The present study investigates the high temperature erosion behavior of HVOF sprayed composite coatings on T11 steel substrates by studying (Cr₃C₂-NiCr)Si and WC-Co/NiCrAlY coatings. Phase composition, cross sectional microstructure, mechanical properties, and erosion resistance were analyzed by XRD, EDS, SEM and three-dimensional optical profilography. The results demonstrate that the WC-Co/NiCrAlY coating has higher erosion resistance and oxidation stability for all temperatures and impact angles tested. Its enhanced performance in high temperature and erosive conditions is attributable to the formation of stable protective oxides such as Al₂O₃ and Cr₂O₃ and intermetallic phases such as Ni₃Al and Cr₃C₂. The NiCrAlY matrix prevents significant decarburization of WC particles, and hence phase stability and oxidation resistance. The (Cr₃C₂-NiCr)Si coating has higher microhardness due to silicide phases, but is more vulnerable to direct impacts and inferior oxidation resistance. The phase transformations for both coatings are favorable at elevated temperatures which enhances erosion resistance. The WC-Co/NiCrAlY coating is smooth and shallower in erosion craters and is perfectly suited for harsh environments demanding high toughness, impact resistance and oxidation stability. For applications in which high hardness is needed in less severe conditions, the (Cr₃C₂-NiCr)Si coating is more suitable.

中文翻译：

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HVOF喷涂（Cr₃C₂-NiCr）Si和WC-Co/NiCrAlY复合涂层的高温侵蚀行为研究


本研究通过研究 （Cr₃C₂-NiCr）Si 和 WC-Co/NiCrAlY 涂层，研究了 HVOF 喷涂复合涂层在 T11 钢基材上的高温侵蚀行为。通过 XRD、EDS、SEM 和三维光学轮廓分析物相组成、横截面微观结构、力学性能和抗侵蚀性。结果表明，WC-Co/NiCrAlY 涂层在所有测试的温度和冲击角度下都具有更高的抗侵蚀性和氧化稳定性。它在高温和侵蚀条件下的增强性能是由于形成了稳定的保护氧化物（如 Al₂O₃ 和 Cr₂O₃）以及金属间化合物相（如 Ni₃Al 和 Cr₃C₂）。NiCrAlY 基体可防止 WC 颗粒的显著脱碳，从而防止相稳定性和抗氧化性。由于硅化物相，（Cr₃C₂-NiCr）Si 涂层具有较高的显微硬度，但更容易受到直接冲击和较差的抗氧化性。两种涂层的相变在高温下都是有利的，这增强了抗侵蚀性。WC-Co/NiCrAlY 涂层在侵蚀坑中光滑且较浅，非常适合要求高韧性、抗冲击性和氧化稳定性的恶劣环境。对于在不太恶劣的条件下需要高硬度的应用，（Cr₃C₂-NiCr）Si 涂层更合适。