Effects Of HVAF Combustion Chamber Pressure And Substrate Cooling On The Fe-based Amorphous Coating

Iron-based amorphous materials have high strength,excellent corrosion resistance and wear resistance due to short-range ordering,long-range disorder and the absence of crystal defects such as grain boundaries and dislocations.However,due to the limitation of amorphous alloy material's ability to form amorphous and preparation technology,it is impossible to realize industrial production.In order to make full use of its excellent properties and expand its application fields,many scholars have carried out extensive research on the preparation of amorphous alloy coatings.In this paper,SAM2X5 amorphous component system is selected to study the coating oxidation,and the effect of cooling on the oxidation and corrosion resistance of the coating in HVOF process is analyzed.On this basis,the influence of different energy output on the performance of coatings during spraying process was studied.In order to understand the effects of different energy changes on the properties of the coatings on the basis of this study,and provide a method and scientific basis for improving the corrosion resistance of iron-based amorphous coatings.In this paper,the Fe based amorphous coating was prepared by supersonic flame spraying.The amorphous coating with different energy input was prepared on the carbon steel substrate by adjusting the combustion chamber pressure during spraying.The alloy was judged to be completely amorphous by X-ray diffraction,and the existence of oxide was qualitatively analyzed.Electrochemical tests were carried out on the coatings with different energy output caused by different combustion chamber pressure to study the pitting resistance behavior of the amorphous alloy coating,and the stability of the passivation film of the amorphous alloy coating was analyzed by electrochemical impedance spectroscopy.The main conclusions are as follows:(1)In the pressure of air and propane is 75/78,82/86 and 92/97 respectively three groups in the preparation of the coating under different combustion chamber pressure,high energy,the combustion chamber pressure into 92/97,coating of coating and spread out best,but the trouble with this is gun spraying temperature increases,lead to increase in the number of oxide layer between plates,the overall average coating oxygen levels rise,through analysis of high-energy coating crystallization phenomenon intensified.(2)For three different combustion chamber pressure coating preparation by electrochemical experiment was carried out in the artificial simulated seawater,the results show that three kinds of different state of coating the corrosion current density Ilow<Ihigh<Imedium,shows that secondary combustion chamber pressure coating corrosion rate is highest,and on three kinds of coating the corrosion potential Ecorr,secondary combustion chamber pressure coating more negative potential,its corrosion resistance is the worst.The comprehensive analysis shows that the coating under medium combustor pressure has the worst corrosion resistance in seawater,while the coating under low combustor pressure and high combustor pressure is better.(3)Under different combustor pressure conditions,the cooling rate of coating microstructure is accelerated under the condition of increasing water cooling on the back of the substrate.XRD analysis showed that internal organization improved crystallization problem,under the scanning electron microscopy(sem)was carried out on the water after coating cross section and surface analysis,the preparation of water-cooled coating layer upon layer under different combustion chamber pressure oxidation problems between all have different degrees of ease,however,secondary combustion chamber pressure and low combustion chamber pressure caused by the addition of water sample preparation by cooling too quickly,the insufficient overlap between particles,leading to spread out a worse state.In the electrochemical test of simulated seawater,the coating samples with high combustor pressure had the lowest self-corrosion current and the best corrosion resistance.The impedance spectra also showed that the passivated coating had the best stability and corrosion resistance.(4)After adding water cooling,the substrate cooling accelerates the thermal energy dissipation of the coating,and the average oxygen content of the three coatings decreases.In the XPS test of the high combustion chamber pressure coating samples,it is found that the oxide content of the water-cooled coating near the substrate has a larger decrease than that of the non water-cooled coating,but with the increase of the thickness of the coating samples,the oxide content of the coating decreases with the water-cooling The reason is that the heat conduction rate of the coating in amorphous state is much lower than that of the matrix in crystalline state,so the effect of water cooling on the reduction of oxide content becomes worse with the increase of coating thickness.(5)Salt spray test showed that the pitting corrosion of the high combustion chamber pressure water-cooled coating occurred around 216 hours,the latest in six groups of coatings,and compared with other coatings,after 408 hours of long-term salt spray test,the corrosion point did not spread significantly,which was the strongest long-term corrosion resistance compared with other groups of coatings,which was consistent with the electrochemical test results,so the high combustion chamber pressure water-cooled coating had the highest corrosion resistance The coating has the best corrosion resistance.