JPH04131693A - Baking sheet - Google Patents

Abstract

PURPOSE:To prevent the generation of carburizing in baked products when a carbide alloy, containing much of cobalt, is baked and provide ceramic powder with a sufficient smoothing property to improve the smoothness of the baded products by a method wherein the ceramic powder and BN as the smoothing constituents are dispersed in the constituents of organic resin. CONSTITUTION:40-85wt.% of ceramics powder 1 and 1-10wt.% of BN 2 as smoothing constituents are dispersed in the constituents 3 of organic resin occupying the balance of the kneaded product. The ceramic powder 1 is a fundamental constituent for preventing reaction between a base plate and a product to be baked upon baking and Al2O3, 3Al2O3.2SiO2, MgO and the like, for examples, are used. The baking sheet is made by a method wherein the kneaded product of these constituents is applied on a carrier film 4. Upon using, it is used by separating it from the carrier film 4 before using, however, separation from the carrier film 4 is easy since the BN constituents increase the smoothness of the sheet and it can be separated without remaining any excessive remaining strain whereby the deformation of the baking sheet upon baking can be reduced.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is aimed at preventing the reaction between plywood and the product to be fired when firing the product such as cemented carbide in a non-oxidizing atmosphere. The present invention relates to a firing sheet used for firing, and particularly to a firing sheet used for firing cemented carbide containing a large amount of cobalt as a binder.

(Prior art) When firing products such as cemented carbide, a bedding powder such as alumina powder has traditionally been used to prevent reactions between the plywood and the product. Laying powder is sprinkled onto the plywood by hand, and there are wide variations (it has the disadvantage that it tends to impair the smoothness of the fired product).

Therefore, the present inventors have developed a number of firing sheets made of organic resin containing ceramic powder as an alternative to bedding powder, and these sheets are particularly suitable for firing cemented carbide. , has developed a mixture of ceramic powder with carbon, phenol resin, etc. to prevent heat shrinkage of the sheet, and has already applied for a patent.

However, when this firing sheet is used, when firing a cemented carbide containing a large amount of cobalt as a binder, carburization occurs in which the carbon in the firing sheet penetrates into the cemented carbide, resulting in a failure in the fired product. The quality of the ceramics tends to be unstable, and when firing heavy items, the slippage is poor, and this, combined with the lack of dispersibility of the ceramic powder, leaves problems with the smoothness of fired products.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional problems, and eliminates carburization in the fired product even when a cemented carbide containing a large amount of cobalt is fired. This was completed in order to provide a sheet for firing that can impart sufficient lubricity to the surface and improve the smoothness of fired products.

(Means for solving the LI problem) The above problem is to disperse 40 to 85% by weight of ceramic powder and 1 to 10% by weight of BN as a lubricating component into the organic resin component that occupies the remainder. This can be achieved by using a sheet for firing which is characterized by the following.

Next, to explain each component, ceramic powder is a basic component to prevent the reaction between the plywood and the product to be fired during firing, and for example, AI! 03341□0.・2S
iO□, MgO, etc. are used. 4 ceramic powders
The reason why it is set at 0 to 85% by weight is because if it is less than this, the amount of ceramic powder will be insufficient and the lubricity will deteriorate, and if it is too much, there will be a lot of loss in the processing after firing and it will be difficult to form a sheet. It is.

Next, the use of BN as a lubricating component is a major feature of the present invention. The BN used here has laminated flaky crystals similar to graphite, and is stable and has excellent lubricity (especially in inert gas up to high temperatures around 3000°C).
It is a substance that exhibits lubricity) and has low wettability and reactivity with melted materials.

N is mixed in the form of powder or fibers, but the reason why the content is set at 1 to 10% is because if it is less than this, the lubricity is insufficient, and if it is too much, the lubricity will be insufficient. This is because there is a risk of reacting with the components in the cemented carbide.

The resin components include water-soluble resins such as PVA, CMC, and methyl cellulose, as well as PVB, styrene,
Organic solvent easily soluble resins such as acrylic, butadiene, acrylic, vinyl acetate and emulsions thereof are used.

(Function) Such a sheet for firing is made by mixing ceramic powder (1) and B N (2) with an organic resin component (3) as shown in Fig. 1.
However, as shown in Example 2 below, it may be produced by a method in which a kneaded product of these components is coated on a carrier film (4).

Before use, as shown in Figure 2, use a carrier film (4
), but since the BN component increases lubricity, it is easy to peel off from the carrier film (4).
It can be peeled off without leaving any residual strain, and the deformation of the firing sheet during firing is reduced.

Also, during firing, the organic resin component (3) first decomposes, and the third
As shown in the figure, a mixture of ceramic powder (1) and B N (2) remains between the product to be fired (5) and the plywood (6). Even in this state, B N (2), which is stable and has excellent lubricity up to high temperatures, is a ceramic powder (1
) Ceramic powder (1
) can move easily and improve the smoothness of the fired product.

Furthermore, B N (2) is a ceramic powder (1) after firing.
It also prevents the product from adhering to the bottom of the fired product, making it easier to perform post-fired inspections and other tasks.

Next, preferred embodiments of the present invention will be shown.

(Example 1) 65% alumina powder (wt%,
The same applies hereinafter) and 3% BN with a particle size of 3 to 5 μ- are dispersed in 30% PVA with 2% glycerin as a plasticizer, and this is used as a raw material with a basis weight of 150 g/I and a film thickness of 250 μ.
m firing sheets were manufactured.

On the other hand, a large number of products to be fired made of cemented carbide with a high cobalt content having an outer diameter of 320 mm, an inner diameter of 100 m, and a thickness of 10 mm were manufactured, and 10 pieces were fired in a vacuum using the above firing sheet. Ten pieces were fired in vacuum using conventional bedding flour.

As a result, carburization did not occur in either case as they did not contain carbon, but when the firing sheet of the present invention was used, there was almost no residue adhesion, whereas when the bedding powder was used, carburization did not occur. A large amount of ceramic powder and carbon adhered to the bottom surface of the fired product, and it took a considerable amount of time to remove it. Further, when the firing sheet of the present invention was used, the average warp of the fired product was 0.8 m, but when the baking sheet was used, the average warp was 1.2 terms. This is considered to be due to the lubricity improving effect of N as shown in FIG.

(Example 2) A slurry of 63% alumina powder, 5% BN, 5% dibutyl phthalate (plastic side), 2% surfactant, and 25% PVB with toluene and denatured alcohol was produced at 40,000 cps.
Adjust the viscosity to 200μ thick on the carrier film.
Painted on the seagull and 450 towers. On the other hand, for comparison, the same raw materials were used, except that the BN content was 0%, and the coating was applied onto a carrier film in the same manner.

When these were dried at 120°C for 15 minutes and then peeled off from the carrier film, the firing sheet of the present invention containing 5% BN could be peeled off smoothly, and the amount of deformation in the width direction at the time of peeling was 1 to 2 kaku/450. It was wa. On the other hand, the firing sheet containing 0% BN causes uneven peeling, and the amount of deformation in the width direction during peeling is 5 to 7 m+/450aa.
It became.

Thus, it can be seen that the firing sheet of the present invention has good releasability and is easy to manufacture.

(Effects of the Invention) As is clear from the above description, the present invention incorporates 40 to 85% by weight of ceramic powder and 1 to 10% by weight of BN as a lubricating component into the organic resin component that occupies the remainder. Since it is a dispersed material and does not contain carbon unlike conventional methods, there is no risk of carburization even if it is used for firing cemented carbide containing a large amount of cobalt as a binder. BN imparts sufficient lubricity to the ceramic powder, which improves peelability from the carrier film during manufacturing, and also allows the ceramic powder to move easily during firing, making it easy to use when firing heavy products. It is also possible to improve the smoothness of fired products.

Therefore, the present invention greatly contributes to the industry as a sheet for firing which eliminates the problems of the conventional sheet.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view conceptually showing the baking sheet of the present invention;
FIG. 2 is a cross-sectional view conceptually showing the situation in which the baking sheet of the present invention is peeled off from a carrier film, and FIG. 3 is a cross-sectional view conceptually showing the situation during baking of the baking sheet of the present invention. . (1): Ceramic powder, (2): B N, (3
): Organic resin component.

Claims (1)

[Claims] 40-85% by weight of ceramic powder (1) and 1-1
A sheet for firing, characterized in that 0% by weight of BN (2) as a lubricating component is dispersed in an organic resin component (3) occupying the remainder.