JPS61178487A - Ceramic multilayer coating structure - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a structure having excellent heat resistance, chemical resistance, impact resistance, etc. The present invention relates to a structure particularly suitable for use in high temperature atmospheres and cold/heat cycles.

(Prior Art) Conventionally, various materials such as metals, ceramics, and resins have been used as materials for various base materials depending on the purpose. In particular, as high-temperature structures, heat-resistant alloys, ceramics, and combinations thereof are generally used, but the current situation is that it is desired to increase the service life temperature year by year.

(Problems to be Solved by the Invention) Among the conventional high-temperature structures mentioned above, structures made of heat-resistant alloys have good workability at room temperature, but have a limited use temperature, which is higher than about 1200°C. When used at high temperatures, the surface of the structure becomes oxidized and becomes unusable, and paired structures such as bolts and nuts tend to fall off.

In terms of temperature alone, ceramic structures can be used at higher temperatures than heat-resistant alloys, but they are mechanically and structurally brittle and may break when subjected to thermal, mechanical, or structural stress. Ta.

Furthermore, even when heat-resistant alloys and ceramics are combined,
If the difference in coefficient of thermal expansion and thermal conductivity is large, the ceramic coating layer may peel or break, which has the drawback of limiting its use.

The purpose of the present invention is to eliminate the above-mentioned problems, and to provide sufficient physical strength against adhesion, adhesion, compression, peeling resistance, chipping, etc., not only at room temperature but also when used at higher temperatures than conventional ones or in cold and hot cycles. It is an object of the present invention to provide a ceramic multilayer coated structure having excellent chemical resistance, impact resistance, etc.

Another object of the present invention is to provide a ceramic multilayer coating structure that can be coated with ceramics on any substrate without being limited to coating substrates.

(Means for Solving the Problems) The ceramic multilayer coating structure of the present invention provides a coating with a multilayer structure of at least two layers consisting of a porous ceramic layer and a non-porous ceramic layer on any base material as a thin film. By coating it as a coating, it improves chemical resistance, durability, corrosion resistance, abrasion resistance, water resistance, heat resistance, peeling resistance, and impact resistance, as well as electrical insulation, moisture proofing, enamel, infrared radiation, electromagnetic wave absorption, etc. It is characterized by the addition of excellent properties.

(Function) In the present invention, by coating a structure such as a heat-resistant alloy with a multilayer structure of at least two layers of a porous ceramic layer and a non-porous ceramic layer, differences in thermal expansion coefficient, thermal conductivity, etc. It is possible to prevent peeling and cracking of the metal and ceramic coating layer due to high temperatures or cold/hot cycles, and even though the coating layer is a very thin layer, it covers the brittleness of ceramics and makes the ceramics more durable. It is possible to obtain a structure having sufficient strength equivalent to the heat resistance of . In addition, the porous ceramic layer has a low thermal expansion coefficient.
It absorbs various negative forces caused by differences in thermal conductivity, etc., and since a porous ceramic layer alone may be corroded by acids, it is coated with at least one non-porous ceramic layer to provide acid resistance, etc. ing. At this time, it is more effective if the outermost layer of the multilayer structure is a non-porous ceramic layer. In addition, in this specification, "porous"
The term "non-porous" refers to ceramics that are qualitatively porous with many pores, etc., and "non-porous" to those with almost no pores.

(Example) The present invention will be described in detail below with reference to the drawings.

Figures 1(a) and 1(b) show an example in which the structure of the present invention is applied to a fixed lid for fixing a heat-resistant lining made of ceramic fiber (hereinafter abbreviated as rcFJ) to a wall surface of a high-temperature industrial furnace. FIG. 1(a) shows the mounting state, and FIG. 1(b) shows the fixing device itself.

Since one end of the stud 1 is welded to the furnace wall and does not come into contact with the external atmosphere, in this example, the ceramic multilayer coating of the present invention is not applied to that part (considering welding). Further, the end of the stud 1 opposite to the end to be welded to the furnace wall is threaded, and the threaded portion 2 and the retainer 3 are engaged to fix the CF lining 4.

This stud 1 is formed by coating a heat-resistant alloy body with multiple layers of porous ceramics and non-porous ceramics. The present invention can be applied to any shape of the threaded portion 2, but in general, when using a stud with a small thread pitch or effective diameter, for example, the threaded portion 2 is 8 mfl1φ or less, the shape shown in Fig. 2(b) is used. As shown in the enlarged view of the threaded part 2, the stud 1 and the second stud with trapezoidal threads are shown.
Retainer 3 with a thread that engages with it as shown in Figure (a)
It is preferable to attach the CF lining 4 by using the following method.

In this example, as shown in FIGS. 2(a) and 2(b), the part in contact with the external atmosphere has a three-layer structure, and the Zr
02. After forming a porous ceramic layer 5 and a porous ceramic layer 6 made of a ceramic such as SiO□ (the same composition may be used), a non-porous ceramic layer 7 is further coated. This coating ceramic layer5.
The thickness of each of 6.7 is preferably about 10 to 50 μm. In addition, in FIG. 2 (a> and (b)), the thickness of each layer is displayed thicker than the actual thickness for convenience of drawing.Since this example has a three-layer structure as described above, Cleaning, peeling, etc. caused by the difference in thermal expansion coefficient, thermal conductivity, etc. between ceramics and heat-resistant alloys are absorbed by the porous ceramic layer and between the ceramic layers, preventing peeling and damage of the ceramic. can.

Hereinafter, a method for manufacturing a structure of the present invention will be explained. First, a heat-resistant alloy is processed into a predetermined shape.

At this time, since the thickness of the ceramic layer is very thin, there is no need to calculate the coating allowance and process it to be smaller than a predetermined size. In parallel with the processing, a pulverized ceramic such as ZrO□ is prepared, a small amount of water or an alcoholic liquid, and an adhesive are mixed therein and then kneaded to prepare a liquid ceramic mixture.

Porous ceramics and non-porous ceramics are created separately by changing their mixing ratios. The reason why the adhesive is mixed here is so that when the multilayer ceramic layer is dried at room temperature or at a temperature up to 150° C., the ceramic powders will adhere to each other and form a layer. That is, in the present invention, in order to form a layer, it is necessary to perform firing at a high temperature after coating the ceramic layer. In other words, if ceramic powder is bonded with adhesive and attached as a structure to a part exposed to high temperatures,
Firing is completed during the first temperature rise, and a ceramic coating layer can be obtained. The ceramics contained include 5i02. ZrO2, A1.0. .

TxO, FR, MgO, etc. are used as appropriate.

Next, the heat-resistant alloy processed into a predetermined shape is immersed in a ceramic mixture prepared in advance to form a first ceramic layer by immersing only the predetermined portions where the ceramic layer is to be formed.
Dry at room temperature or at a temperature below about 150°C. After drying, the same operation is repeated to form a multilayer ceramic layer including the second layer to the third layer. Here, the number of ceramic layers can be set to a desired number, but approximately three layers is suitable. The state of the inner layer does not necessarily have to be such that porous layers and non-porous layers are formed alternately, but at least one layer needs to be a non-porous layer to prevent erosion by acids and the like. Further, the appropriate thickness of each layer is about 30 μm.

After applying the multilayer ceramic coating, at least on the parts exposed to the hot external atmosphere, as described above, the respective structural materials are assembled and put into normal use. During this second use, the ceramic layer bonded with the adhesive is fired, the adhesive (including water and alcohol) is scattered, and a strong ceramic coating layer can be formed. During this assembly,
For example, when a stud and a retainer having the structure shown in FIG. Since it is on the order of 100 μm, there is no need to worry about that.

When we performed CF lining of a high-temperature industrial furnace using a stud and retainer with the structure shown in Figure 1 (C), we found that with conventional heat-resistant alloy studs and retainers, threads, etc. were oxidized and worn out. Even after repeated use at temperatures ranging from 0.degree. C. to 1300.degree. C., there was little change in the multilayer coated studs and retainers of the present invention. In addition, the installation process is the same as when using conventional heat-resistant alloys.
There was no fear of breakage during installation, unlike studs and retainers made entirely of ceramics. Furthermore, since the thickness of the ceramic coating layer was thin, the outer shape of the structure after coating all fell within the maximum dimensional tolerance of 100 μm according to the JIS standard.

The present invention is not limited only to the embodiments described above, and numerous modifications and changes are possible. For example, in the above-mentioned example, an example was shown in which a ceramic multilayer coating material can be suitably used as a high-temperature structural material, but the structure coated with a multilayer of porous layers and non-porous layers according to the present invention does not peel off even at room temperature. In addition to being hard and strong, the surface is coated with a ceramic layer, giving it a glossy finish and also having chemical and weather resistance.Thus, plate-like iron plates coated with multiple layers of ceramics are used on the exterior walls of buildings and in chemical laboratories. It can also be suitably used for desk boards, bottom boards, etc. Further, in the above-described embodiments, the ceramic coating is formed by dipping the heat-resistant alloy structure into the prepared ceramic mixture, but the ceramic coating can also be formed by other methods such as spraying, brushing, rolling, etc.

(Effects of the Invention) As is clear from the detailed explanation above, according to the ceramic multilayer coated structure of the present invention, the surface of the structure can be coated with multiple layers of porous ceramics and non-porous ceramics. Accordingly, a structure particularly suitable for use at high temperatures can be easily obtained without peeling. In addition, since the external surface is made of a ceramic coating layer, it is strong at room temperature, glossy, chemical resistant, and weather resistant, making it suitable for use on external walls of buildings, desk boards, bottom boards, etc. of chemical laboratories. You can get a struct that can be used.

Brief explanation of the previous aspect Figures 1 (a) and (b) show an example in which the structure of the present invention is applied to a fixing device for fixing a heat-resistant lining made of ceramic fiber to a wall surface in a high-temperature industrial furnace. FIGS. 2(a) and 2(b) are enlarged partial cross-sectional views of the fixing device shown in FIG. 1.

1... Stud 2... Threaded portion 3... Retainer 4... Ceramic fiber lining 5.6...
Porous ceramic layer 7...Non-porous ceramic layer Figure 1 (a) (b) Figure 2 (a) (b)

Claims (1)

[Claims] 1. Chemical resistance and durability can be achieved by coating any base material as a thin film with a multilayer structure consisting of at least two layers consisting of a porous ceramic layer and a non-porous ceramic layer. , corrosion resistance, abrasion resistance, water resistance, heat resistance,
A ceramic multilayer coated structure that has enhanced peeling resistance and impact resistance, and has excellent properties such as electrical insulation, moisture proofing, enamel, infrared radiation, and electromagnetic wave absorption. 2. The ceramic multilayer coating structure according to claim 1, wherein the outermost layer of the multilayer structure is a non-porous ceramic layer. 3. The ceramic multilayer coating structure according to claim 1 or 2, wherein the base material is used as a fixing device, a chemical device (for example, a heat exchanger), or a structure. 4. The ceramic multilayer coating structure according to claim 1 or 2, wherein the thickness of the coating layer is 10 to 50 μm per layer.