Effect of Al additive in Si slurry coating on liquid Si infiltration into carbon–carbon composites Original Research Article

Two-dimensional carbon–carbon composites (2D-C/C) applied with a pure Si pre-coating or a Si–6 wt.%Al pre-coating by dipping slurry method were heated above Si melting point to perform liquid Si infiltration. For pure Si slurry pre-coating, liquid Si excessively infiltrated into the C/C composite and many cracks were formed inside resulting in serious degradation of the flexural strength of the C/C composite. For Si–6 wt.%Al pre-coating, only a little amount of liquid Si infiltrated into the C/C composite and the flexural strength was mostly retained after performing liquid Si infiltration. No deleterious effect of the Al additive on the formation of SiC conversion layer was found.