Microstructure And Properties Of Mo₂FeB₂ Cladding Prepared By Surfacing Of Pre-alloyed Wire

Ternary boride metal ceramics have the advantages of high hardness,excellent wear resistance,and corrosion resistance.It is a material with a wide range of applications and a simple preparation process.Boride metal ceramics in the field of surface cladding has a wide range of applications,for the traditional powder and flux cored wire cladding is prone to produce hard phase generation is not sufficient.Therefore,this paper designs a new type of pre-alloyed sintered wire and prepares Mo₂Fe B₂ ternary boride cladding layer by overlaying it on the surface of Q235 steel through argon arc welding,and studies the organization and properties of the boride cladding layer.Firstly,two kinds of pre-alloyed sintered wires were prepared:one was a high hardness wear-resistant wire and the other was a corrosion-resistant wire.Then the changes in the organization and properties of the boride cladding layer were studied at different argon arc overlay currents for the high hardness wear-resistant wire.The results show that the best performance of the boride cladding layer was obtained at a surfacing current of 180A,when the cladding layer was mainly composed of Mo₂Fe B₂,（Mo,Fe,Cr）₃B₂,α-Fe,M₂₃（C,B）₆ and other phases,and the hard phase was fully generated and the particle size was moderate and uniformly distributed.The average microhardness reaches up to 1010.9HV0.5,and the fracture toughness is 13.58Mpa·m^1/2,which is the best comprehensive mechanical properties of the cladding layer.Next,the wear resistance of the overlay fused cladding layer prepared by wear-resistant sintered wire was studied and heat-treated then to study the changes in its organization and properties.The results are as follows:at room temperature,When the wear time is 4h,GCr15 steel wear loss weight reaches 2.25 times of the boride cladding,the wear resistance of the boride cladding is better than that of GCr15 steel,and the wear resistance gradually becomes better as the wear time increases,and the forms of wear are abrasive wear and adhesive wear;at high temperature,the friction coefficient of the boride cladding increases with temperature and then decreases,and as the temperature increases,a friction oxide film is formed on the surface of the boride cladding to protect the cladding,and the forms of wear gradually change from mainly abrasive wear to oxidation wear.The wear form gradually changes from mainly abrasive wear to oxidative wear.Finally,the corrosion-resistant boride cladding was prepared and its corrosion resistance was studied in various environments,Its average microhardness is 864.24HV_0.5.The results showed that its corrosion resistance was better than that of 304 stainless steel in both acidic and neutral environments.The boride cladding was subjected to neutral salt spray tests and it was found that with the extension of the salt spray test,a passivation film was formed on the surface of the cladding to protect it and the main corrosion products were Fe OOH,Fe（OH）₃,Fe₂O₃ and Fe₃O₄.Finally,the cladding was subjected to immersion tests in the acidic and alkaline environment and the corrosion resistance of the cladding was relatively poor in the acidic environment due to the destruction of the passivation film,and in the alkaline environment,the corrosion resistance of the cladding was relatively poor.In the alkaline environment,the dense passivation film formed on the surface of the boride cladding can maintain good corrosion resistance.