33results about How to "Diffusion strengthening" patented technology

The invention relates to a silver-based electrical contact material and a preparation method thereof. The silver-based electrical contact material is characterized in that the material is formed by diamond-cerium oxide nuclear shell compound particles and silver. And the material is prepared by using the method comprising the following steps that: the diamond-cerium oxide nuclear shell compound particles and the silver are added into a blender mixer based on a proportion; a wetting agent is added and mixing is carried out for an uniform effect, and granulation is carried out by using a granulating machine; and a mixed material after the granulation is added into a die to carry out thermo-compression formation and nitrogen or argon filling is carried out in a vacuum sintering furnace under the temperature of 800 to 950 DEG C to protect sintering for 1 to 4 hours. According to the invention, the advantages are as follows: on the basis of granulation, particles with largely different densities are mixed uniformly; and each small particle has the identical components. The diamond-cerium oxide particles after the granulation are distributed uniformly in the electrical contact, so that the molded electrical contact material components are distributed uniformly; and thus the surface temperature is effectively reduced and the fusion welding and electrical ablation can be prevented.

The invention relates to a copper-based silicon dioxide composite material and a preparation method thereof and belongs to the technical field of metal materials and preparation thereof. The compositematerial is prepared from the following components in percent by mass: 0.5-10% of tin, 10-25% of graphite, 2-8% of silicon dioxide, 0-2% of nano silicon dioxide and the balance copper. The preparation method comprises the following steps: proportioning; ball milling; mixing; cold pressure forming; pressurized sintering; and obtaining a product. The tensile strength of the copper-based composite material prepared by the preparation method is higher than 300 MPa, the yield strength is equivalent to that of a copper-based aluminum oxide composite material, the wear rate is smaller than 1*10<-9>cm<3> / J, the heat-resistant coefficient is higher than 35000, and the heat resistance and the wear resistance are better than those of the copper-based aluminum oxide composite material. A wear-resistant part prepared by the material can meet the demand of a product or equipment working normally for a long time in a relatively high temperature condition.

The invention provides a 3D printed cobalt-chromium alloy for dental porcelain restoration and a preparation method thereof, belonging to the field of dental porcelain restoration. The present invention adds Ta element, reduces thermal expansion coefficient, improves metal-ceramic bonding strength, reduces surface active energy, causes solid solution strengthening, improves strength; increases Cr element content, reduces Co element content, increases hcp phase content, is beneficial to metal-ceramic bonding, After the Co element is reduced, the combination of Cr-W, Cr-Mo, Cr-Si, W-Mo is improved, and the strength of the alloy is improved; the vacuum stress relief annealing is used to completely eliminate the residual stress, so that the cobalt-chromium restoration will not be used during service. The microstructure phase transformation will be caused by the residual stress, causing the formation of microcracks at the metal-ceramic bonding interface; solid solution and aging are used to adjust the phase composition of the cobalt-chromium alloy and the precipitation of the second phase, so that the alloy has good mechanical properties, and at the same time The hcp phase is further improved to improve the bonding strength of gold and porcelain.

The invention provides a method for enhancing the service life of a cold-stamping mould of an automobile by a composite coating. The method is characterized by comprising the following steps: firstly, carrying out polishing treatment on the surface of a cast iron mould; afterwards, precipitating the composite coating on the surface of the cast iron mould by chemical reduction, wherein a basal body of the composite coating is Ni-p alloy, 5-20% of spherical particle with nano level size is evenly distributed in an alloy layer, and the spherical particle is nano level artificial diamond or fullerene granules; and then, carrying out polishing treatment on the surface of the cast iron mould. The invention adopts the flexible grinding and polishing of the surface of the mould until a mirror face is smooth, so that the service life of the mould can be enhanced, the smoothness degree of a stamping workpiece is enhanced, and the napping phenomenon of the surface of the workpiece is reduced. The composite coating is precipitated by chemical reduction, the wear resistance of the mould is increased, the stamping frequency of the cast iron mould reaches 8-10 ten thousand times, and the phenomena of tension fracture, napping and scratch formed on the surface of the stamping workpiece are avoided.

This application relates to a scheme for preparing carbide-reinforced high-entropy alloy composites (HEC) by mechanical alloying (MA) and spark plasma sintering (SPS). The method for preparing high-entropy compounds from entropy alloys: (1) Introducing hydrocarbon additives into high-entropy alloys to form carbides through mechanical alloying reactions to prepare in-situ high-entropy alloy composites, referred to as HEC in ; (2) Adding carbide particles to high-entropy alloys to prepare ex-situ high-entropy alloy composites, referred to as HEC ex . This patent takes the preparation of FeCoNiCrMn high-entropy alloy composite material as a typical case to describe in detail. The preparation method is as follows: Fe, Co, Ni, Cr, Mn five metal powders and ball milling control agent C 7 h 16 Preparation of FeCoNiCrMn / C powder by mechanical alloying, i.e. HEC in powder. Then add TaC, TiC powder and mix to obtain FeCoNiCrMn / C / TaC / TiC powder, namely HEC ex powder. Finally, FeCoNiCrMn high-entropy alloy composite (HEC) was obtained by spark plasma sintering.

The invention provides a high-temperature environment barrier coating layer structure and a preparation method thereof. The structure comprises a Gd2O3 doped Si bonding bottom layer, a Gd2SiO5 middlelayer and a Yb2SiO5 surface layer laminated on the surface of a SiC / SiC composite material basal body in sequence. An environment barrier coating layer is of a three-layer structure of vacuum plasma spraying gadolinium oxide doped Si bonding bottom layer+vacuum plasma spraying gadolinium silicate middle layer+vacuum plasma spraying ytterbium silicate surface layer. A Gd2SiO5 coating layer and a Yb2SiO5 coating layer are prepared by adopting a vacuum plasma spraying process; components of the coating layers are maintained well; the material component loss and the silicate decomposition are hardly generated; the phase composition is stable; and the thermal shock resistance of the coating layers is excellent. The physical performance matchability of all the layers is excellent to effectivelyrelieve the thermal stress of the coating layers; the working temperature can reach 1400 DEG C; and the thermal shock resistance, the thermal circulation resistance and the service life of the environment barrier coating layer are greatly improved.

The invention relates to the fields of oceanographic engineering and offshore equipment, and particularly discloses seawater-erosion-resistant machining copper alloy and a preparation method thereof. The copper alloy is composed of, by mass, 0.5-5% of nickel, 2-5% of aluminum, 1-2.5% of magnesium, 0.05-0.15% of phosphorus, 0.15-0.85% of chromium, 0.01-0.02% of tin and the balance copper. During preparation, a medium-frequency iron-core-free induction furnace is adopted, roasting and preheating are conducted to make raw materials be in dark red, and a furnace pipe is formed; the temperature is increased; electrolytic copper, a covering agent, pure chromium, electrolytic nickel, electrolytic aluminum, pure magnesium, pure tin, a covering agent and alloy CuP are sequentially added; stirring and slag salvage are conducted, the temperature is increased, and alloy is discharged out of the furnace and smelted in the atmospheric environment; and annealing is conducted. The preparation method is low in cost and high in product hardness, and the prepared copper alloy has the properties such as seawater-high-flow-rate-erosion resistance and erosion corrosion resistance, and can be used as a structural material, making contact with seawater, such as propellers of oceanographic engineering, pipes for oceanographic engineering pipelines and valve bodies.

The invention designs a preparation method of a novel magnesium alloy composite material, which is characterized in that: the novel magnesium alloy composite material is mixed in proportion with aluminum, zinc, manganese, neodymium, cerium and magnesium, and nickel coating is added to the magnesium alloy melt Nano-SiC particles, while applying an electromagnetic field, electromagnetic simulation of microgravity to uniformly disperse nickel-coated nano-SiC particles in the melt, apply an electric field to the ingot after casting to refine the grains, and finally perform equal-diameter angular extrusion on the new magnesium alloy composite material compression deformation. The neodymium element in the new magnesium alloy composite material has a dispersion strengthening effect, and the formation of a metal compound can prevent grain boundary slippage; the cerium element can improve the alloy structure and refine the grain; the microgravity field makes the nickel-coated nano-SiC particles in the melt The dispersion is uniform; the electric field can increase the undercooling of the melt, reduce the nucleation barrier, and refine the grains; the equal-diameter angular extrusion deformation can further refine the grains and improve the comprehensive mechanical properties of the composite material.

The invention relates to the field of ocean engineering, and particularly discloses an erosion-resistant copper alloy utilized in an ocean working condition and a preparation method thereof. The copper alloy comprises the following elements by mass percent: 7% to 10% of Ni, 5% to 10.5% of Al, 0.15% to 1% of Fe, 0.5% to 1.5% of Mn, 0.15% to 1% of Ti, 0.05% to 0.15% of P, 0.2% to 0.6% of Mg and 0.005% to 0.01% of B, and the balance being copper. The preparation method comprises the steps of sequentially adding electrolytic copper, a covering agent, a CnMn intermediate alloy, a CuCo intermediate alloy, CuFe intermediate alloy, electrolytic nickel, pure chromium, electrolytic aluminium, pure silicon and the covering agent; and then, carrying out phosphor copper deoxidation, stirring slag salvaging, temperature increasing and discharging. The preparation method has the advantages that cost is low and efficiency is high, the copper alloy material has performance like sandy seawater erosion corrosion resistance, ocean organism corrosion resistance and seawater high-speed flow corrosion resistance, and the requirement of ocean engineering on corrosion-resistant and abrasion-resistant materials can be met.