高温クロム酸塩処理をしたアルミニウム黄銅の耐食性について

抄録

Hereunder is given a report of studies made of the corrosion behavior and resistivity of aluminum brass pre-treated with an aqueous solution of K₂Cr₂O₇ at high temperature. The samples were prepared with 0.5W/O solution at various temperatures: 180, 235 and 265°C, and the surface of the metal was covered with thin film. The corrosion rate and static potential of the rotating cylinder-type sample in synthetic sea water with and without small amount of Na₂S and NH₄Cl as contamination were measured at 30°C. The weight loss of the inside surface of the pipe line with stream of contaminated saline water from the Bay of Tokyo for 150 days was determined. The corrosion rate of the sample treated with dichromate solution at 265°C was low, while the sample prepared at temperature lower than 180°C was attacked considerably. The static potential of the sample treated at high temperature was stable in comparison with bare metal whose potential varied by 115mV or more. The chemical analysis shows that the protective film consists of chromic, Cr (III), without chromate, Cr (VI).