Component forming process of ceramic matrix composites——chapter one

Precursor infiltration pyrolysis （ #PIP）, is a new process and technology for material preparation developed from the 1970s to the 1980s. The principle of the PIP process is that the ceramic precursor resin system is impregnated into the fiber woven porous preform by solution or melting. After curing and cross-linking, it is cracked at high temperature in an inert atmosphere and converted into a ceramic matrix. Currently, carbide and nitride matrix are the main ones. .

The advantages of the PIP process are mainly two points: (1) the impregnation and curing can use the conventional molding method of resin #matrixcomposites, and (2) it is suitable for any complex shape products. The disadvantage is that the performance of the composite material is lower than that of the #CVI process, and the preparation cycle is long, usually requiring more than ten "dipping-cracking" processes, and the time is more than 3 months. This is because the cracked matrix has a loose structure, cannot effectively protect the carbon fibers from oxidation, and has poor mechanical properties, so the mechanical properties and oxidation resistance of the composites are low.

The PIP process is a process of repeated impregnation and cracking of precursors. It usually takes more than a dozen PIP cycles to complete the preparation of a batch of CFRCMCs, and the preparation cycle is long. At the same time, the precursors used in the PIPT process are expensive. For example, the precursor for preparing SiC ceramics, polycarbosilane (PCS), currently sells for about ￥5000 /kg.