JPS61124580A - Production of solar heat absorption plate - Google Patents

Abstract

PURPOSE:To produce a solar heart absorption plate having excellent corrosion resistance by coating an Ni metal or Ni alloy at an adequate deposition ratio on the surface of a Cr-contg. steel having a specific compsn. and treating the steel with heat under adequate conditions then treating the steel with an acidic bath of permanganate. CONSTITUTION:The surface of the steel plate contg. <=0.10% C and 1-18% Cr is subjected to a required cleaning and activation treatment and is then electroplated to coat the surface with the Ni metal or the Ni alloy such as Ni-Co or Ni-P at 0.1-20g/m<2> deposition ratio per surface of the steel plate. The steel plate is subjected to the heat treatment for 10-200sec heating time at 600-950 deg.C in a reducing or non-oxidative atmosphere to diffuse the coating layer into the steel. The steel plate is subjected to a dipping treatment or electrolytic oxidation in the acidic soln. of permanganate after the heat treatment to blacken the surface layer enriched with Ni. The inexpensive solar heat absorption plate having the excellent selective solar heat absorption characteristic and corrosion resistance is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a Cr-containing steel sheet that has excellent corrosion resistance and solar heat absorption performance.

(Prior Art) Conventionally, aluminum plates or stainless steel plates plated with black chrome have been generally used as solar heat absorbing plate materials, but aluminum has the problem of high cost.

On the other hand, Japanese Patent Application Laid-Open No. 57-5876 1%
The corrosion resistance performance of steel plates containing 1 to 18% Cr disclosed in the 1257 bulletin etc. is 18*Cr-8%N1 steel and 16%
It is inferior to high-grade stainless steel sheets to which N1 is added, such as Cr-10%Ni-2%Mo steel.

Solar heat absorbing plates generally utilize the selective solar heat absorbing properties of the black chrome plating layer on their surface, but there are also other solar heat absorbing coatings such as black nickel or paint. .

Among these, coating has a high absorption rate α in the visible region as a solar heat absorption characteristic, but has a high emissivity ε in the infrared region, and has poor performance as a selective absorption coating. On the other hand, the black ninkel film acts as a solar heat absorbing film with excellent absorption rate α and emissivity ε.

(Problems to be Solved by the Invention) The present invention was constructed in view of these circumstances, and provides a steel sheet that economically provides superior corrosion resistance and solar heat absorption properties to conventional steel sheets containing 1 to 18% Cr. The purpose of the present invention is to provide a method for manufacturing a heat absorbing plate for hot water.

(Another means to solve the problem) The present invention is to apply Ni metal or Ni-based alloy to the surface of a steel plate containing 0.10 or less C and 1 to 18 C of Cr in an amount of 0.1 to 20.9 per side of the steel plate. /m” and then coated with a temperature of 600 to 950°C in a reducing or non-oxidizing atmosphere for 10 to 10 minutes.
This is a method for producing a solar heat absorbing plate, which is characterized by heat treatment for 200 seconds and then immersion in a permanganate acid bath or electrolytic oxidation in a permanganate acid solution. .

The present invention will be explained in detail below.

The steel sheet used in the present invention is manufactured through normal thin steel sheet manufacturing processes such as steel manufacturing process, casting process, hot rolling, and cold rolling. In the present invention, the reason why the C content in the steel sheet is limited to 0.1% or less is that if the C content exceeds 0.1%, a large amount of chromium carbonoids or cementite will precipitate in the steel.゛Ni, Ni-Co, Ni, which will be described later
This is because the diffusion of the coating layer of Ni metal or Ni-based alloy such as -Mo and N1-P into the steel is inhibited. Preferably 0
．． A C content of less than 0.011 is advantageous. Furthermore,
In the present invention, Cr is 1 to 1 as the most important essential component.
Contain 8%. If the Cr content is less than 1 ts, the good corrosion resistance aimed at by the present invention cannot be obtained, and no significant oxide film is formed in the heat annealing process of the present invention, so an improvement in surface performance cannot be expected. do not have. On the other hand, Cr
Corrosion resistance improves as the content increases, and surface performance is improved by reducing oxide film formation during the heat treatment process, but excessive content is not economical.

Since using a steel plate with a content exceeding 18% Cr as a material would contradict the objective of the present invention, which is to provide an economically inexpensive solar heat absorbing plate, the upper limit of the Cr content was limited to 18%. That is, the Cr content was set to 1 to 18% from the viewpoint of performance improvement and economy. In addition, in the present invention, the steel plate used contains unavoidable impurities.

For example, it may contain P, 81, Mn, Cu, N1, etc.

Steel sheets with such chemical compositions have excellent corrosion resistance after being subjected to surface cleaning and activation treatments necessary for normal electroplating and dipping treatments such as degreasing and degreasing, and are also susceptible to the blackening surface treatment described below. To obtain a suitable surface layer, the amount of adhesion per side should be 0.1~
20117m” of Ni, Ni-Co, Ni-M
o, Coating treatment with Ni metal or Ni-based alloy such as N1-P is performed, and heat treatment is performed in a reducing or non-oxidizing atmosphere. The coating treatment method and coating treatment conditions in this case are not particularly limited, and include the electrolytic plating method described in the first section, the electroless plating method, and the method of applying the metal ion-containing solution using a roll coater or spray method. be exposed.

(1) Ni plating method % formula % (2) Ni-Co alloy plating method Receiving leakage 5 to 150 A/dm” (3), Ni-Mo alloy plating method [Layered plating] Ni plating □ Mo plating ( 4) N1-P alloy plating method % Formula % However, the steel plate obtained by these treatments is annealed for the purpose of softening the material, and at the same time Ni and N1-Co applied to the surface are annealed. , Ni-Mo.

A Ni metal or N1 alloy coating layer such as N1-P is diffused into the steel, and the surface is enriched with Ni or Nl alloy such as F'5-Cr-Ni, Fe-Cr-Ni-Co,
Fe-Cr-Ni-Mo.

A Fe-Cr-N1-P alloy surface layer is formed. That is.

Elements that improve corrosion resistance, elements that promote passivation in a corrosive environment, and elements that reduce pitting corrosion against Ct- ions are concentrated in the surface layer of the Fe--Cr steel base, and the corrosion-resistant life of the steel sheet itself is significantly extended.

In the present invention, the amount of coating layer deposited is 0.117 per side.
m", the amount of diffusion of Ni, etc. in the coating layer due to short-time heat treatment is small, and the concentration of 1 alloy and the thickness of the diffusion alloyed layer are small, and the corrosion resistance that is the objective of the present invention cannot be obtained. The uniform coverage of the coating layer was also insufficient, and some unplated parts of the coating layer were left unplated during the heat treatment.

Due to pinholes and the like, the uniform surface performance that is the objective of the present invention cannot be obtained. On the other hand, the thickness of the coating layer is 20Ii/m
If it exceeds 2, it is difficult to achieve complete diffusion to the outermost layer by the heat treatment according to the present invention.

After the coating treatment, the dried steel plate is heated at a temperature of 600 to 950° C. for 10 to 200 seconds in a heat treatment step maintained in a reducing or non-oxidizing atmosphere in order to diffuse into the steel to be laminated. As the heating atmosphere, in order to prevent surface oxidation, a reducing atmosphere containing hydrogen or a non-oxidizing atmosphere mainly containing nitrogen gas is used. In particular, the coating layer applied using a treatment bath other than electroplating is intended to reduce the coating layer containing metal ions and diffuse them into the steel.

A reducing atmosphere containing hydrogen is desirable.

Regarding the heating temperature in this case, at a low temperature of less than 600°C, it is difficult for the coating layer applied before the heat treatment to completely interdiffusion with the steel sheet, and recrystallization to ensure workability is not possible. It is enough. Furthermore, if the heating temperature exceeds 950c, the crystal grains of the steel sheet itself will become coarse and the temperature will exceed the normal temperature range.

The upper limit was set to 950°C.

In this case, if the heat treatment time is short, less than 10 seconds, mutual diffusion between the coating layer and the steel plate does not occur, and if it exceeds 200 seconds, the heating temperature range becomes narrow.

Economically unfavorable.

Such heat treatment! 'H, Ni-Co, N
i-Mo.

It is preferable to carry out both the diffusion of the N1 metal such as Ni-P or Ni-based alloy coating layer and the annealing for adjusting the mechanical properties of the steel sheet. Taking these points into consideration, the preferred heating temperature and heat treatment time in the present invention are as follows.

650-850°C, 20-90 seconds.

From the above-mentioned effects and economical points of view, it is industrially advantageous to use cold-rolled steel sheets [A+s Co1d materials];
There is no problem in applying the method of the present invention using the material.

When the heat diffusion treated steel sheet thus obtained is immersed in an acidic permanganate solution, the Ni-enriched surface layer on the surface of the steel sheet reacts with the acid solution, and the Ni-enriched surface layer becomes ultra-black.

As the permanganate acid bath, a solution obtained by dissolving sodium permanganate or potassium permanganate in an acid solution such as sulfuric acid is used. The permanganate ion concentration is not particularly limited, but is 5 to 3011/l.

The sulfuric acid content is preferably 10 to 801/l.

The processing temperature is related to the processing time and the composition of the processing solution, but 2
Preferably, the temperature is 0 to 60°C and the treatment time is 5 seconds to 30 seconds.

Note that ultra-blackening can also be achieved by electrolytically oxidizing the Ni-enriched surface layer of the heat-treated steel sheet obtained by the method described above, and by this electrolytic oxidation, a more uniform black surface layer can be obtained.

According to the invention: 1 selective solar absorption properties;

An inexpensive solar heat absorbing plate with excellent corrosion resistance can be obtained.

An embodiment of the present invention will be described below.

Cold rolled steel sheets CAs with various aCr contents
After degreasing and pickling using Co1d material].

Various heat-treated steel plates were manufactured by performing the coating treatment and heat treatment shown in Table 1.

Next, products were obtained by immersion in a permanganate acid bath or electrolytic oxidation treatment as shown in Table 2 as a blackening treatment. Various performance tests were conducted on the obtained product. The results are shown in Table 2.

(1) A 5% salt water spray test was conducted for one month to examine the area where red rust occurred and evaluate its corrosion resistance.

(2) An outdoor exposure test was conducted in a rural area for one year to examine the area where red rust occurred and evaluate its corrosion resistance.

(3) Selective solar heat absorption characteristics. Absorption rate α in the visible range and emissivity ε in the infrared range were measured.

Claims (1)

[Claims] On the surface of a steel plate containing 0.10% or less of C and 1 to 18% of Cr, 0 amount of Ni metal or Ni-based alloy is applied per side of the steel plate.
．． After coating with 1~20g/m^2, heating time 10~2 at a temperature of 600~950℃ in a reducing or non-oxidizing atmosphere.
A method for producing a solar heat absorbing plate, characterized by subjecting it to heat treatment for 00 seconds and then immersing it in an acidic permanganate bath or electrolytically oxidizing it in an acidic permanganate solution.