JPH0417701A - Manufacture of turbine blade - Google Patents

Abstract

PURPOSE:To improve the mechanical strength and durability and smooth the surface a turbine blade by covering a core layer formed of long fiber C/C composite (carbon/carbon series composite material) with a skin layer formed of short fiber C/C composite. CONSTITUTION:A core layer 5 is formed by a cloth layered body comprising carbon fiber cloth 4, in which matrix resin material is impregnated, layered in the width direction of a turbine blade 1. A preform 10 comprises the core layer 5 surrounded by a skin layer 9 comprising carbon fiber felt 7, in which matrix resin material is impregnated. The preform 10 is baked to be carbonized. Thus, each advantage of long fiber and short fiber is made the best use by covering the core 5 formed of a long fiber C/C composite with the skin layer 9 formed of a short fiber C/C composite, as a result, a turbine blade, which is excellent in mechanical strength and durability and whose surface is smooth, can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing turbine blades formed from carbon/carbon-based composite materials (referred to as carbon/carbon composites or C/C composites).

Conventional technology For example, turbine blades used in high-temperature atmospheres of 1500°C or higher are made of carbon/carbon-based composite material (herein referred to as C/C composite) instead of metal. is being tested.

The specific manufacturing method of this C/C composite turbine blade can be roughly divided into Figures 4 (A) and (B).
), (C), and (D).

The turbine blade 13 shown in FIG. 2A is machined from a C/C composite substrate 12 preformed by laminating carbon fiber cloth 11.
The shape is carved out. The turbine blade 14 shown in FIG. 1B is formed by similarly machining a C/C composite substrate 15 that is preformed by laminating carbon fiber cloth 11 along the curvature of the turbine blade 14. The shape is carved out. In both of the above two methods, the substrate 12 or 15 itself is fired and carbonized and then machined.

In addition, the one shown in FIG. 1C is formed by folding carbon fiber cloth 11 impregnated with matrix resin into two and sequentially stacking them in order to follow the curvature of the turbine blade 16 to form a predetermined turbine blade shape. This is what I did.

Furthermore, in the case shown in FIG. 1D, a predetermined shape of a turbine blade 17 is formed by molding using chopped strands of carbon fiber 18 impregnated with Matori and Sox resin. It was designed to be created.

Note that the turbine blade 16 or 17 formed by the method shown in FIGS. 3C and 3D is carbonized in a subsequent process.

Problems to be Solved by the Invention The conventional manufacturing methods described above all have advantages and disadvantages due to limitations in the manufacturing method, and problems still remain regarding the functionality of the manufactured turbine blades themselves. .

That is, in the case of the turbine blades 13 and 14 manufactured by the method shown in FIGS.
Since the ends of each carbon fiber cloth 11 are exposed to the outer peripheral surface of the turbine blade 13.14, delamination and delamination may occur due to erosion when exposed to high temperature gas during turbine operation. Cracks occur and the durability is not sufficient.

In addition, in the case of the turbine blade 16 manufactured by the method shown in FIG. 6(C), although there are no defects such as delamination or cracking as described above, the matrix layer is gradually worn away due to the erosicon phenomenon due to long-term use. , the smoothness of the blade surface is likely to be impaired.

Furthermore, in the case of the turbine blade 17 manufactured by the method shown in FIG. 2(D), although the blade surface can be finished relatively smooth, an improvement in strength cannot be expected because the carbon fibers 18 are short fibers.

The present invention was made in view of the above problems.
The purpose is to provide a manufacturing method that can produce a turbine blade that has excellent mechanical strength and durability and has a smooth surface.

Means for Solving the Problems The present invention provides a method for manufacturing a turbine blade made of a carbon/carbon-based composite material, in which reinforcing fiber cloth impregnated with a matrix resin material is laminated in the thickness direction of the turbine blade. A core layer is formed by the body, and the core layer is surrounded by a skin layer made of reinforced fiber felt impregnated with a matrix resin to form a preform,
This preform is characterized by being carbonized by firing.

Effect According to the above method, the core layer of the turbine blade is formed of a long fiber C/C composite, whereas the skin layer is formed of a short fiber C/C composite. By taking advantage of the advantages of short fibers and short fibers, it is possible to obtain turbine blades with high mechanical strength and smooth surfaces.

Embodiment FIGS. 1 to 3 are diagrams showing an embodiment of the present invention, and the turbine blade l shown in FIGS. It is composed of a fitting anchor part 2 and a blade part 3 integrally formed with the anchor part 2.

In forming the turbine blade 1, Fig. 1 (A)
As shown in the figure, prepregs 6 having carbon fiber cloth 4 as a reinforcing material are folded in half and sequentially laminated to form a core layer 5 having a shape similar to the final product shape.

The prepreg 6 is folded in half and stacked so that the carbon fiber cloth 4 is not cut in the gas flow direction F during turbine operation, and the ends of the carbon fiber cloth 4 are formed on the outer peripheral surface of the blade portion 3. This is to prevent the carbon fiber cloths 4 from being exposed, and the carbon fiber cloths 4 are sequentially stacked so that the abutting portions of the ends thereof are located on the end 3a side of the gas inflow side of the blade portion 3.

Next, as shown in FIG. 1(B), the core layer 5 is surrounded with a prepreg 8 having pitch-based carbon fiber felt 7 as a reinforcing material, and the core layer 5 is covered with a skin layer 9 to form a turbine. A preform 10 of the blade 3 is formed.

The preform 10 thus obtained is heated and pressed in a known curing process to form a hardened molded body, and this hardened molded body is subjected to carbonization/graphitization treatment in a carbonization/graphitization process.

Due to the above carbonization/graphitization treatment, gas is generated due to thermal decomposition of the matrix resin and the cured molded body becomes loose, so the loose molded body is impregnated with pitch and then carbonized again.・Perform graphitization treatment. Then, the pitch impregnation and carbonization/graphitization treatments described above are repeated several times until the specific gravity of the molded body reaches a predetermined specific gravity. Get 1.

In the case of turbine blades used in an oxidizing atmosphere, SiC staple fibers are used as the reinforcing fiber felt, and a protective layer of SiC is coated on the surface of the felt when it is made into a brief. , or the matrix resin impregnated into the reinforcing fiber felt is pre-filled with S.
It is advisable to mix iC powder in advance.

Effects of the Invention As described above, according to the present invention, since the core layer having long fibers as reinforcement is covered with the skin layer having short fibers as reinforcement, it has excellent mechanical strength and has a smooth surface. You can obtain highly durable turbine blades with
This can greatly contribute to the practical application of C/C composite turbine blades.

[Brief explanation of the drawing]

Figures 1 (A), (B), and (C) are process explanatory diagrams showing one embodiment of the present invention, Figure 2 is a perspective view of a turbine blade, and Figure 3 is shown along the line ■-■ in Figure 2. Cross-sectional view along Fig. 4 (A),
(B), (C), and (D) are all explanatory diagrams showing a conventional method for manufacturing a turbine blade. DESCRIPTION OF SYMBOLS 1... Turbine blade, 3... Blade part, 4...
... Carbon fiber cloth (reinforced fiber cloth), 5... Core layer, 7... Carbon fiber felt (reinforced fiber felt), 9
... Epidermal layer, 10... Preform. Figure 2 Gas Gas

Claims (1)

[Claims] (1) In a method for manufacturing a turbine blade formed from a carbon/carbon-based composite material, reinforcing fiber cloth impregnated with a matrix resin material is laminated in the thickness direction of the turbine blade, and the core layer is formed by this cross laminate. A method for manufacturing a turbine blade, characterized in that a core layer is surrounded by a skin layer made of reinforcing fiber felt impregnated with a matrix resin to form a preform, and the preform is fired and carbonized.