Factorial design, processing, characterization and microstructure analysis of PIP-based C/SiC composites

Abstract

Polymer impregnation and pyrolysis (PIP) process-based C/SiC composites are fabricated using the in-house synthesized methyl-polycarbosilane (PCS). Two-level factorial design matrix is employed to carry out experiments to study the effect of four factors on flexural strength of the composite. Total sixteen sets of composite samples are fabricated. Response table, normal probability plot, ANOVA and regression analysis are carried out to determine the statistical significant factors. Composite density (ρ), fibre volume fraction (V f) and pyrolysis temperature (T) are found to be statistically significant, while softening point (SP) of the PCS and interaction of these four factors are found insignificant. Higher levels of the density and V f have shown positive effect, while the pyrolysis temperature has negative effect on the flexural strength of the composites. Flexural strength was found to be in the range of 374-592 MPa depending on the process parameters. The mechanical behaviour of the composites at different process conditions was explained with the help of their microstructures.

SiC-Based Composites Through Liquid Infiltration Routes

“…Critical process parameters are identified using the response table, normal probability curve, analysis of variance (ANOVA), and regression analysis. Apart from the processing parameters like pyrolysis temperature, rate of heating and ceramic yield of the PCS precursor, etc., physical properties of the C/SiC composites like fiber properties, preform type, fiber volume fraction (V f ), density, and test specimen size play vital role to obtain mechanical and thermal properties from a given composite [12,[39][40][41]. Two-level full fractional design of experiments was employed to develop the experimental matrix and to carry out the desired experiments [12], through the factorial design, the most influential parameters are identified.…”

“…The following steps were used [12]: a) Identifying the important and influential process parameters which can be controlled independently as factors b) Fixing of the upper and lower limits of the identified factors c) Developing the experimental design matrix using factorial design of experiments d) Conducting the experiments as per the design matrix e) Assessing the real or chance effect of the factors by constructing response table and normal probability plot f) Analyzing the results using analysis of variance (ANOVA) g) Developing linear expression to estimate flexural strength of UD C/SiC composite as a function of the factors…”

“…The following factors are considered to be important factors which can be controlled independently and have significant influence on the mechanical properties of the C/SiC composite [12,[39][40][41]. Softening point of polycarbosilane-ceramic yield depends on the softening point of PCS, and also it controls the extent of the matrix shrinkage which in turn affects the micro-crack pattern and residual porosity in the composite.…”

“…Softening point of polycarbosilane-ceramic yield depends on the softening point of PCS, and also it controls the extent of the matrix shrinkage which in turn affects the micro-crack pattern and residual porosity in the composite. PCS resin of softening points (110-250 C) results into C/SiC composites having different mechanical properties [12,[39][40][41].…”

“…LSI-based C/SiC composites have been developed by various agencies like DLR, NASA, SNECMA, and DRDO for various advanced applications [1][2][3]. PIP-based C/SiC composites are also being developed by several agencies including those who have developed LSI-based C/SiC composites [1][2][3][10][11][12][13]. In this chapter, a summary of the work done at different leading agencies would be presented, whereas the work carried out by the authors in India would be covered in details.…”