JPH0374626B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a structure that has excellent heat resistance, chemical resistance, impact resistance, etc., and is particularly suitable for use in high temperature atmospheres and cold/heat cycles. It is about a structure.

(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, and cannot be used at temperatures higher than about 120°C. When used at high temperatures, the surface of the structure becomes oxidized and becomes unusable, and pairs of structures such as bolts and nuts tend to fall off.

Also, looking only at temperature, ceramic structures can be used at higher temperatures than heat-resistant alloys, but
It is mechanically and structurally fragile, and may break when subjected to thermal, mechanical, or structural stress, for example.

Furthermore, even when heat-resistant alloys and ceramics are combined, if there is a large difference in their coefficients of thermal expansion and thermal conductivity, the ceramic coating layer will peel or break, which limits 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 during 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 can be coated with a multilayer structure of at least two layers consisting of a porous ceramic layer and a non-porous ceramic layer as a thin film in any desired manner. The thin film coating of each layer was formed by sequentially laminating the foamed or unfoamed liquid ceramic mixture for each layer on the substrate by repeating the procedure of thinly coating and drying the foamed or non-foamed liquid ceramic mixture. It is characterized by:

(Function) In the present invention, by coating a structure such as a heat-resistant alloy with a thin film coating having 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 the 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 ceramics more durable. It is possible to obtain a structure having sufficient strength equivalent to the heat resistance of . In addition, a porous ceramic layer absorbs various stresses caused by differences in thermal expansion coefficient, thermal conductivity, etc., and since a porous ceramic layer alone may be eroded by acids, a non-porous ceramic layer is used. By coating at least one layer, acid resistance etc. are provided. At this time, it is more effective if the outermost layer of the multilayer structure is a non-porous ceramic layer. In this specification, the terms "porous" and "non-porous" refer to "porous" when qualitatively speaking, the ceramic has a large amount of pores, and "porous" when there are almost no pores. Things are called "non-porous."

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

Figures 1a and 1b 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 (hereinafter abbreviated as "CF") to a wall surface in a high-temperature industrial furnace. FIG. 1a shows the mounting state, and FIG. 1b 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 embodiment, that part is not coated with the ceramic multilayer coating of the present invention (for consideration with welding). Further, the end of the stud 1 opposite to the end welded to the furnace wall is threaded, and this threaded part 2 and the retainer 3 are engaged with each other.
It has a configuration in which the CF lining 4 is fixed.
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 part 2, but in general, when using a stud with a small thread pitch or effective diameter, for example, the threaded part 2 has a diameter of 8 mm or less, the threaded part shown in Fig. 2b is used. As shown in the enlarged view of 2,
By means of a stud 1 with a trapezoidal thread and a retainer 3 with an engaging thread shown in Fig. 2a.
It is preferable to attach the CF lining 4.

In this embodiment, as shown in Fig. 2a and b, the part that comes into contact with the external atmosphere has a three-layer structure.
Ceramics such as ZrO ₂ and SiO ₂ (same composition is fine)
After forming a porous ceramic layer 6 similar to the porous ceramic layer 5, a non-porous ceramic layer 7 is further coated. The thickness of each of the ceramic coating layers 5, 6, and 7 is 10 to 50 μm.
Approximately m is suitable. In addition, in FIGS. 2a and 2b, 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, cracks, peeling, etc. caused by differences in thermal expansion coefficient, thermal conductivity, etc. between the ceramic and the heat-resistant alloy can be avoided between the porous ceramic layer and the ceramic layer. It is absorbed between the ceramic layers and can prevent the ceramic from peeling off or breaking.

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, the thickness of the ceramic layer is very thin, so
There is no need to calculate the coating allowance and process it to be smaller than a predetermined size. In parallel with processing, prepare a pulverized ceramic material such as ZrO ₂ and mix it with a small amount of water or alcohol-based liquid and adhesive.
Knead to create a liquid ceramic mixture. Porous ceramics and non-porous ceramics are prepared separately by changing their mixing ratios. The adhesive is mixed into the multi-layered ceramic layer at room temperature or at 150°C.
This is to allow the ceramic powder to adhere and form a layer when dried at a temperature of up to °C. That is, in the present invention, in order to form a layer, it is not necessary to perform firing at a high temperature after coating the ceramic layer. In other words, if the ceramic powder is bonded with an adhesive and attached as a structure to a part exposed to high temperatures, firing will be completed at the first temperature rise, and a ceramic coating layer can be obtained. In addition, the ceramics contained include SiO ₂ , ZrO ₂ ,
Al ₂ O ₃ , TiO ₂ , FR, MgO, etc. are used as appropriate.

Next, the heat-resistant alloy processed into a predetermined shape is immersed in a pre-prepared ceramic mixture in the predetermined areas where the ceramic layer is to be formed to form the first ceramic layer. Dry at below temperature. After drying, the same operation is repeated to form a multi-layered ceramic layer including second and third layers. 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 the multilayer ceramic coating has been applied as described above, at least in the areas exposed to the hot external atmosphere, the respective structural materials are assembled and put into normal use. During this first 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. When assembling, for example, when a stud and a retainer having the structure shown in FIG. Since the thickness is on the order of several hundred μm, there is no need to worry about this.

When we performed CF lining of a high-temperature industrial furnace using studs and retainers with the structure shown in Figure 1c, we found that the threads, etc. of conventional heat-resistant alloy studs and retainers were oxidized and worn out at 1200℃~
Even after repeated use at temperatures of 1300° C., there was little change in the multilayer coated studs and retainers of the present invention. Furthermore, the installation work is similar to that when conventional heat-resistant alloys are used, and there is no risk of breakage during installation, which is the case with studs and retainers made entirely of ceramics. moreover,
Since the thickness of the ceramic coating layer is thin, the outer shape of the structure after coating was all 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, a ceramic multilayer coating material was shown to be suitable for use as a high-temperature structural material, but the structure of the present invention coated with multiple layers of porous and non-porous layers does not peel off even at room temperature. In addition to being hard and strong, the surface is covered with a ceramic coating 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 drawings]

Figures 1a and b are diagrams showing an embodiment 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, and Figures 2a and b FIG. 2 is an enlarged partial cross-sectional view 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.

Claims (1)

[Scope of Claims] 1 A coating having a multilayer structure of at least two or more layers consisting of a porous ceramic layer and a non-porous ceramic layer is coated as a thin film on any desired base material, and the thin film coating of each layer is A ceramic multilayer coating structure, characterized in that it is formed by sequentially laminating a foamed or unfoamed liquid ceramic mixture for each layer on a base material by repeating a procedure of thinly coating and drying the foamed or unfoamed liquid ceramic mixture. 2. The ceramic multilayer coating structure according to claim 1, wherein the outermost layer of the multilayer structure is a non-polar 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.