Complex oxide with negative thermal expansion for producing ceramic matrix composites with invar effect

The article investigates the phase composition of (Al₂O₃-20 wt % ZrO₂)-ZrW₂O₈ ceramic composites obtained by cold-pressing and sintering processes. Using X-ray analysis it has been shown that composites mainly have monoclinic modification of zirconium dioxide and orthorhombic phase of aluminum oxide. After adding zirconium tungstate the phase composition of sintered ceramics changes, followed by the formation of tungsten-aluminates spinel such as Al_x(WO_y)_z. It has been shown that thermal expansion coefficient of material decreases approximatly by 30%, as compared with initial ceramics.