热腐蚀和盐雾腐蚀影响氮化物涂层冲蚀行为的机制

Mechanism of Hot Corrosion and Salt Spray Corrosion Affecting Erosion Behavior of Nitride Coatings

金属氮化物涂层是目前重点关注的航空发动机压气机抗冲蚀涂层体系。为了兼顾热物理化学环境和应力环境的影响,进行涂层的腐蚀-冲蚀耦合行为研究十分重要。本研究对比了TiN/Ti涂层与TiN/ZrN涂层的原始状态、热腐蚀后和盐雾腐蚀后的冲蚀行为。结果表明,对于TiN/Ti涂层,在涂层的缺陷处盐雾腐蚀时形成点蚀坑,这是发生冲蚀的薄弱环节,盐雾腐蚀后TiN/Ti涂层的抗冲蚀能力及结合力低于原始涂层和热腐蚀后的涂层。对于TiN/ZrN涂层,热腐蚀过程中液滴表面形成疏松的腐蚀产物和氧化物,使其在冲蚀时更容易脱落,热腐蚀过程中产生的层间热应力削弱了涂层的结合力。热腐蚀涂层冲蚀后呈现严重的螺旋状剥落,热腐蚀后TiN/ZrN涂层的抗冲蚀能力及结合力低于原始涂层和盐雾腐蚀后涂层。

Nitride coatings have been applied and regarded as key erosion resistant coating system for aircraft compressor.In order to consider the effect of thermophysical and chemical environment as well as stress environment,it was important to study the coupling behavior of corrosion and erosion for these nitride coatings.In the present work,the erosion behaviors of original coating,the hot corroded coating and the salt spray corroded coating were compared for both TiN/Ti coating and TiN/ZrN coating.The results show that for TiN/Ti coating,the pittings caused by coating defects are weak regions to erosion.The salt spray corroded TiN/Ti coating has lower adhesion and erosion resistance than original coating and hot corroded coating.For TiN/ZrN coating,loose corrosion and oxide products form on the surface of droplets during hot corrosion,so they are easier to fall off during erosion.Moreover,the generative interlayer thermal stress in hot corrosion process weakens the adhesion between the coating and substrate.The surface of the hot corroded coating shows the most severe spiral peeling after erosion,and the hot corroded TiN/ZrN coating has lower adhesion and erosion resistance than original coating and salt spray corroded coating.