Papers by Keyword: PIP Process

Abstract: A structural-functional integrative wave-transparent material, consisted of BN coating and SiBN substrate, is synthesized through precursor infiltration pyrolysis (PIP) process. Then the technical parameters and procedures are obtained according to the key properties of the precursors. Studies on the microstructures and properties of the composite show that compact substrate and weak interface enhance the strength, and porous structure improves the dielectric performance of the composite. The composite exhibites good bending strength (~95.12 MPa), tensile strength (~34.95 MPa) and compressive strength (~80.92 MPa). Moreover the composite displays a low dielectric constant (4.17) and a low loss tangent (9.7×10^-3) at room temperature. The composite has a low changing rate of dielectric constant (~2.01% per 100°C). These results imply that the composite with excellent mechanical and dielectric properties can be an excellent wave-transparent material applied in the fields of aerospace.

Abstract: In the polymer impregnation and pyrolysis (PIP) process for the fabrication of SiCf/SiC composite, the curing process should be included to increase the conversion yields. During the curing process, unintended oxygen is introduced. Control of this oxygen is very important to obtain composites with a good high temperature stability. Using the electron beam curing process with full doses of 2~10 MGy and the pyrolysis process at 1300~1500oC, composites with an oxygen contents of less than 1 wt% could be obtained.

Abstract: 3-D braided C fiber preform was used to reinforce SiC matrix by polymer infiltration and pyrolysis (PIP). The effect of PCS pyrolysis process on the uncoated carbon fiber was studied. During the pyrolysis, amorphous SiCxOy and some free silicon yielded. The Si element diffused into the C fiber from the matrix because of the concentration gradient at high temperature and destroyed the intrinsic structure of the uncoated C fiber. At the same time, the free Si reacted with the uncoated C fiber. Thus, strong bonding between the fiber and matrix was formed. As a result, bending strength of the composite was decreased.