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Powder metallurgy preparation method

A powder metallurgy and powder technology, which is applied in the field of powder metallurgy preparation, can solve problems such as fracture, cracking, powder fluidity is not as good as liquid metal, etc., and achieve the effects of avoiding technical difficulties, reducing carbon content, and extending maintenance cycles

Inactive Publication Date: 2016-12-07
CHINALCO JINYUAN RARE EARTH
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  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] Since the fluidity of the powder in the molding process is far inferior to that of liquid metal, there is a large friction force between the powder particles and between the powder and the mold during the pressing process. The elastic aftereffect is formed during the pressing and demoulding process, which is easy to form a special shape. Especially products with a large surface area / volume ratio will cause cracking or even fracture. Therefore, the current powder metallurgy technology still has certain restrictions on the product structure and shape; the existing molding process needs to be carried out under the joint action of the press and the mold. Compression, the size of the press limits the size of the mold, and the size of the mold directly limits the size of the product. The size and shape of the product cannot break through the inherent conditions of the mold and the press itself, and develop special specifications and special structural shapes. Powder metallurgy products are subject to greater restrictions, presses and molds are high-cost consumables, but also limit the promotion and application of powder metallurgy technology

Method used

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  • Powder metallurgy preparation method

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Experimental program
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Embodiment 1

[0029] Weigh the raw materials according to the design formula, put the raw materials into the vacuum smelting casting furnace, vacuumize the system, and heat the materials to reddish at the same time, until the vacuum degree drops below 4Pa, stop vacuuming, fill with argon for protection, and heat with high power The material is melted, the temperature of the molten steel reaches 1400-1500° C., the power is reduced, and the heat is kept for 5-10 minutes before pouring to obtain the NdFeB cast alloy. Hydrogen crushing is carried out on the cast sheet, and then ground into a powder with a particle size of 3-5 μm in a jet mill. In the magnetic field forming press, the powder is oriented and pressed into a small piece of green body, and the size of the green body is 62.8*59.5*47.8 (mm); figure 1 As shown, in the protective gas, use a 300*12*0.65 hacksaw blade to scratch at least one extension surface (59.5*47.8) of the small green body according to the extension direction of the ...

Embodiment 2

[0031] Weigh the raw materials according to the design formula, put the raw materials into the vacuum smelting casting furnace, vacuumize the system, and heat the materials to reddish at the same time, until the vacuum degree drops below 4Pa, stop vacuuming, fill with argon for protection, and heat with high power The material is melted, the temperature of the molten steel reaches 1400-1500° C., the power is reduced, and the heat is kept for 5-10 minutes before pouring to obtain the NdFeB cast alloy. Hydrogen crushing is carried out on the cast sheet, and then ground into a powder with a particle size of 3-5 μm in a jet mill. In the magnetic field forming press, the powder is made into a small shaped green body by means of compression molding, and the size of the green body is R*91*55*55.6 (mm); image 3 As shown, according to the extension direction of the design size, 8 small pieces of green bodies are scratched at least two extension surfaces with a 300*12*0.65 hacksaw blad...

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Abstract

The invention discloses a powder metallurgy preparation method, which comprises the following steps: 1) making small pieces of green bodies; 2) surface pulverization and modification, in a protective gas, at least one of the small pieces of green bodies in step 1) is extended The surface is scratched, the powder produced by the scratches is retained on the surface, and the powder is then laid flat on the extension surface; 3) The small pieces of green bodies in step 2) are arranged and spliced, and the extension surface treated by the scratches is spliced. 4) Put the spliced ​​green body in step 3) into a combined die sleeve, and perform isostatic pressing; 5) sintering heat treatment to obtain a sintered NdFeB blank. In the present invention, the product specification breaks through the limitation of the inherent conditions of the press, and without changing the existing production equipment, the mass production of super-sized and special-shaped products can be quickly realized.

Description

technical field [0001] The invention relates to the technical field of forming and sintering of metal materials, more specifically, it relates to a powder metallurgy preparation method. Background technique [0002] Powder metallurgy is an industrial technology for producing metal powder or using metal powder (or a mixture of metal powder and non-metal powder) as raw material, forming and sintering to produce metal materials, composite materials and various types of products. At present, powder metallurgy technology has been widely used in transportation, machinery, electronics, aerospace, weapons, biology, new energy, information and nuclear industries, and has become one of the most dynamic branches of new material science. Powder metallurgy technology has a series of advantages such as significant energy saving, material saving, excellent performance, high product precision and good stability, but it also has obvious disadvantages. [0003] Since the fluidity of the powd...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22F3/04B22F3/10B22F3/16
CPCB22F3/04B22F3/10B22F3/16
Inventor 李容军曾阳庆甘家毅梁红梅叶春燕
Owner CHINALCO JINYUAN RARE EARTH