High-Temperature Friction And Wear Analysis And Lubricating Study Of Sodium Mechanical Pump Liquid Sodium Hydrostatic Bearings

Sodium mechanical pump is the coolant conveying equipment of sodium cooled fast reactor.Liquid sodium hydrostatic pressure bearing is the key supporting component of the lower end of the shaft system of sodium mechanical pump,which plays a role in balancing the radial force of the fluid received by the impeller.Liquid sodium static and static pressure bearings are lubricated by liquid sodium in the cavity of a sodium mechanical pump.The higher the pump speed is,the greater the pressure of liquid sodium in the cavity is and the stronger the bearing capacity is.The bearing has mechanical wear during the operation of the sodium mechanical pump.The main reasons are as follows: 1.The bearing has no bearing capacity when it is started or stopped,and the pump shaft and the inner wall of the bearing are in direct friction.2.Poor bearing capacity at low speed,sudden vibration will lead to collision and friction between the pump shaft and the inner wall of the bearing.3,bearing material316 LN stainless steel low hardness,poor wear resistance.Firstly,the dynamic and static characteristics of liquid sodium hydrostatic bearing are analyzed.The bearing performance of the bearing under different eccentricities under different working conditions was simulated,and the pump axial surface pressure cloud chart,bearing flow and bearing bearing capacity under different eccentricities under different working conditions were obtained,and the influence of working conditions and eccentricities on the bearing capacity was analyzed.The influence of eccentricity Angle on bearing bearing capacity is studied,and it is found that bearing bearing capacity will change with eccentricity Angle only when eccentricity ratio and liquid supply are large.The effect of temperature fluctuation of liquid and sodium on bearing capacity is studied.It is found that the bearing capacity increases with the increase of vibration speed.Based on the analysis of the fluid pressure distribution on the axial surface of the pump,it is found that the regulating chamber only obtains liquid sodium from the high pressure area at the upper and lower ends.To improve the bearing structure,through adjusting chamber open and annular grooves between Ⅰ connected to the longitudinal slot can adjust chamber from around a stable supply of liquid sodium,in order to improve the bearing capacity.The simulation results show that the bearing capacity is increased by 4%-7.3%.Based on the analysis of bearing flow field and found from the ring grooves Ⅰ part liquid sodium upward through the bearing clearance into the annular grooves Ⅱ,then directly out of the bearing,the part of the liquid sodium is wasted.In order to reduce the leakage of liquid sodium,applied micro texture to improve the bearing structure,the ring grooves Ⅰ and annular grooves between Ⅱ open ring groove.The simulation results show that the annular groove has a certain effect of pressurization and flow reduction,effectively reducing the amount of liquid sodium leakage,and the smaller the annular groove is,the better the flow reduction effect is.Considering the actual working condition,when the annular groove depth is 0.6mm,the best effect is to reduce the leakage amount,and the leakage amount of liquid sodium is reduced by27%-38%.The liquid sodium static-pressure bearing material is 316 LN stainless steel,and the cobalt base alloy is laser cladding in 316 LN stainless steel to improve the high temperature wear resistance of the inner wall of the bearing,and the cobalt base alloy coating with different W content is prepared by taking the high temperature element W as variable.It was found that the hardness of the coating increased with the increase of W content.It was found that the friction coefficient of cobalt alloy coating decreased with the increase of W content.The matrix wear was obviously greater than that of cobalt-based alloy coating,and the wear of cobalt-based alloy coating increased with the increase of W content.When W content is10%,the high temperature wear resistance of the coating is the best.It is found that the friction coefficient of the coating with different W content ranges from the largest to the smallest w10%,W14%,W16% and W12%.The wear amount of cobalt-based alloy coating decreases with the increase of W content.Analysis of friction mechanism shows that: W10%coating wear is mainly adhesive wear,W12% coating has both abrasive wear and mixed wear of adhesive wear,W14% coating is mainly abrasive wear,W16% coating is mainly abrasive wear.Comprehensive analysis shows that the coating has the best high temperature wear resistance when W content is 16%.