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The aim of this work was to apply coarse recycled hardmetal particles in combination with Ni-based matrix to produce wear resistant metal matrix composite (MMC) thick coatings using plasma transferred arc hardfacing (PTA) technology. Assignment of hardmetal waste as initial material can significantly decrease the production costs and improve the mechanical properties of coatings and, consequently, increase their wear resistance. The microstructure of MMC fabricated from a recycled powder was examined by optical and SEM/EDS microscopes, whereas quantitative analyses were performed by image analysis method. Micro-mechanical properties, including hardness and elastic modulus of features, were measured by nanoindentation. Furthermore, behaviour of materials subjected to abrasive and impact conditions was studied. Results show the recycled powder provides hardfacings of high quality which can be successfully used in the fabrication of wear resistant MMC coatings by PTA-technology.

DOI: http://dx.doi.org/10.5755/j01.ms.18.1.1334

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Five different carbide-matrix coatings (laser claddings) have been investigated about correlation of their specific structural parameters-especially volumetric carbide distribution-with ASTM G65 abrasion wear rates. For this study, the hardphase networks of laser claddings have been characterized by specific structural parameters, such as mean inter-particle distance, mean carbide diameter, carbide area fraction, and matrix hardness. To generate quantitative values for the inter-particle distances a particular method was developed. From regression analyses, it has become evident that wear effects arising from carbide inter-particle distance surpass the influence of carbide diameter and that of carbide fraction. Only minor contribution to abrasive wear rates is related with matrix hardness.

Carbide-matrix hardfacings reinforced with spherical and angular particles of different size and density have been investigated about correlation of their specific material parameters-especially matrix hardness and microstructure parameters-with the wear rates in continuous impact abrasion test (CIAT). For this study, 12 different hardfacings have been characterized by the quantitative metallographic method for determination of specific structural parameters, such as the mean carbide diameter, carbide area fraction, and a distribution parameter of inter-particle distances (L IPD ). Results showed the high influence of the matrix hardness on the CIAT wear resistance followed by effect of the mean particle size. The length of inter-particle distance (L IPD ) has exhibited stronger additional effect on CIAT wear rate than carbide area fraction, whereas particle form (spherical or angular) showed no significant differences.