General suspension granulation method for preparing sintered metal-graphite composite

A technology for sintering metal and composite materials, applied in metal processing equipment, transportation and packaging, etc., can solve problems affecting the mechanical properties of materials, graphite layer slippage, hindering the sintering and diffusion process of metal-metal particles, etc., and achieve strong versatility , uniform density and uniform phase distribution

Active Publication Date: 2019-04-16
UNIV OF SCI & TECH BEIJING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, in this process, mutual friction and collision inevitably occur between the metal and the graphite powder, causing the graphite sheets to slip and fall off fine graphite crystallites. These graphite crystallites are easy to adhere to the surface of the metal powder, hindering the The sintering and diffusion process between metal-metal particles is severely affected, which seriously affects the final mechanical properties of the material.

Method used

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  • General suspension granulation method for preparing sintered metal-graphite composite
  • General suspension granulation method for preparing sintered metal-graphite composite
  • General suspension granulation method for preparing sintered metal-graphite composite

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0059] S1: Suspend 1000 g of flake graphite powder with a particle size of 400-550 μm in 6 L of Midi Glatt type fluidized bed airflow; the fluidization gas is dry air, the temperature is 15 ° C, and the fluidization pressure is 0.45 Bar.

[0060] S21: Introduce the binder solution by top spraying, the binder is polyvinyl alcohol, and the spray rate is 2.1g / min.

[0061] S22: Introduce metal powder by tangential spraying method, the metal powder is a mixed powder of copper (18-48 μm), iron (23-75 μm) and ferrochromium (80-230 μm), the weight ratio is 80 / 15 / 5, and the flow rate is controlled. 92g / min.

[0062] Wherein, step S22 is performed simultaneously with step S21.

[0063] S3: Control fluidization time to 1.6h. The pretreated powder thus obtained was dried to obtain a composite powder A.

Embodiment 2

[0065] S1: Suspend 500g of artificial graphite and expanded graphite mixed powder with a particle size of 200-350μm (weight ratio: 1:1) in 4.4L of Midi Glatt type fluidized bed airflow; the fluidization gas is dry air at a temperature of 25°C , fluidization pressure 0.27Bar.

[0066] S21: Introduce the binder solution by top spraying, the binder is polyvinyl alcohol, and the spray rate is 1.8g / min.

[0067] S22: Introduce metal powder by tangential spraying method, the metal powder is a mixed powder of copper (4-10μm), iron (10-18μm) and nickel (23-45μm), the weight ratio is 63 / 24 / 13, and the flow rate is 110g / min.

[0068] Wherein, step S22 lags behind step S21 by about 5s˜60s.

[0069] S3: Control the fluidization time to 0.8h. The pretreated powder thus obtained was dried to obtain a composite powder B.

Embodiment 3

[0071] S1: Suspend 800 g of artificial graphite powder with a particle size of 300-450 μm in 3.75 L of Midi Glatt type fluidized bed airflow; the fluidization gas is dry air, the temperature is 20 ° C, and the fluidization pressure is 0.38 Bar.

[0072] S21: Introduce the binder solution by top spraying, the binder is polyvinyl alcohol, and the spray rate is 0.75g / min.

[0073] S22: Introduce metal powder by tangential spraying, the metal powder is a mixed powder of copper (10-25μm), iron (13-45μm) and chromium (48-75μm), the weight ratio is 72 / 20 / 8, and the flow rate is 62g / min.

[0074] Wherein, step S22 is performed simultaneously with step S21.

[0075] S3: Control fluidization time to 1.2h. The pretreated powder thus obtained was dried to obtain a composite powder C.

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Abstract

The invention relates to a general suspension granulation method for preparing a sintered metal-graphite composite. The general suspension granulation method includes the steps that graphite particlesare suspended in an air flow with a fluidized chamber; binder solutions are introduced into the fluidized chamber; metal powder is introduced into the fluidized chamber; and after preset fluidizationtime, the graphite particles adhere to the metal powder through binders to form core particles. By adjusting the fluidization air pressure and the fluidization time, each graphite particle can adhereto a metal layer with a certain thickness to obtain the core particles with a predetermined critical dimension. At the moment, above the critical dimension, because the fluidized air flow cannot support the gravity of the core particles, the core particles fall and are collected in a material bin at the bottom of a bed body. The method is high in universality and can be applied to raw material granulation processes of a variety of metal-graphite composite products, the phases of subsequent objects manufactured by the obtained composite powder core are uniformly distributed, density is uniform, and mechanical properties are good.

Description

technical field [0001] The invention relates to the field of sintered metal-graphite composite materials, in particular to a general suspension granulation method for preparing sintered metal-graphite composite materials. Background technique [0002] At present, sintered metal-graphite composite materials have been widely used in friction materials, oil bearings, electrical contact materials, conductive materials and mechanical parts materials due to their good electrical and thermal conductivity, excellent friction and wear properties, and low cost. and other fields. Such materials are generally prepared by powder metallurgy process, including a series of processes such as powder pretreatment, mixing, compression molding and final sintering. [0003] Among them, the pretreatment and mixing of powder are the front-end link of the whole preparation process, which largely determines the distribution state and microstructure of each phase in the final material, and has an imp...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22F1/02
CPCB22F2202/15B22F1/103B22F1/16B22F1/10
Inventor 燕青芝彭韬张肖璐
Owner UNIV OF SCI & TECH BEIJING
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