【作者】 李刚；

【导师】 王晓放；

【作者基本信息】 大连理工大学 ， 动力机械及工程， 2006， 硕士

【摘要】 冷气体动力喷涂技术(以下简称冷喷涂技术)是区别于目前广泛应用的“热”喷涂技术的一种新兴材料表面改性技术，其过程为在不足以使涂层粉末及工件的机械性能因熔化或高温而发生改变的常温或较低温度下，利用在缩放喷嘴形成的超音速气流夹带涂层粉末加速并喷射到基板，形成致密涂层的一种材料改性技术。由于避免了“热”喷涂工艺所引起的弊端和不足，冷喷涂技术越来越受到国内、外学者的广泛重视。 深入研究冷喷涂材料改性技术中粉粒对工件的冲击侵彻过程和涂层形成过程的规律，揭示不同材质、不同性能的基板、粉料、热力气动参数之间的关联关系，为确定最佳控制参数，完善试验方案，优化参数配置提供有力依据。这些是本论文工作的重点。 本文利用非线性有限元分析软件LS-DYNA，模拟计算单颗喷涂粒子与基体非垂直碰撞的过程并改变入射角度，研究其对粒子和基体的变形影响以及碰撞过程中塑性应变的变化，绝热剪切失稳发生的条件以及入射角度与碰撞过程中临界速度的关系。通过模拟计算不同金属材料的碰撞过程，研究材料参数对碰撞变形的影响，尤其是弹性模量和屈服极限这两个涉及力学性能的重要参数，分析材料参数对粒子和基体的变形影响以及碰撞过程中塑性应变的变化，特征节点的特征曲线变化。 模拟结果表明：非垂直碰撞过程中，粒子入射速度的法向分量对碰撞过程和粒子沉积起到非常重要的作用；粒子与基体的材料性质是影响涂层形成的重要因素。数值模拟结果与实验结果吻合良好，表明计算结果和分析结论的可靠性。更多还原

【Abstract】 Cold gas dynamic spray (for short: cold spray) is distinguished from thermal spray that is used widely at present. It is a new emerging technology to transform material property. It is a process that with normal or relatively low-temperature unable to melt the powder material and work piece and destroy their mechanical property, the metallic powder is carried by supersonic gas which is formed in a convergent-divergent spray nozzle and sprays onto the substrate to form compact coating. Since the disadvantage and shortage caused from thermal spray technology can be avoided, it is received more and more attentions from internal and external scholars’ recognitions.In this paper, the process that the metallic powder particle impacts the work piece is studied. It is revealed that the relations among different performance powder material, substrate and thermal gas dynamic parameters and is provided that the powerful guarantees for choosing optimum controlling parameters, completing experiment projects, optimizing parameters collocation.In this study, the collision process of single particle impacting substrate under tilting angle is simulated by finite element program LS-DYNA. It is investigated that the distortion behavior of both particle and substrate, the evolution of maximum plastic strain, the occurring of adiabatic shear instability and relation between tilting angle and critical velocity through changing tilting angles. The collisions of different metallic material are also simulated to study the effect of material parameters especially elastic module and yield limit related to mechanical performance. It is analyzed that the distortion behavior of both particle and substrate, the evolution of maximum plastic strain and characteristic curve of characteristic node.It is found that the normal component of impact velocity takes an important role in the impacting process and formation of bonding under oblique collision. The material parameters of particle and substrate are i(?)portant factor in coating formation. The numerical simulated results according with experiment results indicate the analysis conclusions are reliable.更多还原