Friction and Wear Properties of Silicon Carbide in Water from Different Sources

Low friction and low wear of SiC sliding against itself in water at room temperature have been well reported in the past 20 years, and some practical applications have been developed. However, the properties of friction and wear in pure, deionized or distilled water have been mainly observed and not in water from sources in nature. In this article, the fundamental properties of friction and wear between SiC ball and disk are observed in water from ground, river, and sea, and the results are compared with those in deionized water in the viewpoints of modes of lubrication and wear and the resultant values of friction coefficient and wear rate. The smallest friction coefficient (μℓ = 0.005) in steady state is observed in deionized water and the largest (μℓ = 0.013) in sea water. The smallest wear rate (ws = 2.2 × 10−7 mm3/Nm) is observed in sea water and the largest (ws = 3.1 × 10−7 mm3/Nm) in deionized water. The intermediate values of μℓ and ws between the smallest and the largest ones are observed in ground and river water. The modes of lubrication and wear, which generated observed values of μℓ and ws, are considered as mixed lubrication and tribochemical wear. The chemical elements of Na, Cl, Mg, and K in sea water observed on wear particles and pits are thought effective to generate the largest value of μℓ and the smallest value of ws.