KR100314726B1 - A Method For Fabricating Zirconia Coated Alumina Sagger - Google Patents

Abstract

The present invention relates to an alumina fireproof coating coated with zirconia, and to give a surface roughness to the surface of the alumina fireproof coating, and thus can be manufactured at a lower cost than the zirconia coating, which has excellent mechanical properties and does not change the properties of the treated material. I want to provide a way to do that, and that's what it is.

The present invention is a method of manufacturing alumina saggar prepared by mixing and molding a binder in a raw material containing alumina as a main component, followed by baking

Imparting a roughness to the surface of the fireproof molded article during the molding to form a roughness having a surface roughness of 50 μm or less on the surface of the calcined alumina refractory carton;

A method of producing a zirconia-coated alumina sacks by forming a zirconia coating layer having a thickness of 30 μm to 1000 μm on the surface of the calcined alumina sacks having a surface roughness of 50 μm or less.

Description

A method for fabricating zirconia coated alumina sagger}

The present invention relates to an alumina saggar, and more particularly, to an alumina sag coated with zirconia.

Sagger is a container that serves as a container that requires heat treatment and sintering at high temperatures.

When sintering at high temperature or heat treatment such as when BaTi oxide-based capacitor or ferrite core is put in fireproof box and sintered at high temperature, chemical reaction of the fireproof box and contents may occur. This changes the properties of the product.

Therefore, manufacturers using fireproof gloves select and use the material of the fireproof gloves according to the contents to be used.

As a material of the fireproof sacks, alumina fireproof sacks and zirconia fireproof sacks are used.

The zirconia fireproof sacks are 6-7 times more expensive than those of the alumina fireproof sacks, the manufacturing process is difficult, and the mechanical properties such as thermal stress and strength are inferior, but the reactivity with treatment materials such as sintered materials is low. It is mainly used.

For example, when a BaTi-based capacitor is placed in an alumina sag box and sintered, a chemical reaction between the aluminum component and the barium component occurs, thereby deteriorating the product characteristics of the capacitor. In order to prevent such chemical reactivity, zirconia sag instead of alumina sag is used.

On the other hand, there is a known refractory value of zirconia powder sprinkled on the alumina saggar, but when using such saggar, there is a problem, such as the workability is poor, because continuous use is difficult, there is a limit.

In addition, zirconia-based coated alumina sacks are developed and commercialized by Norton Corporation of the United States.

Refractory value developed by Norton Corporation of the United States is the thickness of the coating layer is about 150㎛, its component is known as ZrO ₂ with CaO added about 5wt.

However, in the case of the Norton company product, since the surface roughness of the fireproof coating layer is rough, there is a problem that may cause local stress concentration upon contact with a treatment material such as a capacitor.

If a local stress occurs at the interface between the processing material such as a capacitor and the fireproof coating layer, the non-uniform sintering is performed at this part, thereby changing the electrical properties of the processing material.

The present inventors have conducted research and experiments to improve the above-mentioned problems of the prior art, and based on the results, the present invention proposes the present invention, and the present invention imparts an appropriate surface roughness to the surface of the alumina fireproof coating and then coated zirconia. Therefore, to provide a method for producing a low-cost saggar that has excellent mechanical properties and does not change the properties of the treated material, the purpose is to.

1 is a side view of a conventional zirconia coated inner zirconia sag according to the present invention

Figure 2 is a plan view of the saggar arranged in accordance with the example of the method of coating the zirconia on the surface of the saggar in accordance with the present invention

Explanation of symbols on the main parts of the drawings

One . . . Alumina Refractory 2,3. . . Zirconia Coating Layer

4 . . . Jaw of fireproof armor 5. . . Fireproof

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated.

The present invention is a method of manufacturing alumina saggar prepared by mixing and molding a binder in a raw material containing alumina as a main component, followed by baking

Imparting a roughness to the surface of the fireproof molded article during the molding to form a roughness having a surface roughness of 50 μm or less on the surface of the calcined alumina refractory carton;

After firing, the present invention relates to a method of manufacturing a zirconia coated alumina sacks by forming a zirconia coating layer having a thickness of 30 μm to 1000 μm on the surface of the calcined alumina sacks having a surface roughness of 50 μm or less.

In addition, the present invention is a method of manufacturing the zirconia-coated alumina sacks of the present invention described above, when the angle of the jaw portion of the alumina sacks is 80 degrees or more in a state of rotating the alumina sacks 40-50 degrees The present invention relates to a method of manufacturing a zirconia-coated alumina sacks by fixing and zirconia coating at an oblique angle of 70 degrees or less.

Hereinafter, the present invention will be described in detail.

The present invention is applied to any commonly used alumina saggar.

The alumina sag suitably applicable to the present invention is prepared by mixing and molding a binder in a raw material containing 70 to 95 wt% alumina, 4 to 29 wt% silicon oxide, and other oxides, and then firing.

The other oxides include Fe 2 O 3, CaO, MgO, TiO 2, Na 2 O, K 2 O, and the like, and the Fe 2 O 3 is preferably managed at 0.1-0.4 wt%.

The silicon oxide is added to increase the strength, fire resistance (usable temperature) and thermal stress of the alumina saggar.

The other oxides serve to increase moldability and sinterability in manufacturing the saggar.

As the binder, a binder such as polyvinyl alcohol (PVA) is used. The binder is mixed with the raw material, then molded, and then fired at about 1380 ° C.

In order to coat zirconia according to the present invention on the surface of the alumina saggar prepared as described above, it is required to appropriately adjust the surface roughness of the saggar molded body during molding.

In the present invention, the reason for providing appropriate roughness to the surface of the fireproof molded article during molding is to increase the adhesion of the coating layer when coating zirconia, which is a subsequent process.

In the present invention, the surface roughness of the fireproof sap molded body is preferably selected so that the surface roughness of 50 µm or less is formed on the surface of the calcined alumina saggar.

An example of a method of controlling the surface roughness of the fireproof sap molded body during molding is a method of forming an alumina sag by using a plate having irregularities on its surface, that is, using an embossed plate. A method of forming a fireproof pack can be mentioned.

At this time, the surface roughness of the embossed plate is preferably 50㎛ or less based on the average roughness. Because when the average roughness is 50㎛ or more, it is difficult to uniformly coat the alumina surface when coating the zirconia, which is a subsequent process.

Next, the fireproof pack molded article provided with the surface roughness as described above is fired by a conventional method.

Next, by forming a zirconia coating layer having a thickness of 30 μm to 1000 μm on the surface of the calcined alumina sag having a surface roughness of 50 μm or less, a zirconia coated alumina sag according to the present invention is produced.

As the zirconia coating method that can be applied to the present invention, any method can be used as long as it is a coating method that is commonly used. However, more preferable coating methods that can be applied to the present invention include a plasma spray coating method and a thermal spraying method. (Thermal Spray) A coating method is possible.

The reason why the thermal spray coating method is preferably applied to the present invention is that a separate post-treatment process is not necessary after the thermal spray coating, and since excellent adhesion can be obtained, there is no peeling phenomenon of the zirconia coating layer coated on the upper layer under thermal stress. to be.

On the other hand, in the present invention, the thickness of the zirconia coating layer is selected to 30-1000㎛, the reason is that when the thickness of the coating layer is less than 30㎛ the Al which is a substrate component is diffused to cause a chemical reaction with the product contained in the saggar. This is because a characteristic of the thermal spray coating method is affected by the roughness of the alumina substrate to generate a portion that does not completely coat the alumina surface.

In addition, when the thickness of the zirconia coating layer is more than 1000㎛ because cracks in the coating layer occurs when used for a long time at high temperature, partial peeling occurs, it is also disadvantageous in terms of economics.

Therefore, in this invention, it is preferable to select the thickness of a zirconia coating layer in the range of 30-1000 micrometers.

1 shows a zirconia coated alumina saggar according to the present invention.

As shown in FIG. 1, the saggar pack has a jaw portion 4 having a predetermined angle α.

The jaw angle is generally greater than 80 degrees, in which case the zirconia coating of this jaw 4 is not achieved properly.

Therefore, in order to apply the present invention, it is preferable to configure the saggar so that the angle of the jaw portion is less than 80 degrees.

If the present invention is applied to the fireproof sacks having the jaw angle of 80 degrees or more, as shown in FIG. 2, the alumina fireproof sacks 5 are fixed at a state of 40-50 degrees and preferably 45 degrees, If the zirconia coating is applied at an oblique angle of 70 degrees or less, the zirconia may be more uniformly coated on the jaw portion of the alumina saggar.

In FIG. 1, reference numeral 1 denotes an alumina saber pack, 2 denotes a zirconia coating layer of the upper plate portion, and 3 denotes a zirconia coating layer of the lower plate portion.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1

In this embodiment, the zirconia coating was applied to the plasma spray coating method. In this case, zirconia powder was used as the coating material, and the thermal spraying event was used by the thermal spraying agent of METCO company.

In addition, the thickness of the zirconia coating layer was 150 micrometers.

Inventive Example (1)

In manufacturing the alumina saggar, the average roughness of the surface is 1 占 퐉 or less, and in the shape of the alumina saggar, the jaw portion is molded and sintered so as to have an angle of 30 degrees from the horizontal.

Inventive Example (2,3)

Inventive Examples (2, 3) is a case where the surface roughness is adjusted to about 5㎛, Inventive Example (2) is the angle of the alumina jaw portion 30 degrees, Inventive Example (3) is designed and molded to 60 degrees and sintered This is the case where the alumina saggar was manufactured.

Inventive Example (4)

In the case of manufacturing alumina sacks with an average roughness of 5 μm on the surface of alumina and an angle of 80 degrees at the jaw, in this case, when coating, alumina sacks are rotated at about 45 degrees as shown in FIG. It is a case where it coats after continuously arranging.

Inventive Example (5, 6)

In the case where the surface roughness of the alumina saggar was changed, Inventive Example (5) made the average roughness of the surface of the alumina sag as about 20 µm, and Inventive Example (6) made the average roughness of the surface of about 50 m. .

Comparative Example (1, 2)

Comparative Example (1) was prepared to make the surface roughness of the alumina fireproof box to 5㎛, but to make the angle of the jaw portion to 80 degrees , Comparative Example (2) to make the alumina surface roughness to 70 ~ 80㎛ In this case, the chin is coated with zirconia by preparing alumina sacks to have an angle of 30 degrees.

The coating uniformity, thermal stress resistance, chemical reactivity and fingerprint resistance of the fireproof sacks prepared under the conditions described above were examined, and the results are shown in Table 1 below.

The coating uniformity in the characteristics of Table 1 means how much the coating thickness of the vertical part of the jaw is coated with respect to the coating thickness of the upper plate, and when the coating thickness of the jaw is 60 or more ◎, 40 to 60 ○ , 10 to 40, and 10 or less, x.

In addition, the chemical reactivity of the BaTi-based capacitor is placed on the refractory pack, and then sintered at 1380 ° C. for 3 hours, and then the reaction between the refractory pack and the capacitor is examined. (Triangle | delta), and when reaction area more than 50 is observed, it marks with x.

In addition, the anti-fingerprint of the zirconia coating layer refers to a phenomenon that a portion of the coating layer is buried in the hand when the surface of the product coated with zirconia is touched by hand, in the present invention, the relative comparison with the adhesive tape, the zirconia is (Circle) and an area of 5 or more, it represented with (triangle | delta), and 30 or more, if it did not come out.

The thermal stress resistance of the coating layer is related to the adhesion of the coating layer. In this experiment, the heating rate was 5 ° C. per minute and maintained at 1380 ° C. for 3 hours, followed by cooling at 5 ° C. per minute for 50 cycles. After the test, the peeling phenomenon of the coating layer was observed, and if the coating layer was not peeled off at all and the adhesion was excellent, the adhesiveness was slightly lowered, but if the coating layer was not peeled off at all. , When it occurs at the jaw part and the flat part, it is marked with x.

division Alumina Refractory Substrate rotation angle for spray coating Fireproof Talents Average surface roughness (㎛) Jaw angle Coating uniformity Thermal stress resistance Chemical reactivity Anti-fingerprint Inventive Example 1 <1 30。 0. ◎ ○ ○ ○ Inventive Example 2 5 30。 0. ◎ ◎ ○ ○ Inventive Example 3 5 60。 0. ○ ◎ ○ ○ Inventive Example 4 5 80。 40-50. ○ ◎ ○ ○ Inventive Example 5 To 20 30。 0. ◎ ◎ ○ ○ Inventive Example 6 -50 30。 0. ◎ ○ ○ ○ Comparative Example 1 5 80。 0. △ △ △ ○ Comparative Example 2 70-80 30。 0. × × × △

As shown in Table 1, when the zirconia coating on the surface of the alumina saggar according to the present invention [Invention Example (1-6)] is out of the scope of the present invention it can be seen that the characteristics of the saggar better. have.

Example 2

After the zirconia coating on the surface of the alumina sacks under the coating method, coating material, and coating thickness shown in Table 2, coating uniformity, thermal stress resistance, chemical reactivity and fingerprint resistance were investigated, and the results are shown in the following table. 2 is shown.

In this embodiment, the surface roughness of the alumina saggar was set to 5 µm or less, and the jaw portion of the alumina saggar was prepared to be 60 degrees, and then zirconia was coated on the top plate.

In addition, in the present embodiment, the zirconia coating was applied with a plasma spray coating method and a thermal spray coating method.

In the plasma spray coating method, zirconia powder was used as the coating material, and the spraying case was used by the METCO spraying case. In the thermal spray coating method, zirconia rod was used, and the thermal spraying was made by ROKIDE.

Zirconia used Y ₂ O ₃ (Yttria) or CaO (Calcia) partially stabilized zirconia, whether in powder or rod form.

However, Comparative Examples (7 to 8) are prepared by dispersing a fine zirconia powder of about 1.5 μm in a suitable dispersant without applying a spray coating technique as a coating method, and coating using wet spray and dipping techniques. It was.

division Coating method Coating material Coating thickness Fireproof Coating uniformity Thermal stress resistance Chemical reactivity Anti-fingerprint Inventive Example 7 Plasma Champion YZP To 30 ○ ◎ ○ ○ Inventive Example 8 ~ 150 ◎ ◎ ○ ○ Inventive Example 9 400-450 ◎ ◎ ○ ○ Inventive Example 10 900-1000 ◎ ○ ○ ○ Inventive Example 11 CZP ~ 150 ◎ ◎ ○ ○ Inventive Example 12 Thermal spray CZR -40 ○ ◎ ○ ○ Inventive Example 13 ~ 200 ◎ ◎ ○ ○ Inventive Example 14 800-900 ◎ ○ ○ ○ Inventive Example 15 YZR ~ 200 ◎ ◎ ○ ○ Comparative Example 3 Plasma Champion YZP <20 △ ◎ △ ○ Comparative Example 4 YZP 1200 △ × ○ ○ Comparative Example 5 Thermal spray CZR <20 △ ◎ △ ○ Comparative Example 6 1000 × ◎ ○ ○ Comparative Example 7 Wet spray CZP -100 ◎ × ○ × Comparative Example 8 WetDipping CZP ~ 200 △ × ○ ×

* YZP: Yttria partially stabilized zirconia powder, CZP: Calcia partially stabilized zirconia powder, CZR: Calcia partially stabilized zirconia rod (Rod), YZR: Yttria partially stabilized zirconia rod

As shown in Table 2, when the coating thickness of the zirconia is coated between 30 ㎛ to 1000 ㎛ according to the present invention, it can be seen that the zirconia coated alumina sacks having excellent fireproof characteristics can be prepared.

As described above, according to the present invention While maintaining the excellent mechanical properties of the conventional alumina saggar as it is, it is possible to manufacture the saggar at a lower cost than the conventional zirconia saggar.

Therefore, when sintering a product such as a condenser capable of chemical reaction with the alumina component, when using the fireproof sap prepared according to the present invention, it is possible to make excellent characteristics of the product to be sintered, It will have a prolongable effect.

Claims (8)

In a method of manufacturing alumina saggar prepared by mixing and molding a binder in a raw material containing alumina as a main component, and then calcining, Imparting a roughness to the surface of the fireproof molded article during the molding to form a roughness having a surface roughness of 50 μm or less on the surface of the calcined alumina refractory carton; After firing, a method of manufacturing a zirconia coated alumina sacks characterized in that the coating is formed on the surface of the calcined alumina sacks having a surface roughness of 50 μm or less to form a zirconia coating layer having a thickness of 30 μm to 1000 μm. The zirconia coated coating according to claim 1, wherein the alumina sacks are made by mixing and molding a binder in a raw material containing 70 to 95 wt% alumina, 4 to 29 wt% silicon oxide, and other oxides. Of prepared alumina fireproof sacks The method of claim 2, wherein the other oxides are Fe 2 O 3, CaO, MgO, TiO 2, Na 2 O, K 2 O, and the Fe 2 O 3 is 0.1-0.4 wt. The method for producing a zirconia coated alumina sacks according to any one of claims 1 to 3, wherein the zirconia coating method is plasma spraying or thermal spraying. In the method of manufacturing an alumina fireproof sacks having a jaw angle of 80 degrees or more by mixing and molding a binder into a raw material mainly composed of alumina, and then firing the same, Imparting a roughness to the surface of the fireproof molded article during the molding to form a roughness having a surface roughness of 50 μm or less on the surface of the calcined alumina refractory carton; After firing, the alumina sag was fixed in a state of rotating 40-50 degrees, and the coating angle was coated at an oblique line of 70 degrees or less, and the surface of the calcined alumina sacks having a surface roughness of 50 μm or less was 30 μm to 1000 μm. Method for producing a zirconia coated alumina sacks characterized in that to form a thick zirconia coating layer The zirconia coated coating according to claim 5, wherein the alumina sacks are prepared by mixing and molding a binder in a raw material containing 70 to 95 wt% alumina, 4 to 29 wt% silicon oxide, and other oxides. Of prepared alumina fireproof sacks The method of claim 6, wherein the other oxides are Fe 2 O 3, CaO, MgO, TiO 2, Na 2 O, K 2 O, and the Fe 2 O 3 is 0.1-0.4 wt. The method of manufacturing zirconia coated alumina sacks according to any one of claims 5 to 7, wherein the zirconia coating method is plasma spraying or thermal spraying.