Study On Microstructure And Properties Of TZM-xCu Alloy Coating By Spark Plasma Sintered

In this study,spark plasma sintering technology was used to reduce the sintering temperature by adding low melting point Cu.The TZM alloy coating was successfully prepared by low temperature sintering on a 304 stainless steel substrate.The sintering behavior of the alloy coating was studied by observing the structure of the TZM-xCu alloy coating,the element diffusion at the bonding interface of the TZM-xCu alloy coating was analyzed,and the friction and wear characteristics of the TZM-xCu alloy coating were studied.Provide experimental and theoretical basis for the preparation and application of modified TZM alloy coating at low temperature.The main research contents and conclusions are as follows:(1)Through the observation of the structure and element distribution of the TZM-xCu alloy coating,the elements of the alloy coating diffused uniformly during the sintering process,and no obvious aggregation areas were seen.The sintering process of alloy coating can be divided into solid phase sintering phase and liquid phase sintering phase.The solid phase sintering phase mainly occurs the formation and growth of Mo powder particles sintering neck;the liquid phase sintering phase mainly includes the generation of liquid Cu and Mo powder The rearrangement of particles,the solid phase dissolution and reprecipitation of Mo particles and the final formation of Mo skeleton.(2)The cross-section of the TZM-xCu alloy coating exhibits a three-layer structure of coating-transition layer-substrate.The bonding between each layer is relatively tight,no obvious defects are seen,and the bonding strength can reach 36.99 MPa.During the sintering process,the bonding interface of the TZM-xCu alloy coating forms an Fe-Ni diffusion zone with a width of about 15 ?m and a Ni-Mo / Cu diffusion zone with a width of about 10 ?m through interdiffusion of atoms.In the Fe-Ni diffusion zone,it is mainly Fe-Ni infinite solid solution;in the Ni-Mo / Cu diffusion zone,it is mainly Ni-Mo limited solid solution,plus a small amount of Ni-Cu infinite solid solution.(3)The thermal cycle test results show that as the Cu content increases,the thermal stability of the TZM-xCu alloy coating also increases;during the thermal cycle test,the TZM-xCu alloy coating cracks and falls off along the nickel transition layer The main reason for this phenomenon is the thermal stress generated by the difference in thermal expansion coefficient,and the pitting effect of Cl-ions at the interface in high-temperature water promotes the cracking and shedding of the TZM-xCu alloy coating.(4)The wear characteristics of TZM alloy and TZM-xCu alloy coatings are both adhesive wear and abrasive wear.Oxidative corrosion occurs during friction and wear;the addition of Cu can effectively play the role of lubrication and friction reduction,Cu content The higher the friction reduction effect is more obvious;at room temperature,the friction coefficient of the TZM-xCu alloy coating can be reduced by up to 61.1% compared to the TZM alloy coating.