Y_2W_3O_(12)/Ni复合材料的制备及热膨胀性能

为研究Ni基Y2W3O12复合材料的热学性能,首先,采用二次焙烧法制备了负膨胀材料Y2W3O12;然后,将Y2W3O12与金属Ni进行混合,并在1 200℃、50 MPa的条件下热压烧结制得40vol%Y2W3O12/Ni复合材料;最后,对复合材料的成分及热膨胀性能进行了研究。结果表明:在热压烧结过程中,由于Ni的还原性比W差,相对于对比试样40vol%Y2W3O12/Cr复合材料中发生的复杂化学反应,40vol%Y2W3O12/Ni复合材料的两相之间并未发生反应,使40vol%Y2W3O12/Ni复合材料保持了较低的热膨胀系数;经数次循环退火释放热应力及去除Y2W3O12相的结晶水后,40vol%Y2W3O12/Ni复合材料在170~800℃温度范围内的热膨胀系数趋于稳定,约为3.4×10-6 K-1,与理论设计值4.0×10-6 K-1相近。

Preparation and thermal expansion properties of Y2W3O12/Ni composites

In order to investigate the thermology properties of Ni-based Y₂W₃O₁₂ composites, negative thermal expansion material Y₂W₃O₁₂ was prepared by secondary solid-state method firstly. Then, Y₂W₃O₁₂ was mixed with metal Ni, and by hot pressing sintering under the conditions of 1 200 ℃ and 50 MPa, 40vol% Y₂W₃O₁₂/Ni composites were obtained. Finally, the compositions and thermal expansion properties of composites were investigated. The results indicate that during the hot pressing sintering process, comparing with the complex chemical reactions occurring in contrast sample 40vol% Y₂W₃O₁₂/Cr composite, there is no reaction occurred between the two phases of 40vol% Y₂W₃O₁₂/Ni composites, for the reducibility of Ni is weaker than that of W, which makes 40vol% Y₂W₃O₁₂/Ni composite keeps the lower coefficient of thermal expansion. After several cycle annealing to release the thermal stress and remove the crystal water of Y₂W₃O₁₂ phase, the coefficient of thermal expansion of 40vol% Y₂W₃O₁₂/Ni composite in the temperature range of 170-800 ℃ tends to be stable, which is about 3.4×10^-6 K^-1 and close to the theoretical design value of 4.0×10^-6 K^-1.