A Salt film method has been developed for descaling stainless steel. Spraying methods of salt solution were tested in both laboratory and production line environments. The results of these tests are summarized as follows: 1. A wedge shaped test spray unit was developed for the spray of an alkaline solution to hot strips after annealing in a furnace. The device was operated stably even in high temperature atmospheres. 2. In laboratory tests of spray characteristics, adhesion efficiency of the sprayed solution on the strip surfaces was found to be a function of the spray distance, strip temperature, spray pressure and the gas-liquid flow rate. 3. Following incorporation of the salt film descaling method into a production line, it is expected that it will be improved to enable spraying strips at temperatures of un to 400°C.

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Commercially pure aluminum specimens were anodically oxidized in a 13M H₂SO₄ solution at 20°C by applying a constant current density of 1A·dm^-2, the voltage attained being 36-38V. The composition and properties of the oxide formed were investigated by chemical analysis, electrochemical techniques, thermogravimetric analysis, and transmission electron microscopy. The results were compared with those for oxide films formed in a 1.5M solution. (1) The content of SO₄^2- and H₂O were about 40% and 6.5% respectively for the 13M film and 15% and 5.5% for the 1.5M film. Thus, film composition is expressed by Al₂O_2.29 (SO_4)0.71⋅;0.61H₂O and Al₂O_2.81 (SO_4)0.19⋅0.38H₂O. (2) For the 13M films, the thickness of the barrier layer was 330Å and that of the pore wall 270Å, pore diameter was 200Å. The number of pores was 19.6×10⁹cm^-2 for the 13M film and 72.1×10⁹cm^-2 for the 1.5M film. (3) The rate of chemical dissolution of both 13M and 1.5M films was higher in the 1.5M H₂SO₄ solution than that in the 13M solution. In both solutions, the 13M film dissolved faster than the 1.5M film, due to its larger SO₄^2- content. (4) Microvoids were found to have been produced in the barrier layer and pore walls of the 13M film by the expansion of oxide due to the incorporation of a large number of SO₄^2- ions. Because microvoids were present in both the barrier layer and the pore walls, density and abrasion resistance were lower for the 13M film than for the 1.5M film.

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The electrodeposition behavior of copper from Cu (en)₂²⁺, Cu (EDTA)²⁺ and mixture of their complex ions has been investigated. Cathodic current-potential curves were obtained by using a rotating disk electrode and the resistance polarization due to the iR-drop between the electrode and the Luggincapillary was eliminated from the data by the current interrupter method. The slope b of the Tafel relation and the cathodic transfer coefficient α of the discharge reaction of Cu (en)₂²⁺ complex ions were -550mV and 0.145, respectively, at potentials from -750- -1100mV (SCE). Analoguos values for Cu (EDTA)²⁺ complex ions were -250mV and 0.436, respectively, at potentials from -1100- -1250mV (SCE). The exchange current density i_o was determined by extrapolating the Tafel relation to the equilibrium potential, was higher for Cu (en)₂²⁺ than for Cu (EDTA)²⁺.
Further more, for the ligand mixed solution consisting of Cu (EDTA)²⁺ to which etylenediamine had been added, the complexation reaction written
Cu (EDTA)²⁺+nen_??_Cu (en)₂²⁺, Cu (en)₃²⁺, EDTA_free
was controlled by the stability constants of the complex ions (β_EDTA=18.8, β_en=20.0, β_en=19.1). The electrodeposition behavior of copper from mixture of Cu (en)₂²⁺ and Cu (EDTA)²⁺ complex ions is thought to be dependent on electrodeposition of Cu (en)₂²⁺ complex ions.

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