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High-temperature erosion is a detrimental phenomenon in industries where particle flow exists, in which the search for new materials and mixes to increase the lifespan of mechanical components exposed to erosion is crucial. The present work studied the erosion resistance of two coatings at 25 °C (RT) and 900 °C in a sandblast-type rig. The coatings were fabricated with cermet-type powders: (C1) commercial Cr3C2-NiCr and (C2) commercial Cr3C2-NiCr mixed with a laboratory-conditioned powder consisting of NiCrAlY (linking matrix) and SiC (ceramic phase). Both coatings were applied on an Incoloy 330 substrate using an HVOF thermal spray process. The C2 coating was 11% harder than C1 but had a 62.2% decrement in its KIC value. The erosion test results at RT and 900 °C showed better erosion resistance on C1 than C2 at both testing temperatures and the three impact angles (30°, 60°, and 90°); this was attributed to the minor KIC induced by SiC hard particles and the bigger propagation of inter-splat and trans-splat cracks in C2. The erosion mechanisms at RT and 900 °C were similar, but at high temperature, the apparent size of plastic deformation (micro-cutting, grooves, and craters) increased due to an increase in the matrix ductility. Maximum penetration depth always occurred at a 60° impact angle. [ABSTRACT FROM AUTHOR]

This paper presents the results of the adhesion resistance before and after cyclic thermal treatments in NiCoCrAlY bond-coat (BC) coatings reinforced with dispersed SiC-ZrB 2 particles and conventional NiCoCrAlY. The ASTM-C-633 standard test method for the adhesion or cohesion strength of thermal spray coatings was used. The microstructure and morphology of the coatings were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. Microhardness and coefficient of thermal expansion were also measured. The addition of SiC-ZrB 2 particles improved the long-term adhesion resistance by 1825 % compared to the system without reinforcement after 275 cycles. This improvement is attributed firstly to a self-healing mechanism and secondly to the lower thermal expansion coefficient (32.60 % lower) of the BC layer reinforced with SiC-ZrB 2 , which delayed the formation of cracks at earlier stages associated with CTE mismatch. [ABSTRACT FROM AUTHOR]