8results about How to "Avoid compositional segregation" patented technology

This invention discloses a method for preparing high-purity oxygen-free copper, relating to the field of metallurgical technology. The method includes multi-stage electrolytic refining, gradient-heating vacuum melting, inert gas-protected refining, electron beam melting, hydrogen plasma arc melting, directional solidification, and post-treatment steps. The multi-stage electrolytic refining utilizes a specific component electrolyte and periodically commutated current; vacuum melting is combined with bidirectional electromagnetic stirring; inert gas-protected refining is combined with a gradient reduction composite covering agent; electron beam and hydrogen plasma arc melting achieve deep purification and deoxidation; and directional solidification and two-stage annealing ensure product performance. The high-purity oxygen-free copper prepared by this invention has a conductivity of 102.3% IACS, a copper content ≥99.9999%, and an oxygen content <1.0 ppm. It exhibits high purity, low oxygen content, and excellent conductivity. The process is stable and controllable, making it suitable for high-end electronics applications.

The invention relates to the technical field of metal materials, and discloses a shape memory alloy film and a preparation method and application thereof. The shape memory alloy film comprises the following components: 50-55 at.% of Ni, 40-45 at.% of Ti, 3-5 at.% of Cu and 2-4 at.% of M, and M is selected from one or more of Zr, Hf and Nb. The shape memory alloy film has remarkable superelasticity, the recoverable strain of the shape memory alloy film can reach 8% or above, meanwhile, the compressive yield stress exceeds 1.5 GPa, and the shape memory alloy film shows excellent cycle stability. The preparation method is simple in process and high in controllability, a new scheme is provided for solving the problem of unstable performance of an existing NiTi-based film, and the preparation method is particularly suitable for high-performance micro devices such as a micro electro mechanical system.

The application relates to a carbon / ceramic brake disc with wear resistance improved by silicon-chromium alloy synergistic modification and a preparation method thereof. The carbon / ceramic brake disc is prepared through key steps of preparing a carbon fiber preform, a carbon / carbon composite material, ceramic powder and a carbon / ceramic composite material, and the process is through gradient melting impregnation and segmented heat treatment process, thereby avoiding the composition segregation problem caused by the traditional silicon powder embedding melting impregnation method; the structured laying of the ceramic powder positively superimposes the capillary force in the brake disc and the furnace pressure; the ceramic production efficiency is increased by 30%, and the waste rate is reduced to below 1%. In the structure aspect, the porosity of the brake disc prepared by the application is reduced to 2%-3%; in the material composition aspect, the ceramic phase in the matrix is formed by Si-Cr-C three elements to form crystals, so that the wear resistance of the composite material is increased by three times; the brake disc prepared by the application has excellent wear resistance and friction performance, and is suitable for the aerospace field.

The invention discloses a preparation method of an Al-RE intermediate alloy based on an alloy opposite doping method, which comprises the following steps: firstly, industrial pure aluminum Al and mother alloy Al-90RE are taken as raw materials, the raw materials are dried according to a mass ratio meeting the requirement of Al-(10-50) RE, then, the raw materials are melted by adopting a two-stage variable-temperature melting method to obtain an Al-RE melt, then, the Al-(10-50) RE melt is refined, and meanwhile, the Al-RE intermediate alloy is prepared by adopting an alloy opposite doping method. The steel ingot mold is preheated, and finally, the refined Al-RE melt is poured into the preheated steel ingot mold to be cooled, so that an Al-RE intermediate alloy ingot based on the alloy opposite doping method is obtained; rE is one of La, Ce or La + Ce alloy. The obtained Al-RE intermediate alloy is compact in metallographic structure and less in inclusion; in addition, the yield is greater than 90.0%.

The invention discloses a molybdenum-rhenium alloy and a preparation method thereof. Belongs to the alloy field. The preparation method of the molybdenum-rhenium alloy provided by the invention comprises the following steps: smelting molybdenum-rhenium-lanthanum oxide alloy powder by adopting a vacuum electric arc to prepare a molybdenum-rhenium alloy casting blank; machining the molybdenum-rhenium alloy casting blank to obtain a molybdenum-rhenium alloy plate; the molybdenum-rhenium alloy plate is subjected to pre-strain plastic deformation treatment at the temperature of 25-1500 DEG C, and the molybdenum-rhenium alloy is obtained; the pre-strain plastic deformation treatment comprises the following steps: unloading to a zero stress state after applying 0.25%-2.5% of pre-strain quantity each time, and circulating for 100-1000 times. According to the molybdenum-rhenium alloy for improving the alpha texture strength through the deformation cumulative effect, the strength of the molybdenum-rhenium alloy with the low rhenium content is remarkably improved, the dosage dependence of rhenium resources is greatly reduced, and the production cost is reduced.

The application discloses a method for impregnating emitting substances in a ring-shaped impregnated cathode, which comprises the following steps: wrapping a molybdenum sheet around the outer surface of a ring-shaped impregnated cathode base, and then tightening the molybdenum sheet by a plurality of molybdenum wires; placing the ring-shaped impregnated cathode base with the wrapped molybdenum sheet on a molybdenum boat, and placing a conical molybdenum block at the upper end of the ring-shaped impregnated cathode base; placing a required weight of emitting substances in a cylindrical space formed by the molybdenum sheet above the ring-shaped impregnated cathode base; placing the molybdenum boat together with the ring-shaped impregnated cathode base into a hydrogen furnace for heating and heat preservation until the emitting substances are melted and filled into the pores of the ring-shaped impregnated cathode base; taking out the ring-shaped cathode base, removing the molybdenum wires, the molybdenum sheet and the conical molybdenum block, and removing the floating salt on the surface of the ring-shaped cathode base, so that the ring-shaped impregnated cathode is prepared; and the method realizes the accurate control of the impregnation process of the ring-shaped impregnated cathode through the ingenious physical packaging, simplifies the process, avoids the waste of the emitting substances and guarantees the emitting performance.

The utility model provides a multi-element magnesium-based hydrogen storage alloy preparation device. The preparation device comprises a reaction chamber, the rapid quenching pressure unit is arranged in the reaction chamber and comprises a gas inlet pipeline and a swirling gas pipeline, at least part of the gas inlet pipeline extends out of the reaction chamber, and the swirling gas pipeline is obliquely arranged at an inclination angle of 45 degrees relative to the gas inlet pipeline; the smelting and rapid quenching unit is arranged in the reaction chamber; the smelting and rapid quenching unit comprises a drip-type crucible arranged in the reaction chamber, a reaction product is stored in the drip-type crucible, and the inlet end of the drip-type crucible is communicated with the gas outlet end of the swirling gas pipeline, so that inert gas is conveyed into the drip-type crucible through the obliquely arranged swirling gas pipeline; applying uniform pressure to the reaction product in the molten state in the dripping type crucible, so that the reaction product drips out from the bottom of the dripping type crucible; the problem that in the prior art, the pressure applied to the to-be-reacted material is not uniform due to airflow formed by conveying inert gas into the to-be-reacted material is solved.

The invention discloses a method for producing H08A semi-killed low-silicon welding rod steel by adopting a small square billet process, and belongs to the technical field of ferrous metallurgy. The method comprises the four procedures of converter smelting, LF refining, continuous casting and rolling, by optimizing the technological parameters of all the procedures, precise control over the silicon content and effective removal of inclusions are achieved, and the product quality stability is improved; the sulfur content and the phosphorus content are both smaller than or equal to 0.030%, the inclusion rating is smaller than or equal to 1.5 grade, and the purity of the welding rod steel is improved; the silicon mass fraction is stabilized at 0.03-0.07%, and the problem that the welding performance is poor due to the fact that the silicon content in a traditional process exceeds the standard is solved.