Wear Behavior of Plasma Spayed Al-Si/TiB2/h-BN Composite Coating
I. Ozdemir, Dokuz Eylul University, Izmir, Turkey; C. Tekmen, Y. Tsunekawa, Toyota Technological Institute, Nagoya, Japan; T. Grund, B. Wielage, TU Chemnitz, Chemnitz, Germany
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In this work, mechanically alloyed Al–12Si/TiB2/h-BN composite powder was deposited onto an aluminum substrate by atmospheric plasma spraying. The results revealed that the MA process has a significant effect on composite powder morphology and in-situ reaction intensity between the selective powders during plasma spraying. In addition, hexagonal boron nitride (h-BN) powder incorporated as a solid lubricant, which has excellent lubricating properties, decomposed into B and N and formed a solid solution after a long period of milling. More specifically, during plasma spraying a large amount of h-BN reacted with Al to form AlN. Unlubricated ball-on-disk testing ring was used to examine the anti wear performance of the coatings. The worn surfaces were examined using scanning electron and energy dispersive spectroscopy to elucidate the wear mechanisms operating at the sliding interface.
Summary: This study presents wear behaviour of composite coatings tested under dry sliding condition by using ball-on-disk testing rig. the coatings were produced by spraying mechanically alloyed Al–12Si/TiB2/h-BN composite powder onto an aluminum substrate by atmospheric plasma spraying. Results demonstrate that at relatively high milling time h-BN decompose into B and N and form a solid solution. Also, it has been observed that during plasma spraying a large amount of h-BN react with Al to form AlN and the effect of plasma parameters on in-situ reaction intensity is insignificant.
