高速循环"热"交变"力"耦合条件下涂层/基体界面元素扩散行为及对界面组织形成、涂层功能退化的作用机制

MCrAlY metal coating as engine blade surface protective coating and binding layer in thermal barrier coating services in circulation "thermal" alternative "stress" coupling environment. The diffusion behavior of alloy element and formation mechanism of phase structure in interface between coating and substrate, which was driven by the gradient of composition, temperature and stress, are different from high temperature oxidation environment. An inverse diffusion of element at local area of interface is to form a "new reaction area", and which influences the property of oxidation resistant and protection function in the coating. ..A self-made environment simulation system with real-time test, rapid cyclic in temperature and data acquisition function will be used to simulate the quickly recycling "heat," alternative "force" coupling environment. The FIB-SEM and SDD-TEM techniques will be used to realize the analysis of elements distribution at interface area and drafting TEM samples at interface in 3D directions. The mutual diffusion behavior of elements and the formation mechanism of phase structure at interface coating and substrate under driving of gradient of composition, the temperature and stress at interface will be researched. Under coupled conditions both thermal and stress, the effect of elements diffusion behavior at the interface on the formation and evolution mechanism of phase structure will be shown. The element diffusion and structure evolution model at interface under the condition of coupled thermal and stress will be established. The coating protection function degradation and mechanism of coating failure will be demonstrated. A theory foundation will be provided for designing and developing a new generation of metal protective coating and thermal barrier coating.

MCrAlY金属涂层作为发动机叶片表面防护涂层和热障涂层粘结层，服役在高速循环"热"、交变"力"耦合的环境中，涂层/基体界面存在大温度梯度及应力梯度。界面合金元素在浓度、温度及应力梯度共同作用驱动下局部区域的"逆扩散"行为及形成的"新反应区"严重影响涂层的抗高温防护功能及服役寿命。.采用具有快速升降温、实时测试及数据采集功能的环境模拟系统，实现高速循环"热"、交变"力"耦合的发动机服役环境模拟；采用FIB-SEM及SDD-TEM技术，实现界面微区特征组织TEM样品的三维定位精确制取及界面微区元素的精细分析。研究涂层基体界面成分、温度及应力梯度共同作用下界面元素的互扩散行为及界面相组织形成机制；揭示热力耦合条件下界面元素的扩散对相组织形成的作用机理；建立热力耦合下涂层/基体界面元素扩散及组织演化模型；掌握涂层防护功能退化及损伤失效的实质，为设计发展新一代金属防护涂层及热障涂层提供理论基础。

航空发动机高温防护涂层长期服役在高速循环 “热”、交变“力”耦合的环境中，陶瓷/金属涂层及金属/合金基体界面的浓度梯度、温度梯度及应力梯度共同作用驱动下会发生一系列严重的互扩散行为、显微组织结构演变行为、裂纹萌生扩展行为，严重影响涂层的抗高温防护功能及服役寿命。为弄清高温防护涂层服役环境下的界面元素互扩散特性、显微组织演变规律、失效破坏机制，采用扩散偶的方法系统研究了界面元素互扩散行为；采用电子束物理气相沉积(EB-PVD)技术制备的高温防护涂层，研究了循环 “热”、交变“力”耦合环境下陶瓷/金属涂层及金属/合金基体等界面互扩散行为、组织结构演变行为、失效破坏行为，为新型高温防护涂层的设计发展提供理论支撑。.采用扩散偶的方法，研究1100℃恒温及热循环条件下，金属涂层/合金基体界面元素扩散行为及微观组织特征，探讨热循环对金属涂层/合金基体界面元素互扩散特性和显微组织演变行为的影响，表明热循环过程中热-力耦合效应提高界面元素互扩散系数~60%左右，促进界面元素的互扩散，加速了界面处基体中TCP相的析出，引发界面褶皱等组织演变行为。揭示热循环条件下“热”“力”对界面元素扩散的作用机制及微观组织演变机制，提出热循环条件下界面组织演变模型。.采用EB-PVD技术制备的高温防护涂层，研究复杂服役条件下金属涂层/合金基体界面元素互扩散及组织演变行为、陶瓷涂层/金属涂层界面应力状态及界面失效行为，表明热力耦合作用下，金属涂层/合金基体界面处的二次反应(SDZ)区域扩大1倍左右及区域中的TCP相变长，促进裂纹源萌生扩展，加速氧与铝元素的扩散；陶瓷涂层/金属涂层界面处较大的拉应力与剪切应力，导致界面处元素加速扩散与组织失稳。揭示循环“热”交变“力”耦合条件下金属涂层/合金基体界面元素互扩散对其组织演变的作用机制及对陶瓷涂层/金属涂层界面组织结构演变及失效破坏机制，建立了循环“热”交变“力”耦合条件下NiAl基涂层/Ni基高温合金界面组织演化模型及涂层界面失效破坏模型。