WC thermal spray based powders are now frequently used as chrome replacement alternatives for a wide range of industrial and aeronautical applications. In numerous cases, the carbide materials outperform the hard chrome in many property evaluations However, its usage on highly stressed parts, especially in fatigue loading, can be limited by spalling resistance of the coating. While HVOF is being used on many flight critical parts, stringent applications like the carrier based landing gear components are still under investigation. This work, on WC-17%Co, relates the processing history of different HVOF processes used at a variety of industrial sources for hard chrome replacement to the coating microstructure and mechanical properties. The thermal history of the WC particles was monitored using a DPV-2000. The mechanical properties of the coatings were assessed following an instrumented four-point bend test as well as uniaxial cyclic loading. The coating microstructures were characterized using X-Ray diffraction and electron microscopy in order to investigate the phase content and nature. In particular, the cracks generated during the bend test were measured using SEM on samples cross sections to measure characteristics such as spacing and crack penetration to the substrate. The goal of the investigation was to better understand the interaction of processing parameters with the cracking/spalling resistance of the varied coating deposits. Abstract only; no full-text paper available.

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