3results about How to "Increase the nucleation rate" patented technology

This invention provides a QPQ surface strengthening method for flexible and rigid wheels in harmonic reducers, comprising the following steps: after machining the flexible or rigid wheel, it is sequentially degreased, cleaned, dried, and preheated; the preheated flexible or rigid wheel is nitrided to form a nitrided layer on its surface; the surface of the flexible or rigid wheel is treated mechanically or by tumbling; the polished flexible or rigid wheel is placed in molten oxide salt for oxidation treatment to form an oxide layer on the surface of the nitrided layer; after the oxidized flexible or rigid wheel is air-cooled, it is immediately rinsed with clean water and dried with hot air, and then coated with anti-rust oil. Compared with the prior art, this invention uses low-temperature salt bath nitriding and oxidation treatment, the QPQ process is short, has fewer process steps and is easy to control, and the salt bath can be recycled. The surface hardness of the workpiece reaches 800-850 HV, and the wear rate is reduced by more than 70% compared with the traditional tempering process, significantly extending the service life of the workpiece.

The application provides a method for in-situ combustion synthesis of high-purity nanometer silicon carbide powder, and belongs to the technical field of inorganic nanometer material preparation, and comprises the following steps: placing water-soluble saccharide substances, gel monomers, water-soluble solutions of a crosslinking agent and an initiator into ion exchange columns respectively for filtration purification, then mixing the water-soluble saccharide substances, the gel material and high-purity silicon powder to form a sol, further carrying out in-situ gel solidification and pre-carbonization treatment to obtain a Si / C composite material block; carrying out combustion synthesis reaction on the obtained Si / C composite material, grinding the obtained block-shaped product to obtain the high-purity nanometer silicon carbide powder. The high-purity carbon source and the silicon source are fixed by the gel network, the silicon powder is uniformly embedded in the carbon skeleton, uniform dispersion and close combination of the two are realized, and the in-situ combustion synthesis reaction is efficiently promoted. The raw material cost in the application is low, the preparation process is simple, the environment is friendly, and the application is suitable for industrialized large-scale production of high-purity nanometer silicon carbide powder.

The application belongs to the technical field of aluminum alloy processing, and particularly relates to a high-strength and high-toughness 7-series aluminum alloy plate with equiaxed crystal structure and a short-process preparation method thereof. The application improves the comprehensive performance of the aluminum alloy by combining extrusion, cold rolling and heat treatment, and can effectively solve the problems of grain deformation, anisotropy of the structure and mechanical properties of the 7-series aluminum alloy plate in the production process. The 7-series aluminum alloy plate is prepared from an aluminum alloy ingot, and the aluminum alloy ingot is composed of the following components in percentage by mass: Zn: 4.5-6.8%, Mg: 1.8-3.0%, Cu: 0.30-0.70%, Mn: 0.30-0.70%, Zr: 0.10-0.20%, Yb: 0.10-0.40%, and the rest is Al, wherein the mass fraction ratio of Zn and Mg is Zn / Mg: (2.7-3.1):1. The application adopts a short-process high-efficiency preparation method, eliminates the original fibrous structure, improves the anisotropy of the mechanical properties of the material, and obtains the 7-series aluminum alloy plate with equiaxed crystal structure, a tensile strength greater than 550 MPa, an elongation after fracture greater than 12% and other excellent comprehensive properties.