负热膨胀材料ZrV_2O_7与金属Al的复合行为及特性

SYNTHESIS AND PROPERTIES OF NTE ZrV_2O_7 AND Al/ZrV_2O_7 COMPOSITES

利用湿化学法制备先驱体-煅烧合成制备钒酸锆-ZrV2O7的新技术,采用粉末冶金方法,研究了ZrV2O7与金属Al两类不同材料的复合行为及其热膨胀特性.X射线衍射结果表明:利用上述技术合成的ZrV2O7纯度高,杂质含量极少.采用合成的ZrV2O7粉体与金属Al粉末混合,按不同成形-烧结工艺制备ZrV2O7与金属Al的复合材料试样,经扫描电子显微组织分析、微区电子探针能谱成分分析及X射线衍射分析发现,在一定烧结温度范围内,ZrV2O7与金属Al(无论是固态还是熔融态)均表现出了良好的烧结性与浸渍性,但在烧结温度下在ZrV2O7与金属Al之间存在Al对Zr的置换反应,且随温度升高而加剧.用热膨胀仪分别对合成的ZrV2O7及其与金属Al烧结而成的复合材料进行热膨胀特性测试,结果表明:ZrV2O7在400～680 K的温度区间具有很强的负膨胀特性;其与金属Al的复合材料虽然仍具有正的热膨胀特性,但其膨胀率较金属Al低得多.

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 wetchemical 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 A1^3＋ can displace with the Zr^4＋ ions and the reaction degrees will increase with sintered-temperature. The results of dilatometer show that ZrV2O7 has a strong isotropie 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.