超硬合金の水溶液中腐食に及ぼすNaCl濃度の影響 Effect of NaCl Concentration an Aqueous Solution on Corrosion Resistance of Cemented Carbide
Cemented carbides with nickel binder have been widely used as wear and corrosion resistant material because of its improved corrosion resistance. However, WC-Ni cemented carbides were occasionally corroded in the aqueous solution with high NaCl concentration such as sea water. In this study, the effects of carbon content and NaCl concentration on the corrosion resistance of WC-Ni-Cr<SUB>3</SUB>C<SUB>2</SUB> cemented carbides were investigated by immersion test and electrochemical measurements in 0.03, 0.3, 3, 10%NaCl solutions.<BR>Ni was the main dissolved element, and the corrosion rate of high carbon alloy was lager than that of the low carbon alloy. The amount of dissolved metals increased with increasing NaCl concentration. The dissolution of Cr was increased with increasing NaCl concentration too, but not depended on carbon content in the alloy. The corrosion resistance declined with the increasing NaCl concentration owing to the destruction of the passive film with dissolution of Cr. The corrosion resistance largely depended on the passive film formed in solution, therefore influenced by the composition of the binder phase. The stable corrosion resistance was obtained with low carbon content alloy.
粉体および粉末冶金 49(4), 264-269, 2002-04-15
Japan Society of Powder and Powder Metallurgy