A three-layered experimental thermal and environmental barrier coating (TEBC) was deposited using air plasma spraying technology on cylindrical specimens of nickel-based superalloy MAR-M247. TEBC consists of mullite (Al6Si2O13) and hexacelsian (BaAl2Si2O8) upper layer, Y2O3 stabilised ZrO2 interlayer and CoNiCrAlY bond coat deposited on the grit-blasted surface of MAR-M247. The cyclic plastic response and damage mechanisms in uncoated and TEBC-coated MAR-M247 have been studied in isothermal dwell-fatigue tests conducted under strain control with constant strain amplitude at 900 °C. In each cycle, 5-minute dwells were introduced in both tensile and compression peaks of the hysteresis loop. Fatigue hardening/softening curves, stress relaxation curves, cyclic stress–strain curves and fatigue life curves are reported. Ceaseless mild softening has been found in both uncoated and TEBC-coated MAR-M247. TEBC-coated MAR-M247 showed an improved lifetime in the whole range of tested strain amplitudes. Data obtained from stress relaxation curves were used to assess the fraction of creep damage. The generalised damage accumulation rule was used to evaluate damage due to fatigue-creep-environment interaction. A study of the surface relief and internal microstructure using SEM and TEM helped to interpret the specifics of fatigue behaviour of uncoated and TEBC-coated material. The effectiveness of this newly developed TEBC, together with the dwell sensitivity of MAR-M247, were discussed from the perspective relevant to dwell-fatigue cyclic straining.

中文翻译：

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多层热和环境阻隔涂层涂层的镍基高温合金的保留疲劳性能评估


使用空气等离子喷涂技术在镍基高温合金 MAR-M247 的圆柱形试样上沉积了三层实验热和环境阻隔涂层 （TEBC）。TEBC 由莫来石 （Al6Si2O13） 和六孔体 （BaAl2Si2O8） 上层、Y2O3 稳定的 ZrO2 夹层和沉积在 MAR-M247 喷砂表面上的 CoNiCrAlY 粘结层组成。在应变控制下以 900 °C 的恒定应变幅进行的等温驻留疲劳测试中研究了无涂层和 TEBC 涂层 MAR-M247 中的循环塑性响应和损伤机制。 在每个周期中，在磁滞回线的拉伸和压缩峰中都引入了 5 分钟的驻留。报告了疲劳硬化/软化曲线、应力松弛曲线、循环应力-应变曲线和疲劳寿命曲线。在未涂层和 TEBC 涂层的 MAR-M247 中均发现持续温和的软化。TEBC 涂层的 MAR-M247 在整个测试应变幅度范围内显示出更长的使用寿命。从应力松弛曲线获得的数据用于评估蠕变损伤的分数。广义损伤累积规则用于评估疲劳-蠕变-环境相互作用引起的损伤。使用 SEM 和 TEM 对表面起伏和内部微观结构的研究有助于解释无涂层和 TEBC 涂层材料的疲劳行为细节。从与驻留疲劳循环应变相关的角度讨论了这种新开发的 TEBC 的有效性以及 MAR-M247 的驻留敏感性。