Thermal-sprayed Fe-10Cr-13P-7C amorphous coatings possessing excellent corrosion resistance

An alloy of Fe-10Cr-13P-7C was thermally sprayed by three different processes: (1) 80 kW low-pressure plasma spraying (LPPS), (2) high-velocity oxyfuel (HVOF) spraying, and (3) 250 kW high-energy plasma spraying (HPS). The as-sprayed coating obtained by the LPPS process was composed of an amorphous phase, In contrast, the as-sprayed coatings obtained by the HVOF and HPS processes were a mixture of amorphous and crystalline phases, The as-sprayed coatings showed a high hardness of 700 DPN. A very fine structure composed of ferrite, carbide, and phosphide was formed, producing a maximum hardness of greater than 1000 DPN in the LPPS coating just after crystallization on tempering. The corrosion resistance of the amorphous coating was superior to a SUS316L stainless steel coating in 1 N H2SO4 solution and 1 N HCl solution. Furthermore, the amorphous coating underwent neither general nor pitting corrosion in 1 N HCl solution and 6% FeCl3 . 6H(2)O solution containing 0.05 N HCl, whereas the SUS316L stainless steel coating was attacked aggressively.