【作者】 徐驰；

【导师】 程晓农；

【作者基本信息】 江苏大学 ， 材料学， 2010， 硕士

【摘要】 钨酸锆是各向同性的负热膨胀材料,对其负热膨胀性能及其复合材料的研究是当今材料科学的研究热点之一。本课题组用固相法、共沉淀法、溶胶凝胶法等制备方法得到了高纯度的钨酸锆粉体,用磁控溅射和脉冲激光溅射法制备了钨酸锆薄膜,并得到了铜／钨酸锆功能梯度薄膜。铜／钨酸锆功能梯度薄膜可用于电子器件热应力缓冲层,提高电子器件热稳定性,延长电子器件寿命。用有限元方法模拟不同技术参数制备的铜／钨酸锆功能梯度薄膜的热-应力场,可以提高研发效率,在重复实验次数的很少情况下,得到从基底层到表层热应力平缓变化的梯度薄膜。具体优化设计流程为总结以往的材料性能参数,建立数学模型模拟实际工况,得到各类铜／钨酸锆功能梯度薄膜的热-应力场特征；以数值模拟得到的技术参数制备功能梯度薄膜；表征薄膜性能,以优化后的参数带入数学模型进行验证计算,在实验3-4组后即可得到优化的薄膜技术参数。数值模拟分析过程中,用有限元软件ANSYS 11.0建立了铜／钨酸锆缓冲热应力功能梯度薄膜的数学模型,讨论了梯度薄膜的层数N,成分分布指数P,梯度层厚度Hf,基片厚度Hm与纯铜层厚Hc以及不同工作环境温度T对薄膜热应力场分布的影响。由热力学计算可知：梯度层数越多,缓和热应力效果越好。考虑到制备工艺复杂程度,参考数值模拟结果可知：当P=1N≥5时,可以达到减小热应力最大值的效果,热应力最大值出现在基体与梯度层的界面处；当N=5,P值介于2和3之间时,热应力最大值位于梯度薄膜中间层；适量增加梯度层厚度Hf和基片厚度Hm有利于减小热应力最大值,此梯度缓冲层在室温到α相钨酸锆陶瓷的相变温度(120℃)区间内,对于各厚度的纯铜层都能有良好的保护作用。依据优化结果,用磁控溅射法制备了铜／钨酸锆功能梯度薄膜。用x射线衍射法(XRD)分析薄膜的物相组成；扫描电镜(SEM)分析薄膜的表面形貌；X射线应力测试仪对薄膜残余热应力状况进行了表征。结果表明：薄膜残余热应力分布状况和数值模拟结果相吻合。以数值模拟优化结果为依据而制备的功能梯度薄膜可以使热应力值降低到原来的72%,且热应力最大值分布在功能梯度薄膜中间层。更多还原

【Abstract】 Zirconium tungstate is a kind of isotropic negative thermal expansion material, the properties and the composite materials of Zirconium tungstate are new frontiers of material science. Zirconium tungstate powders were synthesized by solid state reaction; co-precipitation method; Sol-Gel method. Zirconium tungstate films were synthesized by the magnetic sputtering and laser sputtering. Cu/Zirconium tungstate functionally graded films prepared by magnetic sputtering would be used to decrease the heat stress on the surfaces of electronic equipments.Optimization on parametres of Cu/Zirconium tungstate functionally graded films by finite element method could accelerate the research progress:to establish mathmetical model with the parametres gotten from the previous experiments; to prepare functionally films according with the pre-optimized parametres; to measure the properties of film, then to modify the optimized parametres.A mathematical model of the Cu/ZrW₂O₈ functionally graded films was built using finite element method.The effects of the parameters, such as the quantity of layers （N）, distribution of components （P）, thickness of graded films （Hf）, thickness of S substrate （Hm）, thickness of pure Cu layer （Hc） and temperature （Τ）, on the thermal stress fields of Cu/ZrW₂O₈ functionally graded films were discussed. The results of thermodynamic calculation show that the more layers of the functionally graded films, the more the thermal stress can reduce. When P= 1 and N≥5, the maximum value of heat stress between the silicon and the functionally graded films decreased. When N= 5 and 3≥P≥2, the maximum value of heat stress appeared inside the functionally graded films. The increased values of H_f and Hm can favor the reduction of the maximum value of heat stress. This functionally graded film can protect the pure Cu layer from room temperature to the a-ZrW₂O₈ phase transformation temperature （120℃）.Several characterization methods were applied to analyse the phases constitute, the surface morphology, and the thermal stress of the film using the XRD, SEM, X-ray stress tester, respectively. The result show that the thermal stress distribution is similar to that from the numerical calculation. The maximum value of thermal stress decreases to 72%of the original coating without the functionally graded films, and it do appear in the middle of the functionally graded film.更多还原