Abstract
In order to improve a high velocity oxygen fuel (HVOF) spraying and to reduce the CO2 exhaust during the processing,Fe-based metallic glass coating,which has been sprayed by HVOF with a hydrogen gas and without a fusing process, was investigated.Crystallization phenomena of metallic glass were also evaluated at elevated temperatures.The Fe-Cr-Mo-based alloy was sprayed on mild steel by hydrogen-specific gun,and a metallographical observation reveals that the alloy is successfully coated on the substrate even by hydrogen.Then a corrosion resistance was investigated by the combined cyclic corrosion test.Formation of serious rust is prevented until 1578 h by sealing treatment even without fusion process.The metallic glass coating was heat-treated at 500 to 800℃ and then performed X-ray diffraction analysis.The broad peak from metallic glass decreases and the sharp peaks from the crystal phase appear depending on the holding time and temperature.Crystallization process could be followed the Avrami equation regarding nucleation and growth.Vickers hardness of the as-sprayed specimen is 778HV,and improved to 1029HV by crystallization of about 80%,that indicates that the nano-scopic crystallization enhance the hardness for the metallic glass.
