Preparation And Performance Of Self Lubricating Joint Bearing For Nuclear Steam Generator

In this paper,the self-lubricating joint bearing was prepared for nuclear power steam generator.And its performance under nuclear electrical conditions was studied.Firstly,the structure of the self-lubricating joint bearing was carried out by theoretical calculation.And the lubrication mechanism of the self-lubricating joint bearing was analyzed.Combined with the finite element simulation technology,the structural analysis of the self-lubricating joint bearing was carried out,and the reliability of the self-lubricating joint bearing structure was analyzed.Combined with theoretical calculation and the finite element simulation,the influence of the clearance of self-lubricating joint bearing on its performance was analyzed.Secondly,the process performance of the outer ring material 05Cr17Ni4Cu4 Nb and the inner ring material Cu-15Ni-8Sn of the self-lubricating joint bearing was optimized.Through the subsequent heat treatment processes,the mechanical properties of the outer ring and the inner ring materials were improved to meet the severing performance under the nuclear power working conditions.Thirdly,through a pin-on-disk friction and wear test,the inner ring material inlaid with two different types of graphite materials was subjected to a friction test with the outer ring material 05Cr17Ni4Cu4 Nb,and the graphite ring made of two different types of graphite materials was subjected to a friction test with the outer ring material 05Cr17Ni4Cu4 Nb.The differences in friction and wear properties of two graphite materials were investigated.Analyzed the differences between inlaid and pure graphite rings in friction and wear test.At the same time,the influence of loads on the friction and wear properties of graphites was analyzed.Finally,the self-lubricating joint bearings were simulated by the finite element analysis and a bench life test.The effect of self-lubricating materials inlaying on the surface of self-lubricating joint bearing under actual working conditions was studied by the finite element simulation.Through the bench life test,the reliability and stability of the self-lubricating joint bearing of this paper in the actual service process were studied.The main conclusions are as follows:(1)When the radial load is constant,the change of the initial clearance has an effect on the deformation of the joint bearing,but not the larger the clearance value is,the greater the effect on the performance of the joint bearing is.Excessive initial clearance will result in insufficient fit between the inner and outer rings,which leads to large positional movement of the inner ring,which affects the overall performance of the self-lubricating joint bearing.When the initial clearance is constant,the inner ring of the self-lubricating joint bearing prepared in this paper will produce obvious elastic deformation when under a radial load greater than 5000 KN.The maximum stress of the contact surface is lower than the yield strength of the inner ring materials and the yield strength of the outer ring materials.Therefore,the service performance is reliable.When the initial clearance value is constant,the inner ring will move under the axial load.As the load increases,the contact surface stress will gradually increase.When the load exceeds 800 KN,a certain amount of deformation occurs in the contact surface between the inner and outer rings,which affects the force of the spherical surface in the outer ring.(2)Under the action of dynamic load,the effect of the centripetal inlay on the inner ring structure is less than that in the vertical inlay.The strain of the former graphite material is also smaller than the latter material.Therefore,under the action of dynamic load,the effect of the centripetal inlay on the structural integrity of the self-lubricating joint bearing and the effect on the material properties is better than the vertical inlay.The self-lubricating joint bearing of the centripetal inlaid structure is better than the vertical type of self-lubricating joint bearing under the dynamic load.Under the action of variable temperature load,the influence of the centripetal mosaic method on the overall structure of the inner ring is greater than that of the vertical form.Since the deformation of the inlaid hole in the centripetal form is larger than that of the vertical form,the graphite of the former is squeezed and produces more deformation.Under the action of variable temperature load,the service performance of the self-lubricating joint bearing of the centripetal inlaid structure is inferior to the self-lubricating joint bearing of the vertical inlaid structure,but the simulation results show that the performance difference is not large.(3)The outer ring materials(05Cr17Ni4Cu4Nb)will have good mechanical properties and better elastic deformation properties after the heat treatment process(H1025 550?/4h).After a process of homogenization and forging,the inner ring materials(Cu-15Ni-8Sn)will have good properties.When the graphite rings were subjected to the pin-on-disk test,the results show that the tribological properties of C2 graphite material is better than C1 graphite material.The rings inlaid with C2 is better than the rings inlaid with C1.Under different loads,the wear resistance properties of the pure rings inlaid with graphite materials is better than the the rings which inlaid with the graphite materials.However,the strength of the pure graphite is lower than the inlaying rings,and at the same time,the mosaic graphite pattern is consistent with the self-lubricating ball hinge studied in this paper.C2 graphite materials should be more suitable for nuclear power conditions.(4)In the 800-times normal temperature swing wear test,the self-lubricating joint bearing has good service performance,and the friction coefficient of the contact surfaces between inner and outer ring can be stabilized below 0.30,and the self-lubricating performance of graphite is good.It can be seen from the spray test that the material of the self-lubricating joint bearing has good corrosion resistance under the nuclear electric corrosion environment.In the high temperature overload oscillating wear test,the friction coefficient between the inner and outer rings of the joint bearing fluctuates stably around 0.10,which indicates that under the service condition of high temperature overload,the friction coefficient of the self-lubricating joint bearing prepared in this paper is stable below 0.15,and the tribological performance is excellent.