As HfO₂-doped Si bond coat acts a pivotal part in application of progressive environmental barrier coating (EBC) system owing to improving the high-temperature capability and creep properties of bond coat, it is essential to control the doping content and to balance the mechanical and thermal properties of doped coatings challenge in terms of upgrading service life and operating temperature of EBC system. In this study, the physical properties and thermal shock performance at 1723 K of HfO₂-Si composite coatings with three different compositions were investigated via first-principle calculations and micromechanical model. Evidently, the composite coatings deposited by magnetron sputtering exhibit a better resistance towards crack initiation and propagation than pure Si bond coat up to 100 h thermal cycling time. Such improvement is attributed to the dispersion toughening effect caused by the characteristic structure of dispersed HfSiO₄ particle within cristobalite “mortar”. With thermal cycling, the continuous Ostwald ripening of HfSiO₄ particles decreased the elastic modulus and effective thermal expansion coefficient gap at room and high temperature of composite coatings, which was advantageous to thermal shock resistance. Unfortunately, as a consequence of excessive volume expansion during particle ripening, the composite coatings encountered varying degrees of interface separation after 100 cycles and hence not protective anymore. The results suggested that the further modification for low-frequency vibration patterns of HfSiO₄ and realizing the interfacial metallurgical bonding can reduce the thermal expansion coefficient of HfO₂-doped Si composite coatings and strengthen interface adhesion.

由于 HfO ₂掺杂的 Si 键合涂层由于提高了键合涂层的高温性能和蠕变性能，因此在渐进式环境屏障涂层 (EBC) 系统的应用中起着关键作用，因此必须控制掺杂含量并平衡掺杂涂层的机械和热性能在提高 EBC 系统的使用寿命和工作温度方面面临挑战。在本研究中，HfO ₂在 1723 K 下的物理性质和热冲击性能通过第一性原理计算和微观力学模型研究了具有三种不同成分的 -Si 复合涂层。显然，通过磁控溅射沉积的复合涂层在长达 100 小时的热循环时间内表现出比纯 Si 键合涂层更好的抗裂纹萌生和扩展能力。这种改进归因于方石英“砂浆”中分散的HfSiO ₄颗粒的特征结构引起的分散增韧效应。通过热循环，HfSiO ₄的连续 Ostwald 熟化颗粒降低了复合涂层在室温和高温下的弹性模量和有效热膨胀系数间隙，有利于抗热震性。不幸的是，由于颗粒成熟过程中体积膨胀过度，复合涂层在 100 次循环后遇到不同程度的界面分离，因此不再具有保护作用。结果表明，进一步改进HfSiO ₄的低频振动模式并实现界面冶金结合，可以降低HfO ₂掺杂Si复合涂层的热膨胀系数，增强界面附着力。