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High-fluidity polyformaldehyde-based binder for metal injection formation and preparation method of fed material for metal injection formation

A technology of injection molding and binder, which is applied in the field of powder metallurgy, can solve the problems of poor rheological properties of feeding materials, under-injection of green bodies, and reduced yield, so as to improve the uniformity of feeding materials, improve rheological properties, Yield improvement effect

Inactive Publication Date: 2020-04-17
CENT SOUTH UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Among the polyoxymethylene-based binders, the viscosity of polyoxymethylene itself is relatively high, and the rheological properties of the prepared feedstock are poor, which usually leads to defects such as underfilling and cracks in the green body, resulting in a greatly reduced yield
For the problem of poor feed rheological properties, the existing solution is generally to increase the fluidity of the feed by adding lubricants, but it cannot effectively improve the rheological properties of the feed

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] A polyoxymethylene-based binder for 17-4PH stainless steel metal injection molding and a preparation method thereof, comprising the following steps:

[0018] 1) The binder used is composed of: 85% homopolyoxymethylene, 12% high-density polyethylene, and 3% polytetrahydrofuran in terms of mass fraction. Add 17-4PH stainless steel powder with a volume percentage of 58% and 42% binder into the kneader, the mixing temperature is 190°C, the speed is 45r / min, and the mixing time is 3.5h.

[0019] 2) After mixing, it is extruded through a single-screw extruder at an extrusion temperature of 185° C. After extrusion, it is granulated to obtain feed.

[0020] The 17-4PH stainless steel feed material prepared by the present invention is at a temperature of 190°C and a shear rate of 1000s -1 The viscosity, non-Newtonian index, activation energy of viscous flow and comprehensive rheological factor are 253.09Pa·s, 0.42, 21.71kJ·mol respectively -1 , 10.58×10 -7 , with good rheolog...

Embodiment 2

[0022] A polyoxymethylene-based binder for 17-4PH stainless steel metal injection molding and a preparation method thereof, comprising the following steps:

[0023] 1) The binder used is composed of: 85% homopolyoxymethylene, 12% high-density polyethylene, and 5% modified ethylene bisfatty acid amide according to the mass fraction. Add 17-4PH stainless steel powder with a volume percentage of 58% and 42% binder into the kneader, the mixing temperature is 190°C, the speed is 45r / min, and the mixing time is 3.5h.

[0024] 2) After mixing, it is extruded through a single-screw extruder at an extrusion temperature of 185° C. After extrusion, it is granulated to obtain feed.

[0025] The prepared 17-4PH stainless steel feeding material of the present invention is at temperature 185 ℃, shear rate 965s -1 Under these conditions, the viscosity, non-Newtonian exponent, activation energy of viscous flow and comprehensive rheological factor are 192.48Pa·s, 0.415, 28.72, 6.567×10 -7 , w...

Embodiment 3

[0027] A kind of polyoxymethylene-based binder for Fe-Cu-C porous material and feeding preparation method thereof, comprises the following steps:

[0028] 1) The binder used is composed of: 89% homopolyoxymethylene, 9% high-density polyethylene, and 2% stearic acid according to the mass fraction. Add metal powder with a volume percentage of 58% and binder with 42% into the kneader, the mixing temperature is 195° C., the rotation speed is 45 r / min, and the mixing time is 3 hours.

[0029] 2) After mixing, it is extruded by a single-screw extruder at an extrusion temperature of 190° C. After extrusion, it is granulated to obtain feed.

[0030] The prepared feeding material of the present invention is at temperature 185 ℃, shear rate 1961s -1 The viscosity, non-Newtonian index, activation energy of viscous flow and comprehensive rheological factor are 207.55Pa·s, 0.46, 40.89kJ·mol respectively -1 , 5.29×10 -7 , with good rheological properties.

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PUM

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Abstract

The invention relates to the technical field of powder metallurgy and particularly discloses a polyformaldehyde-based binder for metal injection formation and a preparation method of a fed material for metal injection formation. The binder comprises the following raw materials by weight percent: 75-90% of polyformaldehyde, 5-15% of polyethylene and 1-10% of a flow promoting agent. The preparationmethod of the fed material comprises the steps that metal powder and the binder are added into a kneading machine according to a certain proportion for mixing, extrusion for granulation is performed according to a single-screw extruder, and thus the granular fed material is obtained. The binder is low in viscosity and good in fluidity and has good mold filling capacity during injection formation,the defect of a green compact is reduced, and the yield is effectively increased.

Description

technical field [0001] The invention belongs to the technical field of powder metallurgy, and in particular relates to a method for preparing a binder for metal injection molding and a feeding material thereof. Background technique [0002] Metal injection molding (Metal injection molding, MIM) is a new type of powder metallurgy near-net shape technology that combines powder metallurgy technology and plastic injection molding technology. MIM technology uses molds to inject molded blanks, and then quickly manufactures high-density plastics through sintering. , Structural components with high dimensional accuracy and complex geometric shapes can quickly and accurately materialize design ideas into products with specific structures and functions, and can be directly mass-produced. Its products are widely used in electronic information engineering, biomedical equipment, automobiles, machinery, hardware, aerospace and other industrial fields. [0003] Binder is the core of MIM t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22F1/00B22F3/22
CPCB22F3/225B22F1/103B22F1/10
Inventor 李笃信魏梦玲丁楚雄卢仁伟杨忠臣
Owner CENT SOUTH UNIV
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