Coefficient aluminium titanate

For most particulate composites the mismatch between the particles and the matrix is more important than the anisotropy of either component (though alumina/aluminium titanate composites provide a notable exception and are described below). The main features of the stresses can therefore be understood in terms of a simple elastic model assuming thermoelastic isotropy and consisting of a spherical particle in a concentric spherical shell of matrix with dimensions chosen to give the appropriate volume fractions. The particles are predicted to be under a uniform hydrostatic stress, ap after cooling. If the particles have a larger thermal expansion coefficient than the matrix, this stress is tensile, and vice versa. For small particle volume fractions the stress... 

Table 1 Weight Fraction of Minor Phases and Mass Attenuation Coefficient of Aluminium Titanate/Zirconia-Alumina Composites as a Function of Sample...

The improvement of the thermal shock behaviour of the composites may be attributed to a combination of a lower coefficient of thermal expansion and the higher thermal conductivity expected on the incorporation of metallic, SiC or aluminium titanate particles or of carbon fibres into the silicate matrices [108]. 

Some anisotropic crystals have negative linear coefficients of thermal expansion in one direction, and the volume expansion of such materials is low. The low expansion of cordierite, aluminium titanates, and lithium alumosilicates is explained by the strong crystal lattice anisotropy. The material made from these substances may have a very high thermal shock resistance. Yet in the process of... 

To demonstrate the method an aluminium titanate-titaniumoxide eutectic as ceramic matrix phase and nickel as the included metal phase of a cermet has been chosen. The thermal expansion coefficients of nickel and the ceramic phase have been measured separately in a Netzsch dilatometer (fig. 8). 

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