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The thermal diffusivity and conductivity of several ceramic composites were determined experimentally to observe the effect of temperature, heat treatment and orientation on these properties. The thermal conductivity and diffusivity of SiC whisker reinforced Ba-osumilite glass-ceramic exceeded that of SiC fiber reinforced osumilite due to higher thermal conductivity and diffusivity of the whiskers. An anisotropy was observed in thermal conductivity of the whisker composite due to whisker orientation normal to hot-pressing direction. Thermal conductivity of carbon fiber reinforced borosilicate glass parallel to the fiber plane was about twice that of the normal orientation and of the matrix. Heating the composite to above 600°C resulted in permanent decrease in thermal conductivity due to void formation by relaxation of the elastically bent fibers by viscous flow of the matrix. Thermal conductivity of iniaxial carbon fiber reinforced lithia-aluminosilicate glass-ceramic was over ten times higher parallel to the fibers than perpendicular. Permanent decrease of thermal conductivity normal to the fibers was due to matrix cracking caused by relief of internal stresses due to matrix crystallization and thermal gradients during fabrication. Modification of the original theories of Maxwell and Rayleigh permitted derivation of expressions for thermal conductivity of composites of a continuous matrix with dilute concentrations of spherical and cylindrical geometries and of parallel flat plates with thermal resistance at the interfaces.

The purpose of this study is to determine how accurately the academic success of one hundred and sixty-seven freshmen at North Texas State College could have been predicted by the American Council on Education Psychological examinations. The question studied is: Can freshman success, as indicated by first term freshman grades, be better predicted by psychological examination scores than by analysis of their high school grades? In an attempt to answer this question, the relationships existing between the high school grades, psychological examination scores and first term college grades of the freshman class entering North Texas State College in the fall of 1949 have been studied.