The initial corrosion behavior of carbon steels has been examined under airborne sea salt deposition and artificial seawater droplets in a chamber. The airborne sea salt was collected on graphite at a marine site for two hours. The droplets were prepared by dropping 5μl droplets of the artificial seawater using a micropipette. The diameter of the airborne sea salt particle was about 20μm at 30% R.H. (Relative Humidity), and it was about 1/10 compared with the artificial seawater droplets. As the relative humidity increases gradually, both the sea salt particles started to absorb the water from their environment. Both sea salts represented almost the same water absorption behavior as the thermodynamic calculation, but the artificial seawater droplets needed a longer time to transform into a liquid than the airborne sea salt. Furthermore, a corrosion test of carbon steels was conducted under the airborne sea salt deposition and the artificial seawater droplets, and the corrosion behaviors also showed different trends. The difference in the corrosion behavior is attributed to the water absorption behavior of the sea salt, that is, the particle size of the dried sea salt.
The effects of the ambient humidity on the friction and wear properties of Ni-W-P alloy platings with various phosphorus contents were examined by horizontal reciprocating friction and wear tests and XPS. To clarify the role of phosphorus in the friction and wear behavior of alloy plating, the same experiments were carried out to for electroless Ni-P, Ni-W alloy and Cr platings. The friction and wear properties of Ni-W-P alloy plating were affected greatly by the ambient humidity depending on the phosphorus content. Both the friction coefficient and the wear amount of the alloy plating have decreased with increase in the ambient humidity and also the phosphorus content of the alloy plating. By XPS measurements, a phosphorus oxide layer was found to be formed on the sliding surfaces in moist atmospheres, and to contribute to low friction and the wear characteristics of the Ni-W-P alloy plating.
Small Al electrodes connected to the pins of a model IC were subjected to zincate pretreatment to simulate the plating process in an LSI manufacturing line. From SEM observation, deposition of Zn and dissolution of Al substrate depended on the potential of Al electrodes under the potentiostatic polarization in the zincate solution. Difference in electric impedance of IC pins affected the immersion potenial of Al electrodes in the zincate solution and thus the amount of Zn deposition. Visible light illumination on the separated p-Si electrode additionally connected to the power supply pin of the IC generated photocurrent. This caused a shift in immersion potential of Al electrodes connected to the other pins of the IC in a noble direction, resulting in suppression of Zn deposition in the zincate pretreatment.