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A low-density cemented carbide ball with a diameter of more than 108 and its preparation method

A cemented carbide, density technology, applied in metal processing equipment, transportation and packaging, etc., can solve the problems of uneven density of green compact, poor effect of forming agent, difficulty in fine grinding, etc., achieve excellent processing performance, solve pressing problems Defects, the effect of broadening the scope of use

Active Publication Date: 2021-06-01
SICHUAN YR NEW MATERIAL TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The cemented carbide balls produced by this powder metallurgy process generally have the following problems: (1) The density of ordinary cemented carbide valve balls is above 9g / cm³; (2) Due to the poor effect of the former forming agent, it is not conducive to compacting The forming agent is completely removed during processing and sintering, resulting in sintering cracks of alloy balls with a diameter of more than 108, the product has a graphite phase, the porosity does not reach A02, B02, and holes greater than or equal to 25 microns appear; (3) Green compact density Inhomogeneous, consistent linear shrinkage coefficients in all directions during sintering, low dimensional accuracy, ellipticity above 1mm, subsequent fine grinding is very difficult
In addition, when the diameter of the ball exceeds 108mm, the reject rate increases greatly
At present, there is no mass production process of cemented carbide balls with a density lower than 7.1-7.3g / cm³ and a diameter of more than 108 at home and abroad

Method used

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  • A low-density cemented carbide ball with a diameter of more than 108 and its preparation method

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] (1) The alloy powder used to configure the alloy ball, the mass percentage of each alloy powder is: tungsten carbide, 28%; titanium carbide, 43%; nickel, 20%; chromium carbide, 1.5%; molybdenum, 7.5%;

[0029] (2) Carry out wet grinding for 68-74 hours after batching according to the composition ratio described in step (1), during which 2.0-2.5% of a special forming agent (paraffin: rubber = 7:3) is added, and after drying and homogenization, Achieving a mixture with uniform distribution of raw materials and molding agents;

[0030] (3) After the steel mold is poured into the mixture, it is placed on the hydraulic press, the pressure is 100MPa, and the mold is released after pressing and maintaining the pressure for 3-5 minutes;

[0031] (4) Put the demolded compact into the soft mold, and carry out cold isostatic pressing processing. After the cold isostatic pressing process, the density of the green compact is highly uniform, which ensures that the linear shrinkage c...

Embodiment 2

[0035] (1) The alloy powder used to configure the alloy ball, the mass percentage of each alloy powder is: tungsten carbide, 27%; titanium carbide, 44%; nickel, 19%; chromium carbide, 1.8%; molybdenum, 8.2%;

[0036] (2) Carry out wet grinding for 68-74 hours after batching according to the composition ratio described in step (1), during which 2.0-2.5% of a special forming agent (paraffin: rubber = 7:3) is added, and after drying and homogenization, Achieving a mixture with uniform distribution of raw materials and molding agents;

[0037] (3) After the steel mold is poured into the mixture, it is placed on the hydraulic press, the pressure is 100MPa, and the mold is released after pressing and maintaining the pressure for 3-5 minutes;

[0038] (4) Put the demolded compact into the soft mold, and carry out cold isostatic pressing processing. After the cold isostatic pressing process, the density of the green compact is highly uniform, which ensures that the linear shrinkage c...

Embodiment 3

[0042] (1) The alloy powder used to configure the alloy ball, the mass percentage of each alloy powder is: tungsten carbide, 26%; titanium carbide, 45%; nickel, 18%; chromium carbide, 2%; molybdenum, 9%;

[0043] (2) Carry out wet grinding for 68-74 hours after batching according to the composition ratio described in step (1), during which 2.0-2.5% of a special forming agent (paraffin: rubber = 7:3) is added, and after drying and homogenization, Achieving a mixture with uniform distribution of raw materials and molding agents;

[0044] (3) After the steel mold is poured into the mixture, it is placed on the hydraulic press, the pressure is 100MPa, and the mold is released after pressing and maintaining the pressure for 3-5 minutes;

[0045] (4) Put the demolded compact into the soft mold, and carry out cold isostatic pressing processing. After the cold isostatic pressing process, the density of the green compact is highly uniform, which ensures that the linear shrinkage coeff...

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Abstract

The invention discloses a low-density cemented carbide ball. The alloy powder includes tungsten carbide, titanium carbide, nickel, chromium carbide and molybdenum. The mass percentages of each alloy material are: tungsten carbide, 26%-28%; titanium carbide , 43‑45%; nickel, 18‑20%; chromium carbide, 1.5‑2%; molybdenum, 7‑9%. The density is small, which solves the problems of the previous high-density cemented carbide balls. Due to the large single weight and large impact force, the valve seat is broken and the service life is reduced. The cold isostatic pressing and blank processing are adopted, and the density is uniform and effective. The pressing defects are solved, the product ellipticity is within 0.2mm, the surface finish is ≤3.2, the special paraffin and rubber forming agent are prepared according to a certain proportion, and the addition amount is 2-2.5%, which can ensure that the cemented carbide ball has excellent processing performance. At the same time, the low amount of forming agent used is easy to remove during sintering, effectively avoiding sintering cracks and fluctuations in carbon content.

Description

technical field [0001] The invention relates to the technical field of alloy ball materials and a preparation method thereof, in particular to a low-density cemented carbide ball with a diameter of 108 or more and a preparation method thereof. Background technique [0002] Cemented carbide refers to an alloy material made of a hard compound of a refractory metal and a bonding metal through a powder metallurgy process. Carbide valve balls can be used together with valve seats and need to meet functional requirements such as wear resistance and corrosion resistance. At present, powder metallurgy technology is generally adopted at home and abroad to produce cemented carbide balls. The cemented carbide balls produced by this powder metallurgy process generally have the following problems: (1) the density of ordinary cemented carbide valve balls is above 9g / cm³; (2) due to the poor effect of the former forming agent, it is not conducive to the compaction The forming agent is co...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B22F1/00B22F3/04B22F3/14C22C29/10
CPCB22F3/04B22F3/14C22C29/10C22C29/067B22F2998/10B22F1/10B22F1/103B22F3/02
Inventor 贲昌元喻林蒋西文
Owner SICHUAN YR NEW MATERIAL TECH