Nanosecond laser fabricated multi-scale microtextures for enhancing EBCs adhesion on SiC substrates

Abstract

Spalling failure at the substrate-environmental barrier coatings (EBCs) interface severely limits the service performance of SiC-based components for service in high-temperature water-vapor environments. In this study, nanosecond laser machining was employed to fabricate multi-scale microtextures on the surface of SiC substrates. The influences of texture fraction, texture depth and inner diameter on coating bonding strength were systematically investigated. The underlying interfacial strengthening and failure mechanisms were further clarified based on morphological observations and elemental characterization. The results demonstrate that multi-scale microtextures substantially enlarge the actual interfacial contact area and achieve synergistic strengthening from the combination of mechanical interlocking and interfacial chemical bonding. A relatively high bonding strength is obtained at a texture fraction of 50% with a moderate inner diameter, where full coating-filling and uniform interfacial stress distribution can be achieved simultaneously. Insufficient mechanical interlocking occurs in overly shallow textures, whereas excessively deep textures readily form closed internal pores. Too-small inner diameters hinder coating infiltration; in contrast, overly large inner diameters reduce the effective anchoring depth and aggravate stress concentration. By tuning the interface morphology, laser-fabricated multi-scale microtextures effectively inhibit coating spalling.