2018 Volume 43 Issue 3 Pages 205-208
A porous carbon material made from rice bran (rice bran carbon: RBC) has been developed for the effective utilization of defatted rice bran. RBC has some unique mechanical properties, such as a low Young’s modulus, low coefficient of friction, and high abrasion resistance. Therefore, RBC is used as a sliding element. For example, it can be applied to bearings such as wave-power generation or wind-power generation under the condition of such as beach exposure or seawater immersion. However, RBC contains some deliquescent components and thus has large hygroscopic expansion and a large reduction in mechanical strength under wet and aquatic conditions. Also, a white precipitate forms on the surface of RBC when it is immersed in seawater. In this study, the white precipitates that form on the surface of RBC during seawater immersion was analyzed. The immersion test was carried out with reference to JIS-R-1647. The immersion time was set at under the maximum of 1000 h, and precipitates generated on the surface of the test piece over time were obtained. MgK(PO4)•H2O precipitates were formed on the surface of RBC from three reactants, namely, phosphorus and potassium ions contained in RBC and magnesium ions in seawater.
