Elevated-temperature mechanical properties of sintered iron-base materials containing calcium fluoride additions

1.	It has been established that the alloying of sintered Fe-CaF2 materials with molybdenum (15 wt.%) increases their hardness 2.5–8.6 times and raises their transverse rupture strength to 70–60 kg/mm2 and their compressive strength to 110–70 kg/mm2 at temperatures of up to 650°C.0
2.	Raising the CaF2 content of sintered iron decreases its impact strength at temperatures of up to 650°C. It was found that for Fe6CaF2, Fe9CaF2, and Fe (porous) materials the variation of impact strength as a function of testing temperature is similar in character to that observed with cast Armco iron. The blue-brittleness range for sintered Fe-CaF2 materials extends from 350 to 450°C.
3.	It is shown that the impact strength of sintered Fe15Mo6CaF2 material, unlike that of unalloyed materials, increases up to a temperature of 500°C as a result of migration of the molybdenum from the grain boundaries into the grains. In tests Fe15Mo6CaF2 material cracks by a brittle intergranular rupture mechanism.
4.	Fe15Mo6CaF2 material surpasses in heat resistance all the other sintered CaF2-containing ironbase materials investigated, and can therefore be recommended for operation at temperatures of up to 650°C in friction units which do not experience severe shock loads.