SiC/SiC composite absorbing material for nozzle guide vanes, wing leading edges, turbine blades, and turbine shells

    SiC/SiC composite materialExcellent comprehensive performance, with broad application prospects in aviation, aerospace, nuclear energy and other fields. SiC/SiC composite material refers to the composite material formed by introducing SiC fibers as reinforcing phases into SiC ceramic matrix, and then forming SiC fibers as reinforcing phase and dispersed phase, SiC ceramics as matrix phase and continuous phase. The structural and compositional characteristics of SiC/SiC composite materials determine that this type of material inherits and retains the advantages of high temperature resistance, oxidation resistance, wear resistance, and corrosion resistance of silicon carbide ceramic materials. At the same time, by utilizing the mechanism of SiC fiber reinforcement and toughening, it overcomes the inherent defects of poor toughness and poor resistance to external impact loads of the material. SiC/SiC composite materials have excellent comprehensive properties and broad application prospects in aviation, aerospace, nuclear energy and other fields, especially in the hot end parts of aircraft engine combustion chamber liners, combustion chamber tubes, nozzle guide vanes, wing leading edges, turbine blades and turbine shell rings.

The preparation processes of SiC/SiC composite materials mainly include Polymer Infiltration and Pyrolysis (PIP), Chemical Vapor Infiltration (CVI), Reactive Melt Infiltration (RMI), and Slurry Infiltration and Hot Pressing process (SIHP).

PIP process is one of the rapidly developing ceramic matrix composite material preparation processes in recent years, which involves impregnating polymer organic precursors (solutions) into the interior of fiber preforms and then high-temperature cracking to generate ceramic matrix. Its advantages include lower processing temperature, near net shape, and less damage to fibers. And the matrix has strong designability, which can obtain easily processed intermediate products after several immersion cracking cycles. After fine processing, it can be further densified, making it suitable for preparing large components with complex shapes. But the ceramic yield is low, the manufacturing cycle is long, and the material porosity is high.

The CVI process mainly involves high-temperature cracking of gas-phase precursors to deposit dense composite materials on the surface of fibers. The materials prepared by this method have high purity, a complete crystal structure in the matrix, and excellent mechanical properties. The shape of the obtained composite material is basically determined by the prefabricated body, which can achieve near net forming and prepare complex shaped components; In the same deposition furnace, the deposition of interfacial phases, substrates, and surface coatings of components can be carried out sequentially to prepare composite materials with variable composition or density, achieving optimized material design. The disadvantages are low sedimentation rate, long manufacturing cycle, high cost, and high porosity of composite materials.

The biggest advantage of RMI technology is that it can prepare dense and almost defect free substrates through a single molding process, and the structural size changes between the preform and the component are small. It is considered an effective way to quickly and cost effectively prepare complex shaped components with near net shape. But the main problem with this process is that the temperature during the infiltration process is high, which causes significant damage to the fibers; During the melt infiltration process, the metal reacts with oxygen and other substances to form a dense oxide film, which hinders further reaction of the metal and forms residues inside the material, which may affect the high-temperature stability of the composite material.

Various countries have conducted detailed research on the process of ceramic matrix composites, among which Japan has the technology of preparing polycarbosilane (PCS) and continuous SiC fibers, mainly focusing on the research of PIP process for preparing fiber-reinforced SiC composites, especially in the preparation of SiCf/SiC composites, which has a high level of research; France mainly relies on CVI technology, and its technological level is internationally leading; Germany mainly relies on RMI and PIP technologies, especially RMI technology which is world leading; The United States has conducted research on PIP, CVI, and RMI processes, all of which have a high level of research. Especially, RMI process has become the mainstream process for preparing ceramic based composite materials at GE.

in Chinasilicon carbide matrix compositesThe preparation is mainly based on CVI, PIP, and RMI technologies, and the SiC/SiC composite material processing technology includes traditional mechanical processing, ultrasonic technology, laser processing technology, high-pressure water jet technology, and electrical discharge machining technology. SiC/SiC composite materials have high hardness and are composed of multiple parts such as matrix and fibers, exhibiting significant anisotropy. In addition, the surface morphology, dimensional accuracy, and positional accuracy of composite materials have important impacts on the safety, reliability, and service life of components. Therefore, a combination of traditional mechanical processing techniques and special processing techniques is generally used to achieve precise processing of materials. Japan has obvious advantages in traditional machining fields such as milling, cutting, grinding, and drilling of ceramic matrix composite materials, while countries such as the United States, Germany, the United Kingdom, and Russia have conducted in-depth research in ultrasonic machining, electrical discharge machining, high-pressure water jet machining, and laser machining.