JPH02277554A - Production of catalytic carrier made of sheet metal - Google Patents

Abstract

PURPOSE:To obtain a catalytic carrier made of sheet metal which is lightweight and little in resistance and has high-temp. resistance to oxidation by utilizing stainless steel contg. <=2% Al as a base material and working this stainless steel into a foil having <=100mum thickness, plating and coating the surface of this foil by Al and thereafter performing anodically oxidizing treatment thereon. CONSTITUTION:Stainless steel which is free from Al or contains <=2% Al as a base material is worked into a foil having <=100mum thickness. Then this foil is degreased and washed and Al plating is performed thereon to impart high-temp. resistance to oxidation. Furthermore when anodic-oxidation is performed for the coating plated with Al, the plated layer is made a state extremely enriched in porosity. The anchoring effect for the coated layer of fine gamma-Al2O3 particles in a post-stage is exhibited. Therefore a catalystic carrier which is lightweight and little in resistance and has high-temp. resistance to oxidation is produced at a low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for manufacturing a single-plate metal catalyst carrier for supporting a catalyst such as a metal honeycomb shape for an automobile exhaust gas treatment catalyst.

[Conventional technology]

Metal catalytic converter honeycombs conventionally used for purifying automobile exhaust gas are required to have high temperature oxidation resistance because they are exposed to high temperatures of about 1200°C. Therefore, as the base material of the catalyst carrier, stainless steel in which 5% AI is added to ferritic stainless steel containing 15 to 20% Cr is used. This ferritic stainless steel containing Cr and Al is processed into a foil having a thickness of about 100 I# by hot rolling and cold rolling from the viewpoint of reducing exhaust gas pressure loss. Then, as shown in FIG. 2, in order to increase the catalyst loading rate per unit area, first, the base foil 1 is pre-oxidized for a short time in a low oxygen atmosphere to give α-IV, 0. crystal nucleus 2
After forming v′J8 at a temperature of about 900”C in the atmosphere,
After a long period of full-scale oxidation treatment (secondary oxidation),
A whisker layer 3 of α-Af2(h) with a length of ~3 gm is generated.Although not shown, after this, an alumina sol in which ultrafine particles of γ-A1zO3 suspended, called a wash coat, is applied and dried to support the catalyst. It forms a coating layer with a large specific surface area.

The reason why the whisker layer 3 of α-8 to □03 is generated by this secondary oxidation is to exhibit an anchor effect for the γ-AEz (h coat layer) in the subsequent process.

[Problem to be solved by the invention]

The Al-containing ferritic stainless steel, which is the base material for the carrier, contains 5% AN for high-temperature oxidation resistance, so it is very difficult to obtain a thin foil of approximately 100%. The manufacturing cost of the base foil is high due to the difficulty and therefore low yield.

Further, the secondary oxidation treatment for generating the α-11LCh whisker layer 3 requires strict temperature control and takes a long time of 8 hours, which is a factor in increasing the cost.

The present invention aims to provide a method for manufacturing a thin metal catalyst carrier that solves the problems of the above-mentioned conventional methods.

[Means to solve the problem]

The method for producing a thin metal catalyst carrier of the present invention uses stainless steel that does not contain A2 or has an AH content of 2% or less as a base material, processes the stainless steel into a foil with a thickness of 100 mm or less, and then The surface of the nuclide is plated with 82, and then positive oxidation treatment is performed.

[Effect]

Since the base material is stainless steel that does not contain AN or contains 2% or less of AN, it can be easily processed to a thickness of 1001 or less, thereby reducing the foil manufacturing cost. Further, by plating and coating the surface of this stainless steel with Al, high temperature oxidation resistance can be imparted. Furthermore, the surface of the foil plated 82 is anodized to make the surface of the Al plating coating porous, and the surface of the 7-Al□0. It can exert an anchor effect for the fine particle coating layer.

〔Example〕

The present invention will be explained with reference to an embodiment shown in FIG.

10 is a ferritic stainless steel foil containing Cr and not containing A1, such as 5tlS430, and this foil is produced by hot rolling and cold rolling to a thickness of about 100 mm. At this time, there is Affi in the stainless steel base material.
Since it does not contain , it can be easily rolled into foil. Note that as long as the stainless steel has an AE content of 2% or less, the workability will not be significantly impaired, so it can be used as a base material.

As mentioned above, these stainless steels have good workability, so they can be processed to a thickness of 30 mm or less, and by making them thinner, they can be used as honeycomb-shaped catalytic converters.
It is effective in improving gas exhaust performance and reducing weight.

Next, this foil is degreased and cleaned, and then Al plating is applied to form an AR plating layer 11 on its surface.

This AN plating layer 11 serves to protect the stainless steel base material from high-temperature oxidation, and the thickness of the E plating layer is designed to provide oxidation resistance and the formation of a porous alumina layer by anodizing in the next step. A distance of 0.5 to 10 cm from the point is desirable. As a coating method for such a thickness, a vapor deposition method or a molten salt electroplating method is suitable from the viewpoint of adhesion.

As mentioned above, stainless steel 1 coated with Al plating
The 1il foil is then anodized to create a number of pores 12 in the Affi plating layer 11. This anodization is carried out in an acid solution such as phosphoric acid, sulfuric acid-dichromic acid, or oxalic acid at a current density of 2 to 3 A/dIlz or less. At this time, the pores 12 in the At plating layer 11 obtained have a pore diameter of about 400
The plating layer 11 has a density of about 10''/cm'' and has a very high porosity.

Therefore, when coating with γ-Affixes to be applied later, the effect as an anchor that can stably hold a large number of 7-AlzO fine particles can be significantly exhibited.

Note that the catalyst carrier can be used in a honeycomb-shaped catalyst for treating automobile exhaust gas, a heat exchange type catalyst used as a wall of a combustion section, and the like.

[Effects of the Invention] As explained above, in the present invention, by using stainless steel that does not contain AI or has an Affi content of 2% or less as a base material, it can be easily processed into a foil with a thickness of 100 mm or less. The At plating coating applied to the surface of the foil can provide high temperature oxidation resistance, and further,
By anodizing the At plating coating, the surface of the Al plating coating becomes porous, and the 7-Alt coating in the subsequent process
It can exert an anchoring effect for the coating layer of fine particles of O.

Therefore, according to the present invention, a catalyst carrier that is lightweight, has low resistance, and has high temperature oxidation resistance can be manufactured at low cost.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of one embodiment of the present invention, and Fig. 2 is an explanatory diagram of an embodiment of the present invention.
This is an explanation of a method for manufacturing a sheet metal catalyst carrier. Fig. 1 1...Stainless steel foil with 5% AQ addition, 3...α-
A12os whisker layer, 10... Ferritic stainless steel foil, 11...-Al plating layer, 12
... Pore, Figure 2

Claims (1)

[Claims] Stainless steel that does not contain Al or has an Al content of 2% or less is used as the base material, and the stainless steel is made to a thickness of 100 μm.
1. A method for producing a thin metal catalyst carrier, which comprises processing the foil into a foil having a diameter of 1.0 m or less, plating the surface of the foil with Al, and then subjecting the foil to positive oxidation treatment.