CN115351629A - A kind of recycling method of BN board - Google Patents

Abstract

The invention discloses a method for recycling a BN board, which belongs to the technical field of ceramics and comprises the following steps: coating a used BN board with a carbon-containing slurry; sintering the BN board coated with the slurry; Thinning treatment is carried out on the BN plate, and the thickness of the thinning is 30-50um. The present invention coats the used BN plate with carbon-containing slurry, sinters it, and grinds it after sintering to effectively remove impurities. After treatment, the grinding thickness is greatly reduced (without treatment, need to grind 0.4～0.8mm), so that it can continue to use; at high temperature, YAG has a certain fluidity, and there is a phenomenon of migration from the place with high concentration to the place with low concentration. The present invention utilizes the YAG of carbon and surface layer reaction, thereby promoting the migration of the internal YAG to the surface layer, and only need to grind 30-50um to remove impurities, thus greatly improving the service life of the BN board.

Description

A kind of recycling method of BN board

technical field

The invention relates to the technical field of ceramics, in particular to a method for recycling BN plates.

Background technique

BN plates are usually used in the sintering process of aluminum nitride substrates to act as a firing set. Yttrium aluminum garnet (YAG) will be produced during the sintering process of aluminum nitride. During the sintering process, a small amount of impurities such as yttrium aluminum garnet and alumina will infiltrate into the BN board, and at the same time, the yttrium aluminum garnet will also adsorb a small amount of aluminum nitride on the BN board. The surface affects the sintered appearance, thermal conductivity, strength and other properties of the subsequent aluminum nitride substrate, and also causes the service life of the BN board to be greatly reduced, which increases the production cost.

The existing process usually directly grinds the BN board by grinding treatment, so as to remove the YAG impurities on the surface, but the grinding needs to grind 0.4-0.8mm, which greatly affects the use of the BN board and causes waste of resources. Therefore, how to process the used BN plate to remove the YAG on the surface so that it can continue to be used has become a technical problem to be solved urgently by those skilled in the art.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for recycling BN plates, which can effectively remove impurities, and after treatment, the grinding thickness is greatly reduced (without treatment, it is necessary to grind 0.4 ~ 0.8mm), so that it can continue to use.

In order to achieve the above object, the technical scheme that the present invention takes is:

A kind of recycling method of BN plate, comprises the following steps:

Coating carbonaceous paste on the used BN board;

Sintering the BN plate coated with slurry;

After sintering, the BN plate is thinned to a thickness of 30-50um.

The inventors of the present invention have found in a large number of studies that the surface of the used BN board contains impurities, which affects its appearance and performance, and its continued use will affect the sintered appearance, thermal conductivity, and strength of the aluminum nitride substrate. Therefore, it is necessary to recycle the BN board.

The present invention is by coating carbonaceous slurry on the used BN plate, carries out sintering, after sintering, it is ground, can effectively remove impurity, after above-mentioned treatment, grinding thickness reduces greatly (without treatment , need to grind 0.4 ~ 0.8mm), so that it can continue to use.

The inventor further explored its mechanism and found that at high temperature (sintering), YAG has a certain fluidity, and there is a phenomenon of migration from a place with a high concentration to a place with a low concentration, and the carbon reacts with the YAG on the surface to promote internal The YAG migrates to the surface layer, and only needs to grind 30-50um to remove impurities, thus greatly improving the service life of the BN board.

As a preferred embodiment of the present invention, the carbon-containing slurry includes at least one of graphite slurry, carbon black slurry, activated carbon slurry, carbon nanotube slurry, and graphene slurry.

The inventor explored in a large amount of carbon sources, and found that the above-mentioned inorganic carbon source slurry can effectively react with YAG, thereby removing it by grinding, and using an organic carbon source, because the organic carbon source contains H , O, H and O need to be removed before sintering, which will greatly increase the processing steps and increase the cost. Therefore, in the present invention, it is necessary to select inorganic carbon such as graphite, carbon black, activated carbon, carbon nanotubes, and graphene source.

As a preferred embodiment of the present invention, the carbon-containing slurry includes at least one of graphite slurry, carbon black slurry, and activated carbon slurry.

As a preferred embodiment of the present invention, the carbon-containing slurry is graphite slurry.

As a preferred embodiment of the present invention, the mass concentration of the graphite slurry is 10-50%; the mass concentration of the carbon black slurry is 10-50%; the mass concentration of the activated carbon slurry is 10-50% ; The mass concentration of the carbon nanotube slurry is 10-50%; the mass concentration of the graphene slurry is 10-50%.

It should be noted that, in the present invention, regarding the mass concentration of graphite slurry, carbon black slurry, activated carbon slurry, carbon nanotube slurry, and graphene slurry, there is no special limitation in the present invention, as long as it can promote internal The effect of YAG migration to the surface layer is sufficient.

That is, those skilled in the art can select the specific coating amount according to the mass concentration of graphite slurry, carbon black slurry, activated carbon slurry, carbon nanotube slurry, graphene slurry, so as to achieve the promotion of internal YAG migration to the surface layer Effect, when the mass concentration of the slurry is low, the coating amount can be increased (greater than 10mg/cm ² ), and when the mass concentration of the slurry is high, the coating amount can be appropriately reduced (greater than 10mg/cm ² ).

As a preferred embodiment of the present invention, the coating amount of the carbon-containing slurry is ≥10 mg/cm ² . The inventor explored the coating amount of carbon-containing slurry, and found that when the coating amount of carbon-containing slurry ≥ 10mg/cm ² , it can well promote the migration of YAG to the surface layer, thereby removing it, and if the coating amount When it is lower than 10mg/cm ² , the YAG impurities inside the BN plate are not completely removed, and the impurities cannot be removed by grinding 30-50um. Therefore, in the present invention, it is necessary to strictly control the coating amount of carbon-containing slurry.

As a preferred embodiment of the present invention, the BN board is sintered under a nitrogen atmosphere. Under a nitrogen atmosphere, the carbon and YAG will react to form YN (sintered product), which can then be removed by grinding. The reaction equation is as follows:

C+N ₂ +Y ₂ O ₃ ·Al ₂ O ₃ →YN+AlN+CO.

As a preferred embodiment of the present invention, the sintering of the BN plate is carried out in a graphite furnace. There are generally only two types of sintering furnaces, metal furnace and graphite furnace. When the metal furnace is in use, _H2 needs to be fed to protect the heating element and the skeleton, and _H2 will react with C. Therefore, sintering needs to be carried out in the graphite furnace.

As a preferred embodiment of the present invention, the sintering temperature is 1400-1900° C., preferably 1400-1700° C., and the sintering time is 4-8 hours. The present invention further investigates the effect of sintering temperature and time on the migration effect of YAG, and finds that if the sintering temperature is lower than 1400°C and/or the sintering time is lower than 4h, the impurities inside the BN plate cannot be migrated well, and grinding of 50um is still possible. There are impurities, if the sintering temperature is higher than 1900°C and/or the sintering time is higher than 8h, the energy consumption will be too large, thereby increasing the processing cost.

As a preferred embodiment of the present invention, the thinning treatment is grinding with a grinding wheel.

As a preferred embodiment of the present invention, before sintering, it also includes laminating the BN plates coated with the slurry. It should be noted that, in the present invention, the BN plate coated with the slurry can be sintered by stacking or sintered separately.

As a preferred embodiment of the present invention, the thinned thickness is 30-50um.

The beneficial effects of the present invention are: (1) the present invention is by coating carbonaceous slurry on the used BN plate, carries out sintering, after sintering, it is ground, can effectively remove impurity, after processing, The grinding thickness is greatly reduced (without treatment, it needs to be ground 0.4 ~ 0.8mm), so that it can continue to be used; (2) At high temperature (sintering), YAG has a certain fluidity, and there is a direction from a place with a high concentration. The phenomenon of migration in places with low concentration, the present invention uses carbon to react with YAG on the surface, thereby promoting the migration of internal YAG to the surface, and only needs to grind 30-50um to remove impurities, thereby greatly improving the use of BN boards life.

Description of drawings

Figure 1 is a diagram of the used BN board;

Fig. 2 is the BN board figure that is processed after high temperature sintering of embodiment 1;

Fig. 3 is the BN board figure after the grinding treatment of embodiment 1;

Fig. 4 is embodiment 2 BN plate lamination diagram;

Fig. 5 is the BN plate figure after the grinding treatment of Comparative Example 1;

Fig. 6 is the BN board figure after grinding of comparative example 3;

Fig. 7 is a BN plate diagram after grinding 50um in Comparative Example 4.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. the embodiment. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

The reagents or instruments used in the present invention are not indicated by the manufacturer, and they are all conventional products that can be obtained from the market.

The used BN boards described in the present invention are the same batch of BN boards used for sintering aluminum nitride substrates. As shown in FIG. 1 , there are a large amount of impurities on the surface of the used BN boards.

Example 1

A kind of recycling method of BN plate, comprises the following steps:

Coating graphite slurry on the used BN plate (as shown in Figure 1), the coating amount of the graphite slurry is 10mg/cm ² , and the graphite slurry comprises the following components in mass percentage: 40% graphite powder , 58% absolute ethanol (solvent), 2% polyvinyl butyral (dispersant);

Put the slurry-coated BN plate into a graphite furnace and sinter it under a nitrogen atmosphere. The sintering temperature is 1600°C and the sintering time is 6 hours. The sintered BN plate is shown in Figure 2. It can be seen that after sintering, A large amount of impurities migrate to the surface;

After sintering, the BN board is ground and thinned with a grinding wheel, and the thinning thickness is 30um. The ground BN board is shown in Figure 3. It can be seen that after grinding for 30um, the surface has no impurities and can be used normally.

Example 2

A kind of recycling method of BN plate, comprises the following steps:

Coating graphite slurry on the used BN plate (as shown in Figure 1), the coating amount of the graphite slurry is 10mg/cm ² , and the graphite slurry comprises the following components in mass percentage: 40% graphite powder , 58% absolute ethanol (solvent), 2% polyvinyl butyral (dispersant);

Laminate the BN board coated with the slurry, 50 layers/stack. The laminated BN board is shown in Figure 4. Put it into a graphite furnace and sinter it under a nitrogen atmosphere. The sintering temperature is 1600°C. The sintering time is 6h;

After sintering, the BN plate is ground and thinned with a grinding wheel, and the thinned thickness is 50um.

Example 3

A kind of recycling method of BN plate, comprises the following steps:

Coating graphite slurry on the used BN plate (as shown in Figure 1), the coating amount of the graphite slurry is 15mg/cm ² , and the graphite slurry comprises the following components in mass percentage: 40% graphite powder , 58% absolute ethanol (solvent), 2% polyvinyl butyral (dispersant);

Laminate the BN plates coated with slurry, 50 layers/stack, put them into a graphite furnace, and sinter them under a nitrogen atmosphere. The sintering temperature is 1600°C, and the sintering time is 6h;

After sintering, the BN plate is ground and thinned with a grinding wheel, and the thinned thickness is 50um.

Example 4

A kind of recycling method of BN plate, comprises the following steps:

Coating graphite slurry on the used BN plate (as shown in Figure 1), the coating amount of the graphite slurry is 20mg/cm ² , and the graphite slurry comprises the following components in mass percentage: 40% graphite powder , 58% absolute ethanol (solvent), 2% polyvinyl butyral (dispersant);

Laminate the BN plates coated with slurry, 50 layers/stack, put them into a graphite furnace, and sinter them under a nitrogen atmosphere. The sintering temperature is 1600°C, and the sintering time is 6h;

After sintering, the BN plate is ground and thinned with a grinding wheel, and the thinned thickness is 50um.

Example 5

A kind of recycling method of BN plate, comprises the following steps:

Coating graphite slurry on the used BN plate (as shown in Figure 1), the coating amount of the graphite slurry is 15mg/cm ² , and the graphite slurry comprises the following components in mass percentage: 40% graphite powder , 58% absolute ethanol (solvent), 2% polyvinyl butyral (dispersant);

Laminate the BN plates coated with the slurry, 50 layers/stack, put them into a graphite furnace, and sinter them under a nitrogen atmosphere. The sintering temperature is 1400°C, and the sintering time is 8h;

After sintering, the BN plate is ground and thinned with a grinding wheel, and the thinned thickness is 50um.

Example 6

A kind of recycling method of BN plate, comprises the following steps:

Coating graphite slurry on the used BN plate (as shown in Figure 1), the coating amount of the graphite slurry is 15mg/cm ² , and the graphite slurry comprises the following components in mass percentage: 40% graphite powder , 58% absolute ethanol (solvent), 2% polyvinyl butyral (dispersant);

Laminate the BN plates coated with slurry, 50 layers/stack, put them into a graphite furnace, and sinter them under a nitrogen atmosphere. The sintering temperature is 1700°C, and the sintering time is 4h;

After sintering, the BN plate is ground and thinned with a grinding wheel, and the thinned thickness is 50um.

Example 7

A kind of recycling method of BN plate, comprises the following steps:

Coating graphite slurry on the used BN plate (as shown in Figure 1), the coating amount of the graphite slurry is 20mg/cm ² , and the graphite slurry comprises the following components in mass percentage: 10% graphite powder , 88% absolute ethanol (solvent), 2% polyvinyl butyral (dispersant);

Laminate the BN plates coated with slurry, 50 layers/stack, put them into a graphite furnace, and sinter them under a nitrogen atmosphere. The sintering temperature is 1600°C, and the sintering time is 6h;

After sintering, the BN plate is ground and thinned with a grinding wheel, and the thinned thickness is 50um.

Example 8

A kind of recycling method of BN plate, comprises the following steps:

Coating graphite slurry on the used BN plate (as shown in Figure 1), the coating amount of the graphite slurry is 10mg/cm ² , and the graphite slurry comprises the following components in mass percentage: 50% graphite powder , 48% absolute ethanol (solvent), 2% polyvinyl butyral (dispersant);

Laminate the BN plates coated with slurry, 50 layers/stack, put them into a graphite furnace, and sinter them under a nitrogen atmosphere. The sintering temperature is 1600°C, and the sintering time is 6h;

After sintering, the BN plate is ground and thinned with a grinding wheel, and the thinned thickness is 50um.

Example 9

A kind of recycling method of BN plate, comprises the following steps:

Coating graphite slurry on the used BN plate (as shown in Figure 1), the coating amount of the graphite slurry is 10mg/cm ² , and the graphite slurry comprises the following components in mass percentage: 40% activated carbon, 58% absolute ethanol (solvent), 2% polyvinyl butyral (dispersant);

Laminate the BN plates coated with slurry, 50 layers/stack, put them into a graphite furnace, and sinter them under a nitrogen atmosphere. The sintering temperature is 1600°C, and the sintering time is 6h;

After sintering, the BN plate is ground and thinned with a grinding wheel, and the thinned thickness is 50um.

Example 10

A kind of recycling method of BN plate, comprises the following steps:

Coating graphite slurry on the used BN plate (as shown in Figure 1), the coating amount of the graphite slurry is 10mg/cm ² , and the graphite slurry comprises the following components in mass percentage: 40% carbon black , 58% absolute ethanol (solvent), 2% polyvinyl butyral (dispersant);

Laminate the BN plates coated with slurry, 50 layers/stack, put them into a graphite furnace, and sinter them under a nitrogen atmosphere. The sintering temperature is 1600°C, and the sintering time is 6h;

After sintering, the BN plate is ground and thinned with a grinding wheel, and the thinned thickness is 50um.

Comparative example 1

A kind of recycling method of BN plate, comprises the following steps:

Coating graphite slurry on the used BN plate (as shown in Figure 1), the coating amount of the graphite slurry is 8mg/cm ² , and the graphite slurry comprises the following components in mass percentage: 40% graphite powder , 58% absolute ethanol (solvent), 2% polyvinyl butyral (dispersant);

Laminate the BN plates coated with slurry, 50 layers/stack, put them into a graphite furnace, and sinter them under a nitrogen atmosphere. The sintering temperature is 1600°C, and the sintering time is 6h;

After sintering, the BN board is ground and thinned with a grinding wheel, and the thickness of the thinned BN board is 50um. Lots of impurities.

Comparative example 2

A kind of recycling method of BN plate, comprises the following steps:

Coating graphite slurry on the used BN plate (as shown in Figure 1), the coating amount of the graphite slurry is 10mg/cm ² , and the graphite slurry comprises the following components in mass percentage: 40% graphite powder , 58% absolute ethanol (solvent), 2% polyvinyl butyral (dispersant);

Laminate the BN plates coated with the slurry, 50 layers/stack, put them into a graphite furnace, and sinter them under a nitrogen atmosphere. The sintering temperature is 1300°C, and the sintering time is 6h;

After sintering, the BN plate is ground and thinned with a grinding wheel, and the thinned thickness is 50um.

Comparative example 3

A kind of recycling method of BN plate, comprises the following steps:

Coating graphite slurry on the used BN plate (as shown in Figure 1), the coating amount of the graphite slurry is 10mg/cm ² , and the graphite slurry comprises the following components in mass percentage: 40% graphite powder , 58% absolute ethanol (solvent), 2% polyvinyl butyral (dispersant);

Laminate the BN plates coated with slurry, 50 layers/stack, put them into a graphite furnace, and sinter them under a nitrogen atmosphere. The sintering temperature is 1700°C, and the sintering time is 2h;

After sintering, the BN plate is ground and thinned with a grinding wheel. The thinned thickness is 50um. The thinned BN plate is shown in Figure 6. Due to the short sintering time, there are still a lot of impurities on the surface after the thinning is 50um.

Comparative example 4

Comparative example 4 is the used BN plate (as shown in Figure 1), but without any treatment, after grinding 50um, as shown in Figure 7, there are still a lot of impurities on the surface.

test case

In the recycling methods described in Examples 1 to 10 and Comparative Examples 1 to 4, the coating slurry, coating amount, number of layers, sintering temperature, and sintering time are shown in Table 1, and the experimental results are shown in Table 2 , YN in the table is the sintered product, which is the product of carbon and YAG reaction.

Table 1

Table 2 Test results

It can be seen from Table 1 that the recovery method of the BN board according to the present invention can effectively remove impurities, and after treatment, it can be reused.

Comparing Examples 1-10 with Comparative Example 4, it can be seen that the untreated BN plate is ground to 50um, and the surface still has a lot of impurities, but after the treatment of the present invention, the impurities are removed after grinding to 50um, the surface is smooth, and can be reused .

Comparing Example 2 with Comparative Example 1, it can be seen that if the coating amount is less than 10 mg/m ² , the coating amount is too low, and impurities cannot be completely migrated to the surface to be removed. Therefore, in the present invention, it is necessary to strictly control the coating coverage.

Comparing Example 2 with Comparative Example 2, it can be seen that if the sintering temperature is too low, the fluidity of YAG will be poor, and the impurities cannot be completely migrated to the surface to be removed. Therefore, in the present invention, the sintering temperature needs to be strictly controlled.

Comparing Example 2 and Comparative Example 3, it can be seen that if the sintering time is too short, the impurities cannot be completely migrated to the surface to be removed. Therefore, it is necessary to control the sintering time to allow the impurities to migrate to the surface.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that Modifications or equivalent replacements are made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims (10)

1. A recycling method of BN plate is characterized by comprising the following steps:

coating the used BN plate with a carbon-containing slurry;

sintering the BN plate coated with the slurry;

and thinning the BN plate after sintering, wherein the thinning thickness is 30-50 um.

2. The method for recycling a BN sheet according to claim 1, wherein the carbonaceous slurry comprises at least one of a graphite slurry, a carbon black slurry, an activated carbon slurry, a carbon nanotube slurry, and a graphene slurry; preferably comprises at least one of graphite slurry, carbon black slurry and activated carbon slurry, and more preferably graphite slurry.

3. The method for recycling a BN plate according to claim 2, wherein the amount of the carbon-containing slurry applied is not less than 10mg/cm ² 。

4. The method of recycling a BN plate as claimed in claim 1, wherein the BN plate is sintered under a nitrogen atmosphere.

5. The method of recycling a BN plate as claimed in claim 4, wherein the BN plate sintering is performed in a graphite furnace.

6. The method for recycling a BN plate according to claim 1, wherein the sintering temperature is 1400 to 1900 ℃.

7. The method for recycling a BN plate according to claim 6, wherein the sintering temperature is 1400 to 1700 ℃.

8. The method of claim 1, wherein the sintering time is 4 to 8 hours.

9. The method of recycling a BN plate as claimed in claim 1, wherein said thinning process is grinding with a grinding wheel.

10. The method for recycling a BN plate according to claim 1, further comprising laminating the BN plate coated with the slurry before sintering.

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