Pressureless Melt Infiltrated Non-Oxide Ceramic-Metal Composites

Abstract

In the present study highly dense (open porosity < 1 %), light-weight (d <= 2.85 g/cm(3)) and Al(4)C(3)-free non-oxide ceramic-metal composites were produced at comparatively low temperatures (<= 1250 degrees C) by pressurless melt infiltration. Phase analysis of the SiC-B(4)C-Al composites revealed that a significant amount of hygroscopic Al(4)SiC(4) and Al(4)C(3) phases were formed. Si(3)N(4) powder was added in different amounts to the SiC-B(4)C powder batches to suppress formation of these phases via in-situ reactions during the infiltration process. X-ray diffraction results of the SiC-B(4)C-Si(3)N(4)-Al composites confirmed that the incorporation of Si(3)N(4) to the SiC-B(4)C system reduced or eliminated the formation of the hygroscopic phases and resulted in in-situ formation of AlN, SiC and Si phases in the composite.