JP4379330B2 - Baking furnace shelf - Google Patents

Description

The present invention relates to a baking furnace shelf board having a stainless steel substrate .

  A glassy sintered body, for example, a lightweight building material made of waste glass, is formed by placing a raw material glassy powder compact body on a shelf board, putting it in a firing furnace, and firing it at a temperature of 750 to 1050 ° C. (For example, refer to Patent Document 1). Therefore, heat resistance and thermal shock resistance are required for the baking furnace shelf.

  Conventionally, as a shelf for a baking furnace, a mullite cordierite shelf with a brick quality of 6 to 10 mm, a mullite shelf with a thickness of 25 mm or more, and a silicon carbide generally known in the ceramic industry ( (SiC) -based shelf boards and the like are used.

  Also, as a baking furnace shelf board, normal steel sheet is not suitable for baking furnace shelf board because rust is generated by high-temperature treatment and the surface becomes brittle, etc. Can be used.

In addition, when using a continuous tunnel furnace, etc., it is also considered to carry out a continuous firing process using an endless track composed of a transport roller and a wire mesh, that is, to hold a lightweight building material made of waste glass, etc., with a wire mesh. It is done.
Japanese Patent Publication No. 6-88807

  However, conventionally used shelf boards have caused the following problems in firing a vitreous sintered body such as a waste glass lightweight building material.

  That is, the mullite-cordierite shelf board has a high heat resistance of 1100 ° C. or higher, and is excellent in thermal shock resistance among clay-based materials, but is likely to be warped and fired at 100 to 200. There is a problem that heat cracking occurs when cycled.

  Further, the mullite shelf has a problem that the heat resistance is low although the heat resistance is 1100 ° C. or higher and the heat resistance is high.

  In addition, the silicon carbide (SiC) -based shelf board has a problem that it has a high heat resistance of 1200 ° C. or higher and is excellent in heat shock resistance, but is thick and expensive.

  Furthermore, there is a problem that the cost is high for the bag and the heat resistance is low for the wire mesh (mesh belt) and the cost is high.

  The objective of this invention is providing the shelf board for a low-cost baking furnace which can be used suitably for baking of a vitreous sintered compact.

In order to achieve the above object, the shelf plate for a firing furnace according to the present invention is obtained by spraying glass powder and aluminum oxide powder on a stainless steel substrate made of ferritic stainless steel and firing it at 750 to 1000 ° C. A coating layer made of glass and aluminum oxide is formed on the substrate .

In the coating layer, the glass region is formed discontinuously.

Further, the stainless steel substrate does not contain nickel and contains 11.5 to 18.0% by mass of chromium.

Furthermore, the stainless steel substrate has a thermal expansion coefficient of 12.8 × 10 ^{−6 to} 13.5 × 10 ⁻⁶ (1 / ° C.) at 0 to 1000 ° C.

The stainless steel substrate has a thermal conductivity of 0.023 to 0.028 kJ / (s · m · k).

Further, the average particle size of the glass powder is 5 μm , and the average particle size of the aluminum oxide powder is 45 μm .

According to the baking furnace shelf of the present invention, since the coating layer made of glass and aluminum oxide is formed on the stainless steel substrate, the precipitation of hexavalent chromium harmful to the human body from the stainless steel substrate is suppressed, The softening point of the coating layer can be made higher than the softening point of the glass by the reaction between the glass and aluminum oxide, and therefore, it can be suitably used for firing the vitreous sintered body. Moreover, since the stainless steel substrate is made of ferritic stainless steel, the shelf board can be made magnetic, so that handling operation with a magnet can be easily performed. Furthermore, by using aluminum oxide, peeling and thermal cracking of the coating layer can be reliably prevented.

Moreover, since the glass region is formed discontinuously in the coating layer, peeling and thermal cracking of the coating layer can be prevented.

Furthermore, since the thermal expansion coefficient at 0 to 1000 ° C. of the stainless steel substrate is 12.8 × 10 ^{−6 to} 13.5 × 10 ⁻⁶ (1 / ° C.), the occurrence of warpage can be suppressed.

Furthermore, since the stainless steel substrate has a thermal conductivity of 0.023 to 0.028 kJ / (s · m · k), it is possible to suppress the occurrence of warpage and to raise the temperature of the object to be placed. The speed can be increased compared to a conventional brick shelf.

  As a result of earnest research to achieve the above object, the present inventor has a baking furnace shelf plate comprising a stainless steel substrate and a coating layer formed on the stainless steel substrate and made of glass and metal oxide. And it discovered that it could use suitably for baking of a glassy sintered compact.

  In addition, as a result of earnest research to achieve the above object, the present inventor, as a result, a stainless steel substrate and a shelf plate for a firing furnace comprising a coating layer formed on the stainless steel substrate and made of glass and metal oxide. In the manufacturing method, a preparation step of preparing a stainless steel substrate, a glass powder, and a metal oxide powder, a glass powder dispersion step of dispersing the glass powder on the stainless steel substrate, and a metal oxide powder on the stainless steel substrate on which the glass powder is dispersed When a coating step consisting of a metal oxide powder spraying step for spraying and a firing step for firing a stainless steel substrate on which glass powder and metal oxide powder are sprayed is repeatedly performed, it is suitably used for firing a glassy sintered body. It has been found that a low-cost baking furnace shelf board can be manufactured.

  The present invention has been made based on the results of the above research.

  Embodiments of the present invention will be described below with reference to the drawings.

  1A and 1B are diagrams used for explaining a schematic configuration of a baking furnace shelf according to the present embodiment, in which FIG. 1A shows a cross-sectional view and FIG.

  In FIG. 1A, a shelf plate 100 for a roller hearth furnace (firing furnace) includes a rectangular stainless steel substrate 101 having a size of 1100 mm × 2438 mm × thickness 2 mm, and a coating layer 102 formed on the stainless steel substrate 101. .

The stainless steel substrate 101 is ferritic stainless steel, more specifically, nickel is not contained, chromium is contained 16.0 to 18.0% by mass, and the coefficient of thermal expansion is 12.8 × 10 ⁻⁶ (1 / ° C.) and SUS430 having a thermal conductivity of 0.023 kJ / (s · m · k), and slits having a width of 1 mm and a length of 50 mm are cut at intervals of 300 mm on four sides of the stainless steel substrate 101. .

  In FIG. 1B, the coating layer 102 is made of glass and aluminum oxide. In the coating layer 102, the glass region 102a is formed discontinuously by the interposition of the aluminum oxide region 102b. Here, the aluminum oxide region 102b is laminated on the glass region 102a in a scale shape. Further, at the interface 103, the glass region 102a is mainly in contact with the stainless steel substrate 101.

  FIG. 2 is a flowchart of the manufacturing method of the shelf board of FIG.

In FIG. 2, stainless steel substrate 101 made of SUS430 and having slits with a width of 1 mm and a length of 50 mm cut at intervals of 300 mm on four sides, and about 150 g of glass powder with an average particle size of 5 μm, an average particle size About 300 g of 45 μm aluminum oxide powder is prepared (step S201), and the glass powder is spread on the stainless steel substrate 101 with a sieve having an aperture of 260 μm so as to be 50 g / m ² (step S202). An aluminum oxide powder is sprayed over the entire surface of the dispersed stainless steel substrate 101 with a sieve having an opening of 260 μm so as to be 100 g / m ² (step S203). (Step S204), and the step transferred into the roller hearth furnace. The substrate 101 is heated to about 800 ° C. at a temperature rising rate of 16 ° C./min (step S205), and further baked at about 800 ° C. for 30 minutes (step S206). After baking, the annealing rate is 8 ° C./min. Slowly cool to room temperature (step S207), reverse the slowly cooled stainless steel substrate 101 (step S208), perform the processing of steps S202 to 208 on the back surface (step S209), and further perform the coating processing of steps S202 to 209 to 2 Repeat three times (step S210), and the process is terminated.

According to the shelf 100 according to the present embodiment, the coating layer 102 made of glass and aluminum oxide is formed on the stainless steel substrate 101, so that the hexavalent chromium (Cr ⁺⁶ ) stainless steel substrate harmful to the human body is used. In addition, the softening point of the coating layer 102 can be made higher than the glass softening point by the reaction between glass and aluminum oxide, and thus it can be suitably used for firing a vitreous sintered body.

  In addition, according to the shelf 100 according to the present embodiment, since the substrate is made of stainless steel, it is possible to form a substrate of any shape and thus cannot be placed on a conventional brick shelf. A heated object or the like having a size can also be placed.

  Moreover, according to the shelf board 100 according to the present embodiment, in the coating layer 102, the glass region 102a is formed discontinuously by the intervention of the aluminum oxide region 102b that functions as a coating glass modifier or a buffer material. Therefore, peeling and thermal cracking at the interface 103 of the coating layer 102 caused by the difference in thermal expansion coefficient between the stainless steel substrate 101 and the glass region 102a can be prevented.

  Moreover, according to the manufacturing method of the shelf board 100 which concerns on this Embodiment, since a coating process is repeated 2-3 times, the coating layer 102 in which the glass area | region 102a was formed discontinuously is more firmly attached to the stainless steel substrate 101. Can be attached.

Moreover, according to the manufacturing method of the shelf board 100 according to the present embodiment, the glass powder is sprayed over the stainless steel substrate 101 with a sieve having an opening of 260 μm so that the glass powder becomes 50 g / m ^2. Microscopic irregularities can be formed by the powder, thereby improving the adhesion between the glass powder and the aluminum oxide.

  In the present embodiment, the shelf board 100 is baked at 800 ° C. (step S204), but is not limited thereto, and may be baked at 750 to 1000 ° C. For example, it is preferable that the first firing on the front and back of the shelf board 100 is performed at 750 to 760 ° C., and the second and subsequent firings are performed at 800 ° C. or higher.

  In this embodiment, after the stainless steel substrate 101 is fired, it is gradually cooled to room temperature at a slow cooling rate of 8 ° C./min. However, the present invention is not limited to this. In order to reduce the warpage of the shelf, it is desirable to reduce the slow cooling rate in the temperature range of 600 to 800 ° C.

  Examples of the present invention will be described below.

The inventor has made 1100 mm × 2438 mm × 2 mm thick ferritic stainless steel SUS405, ferritic stainless steel SUS430, austenitic stainless steel SUS310S, and austenitic stainless steel in which slits having a width of 1 mm and a length of 50 mm are cut at 300 mm intervals as a stainless steel substrate. Stainless steel SUS304 was prepared, and experimental pieces 1 to 4 (Examples 1 and 2 and Comparative Examples 1 and 2) in which the coating process of Steps S202 to 209 was repeatedly performed three times on these stainless steel substrates were manufactured and manufactured. The pieces 1 to 4 are transported into a roller hearth furnace by a transport roller, heated to 800 ° C. at a heating rate of 16 ° C./min, baked at about 800 ° C. for 30 minutes, and gradually cooled to room temperature at a slow cooling rate of 8 ° C./min. Surface treatment state, warpage, 6 Precipitation of valent chromium (Cr ⁺⁶ ) was observed.

  The observation results and comprehensive evaluation of the test pieces 1 to 4 are shown in Table 1, the composition of the four types of stainless steel is shown in Table 2, and the physical properties of the four types of stainless steel are shown in Table 3.

In the column of the surface treatment state in Table 1, “◯” indicates that there is no peeling of the coating layer, thermal cracking, and the like, and “x” indicates that there is peeling of the coating layer, thermal cracking, and the like. In the warp column, ◯ indicates that the warp is small, and x indicates that the warp is large. Further, in the column of Cr deposition, ○ indicates that hexavalent chromium (Cr ⁺⁶⁾ of precipitation is small at the surface, × shows that often hexavalent chromium (Cr ⁺⁶⁾ deposition on the surface.

From Table 1, compared with the shelf board of Comparative Examples 1 and 2, the shelf board of Example 1 and 2 has neither peeling of a coating layer, a thermal crack, etc., curvature is small, and hexavalent chromium (Cr ⁺ 6 on the surface). ) Is less precipitated, and is thus suitable as a shelf plate for a firing furnace.

  Here, the shelf plates of Examples 1 and 2 are less warped than the shelf plates of Comparative Examples 1 and 2 because ferritic stainless steel (SUS405 and SUS430, etc.) is austenitic stainless steel (SUS310S and SUS304). The thermal expansion coefficient is small and the thermal conductivity is large (Table 3).

It is a figure used in order to demonstrate schematic structure of the shelf board for baking furnaces concerning this Embodiment, (a) shows sectional drawing, (b) shows a cross-section partial enlarged view. It is a flowchart of the manufacturing method of the shelf board of FIG.

Explanation of symbols

100 Shelf plate 101 Stainless steel substrate 102 Coating layer 102a Glass region 102b Aluminum oxide region 103 Interface

Claims (6)

A coating layer made of glass and aluminum oxide is formed on the stainless steel substrate by spraying glass powder and aluminum oxide powder on a stainless steel substrate made of ferritic stainless steel and firing at 750 to 1000 ° C. A baking furnace shelf board.   2. The baking furnace shelf according to claim 1, wherein the glass region is formed discontinuously in the coating layer. 3. The said stainless steel board | substrate does not contain nickel but contains 11.5-18.0 mass% of chromium, The shelf board for baking furnaces of Claim 1 or 2 characterized by the above-mentioned . The stainless substrate, according to claim 1 or any one of the 3, wherein the thermal expansion coefficient at 0 to 1000 ° C. is ^{12.8 × 10 -6 ~13.5 × 10 -6} (1 / ℃) The baking furnace shelf as described in the item . The shelf board for a firing furnace according to any one of claims 1 to 4, wherein the stainless steel substrate has a thermal conductivity of 0.023 to 0.028 kJ / (s · m · k). The average particle size of the glass powder is 5 μm , and the average particle size of the aluminum oxide powder is 45 μm . The shelf plate for a firing furnace according to claim 1 , wherein the average particle size of the aluminum oxide powder is 45 μm .

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