| In this paper,Cr3C2/NiCr was used as the substrate of high-temperature self lubricating material,and the high-temperature lubricating anti-wear cermet-based coating was prepared on Inconel 718 substrate by atmospheric plasma spraying technology.The tribological properties of solid lubricants Ag,CaF2 and MoO3incorporated in Cr3C2/NiCr cermet coating at a wide temperature range?25oC-800oC?were investigated.The hardness,bonding strength and tribology at the wide temperature ranges of multi lubricants were investigated.The effect of performance,the high temperature tribochemical effect and the high temperature wear mechanism of the cermet coating were detailed discussed.Meantime,the self-lubrication and wear mechanism of cermet coatings with different lubricating phases at a wide temperature ranges were studied.At the same time,the effects of different friction pairs?ZrO2,Al2O3?on the tribological properties and wear mechanism of Cr3C2/NiCr cermet based coatings were systematically investigated.The main findings are as follows:1.Cermet coatings of Cr3C2/NiCr,Cr3C2/NiCr-CaF2,Cr3C2/NiCr-Ag-CaF2 and Cr3C2/NiCr-Ag-CaF2-MoO3 were prepared by APS?Atmospheric Plasma Spraying?technology.The main phases of the cermet coating are Cr3C2 and NiCr,Cr7C3.The phase structure,tribological properties and microstructure of the cermet coatings were investigated.The results show that the addition of Ag can reduce the friction coefficient and wear rate of cermet coatings below 400oC.Adding CaF2 could improve the tribological properties of cermet coatings above 600oC.Incoporated three lubricating phases of Ag,CaF2 and MoO3 in the cermet coating presented that the best tribological performance from room temperature to 800oC;the friction coefficient and wear rate of cermet coating sliding against Al2O3 ceramic ball is 0.2 and2.49×10-5mm3/N·m,while that of sliding against ZrO2 ceramic ball is 0.19 and2.89×10-5mm3/N·m,the addition of lubricating phase will reduce the micro-hardness and bonding strength of the cermet coating,but the overall bonding strength of the composite coating is above 35MPa,and the micro-hardness is above 478.29Hv0.3.The excellent microhardness and bonding strength provides support for the wear resistance of the cermet coating.2.Adding lubricating phases of Ag,CaF2 and MoO3 to the Cr3C2/NiCr cermet coating.It presented that CaF2 and Ag reaction with MoO3 by tribo-chemical to formed silver molybdate and calcium molybdate above 600 oC,molybdates will covered the entire wear surface at 800oC.In addition,the synergistic lubrication of molybdates and CaF2 will significantly improve Cr3C2/NiCr-Ag-CaF2-MoO3tribological properties of cermet coating.3.Cr3C2/NiCr cermet coatings exhibit different tribological properties with different couples.Cr3C2/NiCr-based cermet coating sliding against ZrO2 at below400oC,the Zr element will transfer to the worn surface,which forms a zirconium compounds,causing the ZrO2 ceramic ball sliding against the zirconium compounds,resulting in decreasing the direct sliding contact area and an increase in friction coefficient and wear rate;The Cr3C2/NiCr-Ag-CaF2-MoO3 cermet coating sliding against Al2O3 ceramic ball exhibits the best tribological performance when at 800oC to form a dense self-lubricating film,while sliding against ZrO2 ceramic ball due to the ZrO2 ball thermal insulation property resulting in lubricating film broken leads to increase the friction coefficient and the wear rate.The cermet coating sliding against ZrO2 and Al2O3 ceramic balls exhibits different friction behaviors which may be attributed to the mechanical properties of different friction pairs. |
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