CoCrAlYTaCSi涂层和ZL101铸铝合金的气蚀性能研究

目的对比研究两种材料在RP-3航空煤油和去离子水中的耐气蚀性能,分析材料的气蚀机理以及介质的理化性质对其的影响机制,探讨用去离子水代替航空煤油以便快速筛选航空用耐气蚀材料的可行性。方法采用超音速火焰喷涂技术在铸铝合金(ZL101)表面均匀喷涂CoCrAlYTaCSi涂层。使用X射线衍射仪分析喷涂粉末、涂层和基体材料的物相组成。使用扫描电镜及其自带能谱仪分析材料气蚀前后的形貌以及元素分布。采用纳米压痕仪检测材料的力学性能。使用超声波振动气蚀试验机表征涂层及铸铝合金在航空煤油和去离子水中的气蚀性能。综合考虑两种材料气蚀后的平均侵蚀深度、形貌以及两种液体介质的理化性能,分析相应气蚀机理。结果 CoCrAlYTaCSi涂层主要由AlCo、Al_(80)Cr_(20)、Al_(45)Cr_7等物相组成,且分布均匀;铸铝合金主要由Al和Al_9Si相组成,增强相主要沿晶界分布。涂层的纳米硬度和弹性模量分别约是铸铝的6倍和2倍。气蚀中,铸铝合金晶粒内部的Al最先被损坏,加剧了气蚀进程;而CoCrAlYTaCSi涂层由于物相分布均匀、力学性能优异,所以损坏程度远轻于铸铝合金,在水和航空煤油中的平均侵蚀深度分别仅约为铸铝合金的2%和1%。两种材料在航空煤油中的平均侵蚀深度都比在水中的小。结论 CoCrAlYTaCSi涂层的物相分布均匀,具有较高的致密度、硬度和弹性模量,其在两种介质中均显示出更高的气蚀抵抗力。但材料在两种液体中的气蚀机理并不相同,导致在航空煤油介质中,CoCrAlYTaCSi涂层显示出更加优异的抗气蚀性能。

Cavitation Erosion Performances of CoCrAlYTaCSi Coating and ZL101 Cast Aluminum Alloy

The work aims to comparatively study the cavitation erosion performance of two materials in RP-3 aviation kerosene and deionized water, analyze the cavitation erosion mechanism and the influence of physical and chemical properties of medium and discuss the feasibility to replace aviation kerosene with deionized water so as to quickly select the anti-cavitation erosion materials used in aviation system. CoCrAlYTaCSi coating was prepared on the surface of cast aluminum alloy (ZL101) by high velocity oxy-fuel spraying (HVOF). Phase compositions of spraying powder, coating and substrate were analyzed by X-ray diffraction (XRD), and morphology and distribution of elements on the surface of materials before and after the cavitation erosion tests were detected by scanning electron microscope (SEM) and the built-in energy dispersive X-ray analyzer. A nano-indentation tester was used to measure the mechanical properties of materials. Avibration-induced laboratory cavitation tester was adopted to characterize the cavitation erosion of CoCrAlYTaCSi coating and cast aluminum respectively in aviation kerosene and deionized water. The corresponding cavitation erosion mechanism was analyzed by overall considering the mean depth of erosion and morphology of two materials after cavitation as well as the physical and chemical properties of two liquid medium. CoCrAlYTaCSi coating was mainly composed of AlCo, Al80Cr20 and Al45Cr7 phases, and all the phases were evenly distributed. Cast aluminum was mainly composed of Al and Al9Si phases, and the enhancement phases were mainly distributed along the grain boundaries. The nanohardness and elastic modulus of Co based coating were about 6 and 2 times higher than those of cast aluminum, respectively. The Al phase inside grains of cast aluminum was firstly damaged, thus aggravating its cavitation erosion process. The damage degree of Co based coating was far slighter than that of cast aluminum because of even distribution of phase and excellent mechanical properties. Its mean depth of erosion in water and aviation kerosene were only about 2% and 1% of those in cast aluminum. The mean erosion depth of two materials in aviation kerosene was less than that in water. The CoCrAlYTaCSi coating shows excellent cavitation erosion resistance in two mediums due to even distribution of phase, higher density, hardness and elastic modulus. Furthermore, this coating exhibits far better anti-cavitation erosion performance in aviation kerosene owing to the different cavitation erosion mechanisms in two liquids.