Forming Al2O3-Al composites with controlled compositions by reactive metalpenetration of dense aluminosilicate preforms

Alumina-Al composites with controlled compositions containing 17 to 31 vol% Al were formed by reactive metal penetration (RMP) of molten Al into dense aluminosilicate preforms. A reaction model has been developed to accuratel y predict composite Al content from the SiO2:Al2O3 ratio of the preform. Th e model was tested and validated by comparing predicted composite compositi ons to those measured for RMP composites made from preforms of known compos itions. Aluminosilicate preforms containing 28.1, 39.0, and 54.1 wt% SiO2 w ere reacted with Al to produce composites with 17, 25, and 31 vol% Al, resp ectively. These values compare favorably to Al contents of 17.7, 22.7, and 28.6 vol% Al predicted using the reaction model. The differences between pr edicted and measured values are attributed to the presence of porosity and Si in the composites, as well as impurities in the SiO2 glass phase and por osity in the preforms, none of which is specifically accounted for in the r eaction model.