负热膨胀材料ZrV2O7与金属Al的复合行为及特性

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。 

SYNTHESIS AND PROPERTIES OF NTE ZrV2O7 AND Al/ZrV2O7 COMPOSITES

ZrV_2O_7 with negative-thermal-expansion(NTE)was prepared by calcined-synthesis combined with wet-chemical process.The interface behaviors and thermal expansion character of(ZrV_2O_7/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 ZrV_2O_7.The results of XRD,SEM and EPS demonstrate that(ZrV_2O_7/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 Al~(3+)can displace with the Zr~(4+) ions and the reaction degrees will increase with sintered-temperature.The results of dilatometer show that ZrV_2O_7 has a strong isotropic and stable NTE property from 400K up to(680K) and(ZrV_2O_7/Al) composites with good mould and fine structure were obtained by powder metallurgy technique.At the same time,the coefficient of thermal expansion of(ZrV_2O_7/Al) composites is lower than that of Al,though the coefficient of composites was also positive.