金刚石-硫化锌复合窗口的弹性应变研究

Prediction of thermal strain in diamond-zinc sulfide composite infrared windows

对于金刚石-硫化锌复合红外光学窗口,结构中存在的热应力和挠曲度的大小对其可靠性有很大的影响。利用弹性应变模型研究了在光学焊接中不同粘接温度和金刚石厚度下金刚石-硫化锌复合窗口将发生的最大应力、曲率和衬底到边缘的挠曲度。计算结果表明,当膜厚在极值附近时,复合结构明显弯曲、ZnS表面的应力极大;如果粘接温度较高,复合结构将严重变形,ZnS中所受的应力可能会超过其自身的断裂强度。当对金刚石-硫化锌复合红外窗口设计时,了解结构中存在的热应力和挠曲度的大小是很有用的。

Considering the reliability of diamond/ZnS infrared windows, it is v ery useful to know how much thermal stress and deflection exist in the structure.The stresses, curvat ure and deflection of thickdiamond film bonded to zinc sulfide substrate at elevated temperature were pre dicted. An elastic strain numerical model was used in the calculation.The thermal stresses throughout th e structure after bonding were shown for each condition. Also, the curvature and the edge to center defl ection caused by thermalstresses were reported. Results show that when thickness ratio of diamond film s to ZnS is about 17%and bonding temperature is higher than 250oC, the stresses within the ZnS subs trate are predicted to exceed their rupture strength.