Microstructure And Wear Properties Of Plasma Surfacing Particle Reinforced Iron-based Hypereutectic Composite Coatings

The mechanical properties and wear properties of the plasma composite coatings are directly affected by the size and uniformity of the hypereutectic structure.Fe-based alloy coating?Fe40?,the Cr₃C₂/Fe composite coating with 40%micron Cr₃C₂,Ti/Cr₃C₂/Fe composite coatings with micron Ti?1%,3%?and Y₂O₃/Ti/Cr₃C₂/Fe composite coatings with micron Ti and nano Y₂O₃ on the surface of Q890 low-carbon steel were obtained by plasma surfacing,the effect of multi-scale particles addition and compound addition on the microstructure,mechanical properties?hardness?and wear properties of plasma surfacing Cr₃C₂/Fe hypereutectic composite coating were mainly studied.The Microstructure and phase composition of the coatings were examined by X-ray diffraction?XRD?,optical microscope?OP?,scanning electron microscope?SEM?and energy dispersive X-ray analysis?EDS?;the hardness distribution of the coatings were tested by the hardness tester;the wear properties of the coatings were also studied by sliding wear tester and corrosive abrasion wear tester.The results showed that the Fe40 alloy coating was mainly composed of?-Fe and Cr₂₃C₆;?-Fe,Cr₇C₃ and Cr₃C₂ phases can also be found in the Cr₃C₂/Fe coating.The TiC phase has been found in 3%Ti/Cr₃C₂/Fe composite coating;the phase composition of Y₂O₃/Ti/Cr₃C₂/Fe composite coatings were the same with Ti/Cr₃C₂/Fe composite coatings,but the relative intensity of diffraction peak of the same phases were different.The Fe40 coating was mainly composed of developed?-Fe columnar dendrites and the reticular eutectic structure(?-Fe+Cr₂₃C₆)between the dendrites,the crystallization way changed to hypereutectic way with the addition of 40%Cr₃C₂,and the microstructure of the coatings were composed of primary carbides and dendrite and eutectic structure.The microstructure of Ti/Cr₃C₂/Fe composite coatings were fined with the addition of micro Ti,compared with 1%Ti/Cr₃C₂/Fe composite coating,the size of primary carbides of the3%Ti/Cr₃C₂/Fe composite coating was more fined.The distribution of small block and granular primary carbides of Y₂O₃/Ti/Cr₃C₂/Fe composite coatings were more uniform with the addition of micro Ti and nano Y₂O₃,which led to the more refinement of the dendrites.Compared with Fe40 coating,the microhardness and Rockwell hardness of five coatings were greatly improved,and the microhardness distribution of Ti/Cr₃C₂/Fe coating and Y₂O₃/Ti/Cr₃C₂/Fe coating were even more uniform;the sliding wear performance of five composite coatings were improved,Cr₃C₂/Fe,Ti/Cr₃C₂/Fe?1%,3%?and Y₂O₃/Ti/Cr₃C₂/Fe?1%,3%?coatings were respectively increased by 1.73 times,2.92 times,2.66 times,3.59 times and 2.58 times,the corrosive abrasion wear performance were respectively increased by 1.47 times,1.88 times,1.71 times,2.21 times and 1.83 times.Compared with Cr₃C₂/Fe coating,when Ti were added,the sliding wear properties and corrosive abrasion wear properties of Ti/Cr₃C₂/Fe?1%,3%?coatings were improved,compared with 1%Ti/Cr₃C₂/Fe coating,the wear properties of 3%Ti/Cr₃C₂/Fe coating decreased slightly.The main mechanisms for sliding wear are abrasive wear and adhesive wear,finally leading fatigue spalling;the mechanism for corrosive and abrasive wear is the interaction between corrosion and wear.Compared with Ti/Cr₃C₂/Fe coatings,when Ti and Y₂O₃ were added,the sliding wear properties of Y₂O₃/1%Ti/Cr₃C₂/Fe coating was further improved,but the sliding wear properties of Y₂O₃/3%Ti/Cr₃C₂/Fe coating was decreased slightly,the corrosive abrasion wear properties of two coatings were improved.The results showed that the microstructure and wear performance properties of Cr₃C₂/Fe coating could be obviously improved by the addition of micron Ti,when micro Ti and nano Y₂O₃ were added,the microstructure and wear performance properties of Y₂O₃/Ti/Cr₃C₂/Fe could be furtuherly improved,the Y₂O₃/1%Ti/Cr₃C₂/Fe composite coating has the best wear properties in two kinds of wear forms.