| Fe-based amorphous bulk alloys have received widespread attention due to their excellent properties（yield strength,hardness,wear resistance,corrosion resistance,etc.）and low cost.However,due to their poor plasticity and forming ability,the bulk alloys application are limited.The coatings with performance advantages were prepared by detonation gun（D-gun）,and the coating will inevitably appear pores.Therefore,the surface of coating is sealed by physical vapor deposition（PVD）technology to improve the coating quality,which will expand the application of Fe-based amorphous bulk alloys.In this article,Fe-based amorphous coating with a composition of Fe49.755.0Cr25.027.0Mo16.018.0B2.02.2C2.02.5（wt.%）are prepared on Q235 carbon steel substrate by detonation gun（D-gun）spraying technology.A Cr film is deposited on the surface of the amorphous coating（Cr-Fe based amorphous coating）by physical vapor deposition（PVD）technology.The CHI 760E electrochemical workstation was used to test its corrosion resistance in 3.5 wt.%NaCl solution and different concentrations of H2SO4 solution.The main conclusions are as follows:1)The morphology,hardness,and porosity of the Fe-based amorphous coating were studied,and its corrosion resistance in 3.5 wt.%NaCl solution was studied.The results showed that the coating displayed a typical amorphous phase with a hardness of about 850 HV.The micro-region morphology indicated that the coating was dense without obvious defects and the porosity was about 0.7%.The presence of Cr7C3 further improved the hardness and corrosion resistance of the coating.Compared to the Q235 carbon steel substrate,the Fe-based amorphous coating had a corrected self-corrosion potential of-229 mV and a corrosion current of 2.8×10-6 A.The polarization resistance value of 1.1×104Ω·cm2 indicated that the coating was more resistant to corrosion;XPS elemental analysis results showed that the coating formed a passivation film rich in Cr and Mo in the corrosive medium,which made it exhibit excellent corrosion resistance;2)Physical vapor deposition（PVD）technology was used to deposit a Cr film on the surface of the Fe-based amorphous coating,and its corrosion resistance in 3.5 wt.%NaCl solution was studied.It was found that the problem of pores on the surface of Fe-based amorphous coatings was well solved.Compared with Q235 carbon steel and Fe-based amorphous coatings,the corrosion potential of Cr-Fe based amorphous coating was-387 mV,the corrosion current was 2.2×10-10 A,and the polarization resistance was 2.0×105Ω·cm2,which indicated that the system was more resistant to corrosion after depositing Cr films;XPS elemental analysis results showed that Cr-Fe-based amorphous coatings surface formed a passivation film rich in Cr2O3 and Cr（OH）3 in 3.5 wt.%NaCl solution,which improved the corrosion resistance of Fe-based amorphous coatings;3)The corrosion resistance of Fe-based amorphous coatings and Cr-Fe based amorphous coatings in 0.5 mol/L,1.0 mol/L,and 1.5 mol/L H2SO4 solutions were studied.It was found that both the coating and the coating deposited Cr film had excellent corrosion resistance in H2SO4 solution,of which the Fe-based amorphous coating in the 0.5 mol/L,1.0 mol/L,and1.5 mol/L H2SO4 solution self-corrosion potentials were-763 mV,-680 mV,-687 mV,respectively.Corrosion currents were 1.2×10-6 A,1.1×10-6 A,1.6×10-6 A,respectively.And polarization resistance were 3.7×104Ω·cm2,3.7×104Ω·cm2,2.7×104Ω·cm2;respectively.Self-corrosion potentials of Cr-Fe-based amorphous coatings were-874 mV,-886 mV,-804mV,respectively.Corrosion currents were 7.6×10-7 A,1.5×10-7 A,1.5×10-7 A,respectively.And polarization resistances were 5.6×104Ω·cm2,2.7×105Ω·cm2,7.4×104Ω·cm2,respectively.XPS elemental analysis results showed that passive films mainly consisted of Cr2O3 and Cr2（SO4）3 formed on Fe based amorphous coating,and a passivation film containing Cr2（SO4）3,Cr2O3 was formed on the surface of the Cr-Fe based amorphous coating,so that the coating and the coating with Cr film showed excellent corrosion resistance in H2SO4 solution;... |
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