RELATED APPLICATIONS

The present application is a National Phase of International Application Number PCT/JP2017/043885 filed Dec. 6, 2017 and claims priority to Japanese Application Number 2016-237869 dated Dec. 7, 2016.

TECHNICAL FIELD

The present invention relates to a manufacturing method for a ceramic matrix composite.

BACKGROUND ART

It is studied to use a composite material for a fuselage or engine of an aircraft, and a high-temperature part or a part requiring light weight and high durability in an industrial gas turbine engine. As an example of such a composite material, for example, a ceramic matrix composite (CMC: Ceramic Matrix Composites) described in PTL 1 is known.

The ceramic matrix composite has a woven fabric that has a plurality of fiber bundles and a reinforcing material called a matrix which fills a gap between the fiber bundles. In obtaining the ceramic matrix composite, a technique called a PIP method (Polymer Infiltration and Pyrolysis method) is used as an example. The PIP method includes a step of infiltrating a woven fabric with a polymer in a solution which contains the polymer that becomes a precursor of the matrix, and a step of drying and sintering the infiltrated polymer.

CITATION LIST

Patent Literature

[PTL 1] Japanese Patent No. 5129997

SUMMARY OF INVENTION

Technical Problem

However, in order to obtain a ceramic matrix composite having desired strength characteristics by the PIP method, it is necessary to repeat each of steps of infiltrating, drying, and sintering the polymer a plurality of times. For this reason, it has been a problem that manufacturing time is prolonged. Furthermore, it is also known that in a case where the sintering step is repeated a plurality of times, decreased strength occurs due to deterioration of fiber bundles.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a manufacturing method for a ceramic matrix composite which is unlikely to result in decreased strength and with which it is possible to shorten manufacturing time.

Solution to Problem

According to the present invention, there is provided a manufacturing method for a ceramic matrix composite having a woven fabric that has a plurality of fiber bundles and a matrix that is disposed in a gap between the fiber bundles, the method including a green body formation step of forming a green body by infiltrating the woven fabric with a polymer as a precursor of the matrix and performing sintering, and a densification step of further infiltrating the green body with the polymer and performing sintering, in which the densification step includes a second infiltration step of further infiltrating the green body with the polymer to form an infiltrated green body, a drying step of drying the infiltrated green body to form a dried green body, a steam treatment step of leaving the dried green body under a saturation water vapor pressure to form a treated green body, and a sintering step of sintering the treated green body.

According to this method, by carrying out the steam treatment step, it is possible to increase infiltration efficiency of the polymer with respect to the green body. That is, it is possible to obtain a ceramic matrix composite having desired characteristics without carrying out a subsequent sintering step many times. Furthermore, it is possible to avoid decreased strength due to heat which occurs in a case where the sintering step is repeated.

In addition, in the manufacturing method for a ceramic matrix composite, after the steam treatment step, the second infiltration step, the drying step, and the steam treatment step may be repeated, and in the sintering step, the treated green body for which the second infiltration step, the drying step, and the steam treatment step have been repeated a plurality of times may be calcined.

According to this method, the infiltration efficiency of the polymer with respect to the green body can be further increased.

In addition, in the manufacturing method for a ceramic matrix composite, the steam treatment step may be carried out under saturation water vapor at 30° C. to 200° C.

According to this method, since the treatment can be carried out at a relatively low temperature, the infiltration efficiency of the polymer with respect to the green body can be increased without using a large-scale facility.

In addition, in the manufacturing method for a ceramic matrix composite, the woven fabric may have a sizing agent that covers a periphery of the fiber bundle, and the method may further include an interface coating formation step of forming an interface coating on the fiber bundle by heating the woven fabric under a nitrogen atmosphere to modify the sizing agent, before the green body formation step.

According to this method, it is possible to form the interface coating by using the sizing agent which has adhered, from the beginning, on peripheries of the fiber bundle and fibers that form the fiber bundle. That is, it is possible to form the interface coating on peripheries of the fiber bundle and the fibers without carrying out a desizing step which is carried out in the related art. As a result, it is possible to decrease man-hours.

In addition, in the manufacturing method for a ceramic matrix composite, the sizing agent may be at least one selected from the group consisting of polyurethane, epoxy resin, polybutadiene, polyalkylene glycol, polyolefin resin, vinyl ester resin, saturated polyester resin, unsaturated polyester resin, polyamide resin, polyimide resin, polyamideimide resin, acrylic resin, polypropylene resin, and pitch-based resin.

According to this method, as the sizing agent, at least one selected from the group consisting of polyurethane, epoxy resin, polybutadiene, polyalkylene glycol, polyolefin resin, vinyl ester resin, saturated polyester resin, unsaturated polyester resin, polyamide resin, polyimide resin, polyamideimide resin, acrylic resin, polypropylene resin, and pitch-based resin is used. These chemical species are changed to have a carbon-based molecular structure by being heated under a nitrogen atmosphere. Therefore, according to this method, it is possible to form the interface coating in an easy and inexpensive manner.

In addition, the manufacturing method for a ceramic matrix composite is a manufacturing method for a ceramic matrix composite having a woven fabric that a plurality of fiber bundles and a sizing agent covering a periphery of the fiber bundle, and having a matrix that is disposed in a gap between the fiber bundles, the method including an interface coating formation step of forming an interface coating on the fiber bundle by heating the woven fabric under a nitrogen atmosphere to modify the sizing agent, a green body formation step of forming a green body by infiltrating the woven fabric, on which the interface coating has been formed, with a polymer as a precursor of the matrix, and a densification step of further infiltrating the green body with the polymer and performing sintering.

According to this method, due to the interface coating formation step, it is possible to form the interface coating by using the sizing agent which has adhered, from the beginning, on peripheries of the fiber bundle and fibers that form the fiber bundle. That is, it is possible to form the interface coating on peripheries of the fiber bundle and the fibers without carrying out a desizing step which is carried out in the related art. As a result, it is possible to decrease man-hours and to obtain a ceramic matrix composite having higher strength.

Advantageous Effects of Invention

According to the present invention, it is possible to provide a manufacturing method for a ceramic matrix composite which is unlikely to result in decreased strength and with which it is possible to shorten manufacturing time.

