JPH05330963A - Coarbon material having oxidation resistance at high temperature - Google Patents

Abstract

PURPOSE:To obtain a carbon material having oxidation resistance at high temperature by providing a titanium carbide layer and an alloy layer consisting of iridium and titanium on the surface of a carbon material. CONSTITUTION:The carbon material having oxidation resistance at high temperature consists of a carbon material 3, a layer 2 consisting essentially of TiC and an alloy layer of Ir and Ti. A layer 2 consisting essentially of TiC and having about 10mum thickness is formed on the carbon material 3 by chemical vapor deposition, etc. A Ti layer 5 and an Ir layer 6 are deposited in order thereon by high frequency magnetron spattering. Ir layer 6 and Ti layer 5 are each formed into about 2mum thickness and about 0.8mum thickness so as to have maximum 10wt.%, preferably 8+ or -0.5wt.% Ti content to prepare a laminated film consisting of 6 total layers and having about 8.4mum thickness. Then the coating is heated at about 1400 deg.C for about 10hr in Ar gas. Thereby, Ir is made to react with Ti to form the intermetallic compound Ir3Ti.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high temperature oxidation resistant carbon material, and more particularly to a carbon composite material which is advantageously applied to a heat resistant structural material of a space shuttle and a high temperature member used for a gas turbine jet engine.

[0002]

2. Description of the Related Art FIG. 3 shows a coating structure proposed as a high temperature oxidation resistant coating of graphite or carbon fiber reinforced carbon composite material (hereinafter abbreviated as C / C composite material). In FIG. 3, reference numeral 2 is titanium carbide (TiC), which is formed on the base material (graphite or C / C composite material) 3 by a chemical or physical vapor deposition method, and 4 is iridium (Ir). ), Chemical,
It is formed by a physical vapor deposition method or the like. This layer structure is for adhering Ir excellent in the function of shielding oxygen to the base material. Since Ir has low reactivity with carbon and the adhesion between Ir and the substrate is poor, T has good reactivity with Ir and has good adhesion, and also has good adhesion with graphite.
By using iC between Ir and the base material, the Ir and the base material are brought into close contact with each other. {Reference: J
ames R. Strif., John G. Smeggil and Wayne L. Worrel
l, "Reaction of Iridium with Metal Carbides in the
Temperature Range of 1923K to 2400K ", J. Of Am.C
eram.Soc., Vol. 73 No.4 (1990) p838-845}

[0003]

In the conventional oxidation resistant coating of carbon material by the combination of Ir and TiC, Ir and T
The interface reaction of iC is unavoidable, and TiC is decomposed by the interface reaction and carbon is deposited. When the deposited carbon is formed in a layered form, a decrease in adhesion is expected, and also when dispersed in the reaction layer, the carbon is discharged to the grain boundaries and aggregates at the grain boundaries,
It is considered to be the starting point of oxidation and reduce the oxidation resistance.
In either case, carbon deposition adversely affects adhesion or oxidation resistance. Therefore, the reaction between Ir and TiC causes a decrease in oxidation resistance, and this reaction rate is
Limit the time. By the conventional method, the durability of the Ir film of 10 μm in argon gas at 2300 K for about 3 hours was confirmed, but the durability in the atmosphere is expected to be lower.

In view of the above state of the art, the present invention is based on Ir and Ti.
It is intended to provide a high temperature oxidation resistant carbon material which suppresses the interfacial reaction of C and has excellent durability.

[0005]

Means for Solving the Problems The present invention comprises (1) a carbon material, a titanium carbide layer formed on the surface of the carbon material, and an alloy layer composed of iridium and titanium formed on the surface of the titanium carbide layer. High temperature oxidation resistant carbon material.

(2) The titanium content consisting of iridium and titanium is at most 10 wt%, preferably 8 ± 0.5 w
The high temperature oxidation resistant carbon material according to the above (1), wherein the carbon content is t%. Is.

The carbon material in the present invention means graphite or C / C composite material.

[0008]

In the present invention, in order to suppress the reaction between Ir and TiC which cannot be avoided by the conventional oxidation resistant coating, an alloy containing Ir at most 10 wt% is used instead of Ir. The activity of Ir decreases as the amount of Ti added increases. In particular, a composition range for forming an intermetallic compound,
When the Ti content is 8 ± 0.5 wt%, it becomes thermodynamically stable with respect to TiC. Therefore, by adding Ti to Ir, the reaction between Ir and TiC can be suppressed, and the reduction in the oxidation resistance accompanying the reaction can be reduced.

Further, as shown in Table 1, if the amount of addition of Ti is 10 wt% or less, the oxygen shielding function of Ir is not impaired, but if it exceeds 10 wt%, Ti in the alloy causes internal oxidation. Oxidation progresses rapidly and the oxygen shielding function is impaired.

[0010]

[Table 1]

The structure of the high temperature oxidation resistant carbon material according to the present invention will be described with reference to FIG. In FIG. 1, 3 is a carbon material, 2 is a layer containing TiC as a main component, and 1 is an alloy layer of Ir and Ti. The Ti content of the alloy layer 1 is at most 10 wt%, preferably 8 ± 0.5 wt%. The coating method of the alloy layer 1 includes physical and chemical vapor deposition of alloy, thermal spraying, and the like, but it is also possible to separately coat Ir and Ti and heat-treat to alloy them.

[0012]

EXAMPLE As an example of the present invention, Ti on isotropic graphite
After forming a C layer and a laminated film of Ir and Ti thereon,
From the laminated film of Ir and Ti by heat treatment, the intermetallic compound I
r ₃An example of forming a Ti layer will be described with reference to FIG.

First, a TiC layer 2 of 10 μm is formed on the isotropic graphite 3 by chemical vapor deposition. A Ti layer 5 and an Ir layer 6 are stacked in that order by high frequency magnetron sputtering. The Ir layer 6 and the Ti layer 5 have a film thickness of 2 μm and T so that the Ti content is 8 ± 0.5 wt%.
i layer 5 is 0.8 μm, 6 layers in total, thickness 8.4 μm
m laminated film was prepared, and this coating was formed in Ar gas.
Ir and Ti by heating at 1400 ° C for 10 hours
Were reacted to form an intermetallic compound Ir ₃ Ti.

Oxidation resistance of this test material was evaluated by an acetylene flame exposure test. As a comparative material, 1
The same test was carried out for the case where the Ir layer was formed on the 0 μm TiC layer by 8.4 μm. When the time until the coating was damaged by the acetylene flame and the substrate was significantly thinned was measured, the coating according to the example of the present invention showed no significant damage to the coating even after exposure for 5 minutes. In the comparative material in which the Ir layer was formed on the TiC layer, the base material was significantly thinned by the exposure for about 2 minutes.

[0015]

In the oxidation resistant coating of Ir and TiC according to the prior art, the reaction between the two causes a decrease in the oxidation resistance of the coating. However, in the oxidation resistant coating using Ir-Ti alloy instead of Ir according to the present invention, Ir is used. It has the effect of suppressing the reaction with TiC and reducing the deterioration of the oxidation resistance due to the interfacial reaction, without significantly impairing the originally excellent oxygen-shielding function.

[Brief description of drawings]

FIG. 1 is an explanatory view of the constitution of a high temperature oxidation resistant carbon material of the present invention.

FIG. 2 is an explanatory diagram of an embodiment of the present invention.

FIG. 3 is an explanatory diagram of one embodiment of a conventional high temperature oxidation resistant carbon material.

Claims (2)

[Claims] 1. A high temperature oxidation resistant carbon material comprising a carbon material, a titanium carbide layer formed on the surface of the carbon material, and an alloy layer composed of iridium and titanium formed on the surface of the titanium carbide layer. 2. The high temperature oxidation resistant carbon material according to claim 1, wherein the titanium content of the alloy layer composed of iridium and titanium is at most 10 wt%.