melting deposition process parameter and a corresponding scanning strategy; laser machining program codes of all slice layers of the upper and lowersegments are obtained by utilizing slice software and are introduced into equipment to carry out laser melting deposition forming of the lower-segment portion first; stress relieving annealing is carried out after outward taking; then the lower segment end surface is taken as a substrate to complete deposition of the upper-segment portion, and heat treatment and machining are carried out to obtaina part under a final state. The overall manufacturing method solves the problems that a current forging and machining method is long in machining period, low in material utilization ratio and severein stress deformation, and the high-performance, small-deformation and small-allowance forming of the oxygen-enhancing frame part is realized.

The invention discloses an electronic beam added material manufacturing method of molybdenum base alloy powder. The particle size of the used molybdenum base alloy powder is 55-85 microns; and when powder layers are scanned by electronic beams, a twice scanning mode is adopted. The molybdenum base alloy electronic beam added material manufacturing process finds out manufacturing process parametersof added materials with the highest compactness, and adopts the twice scanning mode to solve the nodulizing and powder splashing problems in the manufacturing of the electronic beam added materials to improve the compactness of components to the casting level.