Method for controlling the defect of sintering expansion of powder metallurgy material and products thereof and mold

A technology of powder metallurgy and sintering expansion, which is applied in the field of sintering and molds to control the sintering expansion defects of powder metallurgy materials and products

Active Publication Date: 2009-09-16
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0011] The first technical problem to be solved by the present invention is to provide a constrained sintering that can effectively control the expansion, deformation, cracking, pores / voids and other defects of powder metallurgy materials and their products during the sintering process, and improve the density and quality of the sintered body. method

Method used

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  • Method for controlling the defect of sintering expansion of powder metallurgy material and products thereof and mold

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] Example 1: Sintering of TiAl intermetallic compound

[0032] Ti powder with a particle size of less than 43 μm and Al powder with a particle size of 10-100 μm are used for mixing according to the atomic ratio of Ti:Al at 1:1, and molded under a pressure of 500 MPa to make a blank with a size of 100mm×15mm body. then put it in figure 1 After being assembled in the mold shown, it is put into a sintering furnace, and sintered according to the sintering process of TiAl alloy. The volume expansion rate of the obtained sintered green body is less than 1.77%, and there are no defects such as deformation and cracks.

Embodiment 2

[0033] Example 2: Sintering of NiAl intermetallics

[0034] Use Ni powder with a particle size of 1-10 μm and Al powder with a particle size of 10-100 μm, mix according to the Ni:Al atomic ratio of 1:1, and mold it under a pressure of 500 MPa to make a size of 100mm×15mm of cold blanks, and then put one of them into figure 1After being assembled in the mold shown, it is put into a sintering furnace, and sintered according to the sintering process of NiAl alloy. The volume expansion rate of the obtained sintered green body is less than 1.15%, and there are no defects such as deformation and cracks.

Embodiment 3

[0035] Example 3: Sintering of FeAl intermetallic compound

[0036] Fe powder with a particle size of less than 147 μm and Al powder with a particle size of 10-100 μm are used for mixing according to the Fe:Al atomic ratio of 1:1, and molded under a pressure of 500 MPa to make a cold steel with a size of φ100mm×15mm. body, and then put one of them into the figure 1 After being assembled in the mold shown, it is put into a sintering furnace, and sintered according to the sintering process of FeAl alloy. The volume expansion rate of the obtained sintered body is less than 1.02%, and there are no defects such as deformation and cracks.

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Abstract

The invention discloses a method for controlling the defect of sintering expansion of powder metallurgy material and products thereof and a mold. In the sintering process of powder body, three-dimensional restraint compressive stress is applied to the body, thus generating restraint action to the body, restraining volume expansion generated by physical or chemical reactions of the body in the sintering process, realizing restraint sintering, controlling sintering densification thereof and eliminating the defects of sintering expansion. A restraint mold (1) is internally provided with an external mold; the matching conicity between the restraint mold (1) and the external mold is Theta which is larger than 5 degrees and smaller than 15 degrees; the external mold is internally provided with an internal mold; and a spacer (6) which is used for preventing the reaction of the body and the mold is arranged between the internal mold and the sintering body. The invention is a restraint sintering method which can effectively prevent the powder metallurgy material and products thereof from generating expansion, deformation, cracking and pore/hole and the like and can improve the sintering density and quality; and the using method of the mold is simple and easy to operate.

Description

technical field [0001] The invention relates to a constrained sintering method and a mold for controlling sintering expansion defects of powder metallurgy materials and products thereof. Background technique [0002] During the sintering preparation process of powder metallurgy materials and their products, defects such as pores / voids, deformation and even cracks appear due to the volume expansion of the green body due to physical or chemical reactions, especially chemical reactions such as self-propagating reactions during the sintering process Powder metallurgy materials [Huang Peiyun. Principles of powder metallurgy. Beijing: Metallurgical Industry Press, 2004: 1-6]. These defects will seriously affect the quality of the sintered body and reduce the yield of subsequent processing. For example, in the process of preparing intermetallic compounds by elemental powder metallurgy, self-propagating combustion reactions between powders will cause thermal explosion effects, which...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22F3/12B22F3/14B22F3/16
Inventor 刘祖铭何晓宇黄伯云刘咏
Owner CENT SOUTH UNIV
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