7results about How to "Effective pinning" patented technology

The invention belongs to the technical field of composite material preparation, and particularly relates to a tungsten infiltrated copper composite material and a preparation method thereof. According to the invention, through a multi-scale through pore network formed by'prefabricated material construction ', molten copper liquid can be rapidly filled along a large pore channel and fully permeates into the tail end of a small pore, so that the defect of'black core' generated by closed pores is thoroughly avoided. According to the prepared composite material, the tungsten phase and the copper phase respectively form a stable and communicated three-dimensional network, so that the unification of high conductivity (greater than or equal to 60% IACS), high strength and toughness (hardness greater than or equal to 100 HB) and excellent arc ablation resistance is fundamentally and synergistically realized, and the long-standing limitation of'impossible performance triangle 'is effectively broken through. And the process is high in integration level, green and remarkable in strengthening effect, and process simplification, environmental protection strengthening and performance improvement are achieved at one stroke. The advantages of raw materials and process cost are outstanding, the industrialization prospect is wide, and the relationship among high performance, designability and mass productivity is perfectly balanced.

The invention discloses Ti-based alloy powder, which is prepared from the nominal components in percentage by atom: (5 to 10) of Ti, (2 to 5) of Al, (1 to 3) of V, (0.5 to 2.0) of Y2O3 and the balance of Ti and inevitable impurities, the preparation method comprises the following steps: 1, weighing raw material powder; 2, charging and sealing; 3, ball milling; and 4, discharging to obtain Ti-based alloy powder. According to the Ti-based alloy powder disclosed by the invention, high-volume nano Y2O3 is introduced and uniformly dispersed in a Ti matrix to form a dispersion strengthening phase, so that the room-temperature and high-temperature strength, creep resistance and thermal stability of the alloy are improved; according to the mechanical alloying process, the ball-to-material ratio, the rotating speed and the time of ball milling are strictly controlled, intermittent ball milling and external cooling are adopted to control temperature rise and pollution, it is guaranteed that Y2O3 forms nanocrystalline and a dispersion strengthening phase in a Ti matrix, the strength, hardness and thermal stability of the alloy are improved, the process is controllable, and repeatability is good.

The invention discloses an X8R type high-reliability ceramic dielectric material with a double-shell design and a preparation method and application thereof, and belongs to the technical field of electronic ceramic materials. According to the ceramic dielectric material, barium titanate is used as a main body material, at least one of Y2O3 and Dy2O3 is used as a first dopant, and at least one of MgO and MnO2 is used as a second dopant. The preparation method comprises the following steps: pre-sintering BaTiO3 and a first doping agent at a high temperature; and then adding a second doping agent for secondary mixing and high-temperature sintering. According to the method, a double-shell structure of a tetragonal phase crystal nucleus, a rare earth-rich inner shell layer and an Mg / Mn-rich outer shell layer is constructed in ceramic crystal grains. The high dielectric property of the BaTiO3 crystal nucleus is reserved, the rare earth-rich inner shell layer is used for inhibiting oxygen vacancy long-range migration, the Mg / Mn-rich outer shell layer is used for optimizing temperature stability, synergistic improvement of the high dielectric constant (epsilon r gt, 2200), X8R wide-temperature stability (delta C / C 25 DEG C is smaller than or equal to + / -15%, minus 55-150 DEG C) and high breakdown field strength (larger than or equal to 6.7 kV / mm) is achieved, and the high-dielectric-temperature-stability high-voltage-resistant MLCC is suitable for manufacturing the high-dielectric-temperature-stability high-voltage-resistant MLCC.

This invention discloses a method for preparing a high-strength, high-thermal-conductivity Mg-Zn-Cu-Mn magnesium alloy, belonging to the field of magnesium alloy preparation technology. Metal raw materials are prepared according to the atomic percentage ratio of each constituent element in the Mg-3Zn-3Cu-xMn alloy (0≤x≤1). Then, alloy melting, homogenization treatment, and hot extrusion deformation are performed sequentially. The extrusion temperature is 260-270℃, and the extrusion speed is 0.3-0.6 mm / s. This invention achieves homogeneous dispersion of Mn to cluster precipitation in the Mg-Zn-Cu magnesium alloy through Mn alloying modification treatment. When 0.6 wt.% Mn is added, the alloy exhibits the best thermal conductivity and tensile strength. This invention refines the grain size of the Mg-Zn-Cu-Mn magnesium alloy and eliminates some casting defects, thereby further improving the alloy's strength and thermal conductivity.

The invention discloses a micro-alloying rapid extrusion flame-retardant magnesium alloy and a preparation method thereof, and belongs to the technical field of metal materials. The microalloying fast extrusion flame-retardant magnesium alloy is prepared from the following components in percentage by mass: 1.0 to 1.8 percent of aluminum, 0.3 to 0.4 percent of calcium, 0.4 to 0.6 percent of manganese, 0 to 0.08 percent of nano particles, less than or equal to 0.02 percent of inevitable impurities and the balance of magnesium. Calcium is preferentially oxidized at high temperature to form a compact CaO layer to block oxygen, so that the ignition point of the alloy is obviously improved; a high-density nanophase is dynamically separated out from aluminum and manganese in the rapid extrusion process, the grain boundary is effectively pinned, grain coarsening is inhibited, and the stability of a microstructure below an oxidation film is enhanced; nanoparticles are combined with ultrasonic melt treatment to refine the structure, surface oxidation film microdefects are filled at the same time, and the self-repairing capacity and compactness are improved. According to the design, through microalloying design (the total element content is smaller than or equal to 2.8%), nanoparticle reinforcement and a rapid extrusion process are cooperated, collaborative optimization of low production cost, good flame retardant property and efficient extrusion capacity of the alloy is achieved, and the industrial prospect is wide.

The invention relates to the technical field of ceramic materials, in particular to SiC-TiB2-TiC composite ceramic, a preparation method and application thereof, and the preparation method comprises the following steps: respectively weighing raw material powder according to a component design ratio; uniformly mixing and fully drying; and sintering in a vacuum atmosphere by using a discharge plasma sintering furnace at the sintering temperature of 1900-2000 DEG C under the pressure of 40-60 MPa for 10-15 minutes to finally obtain the compact SiC-TiB2-TiC composite ceramic. In order to solve the problem that commercial TiB2 powder is large in particle size and is directly introduced to cause insufficient electrical properties and electrical discharge machining properties of the SiC-TiB2 composite ceramic, TiC is introduced into a SiC-TiB2 system, and in-situ formation and grain pinning effects in a reaction sintering process are utilized, so that a microstructure is refined, and the connectivity of a conductive network is enhanced. Compared with the composite ceramic without TiC, the material prepared by the invention has more excellent conductivity and electrical discharge machining performance, the preparation process is simple, and complicated subsequent treatment is not needed.

The application relates to a silver-nickel electric contact, and relates to the technical field of electric contact materials, which is made of the following raw material components: silver-nickel composite powder, nano tungsten powder, high-activity carbon source, tin-germanium pre-alloy powder and nano yttrium oxide. The tin-germanium pre-alloy powder, the nano tungsten powder and the high-activity carbon source are introduced to form a metastable (W, Sn, Ge) Cx ternary carbide transient intermediate phase, which is then decomposed and in-situ nano tungsten carbide reinforcing phases are formed; meanwhile, the separated tin-germanium liquid phase migrates to the surface to form a composite passivation film, so that the electrical stability, the arc ablation resistance and the corrosion resistance of the electric contact material are enhanced. The nano yttrium oxide is reduced to high-activity yttrium atomic oxygen impurity capturing clean interfaces in the sintering process, effectively pins the grain boundary, cooperates with the tungsten carbide reinforcing phase and the composite passivation film to guarantee the structural stability.