Effect of fullerite powder size on the properties of composite materials synthesized at high pressure from iron-C60/70 mixtures

Abstract

Fullerite C60/70 particles of > 315, 315 – 125, 125–60, and < 60 μm in size were used for synthesis of composite materials (CM) from their mixtures with iron powder by heating to temperatures of 1200 – 1400 K at a pressure of 5 GPa. The effect of fullerite particle size in iron matrix on the formation of superelastic hard carbon phase after fullerene molecule collapse has been studied by the methods of high-resolution Raman spectroscopy, light microscopy, and microindentation. The coarsest particles prepared at 1200 K retain polymerized fullerites, while the finest particles prepared at 1400 K exhibit partial graphitization. Tribological tests showed that the wear resistance of the CM is determined by the degree of transformation completion, and the reinforcement effect increases with sand-paper grain refinement. Graphitization of the reinforcing particles leads to a decrease in wear resistance (by a factor of ∼3) at a retention of a relatively low friction coefficient. The most stable results (high wear resistance and friction coefficient of 0.18–0.3) are characteristic of the CM reinforced with carbon particles prepared from fullerites of medium size.