The frictional behavior of detonation nanodiamond and single-crystal fine diamond powders were studied to determine the effect of particle diameter on their lubricative and abrasive characteristics. In vacuum, nanodiamond with an average aggregate size of 75 nm and mechanically crushed single-crystal diamond powders with an average diameter of 50 nm formed a uniform lubricating layer while sliding against a SiC ball and showed very low friction coefficients of 0.03 and less than 0.01, respectively, under moderate conditions of 0.5 N applied load and 3.5 mm/s sliding speed. A clear tendency was observed for both the friction coefficient and specific wear rates to decrease with decreasing particle/aggregate size.
Ternary aluminum silicon carbide Al4SiC4 is a promising material not only in refractory applications, but also in electronics and photocatalysis. However, synthesis of Al4SiC4 requires high‐temperature heat treatment for several hours. In this work, we describe a new, fast and effective method to synthesize single‐phase Al4SiC4 powder. Our method is based on combustion synthesis reaction of Al, Si and C initiated under high‐frequency induction heating. Heating program was optimized to prevent separation of melted aluminum and provide uniform initiation, propagation and completion of the reaction. As a result, pure‐phase Al4SiC4 powder was synthesized in few minutes. Temperature profile of a sample measured during heating process showed appearance of two exothermic peaks, thus confirming propagation of a two‐step combustion reaction. Induction heating provided capability to finely and readily control external heating rate, which is considered to be one of the key factors to reach high‐purity Al4SiC4.
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