CN116003163A - Coating for sintering hard alloy bar - Google Patents

Coating for sintering hard alloy bar Download PDF

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Publication number
CN116003163A
CN116003163A CN202211546372.5A CN202211546372A CN116003163A CN 116003163 A CN116003163 A CN 116003163A CN 202211546372 A CN202211546372 A CN 202211546372A CN 116003163 A CN116003163 A CN 116003163A
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coating
agent
powder
graphite
ethanol
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CN202211546372.5A
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CN116003163B (en
Inventor
王占坡
郭伟波
孙志远
张赣盛
吴天阳
许聪聪
马龙辉
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Zhejiang Hengcheng Cemented Carbide Co Ltd
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Zhejiang Hengcheng Cemented Carbide Co Ltd
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Abstract

The invention discloses a coating for sintering hard alloy bars, which comprises a coating agent A and a coating agent B, wherein the coating agent A is formed by mixing graphite powder with an ethanol solvent, and the coating agent B is formed by mixing aluminum nitride powder, graphite powder and the ethanol solvent. And discloses application of the coating for sintering the hard alloy bar in anti-sticking during high-temperature sintering of the hard alloy bar. The coating for sintering the hard alloy bar provided by the invention has a simple preparation method, can be used for preventing the graphite boat from being bonded during high-temperature sintering, has no carburization phenomenon and no bonding on the surface of the sintered bar product after anti-sticking treatment, and the anti-sticking coating prepared from the recovered AlN can be recycled, so that the anti-sticking coating has the same excellent anti-sticking effect. The recycling greatly reduces the production cost and is beneficial to large-scale industrial production and application.

Description

Coating for sintering hard alloy bar
Technical Field
The invention relates to a coating for sintering hard alloy bars, a preparation method and application thereof, and belongs to the field of rare earth magnets.
Background
In the sintering process of the hard alloy bar, a graphite boat is generally used as a bearing material, and as graphite itself is composed of carbon, the direct contact of the hard alloy and the graphite can cause the adhesion of the alloy to the boat at a high temperature, which is manifested by carburization of the contact position of the alloy and the boat, and bending of the product, a layer of coating is required to be coated above the graphite boat for preventing the adhesion of the alloy in the sintering process of the hard alloy bar at a temperature of more than 1000 ℃.
In the prior art, the anti-sticking coating is generally refractory powder and graphite powder, and no technology for recycling the coating is disclosed.
Chinese patent 031245471 discloses a method for preventing cemented carbide products from binding a boat during high temperature sintering, which comprises placing a disposable release paper in a graphite boat, placing cemented carbide products to be sintered on the release paper, and sintering in a sintering furnace. Because the release paper is paper, the release paper can become a paper film after sintering, and the release paper is very easy to float when moving or in the presence of wind, sintering equipment generally needs to be subjected to pressure sintering in the sintering process, gas scouring can enable the release paper to blow into a hearth, the hearth is dirty, and equipment short circuit can be caused when serious.
In view of the defects of the prior art anti-sticking coating, it is necessary to develop a coating for sintering hard alloy bars, which has good anti-sticking effect, does not carburize, does not pollute equipment, can be recycled and has reduced cost
Disclosure of Invention
Aiming at the technical problems existing at present, the invention provides a coating for sintering a hard alloy bar and application of the coating for sintering the hard alloy bar in anti-sticking.
The technical scheme adopted by the invention is as follows:
the paint for sintering the hard alloy bar comprises a paint A agent and a paint B agent, wherein the paint A agent is formed by mixing graphite powder with an ethanol solvent, and the paint B agent is formed by mixing aluminum nitride powder, graphite powder and the ethanol solvent.
Further, the ethanol is ethanol with a volume fraction of more than 95%.
The average particle size of the graphite powder is 8 microns or less, preferably 1 to 8 microns.
The average particle size of the aluminum nitride powder is 8 microns or less, preferably 1 to 8 microns.
In the paint A agent, the volume dosage of the ethanol is 4-6 mL/g, preferably 5mL/g, based on the mass of graphite powder.
In the coating B agent, the mass ratio of the aluminum nitride powder to the graphite powder is 3:1 to 1.5, preferably 3:1;
in the coating agent B, the volume dosage of the ethanol is 4-6 mL/g, preferably 5mL/g, based on the mass of the graphite powder.
More preferably, the invention provides a coating for sintering hard alloy bars, wherein the coating A agent is formed by mixing graphite powder and an ethanol solvent, and the volume dosage of ethanol is 5mL/g based on the mass of the graphite powder; the coating B agent is formed by mixing aluminum nitride powder, graphite powder and ethanol solvent, wherein the mass ratio of the aluminum nitride powder to the graphite powder is 3:1, the volume consumption of ethanol is 5mL/g based on the mass of graphite powder; the ethanol is ethanol with volume fraction of more than 95%.
AlN was first synthesized in 1877, but its potential for application in the microelectronics field did not stimulate the development of high quality commercially viable materials until mid-1980. AlN is synthesized by carbothermal reduction of alumina or by direct nitridation of aluminum. Its density is 3.26g/cm 3 Although it does not melt, it decomposes at above 2500 ℃ under atmospheric pressure. The material is covalently bonded and is resistant to sintering without the aid of liquid forming additives.
In the invention, ethanol acts as a diluent, and after brushing, ethanol volatilizes, and graphite and ALN remain on the surface of the graphite disk.
The invention also provides an application of the coating for sintering the hard alloy bar in preventing adhesion during high-temperature sintering of the hard alloy bar, which comprises the following steps: and (3) coating the paint A on the cleaned graphite boat, coating the paint B after the graphite boat is dried, and drying to obtain the graphite boat with the anti-sticking coating, wherein the graphite boat can be used for placing hard alloy bars and sintering at high temperature.
The drying is natural drying, and the drying is completed after the ethanol volatilizes. And naturally airing for 10-12 hours.
The invention also provides a method for preventing the hard alloy bar from adhering to the graphite boat during high-temperature sintering, which comprises the following steps: coating a coating agent A on the cleaned graphite boat, coating a coating agent B after the graphite boat is dried, and drying to obtain the graphite boat with an anti-sticking coating, wherein the graphite boat can be used for placing hard alloy bars and sintering at high temperature;
the coating A agent is formed by mixing graphite powder and an ethanol solvent, and the coating B agent is formed by mixing aluminum nitride powder, graphite powder and an ethanol solvent.
The ethanol is ethanol with the volume fraction of more than 95%, and the average granularity of the graphite powder is below 8 microns; the aluminum nitride powder has an average particle size of 8 microns or less;
in the coating A agent, the volume dosage of the ethanol is 4-6 mL/g based on the mass of graphite powder; in the coating B agent, the mass ratio of the aluminum nitride powder to the graphite powder is 3:1 to 1.5; in the coating agent B, the volume dosage of the ethanol is 4-6 mL/g based on the mass of graphite powder.
The paint is required to be uniformly applied.
In the method, the coating B agent used contains AlN and can be recovered.
The recovery method comprises the following steps: after the graphite boat with the anti-sticking coating is sintered at high temperature, the anti-sticking coating is scraped and removed from the graphite boat by automatic disc cleaning equipment or manually, and the graphite boat is sieved by a 50-mesh sieve, so that recovered powder is obtained, and the recovered powder replaces graphite powder in the coating agent B to prepare the recovered coating agent B.
Further, the fresh aluminum nitride powder and the recovered powder are prepared according to the mass ratio of 3:1, mixing the mixture with ethanol to prepare the recovered coating agent B.
The coating for sintering the hard alloy bar provided by the invention has a simple preparation method, can be used for preventing the graphite boat from being bonded during high-temperature sintering, has no carburization phenomenon on the surface of the sintered bar product after anti-sticking treatment, is not bonded, and fully meets the protection requirement in the sintering process of the hard alloy bar.
And AlN can be recycled, and the anti-sticking coating prepared by the recycled AlN has the same excellent anti-sticking effect. The recycling greatly reduces the production cost and is beneficial to large-scale industrial production and application.
Drawings
FIG. 1 is a photograph showing a state of a graphite boat coated with a paint.
FIG. 2 is a photograph of the surface of a sintered rod of the coating prepared in example 1.
FIG. 3 is a photograph of the surface of a sintered rod of the coating prepared in example 2.
Detailed Description
The invention will be further illustrated with reference to the following specific examples, without limiting the invention to these specific embodiments. In order to facilitate an understanding of the present application, a more complete description of the present application will now be provided with reference to the relevant figures. Preferred embodiments of the present application are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Example 1
1kg of graphite powder (average particle size D50 is 2-4.5 microns) and 5L of alcohol with volume concentration higher than 95% are mixed to obtain a coating agent A, then 1kg of graphite (average particle size 2 microns), 3kg of aluminum nitride powder (average particle size D50 is 2-4 microns) and 5L of alcohol with volume concentration higher than 95% are mixed to obtain a coating agent B, and then the coating agent B is coated on a graphite boat.
The brushing method comprises the following steps: and cleaning the graphite boat, brushing the coating A, and brushing the coating B after the graphite boat is naturally dried. Can be directly used for placing and sintering hard alloy bars after drying. The painting photograph of the graphite boat is shown in fig. 1, 1 is the cleaned graphite boat surface, no paint is painted yet, 2 is the graphite boat surface painted with paint a, and 3 is the graphite boat surface painted with paint B.
The surface photo of the sintered bar is shown in fig. 2, and the result shows that the surface of the sintered bar is free from carburization after being cleaned, so that the coating has a qualified protective effect on the production of the hard alloy bar.
Example 2
Because ALN material itself price is high, in order to save cost, the invention researches on recycling AlN.
The AlN recovery method comprises the following steps: in example 1, after the graphite boat having the anti-sticking coating was sintered at high temperature, the anti-sticking coating was brushed off with an automatic disc cleaning apparatus or manually, collected, sieved through a 50 mesh sieve, and collected to obtain a recovered powder, which was used to replace the graphite material in the paint B.
The recovered AlN powder was used for preparing a paint B-1 agent, and 1kg of the recovered powder, 3kg of fresh aluminum nitride powder and 5L of alcohol with a volume concentration of more than 95% were mixed to obtain a paint B-1 agent, which was then painted on a graphite boat. The preparation method of the coating A agent is the same as in example 1.
The brushing method comprises the following steps: cleaning the graphite boat, brushing the coating A, and brushing the coating B-1 after the graphite boat is dried. Can be directly used for placing and sintering hard alloy bars after drying.
The painting photograph of the graphite boat is shown in fig. 1, and in fig. 1, 4 is the surface of the graphite boat coated with the paint B-1.
The surface photo of the sintered bar is shown in fig. 3, and the result shows that the surface of the sintered bar is free from carburization after cleaning, and the anti-sticking effect of the recovered ALN coating also meets the production requirement.
The comparison of sintering results of the recovered ALN coating and the original ALN coating shows that the surface state and straightness trend of the sintered alloy of the recovered ALN coating are similar to those of the original ALN coating, and no obvious difference exists. It can be determined that recycling of the ALN coating is possible.
Example 3
Service life of recovered AlN coating
The AlN coating in the graphite boat after sintering of example 2 was recovered again, the coating was prepared and the bar was sintered according to the method of example 2, and the repeated cycles were performed, and the experiment showed that the use of the recovered AlN coating after at least 180 cycles had no negative effect on the surface state of the product.
This period is sufficient to meet the production recycling requirements, considering that a new ALN coating is added each time it is painted.
Comparative example 1
Coating agent B was prepared by replacing the aluminum nitride in example 1 with aluminum oxide, then a release coating was prepared and sintering of cemented carbide bars was performed following the procedure of example 1.
The result shows that the alumina filler can reduce carbon in the sintering process of the product, seriously decarbonizes the product and influences the service performance of the product.
Comparative example 2
A coating agent B was prepared by replacing the aluminum nitride in example 1 with carbon black composite filler (including alumina, carbon black and zirconia), and then a release coating was prepared and cemented carbide bar was sintered in accordance with the procedure of example 1.
The result shows that the carbon black composite filler can lead the product to be carburised in the sintering process, and the carburised product can lead the product to be carburized seriously, thereby influencing the service life of the product.
The aluminum nitride filler provided by the invention does not influence the carbon potential of the product, so that an accurate reference can be provided for raw material carbon matching.

Claims (10)

1. The paint for sintering the hard alloy bar is characterized by comprising a paint A agent and a paint B agent, wherein the paint A agent is formed by mixing graphite powder with an ethanol solvent, and the paint B agent is formed by mixing aluminum nitride powder, graphite powder and the ethanol solvent.
2. The paint for sintering a cemented carbide rod according to claim 1, wherein the ethanol is 95% or more by volume.
3. The paint for sintering a cemented carbide rod according to claim 1, wherein the graphite powder has an average particle size of 8 μm or less; the aluminum nitride powder has an average particle size of 8 microns or less.
4. The coating for sintering the hard alloy bar according to claim 1, wherein in the coating A agent, the volume amount of ethanol is 4-6 mL/g based on the mass of graphite powder; in the coating B agent, the mass ratio of the aluminum nitride powder to the graphite powder is 3:1 to 1.5; in the coating agent B, the volume dosage of the ethanol is 4-6 mL/g based on the mass of graphite powder.
5. The coating for sintering the hard alloy bar according to claim 1, wherein the coating A agent is formed by mixing graphite powder and an ethanol solvent, and the volume amount of ethanol is 5mL/g based on the mass of the graphite powder; the coating B agent is formed by mixing aluminum nitride powder, graphite powder and ethanol solvent, wherein the mass ratio of the aluminum nitride powder to the graphite powder is 3:1, the volume consumption of ethanol is 5mL/g based on the mass of graphite powder; the ethanol is ethanol with volume fraction of more than 95%.
6. Use of the coating for sintering cemented carbide bars according to any one of claims 1-5 for preventing sticking during high temperature sintering of cemented carbide bars, characterized in that the method of application is: and (3) coating the paint A on the cleaned graphite boat, coating the paint B after the graphite boat is dried, and drying to obtain the graphite boat with the anti-sticking coating, wherein the graphite boat is used for placing hard alloy bars and sintering at high temperature.
7. A method for preventing a hard alloy bar from adhering to a graphite boat during high-temperature sintering, which is characterized by comprising the following steps: coating a coating agent A on the cleaned graphite boat, coating a coating agent B after the graphite boat is dried, and drying to obtain the graphite boat with an anti-sticking coating, wherein the graphite boat is used for placing hard alloy bars and sintering at high temperature;
the coating A agent is formed by mixing graphite powder and an ethanol solvent, and the coating B agent is formed by mixing aluminum nitride powder, graphite powder and an ethanol solvent.
8. The method of claim 7, wherein the ethanol is 95% ethanol by volume or more and the graphite powder has an average particle size of 8 microns or less; the aluminum nitride powder has an average particle size of 8 microns or less;
in the coating A agent, the volume dosage of the ethanol is 4-6 mL/g based on the mass of graphite powder; in the coating B agent, the mass ratio of the aluminum nitride powder to the graphite powder is 3:1 to 1.5; in the coating agent B, the volume dosage of the ethanol is 4-6 mL/g based on the mass of graphite powder.
9. The method of claim 7, wherein the method comprises recovering aluminum nitride by: after the graphite boat with the anti-sticking coating is sintered at high temperature, the anti-sticking coating is scraped and removed from the graphite boat by automatic disc cleaning equipment or manually, and the graphite boat is sieved by a 50-mesh sieve, so that recovered powder is obtained, and the recovered powder replaces graphite powder in the coating agent B to prepare the recovered coating agent B.
10. The method of claim 9, wherein the fresh aluminum nitride powder and the reclaimed powder are mixed according to a mass ratio of 3:1, mixing the mixture with ethanol to prepare the recovered coating agent B.
CN202211546372.5A 2022-12-05 2022-12-05 Coating for sintering hard alloy bar Active CN116003163B (en)

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Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003095754A (en) * 2001-09-25 2003-04-03 Nittetsu Mining Co Ltd Release paper for ceramic firing
CN1565778A (en) * 2003-06-13 2005-01-19 闵小兵 Method and anti-sticking paper for preventing hard metal article from sticking to container in high sintering process
CN102367333A (en) * 2011-09-01 2012-03-07 四川科力特硬质合金股份有限公司 Anti-sticking paint for cemented carbide vacuum sintering
CN102744404A (en) * 2012-07-26 2012-10-24 江西稀有稀土金属钨业集团有限公司 Surface bonding-proof method for hard alloy parison sintering boat
CN104017396A (en) * 2014-05-07 2014-09-03 东莞理工学院 Anti-sticking coating for vacuum sintering of hard alloy and preparation method of anti-sticking coating
CN104399983A (en) * 2014-10-31 2015-03-11 东莞理工学院 Method for reducing bending rate of hard alloy short bar materials
CN106147557A (en) * 2016-07-29 2016-11-23 株洲硬质合金集团有限公司 Release coating and preparation, using method for sintering cemented carbide
CN108456439A (en) * 2018-01-08 2018-08-28 三峡大学 A kind of sintering coating of the low Binder Phase cermet of environment-friendly type
CN112159946A (en) * 2020-09-04 2021-01-01 崇义章源钨业股份有限公司 Anti-sticking coating, carbon-based boat and preparation method of anti-sticking coating

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003095754A (en) * 2001-09-25 2003-04-03 Nittetsu Mining Co Ltd Release paper for ceramic firing
CN1565778A (en) * 2003-06-13 2005-01-19 闵小兵 Method and anti-sticking paper for preventing hard metal article from sticking to container in high sintering process
CN102367333A (en) * 2011-09-01 2012-03-07 四川科力特硬质合金股份有限公司 Anti-sticking paint for cemented carbide vacuum sintering
CN102744404A (en) * 2012-07-26 2012-10-24 江西稀有稀土金属钨业集团有限公司 Surface bonding-proof method for hard alloy parison sintering boat
CN104017396A (en) * 2014-05-07 2014-09-03 东莞理工学院 Anti-sticking coating for vacuum sintering of hard alloy and preparation method of anti-sticking coating
CN104399983A (en) * 2014-10-31 2015-03-11 东莞理工学院 Method for reducing bending rate of hard alloy short bar materials
CN106147557A (en) * 2016-07-29 2016-11-23 株洲硬质合金集团有限公司 Release coating and preparation, using method for sintering cemented carbide
CN108456439A (en) * 2018-01-08 2018-08-28 三峡大学 A kind of sintering coating of the low Binder Phase cermet of environment-friendly type
CN112159946A (en) * 2020-09-04 2021-01-01 崇义章源钨业股份有限公司 Anti-sticking coating, carbon-based boat and preparation method of anti-sticking coating

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