JP2005248189A - ENAMELLED Al-PLATED STAINLESS STEEL SHEET - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an enamelled Al-plated stainless steel having excellent adhesion of enamel, and further having satisfactory workability and designing properties. <P>SOLUTION: A thermal expansion difference ΔE=(1 to 4)×10<SP>-6</SP>/°C is imparted between the thermal expansion coefficient E<SB>0</SB>of an Al-plated stainless steel sheet 1 and the thermal expansion coefficient E<SB>1</SB>of an enamel layer 2, and the enamel layer 2 in which fine cracks 2a are uniformly dispersed is formed. The enamel layer 2 may be stacked with a clear enamel layer 3. Thermal stress generated at the time of firing enamelling glaze is absorbed on the fine cracks 2a, and the enamelled steel sheet having satisfactory adhesion of enamel and workability can be obtained. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an Al-plated stainless steel sheet that is excellent in corrosion resistance and heat resistance, and has improved adhesion of the eaves layer.

The steel sheet is maintained in a beautiful surface state for a long time because the hard steel layer does not easily wrinkle and oil stains can be easily removed. The color tone of the steel sheet can also be changed according to the needs depending on the frit, pigment, etc. to be blended in the steel sheet. When stainless steel is used for the cocoon plate, the heat resistance and corrosion resistance inherent to stainless steel are also utilized, and a material suitable for a heating cooker used in a harsh atmosphere can be obtained. An example in which an Al-plated stainless steel plate is used for the cocoon plate has also been reported.
When a stainless steel plate or an Al-plated stainless steel plate is applied, the coefficient of thermal expansion differs between the base steel and the soot layer, and thermal stress during glaze firing remains in the soot layer. Residual stress is the cause of defects such as cracks and delamination in the soot layer. In particular, in the austenitic stainless steel, the thermal expansion coefficient of which is greatly different from that of the cocoon layer, cracks, delamination, and the like due to thermal stress frequently occur in the cocoon layer, and the heel adhesion is extremely lowered.

By providing an aluminum oxide film, a Ni plating layer (Patent Document 1) and a chromate film (Patent Document 2) on the soot plate, the soot adhesion can be improved to some extent, but defects due to thermal stress are still unavoidable. By using a glaze with a thermal expansion coefficient that matches the base material, defects such as cracks and delamination can be suppressed, but the restrictions imposed on the glaze increase, making it difficult to form a glaze surface that meets your needs. .
JP 2002-220683 A JP 2003-119579 A

The present inventors have assumed that defects such as cracks and delamination are unavoidably introduced into the soot layer due to thermal stress generated during the firing of the glaze, and the thermal expansion characteristics of the soot layer are The effect was investigated. As a result, it was found that when the crack generation due to thermal stress is positively utilized, the adhesion of the steel layer to the Al-plated stainless steel plate of the base material is improved, and a steel plate with an unprecedented design can be obtained. It was.
The present invention has been completed on the basis of such knowledge, and by using a glaze whose thermal expansion coefficient is specified in relation to the Al-plated stainless steel sheet of the base material, the adhesiveness, design, and processing It aims at providing the steel plate excellent in property.

The Al-plated stainless steel sheet of the present invention is based on an Al-plated stainless steel sheet having a thermal expansion coefficient E ₀ , and the thermal expansion coefficient E ₁ is adjusted to a range of E ₀ + (1-4) × 10 ⁻⁶ / ° C. A wrinkle layer formed from the glaze is formed on the surface of the base material. Cracks due to the difference in thermal expansion between the base material and the cocoon layer are included in the cocoon layer, but the cracks are fine and uniformly dispersed in the cocoon layer. In applications where it is not desirable for the microcrack to be directly desired to the outside, it is preferable to laminate a clear soot layer on the soot layer containing the microcrack.

The plated Al-plated stainless steel sheet uses the Al-plated stainless steel sheet 1 provided with the Al-plated layer 1b on the surface of the stainless steel 1a as a base material, and the surface of the base material is covered with the saddle layer 2 (FIG. 1). The Al-plated stainless steel sheet 1 has a coefficient of thermal expansion slightly different depending on the steel type of the stainless steel 1a, but is (10.0 to 10.9) × 10 ⁻⁶ / ° C. in the ferrite type and (14.5 to 17 in the austenitic type). .4) The coefficient of thermal expansion E ₀ is in the range of × 10 ^-6 / ° C. The thermal expansion coefficient E ₁ of the glaze layer 2 is adjusted to a range of E ₀ + (1-4) × 10 ⁻⁶ / ° C. by adjusting the composition of the glaze.

Since there is a difference in thermal expansion ΔE [= (1-4) × 10 ⁻⁶ / ° C.] between the Al-plated stainless steel plate 1 and the glaze layer 2, the glaze applied to the Al-plated stainless steel plate 1 is fired. In the process of forming the layer 2, thermal stress due to the thermal expansion difference ΔE is generated in the soot layer 2. When a thermal stress exceeding the proof stress is applied, a crack is generated in the eaves layer 2, but since the thermal expansion difference ΔE is appropriately controlled, the crack 2a is formed. Since the fine crack 2a uniformly enters the entire area of the eaves layer 2, the thermal stress is absorbed by the fine crack 2a, and the residual stress of the formed eaves layer 2 is greatly reduced. As a result, the adhesion of the eaves layer 2 to the Al-plated stainless steel plate 1 is also improved, and even when the plated Al-plated stainless steel plate 1 is processed, the processing stress is dispersed in the fine cracks 2a, resulting from stress concentration. The peeling of the heel layer 2 is also suppressed.

The fine crack 2a not only improves the adhesion of the eaves layer 2, but also promotes the scattering of incident light to impart a new design to the eaves layer 2. The ordinary flatness often found in conventional steel sheets is also mitigated by the fine cracks 2a, and the steel layer 2 is modified to a natural surface state that is easy to harmonize with the surroundings.
Even if the fine crack 2a enters the heel layer 2, since the stainless steel 1a provided with the Al plating layer 1b on the base material is used, there is no occurrence of corrosion starting from the crack 2a. Therefore, the product can be used as a product with the fine crack 2a exposed to the outside, but a clear soot layer 3 covering the fine crack 2a may be laminated on the soot layer 2 (FIG. 2). The clear wrinkle layer 3 is preferably a thin layer having a high transparency so as not to impair the color tone of the wrinkle layer 2. Since the clear glaze layer 3 is baked in a state where the glaze penetrates into the fine cracks 2 a, the clear glaze layer 3 exhibits excellent adhesion due to mechanical engagement with the glaze layer 2.

  As the base plate, an Al plated stainless steel plate in which an Al plated layer or an Al plated layer containing 3 to 15% by mass of Si is provided on a stainless steel plate such as SUS409, SUS430, SUS301, SOS304, SUS316 or the like is used. Table 1 shows the thermal expansion coefficient of each Al-plated stainless steel sheet.

The Al-plated stainless steel sheet is freed of oil adhering to the steel sheet surface by alkali degreasing or baking at 550 to 550 ° C. for 3 to 5 minutes prior to hanging.
In consideration of the melting point of the Al plating layer formed on the surface of the stainless steel plate and the warpage of the base material due to thermal strain, the glaze for the base glaze layer 2 is preferably a low melting point glaze of 600 ° C. or lower. As the frit blended with the glaze, SiO ₂ type, P ₂ O ₅ type, etc., which have a larger thermal expansion coefficient than that of the Al-plated stainless steel plate, are preferable. Frit: A glaze is prepared by blending 1 to 30 parts by mass of pigment, dispersant, water and the like as required with respect to 100% by mass, and pulverizing and mixing with a ball mill or the like.

Lithium aluminum silica such as aluminum titanate, cordierite, β-eucryptite, etc. in order to adjust the thermal expansion difference ΔE between the base material 1 and the eaves layer 2 to (1-4) × 10 ⁻⁶ / ° C. Thermal expansion regulators such as acid salts are blended. For example, when ₂ to 20 parts by mass of cordierite is blended with 100 parts by mass of the SiO ₂ frit, the thermal expansion coefficient of the eaves layer 2 decreases by 1 to 9 × 10 ⁻⁶ / ° C., and the Al-plated stainless steel sheet 1 and the underlying eaves layer 2 Is adjusted to a range of (1-4) × 10 ⁻⁶ / ° C. As a result, fine cracks 2a are formed in the soot layer 2 due to thermal stress generated during soot firing. However, when the thermal expansion difference ΔE is excessively large, excessive thermal stress is generated to such an extent that the adhesion of the heel layer 2 is lowered.

The glaze layer 2 is formed by applying a glaze in an amount of 30 to 80 μm and baking at 520 to 600 ° C. When the thickness of the cocoon layer 2 is 30 μm or more, sufficient concealing properties are exhibited. However, in the cocoon layer 2 having a thickness of more than 70 μm, there is a concern that adhesion and workability are deteriorated. Further, at a firing temperature lower than 520 ° C., insufficient melting occurs, and the adhesiveness of the eaves layer 2 tends to decrease. On the other hand, when the firing temperature exceeds 600 ° C., thermal deformation becomes too large, and correction processing after firing is required.
When the eaves layer 2 formed on the Al-plated stainless steel plate is observed with a microscope, fine cracks 2a having an average size of 300 μm or less uniformly dispersed on the surface of the eaves layer 2 are detected. And is firmly bonded to the stainless steel 1a.

  The heel layer 2 has a matte appearance due to the fine cracks 2a formed on the entire surface. As the appearance of matte tone, the eaves layer 2 showing 10 to 40 by gloss measurement at an incident angle of 60 degrees and 40 to 80 by gloss measurement at an incident angle of 85 degrees is preferable. The collar layer 2 whose appearance has been adjusted exhibits a glossy surface when observed from the horizontal direction and a matte surface when observed from the vertical direction, so that an unprecedented design can be obtained.

As the clear glaze for the clear glaze layer 3, a low-temperature firing frit having a smaller thermal expansion coefficient than that of the base material is used. Specifically, P ₂ O ₅ frit (softening point: about 480 ° C.) with a thermal expansion coefficient of 10.2 × 10 ⁻⁶ / ° C., austenite Al plating for ferritic Al plated stainless steel sheet For a stainless steel plate, a SiO ₂ frit (softening point: about 490 ° C.) having a thermal expansion coefficient of 14.6 × 10 ⁻⁶ / ° C. is used. A clear glaze is prepared by adding a dispersant, water, etc. to the frit, pulverizing and mixing with a ball mill, and classifying.

  A clear glaze layer 3 is formed by applying clear glaze on the base glaze layer 2 and baking at 520 to 600 ° C. In order to impart transparency, it is preferable to select the coating amount of the clear glaze so that the film thickness of the clear glaze layer 3 is 5 μm or more. However, if the total thickness of the heel layer 2 and the clear heel layer 3 exceeds 70 μm, there is a concern about deterioration of adhesion and workability. Set. The firing temperature is set in the range of 520 to 600 ° C. for the same reason as that of the undercoat layer 2.

  Since the clear soot layer 3 is laminated on the base soot layer 2 containing the fine crack 2a, a part of the clear soot layer 3 penetrates into the fine crack 2a and the adhesion to the base soot layer 2 becomes extremely high. And since the clear soot layer 3 is formed in the state without a fine crack, the penetration | invasion of corrosive ion is prevented and the soot product which can endure a severe use environment is obtained. Furthermore, since the clear wrinkle layer 3 has a high gloss surface and the matte tone of the base wrinkle layer 2 appears as bottom gloss, it becomes a wrinkle product exhibiting a unique appearance.

Weight per unit area: 80 g / m ² -Both-sided SUS304Al-plated stainless steel plate and SUS304Al-plated stainless steel plate were used as the base plate and baked at 550 ° C. for 5 minutes.
The glaze for forming the glazing layer 2 includes, in terms of oxide, SiO ₂ : 48 mass%, Na ₂ O + K ₂ O: 15 mass%, TiO ₂ : 15 mass%, B ₂ O ₃ : 12 mass%, ZnO: A frit of 7% by mass and V ₂ O ₃ : 3% by mass was used. The thermal expansion coefficient of the glaze was adjusted by adding cordierite synthesized from artificial raw materials such as alumina, magnesia, and silica.
A frit was spray-coated on the baked cocoon original plate, and a cocoon layer 2 having a thickness of 50 μm was formed by baking at 550 ° C. for 5 minutes.

The cocoon layer 2 was observed with a microscope to investigate the occurrence of microcracks 2a, and the peeling state of the cocoon layer 2 was investigated by JIS Z2247 “Ericssen test method” (3 mm aperture, concave). The test piece in which peeling was detected was evaluated as x, and the test piece that was not peeled was evaluated as o.
As seen in the test results of Table 2, Examples 1 and 2 of the present invention in which the difference in thermal expansion between the Al-plated stainless steel sheet and the heel layer 2 was adjusted to ΔE = (1-4) × 10 ⁻⁶ / ° C. Then, fine cracks 2a having an average size of 300 μm or less were uniformly dispersed in the eaves layer 2, and the eaves layer 2 also showed excellent adhesion. In Comparative Examples 1 and 2, where the thermal expansion difference ΔE is too large (5 to 6.2) × 10 ⁻⁶ / ° C., cracks with an average size exceeding 400 μm are included in the soot layer 2, and the adhesiveness of the soot layer 2 Also showed a low value.

Further, as a glaze for forming the clear glaze layer 3, in the case of a SUS430Al-plated stainless steel plate, P ₂ O ₅ : 30% by mass, Al ₂ O ₃ : 28% by mass, Na ₂ O: 16% by mass, Sb ₂ O ₃ : 14 Mass%, B ₂ O ₃ : 112 mass% P ₂ O ₅ series frit, SUS304Al-plated stainless steel sheet, SiO ₂ : 41 mass%, Na ₂ O + K ₂ O: 30 mass%, B ₂ O ₃ : 20 mass% , ZnO: 6% by mass, V ₂ O ₅ : 3% by mass SiO ₂ type frit was used. A clear glaze was prepared by adding a dispersant, water, etc. to the frit and grinding and mixing with a ball mill.

The clear glaze was spray-coated on the glaze layer 2 of Invention Examples 1 and 2, and baked at 550 ° C. for 4 minutes to form a clear glaze layer 3 having a film thickness of 15 μm.
Next, the steel sheet was bent 90 degrees at 1R to 3R with the clear steel layer 3 facing outside, and the peeled state of the steel layer was visually observed. As a result, peeling occurred in a part of the soot layer in 1R bending, but a sound soot layer without peeling was maintained in 2R and 3R bending.

As described above, the thermal expansion coefficient E ₁ of the eaves layer 2 provided on the Al-plated stainless steel sheet 1 is related to the thermal expansion coefficient E ₀ of the Al-plated stainless steel sheet 1 by E ₁ = E ₀ + (1-4 ) × 10 ⁻⁶ / ° C., and when the thermal expansion difference ΔE of (1 to 4) × 10 ⁻⁶ / ° C. is provided between the Al-plated stainless steel plate 1 and the eaves layer 2, The microcracks 2a enter the soot layer 2 due to the generated thermal stress. Since the fine cracks 2a are uniformly dispersed in the eaves layer 2, the residual stress of the eaves layer 2 is greatly reduced, and an eaves steel sheet with eaves adhesion and workability imparted with designability is obtained. In addition, since the base material is the Al-plated stainless steel plate 1, the occurrence and growth of corrosion starting from the crack 2a can be suppressed even though the fine crack 2a is exposed to the outside. Al-plated stainless steel sheet is used in a wide range of fields, such as cooking utensils that require corrosion resistance, heat resistance, and aesthetics, as well as interior materials, surface materials, and heating device skins. The

Sectional view of an Al-plated stainless steel sheet with a flaw layer with microcracks Cross section of an Al-plated stainless steel sheet with a clear glazing layer on the heel layer

Explanation of symbols

1: Al-plated stainless steel plate 1a: Stainless steel 1b: Al-plated layer 2: Saddle layer 2a: Fine crack 3: Clear soot layer

Claims (2)

An eaves layer formed from a glaze whose base material is an Al-plated stainless steel plate having a thermal expansion coefficient E _{0 and} whose thermal expansion coefficient E ₁ is adjusted to a range of E ₀ + (1-4) × 10 ⁻⁶ / ° C. A hung Al-plated stainless steel sheet formed on the surface of a base material, wherein fine cracks are uniformly dispersed in the ridge layer.   The hung Al-plated stainless steel sheet according to claim 1, wherein a clear wrinkle layer is provided on a wrinkle layer in which fine cracks are uniformly dispersed.

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