JPH05115798A - Formation of supporting layer reinforcing interlayer on metal substrate for catalyst - Google Patents

Abstract

PURPOSE:To provide a method to form a reinforcing interlayer, which can strengthen the bonding strength with a supporting layer for catalyst support to a metal substrate for a catalyst, on the surface of the substrate without decreasing the creep strength of the metal substrate for a catalyst. CONSTITUTION:A method to form a supporting layer reinforcing interlayer on a metal substrate for a catalyst involves plasma-spraying Al or Zr to the metal substrate for a catalyst in an inert gas atmosphere and then carrying out oxidizing treatment to form an oxide layer of Al2O3 or ZrO2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a reinforcing intermediate layer on the surface of a metal substrate in order to enhance the bonding strength of the carrier layer when forming a catalyst supporting carrier layer on a metal substrate such as a combustion catalyst or an exhaust gas catalyst. To a method of forming.

[0002]

2. Description of the Related Art Conventionally, in order to form a carrier layer for supporting a catalyst on a metal substrate for catalyst, as shown in JP-A-56-152965, a metal substrate of ferritic stainless steel containing Al is heat treated. In general, an Al ₂ O ₃ whisker layer is formed on the surface, and an Al ₂ O ₃ high surface area ceramic carrier is fixed on it.

By the way, in this method of forming the catalyst-supporting carrier layer, Al in the ferritic stainless steel is forcibly drawn to the surface by heat treatment to form an Al ₂ O ₃ whisker layer. Defects will occur and the creep strength will decrease. This is a fatal drawback when used in a high temperature and severe condition such as a fuel gas combustion catalyst for a gas turbine.

[0004]

SUMMARY OF THE INVENTION Therefore, the present invention provides a reinforcing intermediate layer for strengthening the bond with the catalyst-supporting carrier layer on the surface of the catalytic metal substrate without lowering the creep strength of the catalytic metal substrate. It is intended to provide a method of forming.

[0005]

One of the methods for forming a carrier layer reinforcing intermediate layer on a metal substrate for a catalyst of the present invention for solving the above problems is to prevent Al or Zr from being deposited on the metal substrate for a catalyst. It is characterized in that plasma spraying is carried out in an active atmosphere, and then it is oxidized to form an oxide layer of Al ₂ O ₃ or ZrO _{2 on} the surface.

Another method of forming the carrier layer-reinforcing intermediate layer on the catalyst metal substrate according to the present invention is as follows.
l or Zr is plasma sprayed in an inert atmosphere, and at the same time, any of Mo, Nb, Si, Ba, Ta, Hf, Cr, W, etc. is plasma sprayed in an inert atmosphere, and then oxidized. And forming a complex oxide layer on the surface.

[0007]

When the carrier layer reinforcing intermediate layer of the oxide layer or the complex oxide layer is formed on the surface of the catalyst metal substrate by the method for forming the carrier layer reinforcing intermediate layer on the catalyst metal substrate of the present invention as described above. The catalyst metal base does not have any defects, the creep strength does not decrease, and the carrier layer reinforcing intermediate layer is firmly bonded to the catalyst metal base. Therefore, on this carrier layer reinforcing intermediate _{layer, Al 2 O 3, Al 2} O 3 -SiO 2, ZrO 2, ZrO 2
-The formation of a carrier layer of high surface area ceramics such as SiO ₂ and barium hexaaluminate does not cause the creep strength of the metal substrate for the catalyst to decrease, and the catalyst is supported on the carrier layer for fuel gas combustion for gas turbines. It can sufficiently withstand use under severe conditions of high temperature such as a catalyst.

[0008]

EXAMPLES Examples and conventional examples of the method of forming the carrier layer reinforcing intermediate layer on the catalyst metal substrate of the present invention will be described.

First, the examples will be described. Ferritic stainless steel (75% Fe-20% Cr-20% other 5%)
Al is plasma-sprayed to a thickness of 10 μm in a nitrogen gas atmosphere on a metallic substrate for catalysts, and then 500 ° C.
Then, the intermediate layer for reinforcing the carrier layer consisting of the oxide layer of Al ₂ O ₃ was formed on the surface of the metal substrate for the catalyst by performing an oxidation treatment for 1 hour.

[0010] On the other hand, to explain the conventional example, a catalytic metal base made of ferritic stainless steel containing Al was heat treated at 950 ° C for 20 hours to form an Al ₂ O ₃ whisker layer on the surface.

However, when the creep test of the catalytic metal bases of these examples and the conventional example was carried out at a load of 1 kg / mm ² and a temperature of 1000 ° C., the conventional catalytic metal bases broke in about 12 hours, while The metal substrate for catalyst of the example could withstand about 16 hours.

On the carrier layer-reinforced intermediate layer of the sample of the example, 20 wt% of Al ₂ O ₃ powder was applied by plasma spraying and heat-treated at 800 ° C. for 5 hours to obtain a high surface area Al ₂ O ₃ carrier. Layers were formed. Similarly, on the Al ₂ O ₃ whisker layer of the conventional sample, Al ₂ O ₃ powder was plasma sprayed for 20 w.
High surface area Al ₂ O _{3 after} heat treatment at 800 ℃ for 5 hours
To form a carrier layer.

Then, these cross sections were cut so that they could be seen, and the cross sections were ground for 2 minutes with a sanding machine having a rotation speed of 300 rpm, at which time the load was sequentially applied to 10 g, 20 g, and 30 g,
When the amount of the carrier layer peeled off was observed with an SEM, the conventional example peeled off at 180 g, while the example one peeled off.
It was found that the bonding strength was high without peeling up to 200 g.

[0014]

As can be seen from the above description, according to the method for forming a carrier layer reinforcing intermediate layer on a metal base for a catalyst of the present invention, the metal base for a catalyst can be produced without lowering the creep strength of the metal base for a catalyst. A reinforcing intermediate layer capable of strengthening the bond with the catalyst-supporting carrier layer can be formed on the surface of the. Therefore, it is possible to easily obtain a catalyst, such as a fuel gas combustion catalyst for a gas turbine, which can sufficiently withstand use even under high temperature and severe conditions.

Claims (2)

[Claims] 1. A catalytic metal substrate on which Al or Zr is plasma sprayed in an inert atmosphere, and then oxidized to form an oxide layer of Al ₂ O ₃ or ZrO ₂ on the surface. A method for forming a carrier layer-reinforcing intermediate layer on a metal substrate for a catalyst, comprising: 2. A catalyst metal substrate is plasma sprayed with Al or Zr in an inert atmosphere and at the same time Mo, Nb,
For a catalyst characterized by plasma-spraying any one of Si, Ba, Ta, Hf, Cr, W, etc. in an inert atmosphere, and then oxidizing it to form a complex oxide layer on the surface. A method for forming a carrier layer reinforcing intermediate layer on a metal substrate.