JP2014073950A - Coating high temperature radiating coating material on ceramic fiber surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive coating method of a high temperature radiating coating material on a ceramic fiber.SOLUTION: Adhesive coating of a high temperature radiating coating material can be achieved by controlling a shape, a fiber diameter, a density and heat expansion coefficients of a ceramic fiber. A surface heat radiation rate of a ceramic fiber heat insulator can be 0.9 or more.

Description

  The present invention aims to improve the surface radiation rate of the ceramic fiber by applying a high-temperature radiation coating on the surface of the ceramic fiber heat insulating material, thereby improving the heating efficiency in the high-temperature furnace and saving energy.

  Conventionally, ceramic fiber is used as an insulation material for industrial furnace walls. Figure 1 is a conceptual diagram. The reason is that the thermal conductivity of the ceramic fiber is small. However, the surface color of the ceramic fiber is white, and the surface thermal emissivity is 0.4-0.6. Since the thermal efficiency of a high temperature furnace is occupied by radiant heat transfer from the furnace inner wall surface by 80% or more, the surface of the ceramic fiber is disadvantageous in terms of radiation rate. However, since the ceramic fiber is soft, even if a high thermal emissivity paint is directly applied to the surface of the ceramic fiber, it does not endure the heat cycle and peels off. At present, the ceramic fiber surface is not coated. This is because the difference between the expansion coefficient of the ceramic fiber and the expansion coefficient of the paint leads to peeling. There is a demand for a method of applying a paint having a high thermal radiation rate (0.9 or more) on the surface of the ceramic fiber. A ceramic fiber surface is covered with a SUS steel plate, and the surface of the steel plate is ceramic coated.

Patent Publication 2008-212276

  However, the SUS steel sheet absorbs heat unnecessarily and heat loss occurs due to heat conduction, and the overall thermal efficiency is poor. The present invention made it possible to paint a high emissivity material directly on the surface of a ceramic fiber having a low heat emissivity. In addition to the heat insulation function of ceramic fiber, a function to improve the heat radiation rate, which is important during high temperature heating, has been added. An object of the present invention is to provide a coating method in which a high thermal radiation coating is adhered to the ceramic fiber.

  In order to solve the above-mentioned problems, the means taken by the present invention is a method characterized by controlling the shape, fiber diameter, density, and thermal expansion coefficient difference between the ceramic fiber and the paint.

  Controlling the shape, composition, fiber diameter, density, and thermal expansion coefficient of ceramic fiber, it was possible to paint an adhesive heat radiation material that could withstand practical use. We were able to.

It is one example of the application environment of this invention It is a perspective view which shows one Embodiment of this invention. It is a temperature time figure of the thermal fatigue experiment of the ceramic fiber coated with the high temperature radiation paint. It is a surface shape figure after a thermal fatigue experiment. It is the adhesiveness experimental result which peels off a tape.

One embodiment of the present invention is shown in FIG. The surface of the white ceramic fiber is coated with black Cr ₂ O ₃ based thermal radiation paint. For comparison, high temperature radiation paint with the same film thickness was applied to different ceramic fibers. Place in the same furnace and heat from room temperature to 1250 ° C. as shown in FIG. 3 and hold for 10 minutes. Thereafter, the temperature was lowered to 750 ° C. The temperature is raised and lowered 15 times between 1250 ° C. and 750 ° C. The furnace was cooled to room temperature and the surface state of the ceramic fiber was observed.
"Effect of the embodiment"

According to this embodiment, sample A (average fiber diameter 5-7 μm, linear heat shrinkage rate: 0.8% (1500 ° C. for 24 hours), density: 0.3 g / cm ³ ) as shown in FIG. It was found that there was no large crack on the surface of the ceramic fiberboard, and it was firmly attached. On the contrary, as shown in FIG. 4-2, on the surface of the ceramic fiber board of Sample B (average fiber diameter of 3 μm or less, linear heat shrinkage: 2.8% (1200 ° C. for 24 hours), density: 0.25 g / cm ³ ). There was a big crack, and part of it peeled off.
The same sample was cut out of a 4cm * 4cm square paint layer, and the paint was peeled off with a commercial cloth scotch tape. As shown in FIGS. On the other hand, all of sample b was peeled off. The difference in adhesion is obvious.

  The following three fields are possible for industrial use. 1. 1. Petroleum refining, petrochemical related: heating furnace, cracking furnace, reforming furnace, other furnaces; 2. Steel, metal, non-ferrous metal Electricity, automobile related: heat treatment furnace, heating furnace, other furnaces; Ceramic industry related.

Claims (10)

A coating method characterized in that a thermal radiation paint is applied to the surface of the ceramic fiber by spraying or the like. The ceramic fiber is a coating method characterized by comprising at least one of mainly Al ₂ O ₃ , SiO ₂ , ZrO ₂ , and TiO ₂ . The thermal radiation paint according to claim 1 is at least one of Cr ₂ O ₃ base, reduced TiO _x base, (FeMn) ₂ O ₃ base and SiC base. In addition to the ceramic fiber of claim 1, it is composed of at least one of the following MgO, Fe ₂ O ₃ , BeO, MoO, NiO, Cr ₂ O ₃ , ZnO, SiC, SiN, AlN, LaB _6. This is the painting method. The average fiber diameter of the ceramic fiber of claim 1 is 3 micrometer (μm) or more. The density of the ceramic fiber according to claim 1 is 0.3 g / cm ³ or more. The linear thermal expansion coefficient (1000 ° C. or more and 24 hours) of the ceramic fiber of claim 1 is 1% or less. The shape of the ceramic fiber is fibrous, not an indeterminate shape, but a board shape or the like having a high hardness and a stable surface is desirable. The ceramic fiber contains 60% or more of an alumina fiber component. A ceramic fiber coated with a high heat radiation material is laid on the inner surface side of the heating furnace, and is composed of a heat insulating ceramic fiber laminated structure having a normal density of 0.3 g / cm ³ or less between the furnace wall and the furnace wall. is there.