Improved Mechanical Properties of Coatings and Bulk Components as a Function of Grain Size

Thermal sprayed coatings produced from ultrafine- and nano- and near-nano grained powders of tungsten carbide-10 wt.% cobalt-4 wt.% chromium (WC-10Co-4Cr) are reported to provide improved properties as compared to conventional powders.  These materials show great potential for applications in the aerospace, industrial gas turbine and other industries.  A study is proposed to investigate the influence of WC grain size on HVOF coating properties.   Thermal spray coatings will be produced from powders consisting of grains of WC from micron- to near-nano in size in a Co-Cr matrix.   The Hall-Petch relationship cites the strengthening of materials by reducing the average crystallite (grain) size.  An examination of consolidated forms will be performed using the same powders used in thermal spray in the spark plasma sintering (SPS) consolidation.  The mechanical properties of thermal spray coatings have been reported to relate to those of bulk materials.  Improvements observed in the HVOF spray coatings will be compared to those of bulk samples produced using spark plasma sintering.