JPH0830237B2 - Heat resistant composite material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a heat resistant composite material, and more particularly to a heat resistant composite material having excellent strength even at high temperatures.

(Prior Art) Recently, from the viewpoint of resource saving, high efficiency of large-sized energy conversion equipment represented by a gas turbine is emphasized. As a basic means for increasing efficiency, it is possible to raise the operating temperature of the equipment. In this case, the service temperature of the member used in the device becomes a structural problem.

By the way, conventionally, a superalloy such as an iron group (Fe group), a cobalt group (Co group) or a nickel group (Ni group) has been used as a material for the energy conversion device. However, these superalloys are near the limit of development for increasing the service temperature.

From such a fact, as a next-generation heat-resistant material, a composite material in which the above superalloy is reinforced with a refractory metal fiber is beginning to be noticed. As such a composite material, for example, a material having a structure in which a tungsten (W) wire which is a refractory metal fiber is embedded in a superalloy to be integrated. This is a combination of the excellent mechanical properties of W wire at high temperature and the excellent corrosion resistance of superalloy at high temperature. In such a combination of refractory metal fiber and superalloy, mutual diffusion at high temperature becomes a serious problem, but as a combination with a relatively low degree of mutual diffusion, a W-wire reinforced Fe-based alloy composite is used. The material has already been proposed.

However, even the W-line reinforced Fe-based alloy composite material cannot prevent the strength deterioration of W-line at a high temperature of 1100 ° C or higher, and has a problem that it is limited to 1000 ° C or lower in actual use. It was

In addition, since most of refractory metals including W wire have a smaller coefficient of thermal expansion than other metals, there is a problem that thermal stress generated between the refractory metals and the matrix cannot be avoided even when they are compounded.

(Problems to be solved by the invention) The present invention has been made to solve the above-mentioned conventional problems, and it is difficult to cause mutual diffusion between the refractory metal fiber and the superalloy at a high temperature of 1000 ° C. or higher, and An object of the present invention is to provide a heat-resistant composite material that is unlikely to be thermally deformed due to the difference in the coefficient of thermal expansion and can be used stably over a long period of time.

[Structure of the Invention] (Means for Solving Problems) The present invention relates to a refractory metal mainly composed of iron-based, cobalt-based or nickel-based superalloy with W, Mo or Ta covered with niobium on the periphery. A heat-resistant composite material having a structure in which fibers are embedded.

Niobium (Nb) coated around the refractory metal fibers
Acts as a barrier layer that prevents interdiffusion between the metal fibers and the superalloy in which they are embedded. Like this
As a means for forming the Nb barrier layer, for example, Nb powder is applied to the surface of the refractory metal fiber together with an organic pressure-sensitive adhesive, and then integrated by a powder metallurgy method, or coated by plasma spraying,
A method of integration can be adopted.

The refractory metal fiber is mainly composed of W, Mo or Ta. Examples thereof include W, Mo or Ta, or W doped with any one of ThO ₂ , K, Si and Al. be able to. In particular, W with ThO ₂ etc. is 1000
It is suitable because it is hard to cause recrystallization which causes strength deterioration at a high temperature of ℃ or more. The diameter of such refractory metal fibers is
It is desirable to set the lower limit to 0.1 mm from the viewpoint of handling and the like and the upper limit to 0.5 mm from the viewpoint of improving strength.

(Function) Therefore, according to the present invention, by covering the periphery of the refractory metal fiber embedded in the iron-based, cobalt-based or nickel-based superalloy with Nb, the Nb is converted from the superalloy as a matrix to the refractory metal fiber. Since it functions as a barrier layer that prevents various elements from diffusing, deterioration of the refractory metal fiber can be prevented. Further, since Nb has a thermal expansion coefficient intermediate between that of the refractory metal fiber and the matrix metal such as the Fe-based superalloy, it is possible to suppress thermal deformation when a repeated thermal load from high temperature to normal temperature is applied. Therefore, there is little deterioration in strength above 1000 ° C,
It is possible to obtain a heat resistant composite material having excellent high temperature characteristics in which thermal deformation hardly occurs.

(Examples of the Invention) Examples of the present invention will be described in detail below.

Example 1 First, a W wire 30 having a diameter of 0.3 mm to which 1% of ThO ₂ was doped 30
The books were arranged side by side at intervals of 0.15 mm and fixed to a frame, and these W lines were coated with Nb by 0.05 mm by low pressure atmosphere plasma spraying. Then, by similar low pressure atmosphere plasma spraying
The FeCrAlY alloy was coated with 0.2 mm to prepare a W / Ne / FeCrAlY sheet. Next, 10 sheets of this sheet were laminated by sandwiching the Fe-based brazing filler metal between them, and were placed under an H ₂ gas atmosphere at 1100 ° C × 15
A composite material containing about 30% by volume of W line was manufactured by performing heat treatment for 1 minute.

The obtained composite material of Example 1 was 30 kg / mm ² at 1100 ° C.
It was found to have a creep rupture strength of 1000 hours under the load of. In addition, it was not deformed even if it was given a heat load of reciprocating 5000 times or more between room temperature and 1100 ° C.

Example 2 First, 300 W lines having a diameter of 0.3 mm were horizontally arranged at intervals of 0.15 mm and fixed to a frame, and an organic adhesive obtained by dissolving etimecellulose in alcohol on these W lines had an average particle size of 30 μm Nb fine particles. The paste-like material in which the powder was dispersed was applied to a thickness of 0.1 mm. Then, after drying, a paste-like material in which FeCrAlY alloy powder is dispersed in the same organic adhesive as above is applied to the W wire coated with paste to a thickness of 0.2 mm, and the whole is dried to W / N.
An e / FeCrAlY sheet was prepared. Then, 10 sheets of this sheet were laminated by sandwiching the Fe-based brazing filler metal between them, heated to 1200 ° C. in a vacuum, loaded with a load of 600 kg / cm ² , and held for 5 minutes so that the W-line was about 30 A composite material containing a volume percent was produced.

The obtained composite material of Example 2 was 30 kg / mm ² at 1100 ° C.
It was found to have a creep rupture strength of 650 hours under the load of. Further, the characteristics of the repeated heat load were substantially the same as in Example 1.

[Effects of the Invention] As described in detail above, according to the present invention, it has excellent mechanical strength at high temperatures and can prevent deformation due to repeated heat loads, and thus, a heat-resistant material for large-scale energy conversion equipment such as gas turbines. As a result, a heat resistant composite material can be provided.

Claims (1)

[Claims] 1. A heat-resistant composite having a structure in which a refractory metal fiber mainly containing W, Mo or Ta whose periphery is covered with niobium is embedded in an iron-based, cobalt-based or nickel-based superalloy. material.