Effect Of Transition Layer On Microstructure And Tribological Properties Of Laser Cladding Fe-based Metallic Glass Coating

In modern industrial production,the material of various performance had the higher request to be able to adapt to the harsh complex working environment.Amorphous alloys have been attracting the attention for their extremely high strength,toughness,weal resistance and corrosion resistance.Among them,Fe-based amorphous alloys have promising application prospects because of their abundant natural resources and unique physical and mechanical properties.However,high cooling rates(10~6K/s)are generally required for the formation of amorphous phase from the liquid state,which greatly restrict their application.Amorphous coating can be obtained by laser cladding technique due to the rapid heating and cooling characteristics of the laser treatment.Therefore,using this method call enhance the strength,hardness,wear resistance and corrosion resistance properties of the substrate surface.In this article,using the TJ-HL-T5000 pulsed laser,the Fe-based amorphous coatings were fabricated on the surface of Q235 steel.By means of X-ray diffraction(XRD),scanning electron microscope(SEM)and energy spectrum analysis(EDS),analyzes the phase composition,microstructure and composition distribution of cladding layer;By LM700AT micro-hardness tester and UMT2 Micro-Tribotester,analyzes the mechanical properties and wear resistance of cladding layer.In order to reduce the coefficient of friction of laser cladding Fe-based metallic glass coating,the Ni-P transition layer was electro plated on the substrate firstly,and then a Fe-based metallic glass coating was laser cladded on the Ni-P transition coating.The coefficient of friction and wear behavior of the laser cladding Fe-based metallic glass coating were systematically investigated.It was found that the coating has a homogenous and fine microstructure.Cladding layer is divided into three parts of cladding region,combining zone and heat affected zone.This paper studies the process parameters to phase composition,microstructure,micro-hardness and wear resistance of the cladding layer.Results show that with the increase of P content in the transition layer,the diffraction peaks of the crystal phase will be decreased,and amorphous content will be increased,the coefficient of friction of the coating decreased from 0.65 to 0.35.The Fe-based coating has a high micro-hardness of about 1050 HV which is slightly higher than the coating with Ni-P transition layer.The wear volume decreased from 0.012 to 0.006 with increasing P content in the transition layer,showing that the Ni-P transition layer is able to improve the wear resistance of laser cladding Fe-based coating.The wear mechanism is mainly associated with the diffusion of Ni from the transition layer to the coating,and generate FeNi phase in the coating.The cladding layer remains amorphous after the transition layer is annealed at 150?,250?.With the increase of heat treatment temperature,the diffraction peaks of the crystal phase will be increase and strengthen,amorphous content will be reduced,micro-hardness of the cladding layer present a lower trend,and the coefficient of friction of the coating increase from 0.43 to 0.58.The present results imply that the Fe-based amorphous coating is promising for industry applications in automobile,such as reducing friction between bearings.