Thermal sprayed coatings produced from ultrafine, near-nano and nano grained powders provide improved properties as compared to conventional (micron size) powders. These ultrafine, near-nano and nano grained materials show significant potential for applications in the aerospace, energy, oil & gas and a great many other industries. A study was conducted to investigate the influence of grain size on the microstructures formed and mechanical properties of conventional, ultrafine, near-nano and nano size WC materials. Powders and coatings as well as consolidated forms of tungsten-carbide-10% cobalt- 4% chromium (WC-10Co-4Cr) and tungsten-carbide- 12% cobalt (WC-12Co) materials are examined. Thermal spray coatings are produced of carbides of several different grain sizes using high velocity oxygen-fuel (HVOF) thermal spray processing. Spark Plasma Sintering (SPS) is performed to provide consolidated forms of WC-10Co-4Cr materials. An examination of the thermal sprayed coatings is conducted using microstructural analysis and mechanical property testing. A brief examination of the wear and bend performance of a near-nano, and nano-enhanced material will be compared to a conventional material (micron sized).

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, oil & gas, power, and many 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.

This study examines the influence of nano- and near-nano grains in bulk powder metal processing thus providing a baseline for understanding the potential of nanopowders for thermal spray application. Two light alloys (Al and Ti) and two tungsten carbide blends (WC-NiCrBSi and WC-CoCr) are cryomilled into nanocrystalline powders. The nanopowders are consolidated via hot isostatic pressing or spark plasma sintering and tested along with consolidated forms of virgin (micron scale) grains, shedding light on property improvements achieved through nanograined materials. HVOF coatings produced from nano- and micro-crystalline powders are tested as well, and the results are correlated with the improvements observed in the consolidated material forms.