Study on some properties of iron-base materials with calcium fluoride additions for friction nodes in nuclear plants

The effect of neutron irradiation on friction properties of iron-based sintered materials containing 6 and 9 wt.% CaF2, and the materials additionally alloyed by 15 wt.% molybdenum has been studied. Their corrosion resistance and inclination to diffusion welding with the Kh18N10T steel in liquid sodium at temperatures up to 650 deg C have been investigated. The corrosion resistance in liquid sodium (T=650 deg C, tau=3000 hours) proves satisfactory, and there has been no diffusion welding with the said steel under loads up to 500 kg/cm2 and temperature up to 620 deg C. Neutron irradiation (integral dose 0.56x1020 fast neutrons/cm3) is shown not to deteriorate the friction properties of the sintered material Fe15Mo6CaF2 (the friction tests carried out in argon atmosphere containing Na vapor, specific loading 25 kg/cm2, gliding velocity 5 m/min, temperature 350 deg C)