Takumi Kosaba

In 100-times diluted synthetic seawater at 298 K (pH 8.2), the effect of anodizing on the galvanic corrosion resistance of AA5083 coupled to pure Fe, Type 430, or 304 stainless steel was investigated by measuring the galvanic current densities and electrode potentials. Anodizing in H 2 SO 4 effectively suppressed the galvanic corrosion of AA5083. It was shown that an increase in pitting potential by anodizing alone could not determine whether galvanic corrosion would occur or not. The cathodic a

To ascertain the effect of solution pH of Na2MoO4 chemical conversion treatment for aluminum/steel joints on corrosion resistance, AA5083 aluminum alloy and AISI 1045 carbon steel were immersed in 50 mM Na2MoO4 at pH ranges of 8–12 under galvanically coupled condition. Subsequently, in diluted synthetic seawater, the galvanic corrosion resistance of the AA5083 alloy connected to the AISI 1045 carbon steel was assessed. The number of localized corrosion damages was counted, and AA5083 treated at

The role of KMnO4–NaF conversion treatment in the galvanic corrosion resistance of AA5083 aluminum alloy coupled to AISI 1045 carbon steel in synthetic seawater (diluted 100 times) was investigated. The 10 min-treated AA5083 was observed to reduce the period of high current density during the early stage of coupling and decrease the number of localized corrosion damages on the AA5083. The 10 min conversion treatment significantly reduced the electrode potential of bulk Al6(Fe, Mn), and it was co

Multimaterial structures are effective for weight reduction of automobiles, which contributes to the prevention of global warming and the decrease in CO 2 emission. Steel-aluminum joints have many advantages such as low cost, high strength, and high corrosion resistance. However, galvanic corrosion was expected to occur because the corrosion potential of aluminum alloys is usually different from those of iron and steels. Considering the galvanic corrosion processes in chloride-containing near-ne

• The compositional change of surface films on the Al-matrix and Al 6 (Fe, Mn) was observed due to the Na 2 MoO 4 conversion treatment. • Na 2 MoO 4 conversion treatment inhibited the galvanic corrosion damage on AA5083 coupled to AISI 1045 carbon steel in diluted synthetic seawater. • The inhibition was caused by the decrease in the cathodic activity of the Al 6 (Fe, Mn) particles and the increase in the alkaline dissolution resistance of the surrounding Al-matrix. This study demonstrates that

In chloride containing solutions like atmospheric environments, an interface between intermetallic particles (IMPs) and Al-matrix is mainly one of the initiation sites in localized corrosion of Al alloys. It has been widely reported that Al-matrix around IMPs containing Fe and/or Cu was dissolved like trenching due to the oxygen reduction reaction on the IMPs and the subsequent alkalization on and around the IMPs. The trenching is precursory stage of localized corrosion on Al alloys. In the case

The joints between steels and aluminum alloys are expected to be used as multi-material structures due to their low cost, high stiffness, and high corrosion resistance. When aluminum alloys are connected to steels, galvanic corrosion is expected to occur because the corrosion potentials of aluminum alloys are lower than those of iron and steels. In the case of the galvanic corrosion in chloride solutions at near-neutral pH, the anodic reaction on aluminum alloys are oxide film formation and/or p