SYNTHESIS AND PROPERTIES OF NTE ZrV₂O₇ AND Al/ZrV₂O₇ COMPOSITES

ZrV₂O₇ with negative-thermal-expansion(NTE)was prepared by calcined-synthesis combined with wet-chemical process. The interface behaviors and thermal expansion character of ZrV₂O₇/Al composites were studied by powdermetallurgy. The results of XRD show that the samples with calcined-synthesis combined with wet-chemical process almost contain single phase of ZrV₂O₇. The results of XRD,SEM and EPS demonstrate that ZrV₂O₇/Al composites made by different press-formed and sintered-synthesis techniques have good sintered and dipped characters in a certain scope of sintered-temperature, whether they are in solid-state or molt-state. But the more reactive Al³⁺can displace with the Zr⁴⁺ ions and the reaction degrees will increase with sintered-temperature. The results of dilatometer show that ZrV₂O₇ has a strong isotropic and stable NTE property from 400K up to 680K and ZrV₂O₇/Al composites with good mould and fine structure were obtained by powder metallurgy technique. At the same time, the coefficient of thermal expansion of ZrV₂O₇/Al composites is lower than that of Al, though the coefficient of composites was also positive.