JPS59150948A - Parts used in combustion engine - Google Patents

Abstract

PURPOSE:To purify exhaust gas and to improve combustion characteristics of an internal combustion engine, by forming a catalytic layer over the surface of parts such as a piston head, valves, etc. used in the combustion system of the engine and parts such as exhaust ports, etc. used in the exhaust system by way of flame spraying of the powder of a heat-resisting ceramics carrying thereon a catalytic metal. CONSTITUTION:At first, an undercoating layer 3 of Mo, Ni-Cr, Ni-Al, etc. is applied, by way of flame spraying, over the surface of the base material 1 of parts such as a piston head, valves, a cylinder liner, a cylinder head, a glow plug, etc. used in the combustion system and parts such as exhaust ports, an exhaust manifold, an O2-sensor, an exhaust pipe, a muffler, etc. used in the exhaust system of an internal combustion engine. Then, a layer 2-2 of a catalytic metal is applied over the surface of the powder 2-1 of a heat-resisting ceramices such as Al2O3, ZrO2 or the like that is flame-sprayed over the surface of said undercoating layer 3.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to components for combustion engines, and particularly to such components having catalyzed surfaces.

(2) Prior Art and Problems The use of catalysts has been widely studied, implemented, and implemented for the purpose of improving combustion in internal combustion engines and purifying exhaust gas. One example is combustion system parts such as pistons, heads, valves, cylinder liners (upper part), cylinder heads, diesel chambers, and glow plaques.

Or exhaust system parts, such as exhaust boats.

There are products that catalyze the surfaces of exhaust manifolds, 02 sensors, exhaust pipes, exhaust pipes, etc.

Conventional surface catalytic technologies include (1) directly coating the surface of the part with a catalytic metal; and (2) converting the surface of the part into a catalyst carrier and supporting the catalyst on it. However, method (a) Since the catalyst metal is supported directly on the surface of the two parts, if it is exposed to high-temperature exhaust gas during use, the part surface may oxidize or corrode and cover the supported catalyst metal, or combustion products may cover the catalyst metal. On the other hand, in method (b), the problems of oxidation and corrosion on the surface of parts are almost eliminated by the presence of the carrier layer. However, although the influence of combustion products is reduced, since the catalyst metal is concentrated on the surface, it cannot be said that reactions with combustion products can be sufficiently eliminated.Next, as a method for supporting catalyst metal, The following methods are used: i) A method of coating and firing a catalytic metal salt; h) A method of supporting a catalytic metal by sputtering, plating, etc.; however, in both methods, the entire part is placed in a furnace or tank during the supporting process. Generally, there are only a few parts of the part that need to be catalyzed, which is extremely inefficient, leading to high costs and low productivity. In addition, the catalytic process often causes adverse effects on parts other than the catalyzed parts, such as corrosion due to pretreatment and distortion and deterioration due to firing.

(3) Purpose of the Invention In view of the current state of the prior art as described above, the present invention aims to completely improve the durability of the catalyst in combustion engine combustion and exhaust system parts and improve productivity when catalyzing the surfaces of combustion engine and exhaust system parts. ,
The purpose is to improve costs.

(4) Object of the Invention The present invention achieves the above object by thermally spraying a heat-resistant ceramic powder supporting a catalytic metal to form a catalytic layer on the surface of combustion and exhaust system parts for a combustion engine where a catalyst is required. It is characterized by forming.

Combustion system parts of combustion engines to which the present invention is applied include piston heads, valves, cylinder heads (upper part), cylinder heads, diesel chand glow plugs, etc. Exhaust system parts include exhaust boats, exhaust snifolds, 0□ There are sensors, exhaust pipes, exhaust mufflers, etc., and these materials are generally steel or cast iron.

Examples include aluminum alloy, ceramic, etc., but are not particularly limited.

The thermal spray material used in the present invention, as shown in FIG. 1, is one in which a catalyst metal 2-2 is supported on the surface of a heat-resistant ceramic powder 2-1. As a heat-resistant ceramic powder, A'203
s Al2O3・MgO, ZrO2 (including Y2O3, CaO, MgO, etc. as stabilizers), etc. can be used, and the particle size may be the same as that of ordinary thermal spray powder,
Usually less than 100 meth is used. As the catalytic metal, those commonly used as catalysts can be used. For example, platinum.

There are single substances such as palladium and rhodium, alloys, and others. The amount of catalyst metal supported is 0 of the weight of the heat-resistant ceramic powder.
．． 5-5% is suitable. This kind of thermal spray material is applied to the second
As shown in the figure, a catalyst layer 2 is formed by thermal spraying on a portion 1 of a combustion engine component where catalyticization is desired. Each catalyst layer has a thickness of 20 to 30 mm
0 μm, porosity 0.5-20, pore diameter 0.01-10
It is appropriate and preferable to make the thickness on the order of μm.

In manufacturing the combustion engine parts of the present invention, the surfaces of the parts are subjected to normal pretreatment steps such as cleaning (degreasing) and blasting before thermal spraying, and then heat-resistant ceramic powder coated with catalytic metal is thermally sprayed.

Thermal spraying is preferably done by plasma spraying or gas powder spraying. In addition, methods for thermally spraying catalyst metal onto heat-resistant ceramic powder include, for example, (1) adding heat-resistant ceramic powder to a chloride solution of catalyst metal (alloy), stirring, dipping, drying, and firing; and (2) heat-resistant ceramic powder. Coating with γ-alumina and further coating with a catalyst metal with a);
or c) coating by electroplating method,
In the above, the heat-resistant ceramic powder coated on the catalyst metal was directly sprayed onto the component base material 1, but as shown in Fig. 3,
After first forming (spraying) undercoat #3' on the component base material 1, heat-resistant ceramic powder coated with a catalyst metal may be thermally sprayed. This is advantageous when the adhesion between the base material 1 and the catalyst sprayed layer 2 is poor, when the difference in coefficient of thermal expansion between them is large, or when the base material 1 has poor heat resistance and corrosion resistance. The i family of Underco) 1 includes molybdenum, Ni-Cr, Ni-AI, Ni-
Cr-Aj2゜Ni-Cr-Aj? -Y, C
o-Cr-Ae-Y etc. are often used.

(5) Embodiments of the Invention Example 1 A 5US310S stainless steel plate with a thickness of 0.3 mm was used with 7 IO holes in a metal box with a long axis width of 8 mm, a short axis width of 3 mm, and a notch width of 0.8 rrm. This was degreased in a triclene steam bath and coated with No. 60 calcined alumina T5 on both sides.
Plasted at a pressure of kg/crti. Next, on this base material, 8ONi-20Cr alloy powder t (viscosity 10 μm
~150μm) was sprayed to a thickness of about 30μm by plasma spraying. Furthermore, 2 layers of platinum-coated alumina powder (10 to 80 .mu.m) = 1 was sprayed by plasma spraying to a thickness of about 50 .mu.m.

Next, this was wound and formed into a diameter of 30M and a thickness of 50mm.

The platinum coating on alumina powder is dinitrodiamine platinum [, P t (NH8)2 (No□)2]
The process involved immersing alumina powder in a solution, drying it, and then firing it at a temperature of 500°C for 30 minutes.

Reference Example 1 Plus) T was carried out in the same manner as in Example 1, and the same amount of platinum as in Example 1 was coated per unit surface area of the metal lath by sputtering, and rolled and formed in the same manner as in Example 1.○ Reference Example 2 Platinum A rolled product was obtained in the same manner as in Example 1, except that the alumina powder was not coated and the entire surface was thermally sprayed.

Thereafter, the same amount of platinum as in Example 1 was supported on the wound molded product in the same manner as in Example 1 in which the alumina powder was coated.

After the support, the pt support depth of the cross section was measured using ftEPMA, and the depth was approximately 10 μm.

Example 2 Using the catalyst-wrapped molded products prepared in Example 1 and Reference Examples 1 and 2, the catalyst oiliness was evaluated in a mini reactor.

The evaluation conditions are as follows.

Gas input amount: ioz/min (S, V, value 17000Hr-
') Input gas composition: C3HB 200 ppmC3H
6g 00 ppm C01qb CO210chi0□2chiH2010N2Ba1ance Large gas temperature: 150-450°C (continuous change) The results are shown in Table 1 (new).

Next, this catalyst was installed in the exhaust pipe of a 11988 cc gasoline engine and operated for 900 hours (fuel: unleaded gasoline with an octane number of 93). The catalyst inlet temperature during operation is 400
The temperature was ~670°C, and the air-fuel ratio was 13.5-20.5. After the operation was completed, the catalyst was taken out and the mini-reactor evaluation described above was performed. Table 1 shows the results.

In the surface observation of the catalyst of Reference Example 1 using an X-ray microanalyzer after operation, no platinum was found due to combustion adult particles and oxidation and corrosion of the substrate surface.

In the catalyst of Reference Example 2, intrusion of sulfur, phosphorus, etc. was observed to a depth of about 20 μm from the catalyst surface.

(Similar to Example 1) Example 3 Using the same Mini 9 Actor as in Example 1, this time the gas circuit was completely closed, normal cetane (n-C, 6H34) was injected, and the catalyst bed temperature was adjusted to 20 to 1000. The combustion temperature (temperature at which 80 times the theoretical CO□ generation amount is generated) when raised to ℃ was determined. The results are shown in Table @2.

As is clear from the above explanation, the present invention provides combustion or exhaust system catalytic parts for gasoline engines, diesel engines, etc., which have higher catalyst durability and higher productivity than conventional ones, and improve exhaust purification and combustibility. can contribute to

[Brief explanation of drawings]

Figure 1 is a schematic cross-sectional view of the thermal spray powder used in the present invention;
The figure is a schematic sectional view of a portion of a catalyzed component of the present invention, and FIG. 3 is a schematic sectional view of a portion of another catalyzed component of the present invention. 1... Part base material, 2... Catalyst layer, 2-
1...Heat-resistant ceramic powder, 2-2...
- Catalyst metal, 3...undercoat layer. Patent applicant Toyota Motor Corporation Patent agent Akira Miyagi Patent attorney Kazuyuki Nishidate Patent attorney Tetsuji Koga Patent attorney Akira Yamaguchi

Claims (1)

[Claims] 1. In the necessary parts of the combustion system or exhaust system parts for combustion engines,
A combustion engine component characterized by having a catalyst layer formed by thermally spraying heat-resistant ceramic powder supporting a catalyst metal.