Study On Fretting Wear Performance Of Several Typical ATF Cladding Materials

In a nuclear power plant reactor,the service conditions of nuclear fuel cladding tubes are very complicated.In addition to high temperature,high pressure,and strong neutron radiation,they are also affected by fluid-induced vibration,alternating loads,and internal and external pressure differences.These unstable environmental factors will cause micro vibration of the cladding tube,which will affect the service life of the cladding tube inside the reactor and bring hidden safety hazards to nuclear power plants.This paper explores the tribological properties of different cladding materials by simulating the fretting wear behavior of the cladding tube and its supporting grid.The research results in this paper provide some theoretical support for the selection of nuclear power plant cladding tubes,and have engineering application value for improving the performance of key components of nuclear power plants.In this paper,a new type of tangential fretting wear equipment,energy control mode impact fretting wear equipment,and self-made impact/sliding fretting wear equipment were used to study the fretting wear characteristics of 4 ATF candidate cladding materials(Zr/Cr,FeCrAl,ODS-FeCrAl,and Si C)and a reference Zr alloy.The material of the friction pair was Inconel 718 nickel alloy.The contact method adopted the method of cross-point contact between the column and the tube,and the test was performed in the atmospheric environment at normal temperature.After the test,OM,SEM,EDS etc.were used to study the wear scars microscopically.The 3D-contour was used to analyze the two-dimensional shape and volumes of the wear scars.The fretting wear mechanism of different cladding materials was systematically studied and following conclusions are obtained:1.The tangential fretting wear tests on five ATF cladding materials showed that under the conditions of a load of 50 N,a frequency of 10 Hz,and a displacement of ± 20 μm,the fretting of the five materials was in a partial slip zone,and they all showed well wear resistance.The wear mechanism of Si C was mainly abrasive wear,and the wear mechanisms of the other four materials were abrasive wear and adhesive wear.By comparing the wear scar morphology and wear volumes under different cycles,we can find that the Zr/Cr coating has better wear resistance than Zr,and ODS-FeCrAl has better wear resistance than FeCrAl.2.The impact fretting wear test on Zr alloy,Zr/Cr and ODS-FeCrAl ATF cladding materials shows that under the condition of impact kinetic energy of 4.32 mJ,there was no cracks or fractures occur in Zr alloy and Zr/Cr tests during 24 hours,which means they showed good impact wear resistance,ODS-FeCrAl cracks appeared in 6 hours’ test,and showed a tendency to expand to both ends as the test duration increased,showing poor impact wear resistance.Zr alloy and Zr/Cr have similar dynamic responses,while Zr/Cr shows higher surface hardness and energy absorption rate.During impact fretting wear,the main wear mechanism of Zr alloy and ODS-FeCrAl were oxidation wear and adhesive wear,and the wear mechanism of Zr/Cr was mainly adhesive wear.Zr/Cr had smaller wear scar depth and wear volumes than Zr alloy and ODS-FeCrAl,showed better impact wear resistance.3.The impact/sliding fretting wear test on Zr alloy,Zr/Cr and ODS-FeCrAl ATF cladding materials showed that under the conditions of impact kinetic energy of 4.32 mJ and tangential velocity of 60 mm / s,three kinds of The material did not show cracks or fractures during the24-hour test period,and showed good wear resistance.The dynamic response during the impact/sliding fretting wear test was similar to that of impact fretting wear test,Zr/Cr exhibited higher surface hardness and energy absorption.The wear mechanism of Zr alloy were abrasive wear and adhesive wear,while the wear mechanism of Zr/Cr and ODS-FeCrAl were mainly adhesive wear.As a result of the two-dimensional morphology and volumes of the wear scar,the Zr/Cr showed better impact/sliding wear resistance.