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[摘要]:An atypical "swirling" phenomenon observed during the laser deposition of tungsten carbide-cobalt cermets by laser engineered net shaping (LENS (R)) was studied using in-situ high-speed thermal imaging. To provide fundamental insight into this phenomenon, the thermal behavior of pure cobalt during LENS was also investigated for comparison. Several factors were considered as the possible source of the observed differences. Of those, phase difference, material emissivity, momentum transfer, and free surface disruption from the powder jets, and, to a lesser extent, Marangoni convection were identified as the relevant mechanisms. (C) 2012 American Institute of Physics. [doi:10.1063/ 1.3676420] |
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