Micromechanical properties and erosive wear performance of chromium carbide based cermets

摘要

Micromechanical properties and microstructural features are highly interrelated and influence the wear performance of composites. In this study, the nanoindentation, X-ray analysis and microstructural SEM tests have been used to reveal the structural features of complex structured Cr_3C_2-Cr_7C_3-CrNi_3 cermets with different additives and to measure micromechanical properties (nano-hardness and modulus of elasticity) of the constituent phases. To evaluate the erosive wear performance a conventional centrifugal particles accelerator has been used. The results indicate that metallurgical aspects such as the nature and the amount of additives influence cermets' durability to a great extent while the nano-hardness and Young's modulus of the phases remain less affected by structural features and are not of decisive importance. Furthermore, the hardness of the binder alloys was detected to be higher in cermets as compared to the bulk hardness of an alloy of the same composition and only slight variations in hardness were found for binder phases with different additives. Residual stresses are also affected by additives but their influence on the erosion rate cannot be interpreted in a definite manner. For all materials, the formation of the mechanically mixed layer during erosion and subsurface lateral cracking of the carbide skeleton are found to be the dominant mechanisms of material degradation.