| The in-situ generated ternary boride cermet material has excellent wear resistance,corrosion resistance,high temperature resistance and other characteristics.It is a new structural material with simple process preparation and wide application range.Therefore,it is of great significance to apply ternary boride cermet to the field of traditional material surface welding.In this paper,a Mo-Fe-B-Cr series flux-cored wire is designed and prepared.Plasma cladding is used to prepare a boride cermet coating on the surface of 316 stainless steel.The structure and properties of the boride coating are analyzed and studied.Firstly,the influence of the cladding pass on the structure,hardness and fracture toughness of the boride coating on the surface of 316 stainless steel was studied.The results show that As the number of welding passes increases,the proportion of the dispersed hard phase particles in the coating structure gradually increases,and at the same time,the reticulated boride evolved from an intermittent network structure to a continuous network structure;The microhardness of the boride coating shows a gradual increase from the substrate to the surface of the coating,which is about 3 times the microhardness of the substrate;A good metallurgical bonding interface is formed between the boride coating and the 316 stainless steel substrate,without macro defects such as cracks and pores.Secondly,through the heat treatment test,explore the effect of heat treatment on the structure and performance of the boride coating.The results show that:after the coating is heat-treated and insulated,enough time and temperature are given to allow the elements in the coating to diffuse sufficiently,and more hard phase particles Mo2FeB2 are generated;As the wear time increases,the wear resistance advantage of the coating becomes more obvious after heat treatment.The wear of the coating is mainly the abrasive wear formed by the brittle exfoliation of the hard phase particles.At the same time,the oxide buffer layer formed on the surface of the bonding phase plays a self-lubricating effect,which further improves the wear resistance of the coating.Finally,the focus is on the corrosion resistance of the boride coating.The results show that the corrosion resistance of the boride coating and 316 stainless steel substrate is not much different when electrochemically corroded under acidic or neutral conditions.After different periods of neutral salt spray,the coating exhibits good corrosion resistance.The EIS pattern of the coating shows that the impedance arc first increases and then decreases.The final corrosion products are ?-FeOOH,Fe3O4 and ?-FeOOH.The high concentration of Mo,Cr and other elements in the cladding network boride forms a passivation film,which further improves the pitting resistance of the coating. |
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