Hot-dipped aluminum coated steel shows the evidence of at least two more distinct layers in its structure. The prediction of the mechanical properties of such composite material is very difficult and further researches will follow on this subject. The result of this research was as follows:
(1) From the structural changes during the dipping process, it is considered that the mechanical properties of aluminum coated steel is almost the same as those of annealed state of base metal.
(2) If the base metal is in annealed state, the coated layer has no effect on mechanical properties of dipped specimen when γ (sectional area of alloy layer/sectional area of base metal) is less than 0.10.
(3)If γ is more than 0.10, they have an important effect on the properties of dipped specimen according to the thickness of alloy layer.
(4)The alloy layer has an ultimate strength of 12kg/mm² approximately.
(5)The mechanical properties of aluminum coated steel sheet of 1.0mm thickness at 900°C is superior to the base metal in proportion to the increase of heating time.
(6) In the tensile test, the cracks and flakes in the surface aluminum layer are observed when the elongation of specimen is more than 25% and local contraction is produced.

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Electrodeposition of titanium on other metals has already been studied by many investigators, but it still has much to be studied ahead. The authors made a series of experiments using many aqueous baths, such as sulphate, chloride, fluoborate and titanate, and organic baths of chloride, and the appearance of deposit from each bath was observed. The results were as follows:
Black powdery deposit were generally obtained with sulphate, chloride, fluoborate and organic baths, and adherent deposits only with titanate bath. Thick deposits, howrever, could not be obtained with these baths.

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The electropolishing bath prepared from phosphoric and chromic acid is regarded to be very important because it gives high lustre and anticorrosive property to the polished iron, steel, stainless steel, aluminium and copper. However, the short life of this bath, owing to the reduction of CrO₃, is considered to be its only defect. In the electropolishing baths for iron. for example, the aging appears as soon as about 30% of CrO₃ is reduced. Therefore, it is prerequisite to prolong the life of bath. So the authors made experiments for that purpose by the following two methods:
(1) Regeneration of CrO₃ by means of the electrolytic oxidation of Cr³⁺, and
(2) Prevention of the cathodic reduction by using a ceramic diaphragm to separate the cathode.
The result obtained were as follows:
In case of concentrated phosphoric acid bath, the electrolytic oxidation of Cr-Alum used as trivalent chromium salt was observed, which resulted in the low current efficiency and poor yield. While, in the oxidation of diluted acid bath, such as below 40 Vol.% of the acid, both values of current efficiency and yield were relatively high, although inferior to those examind with sulphric acid bath.
So that the generation of CrO₃ is not desirable for prolonging the life of concentrated phosphoric acid bath for clectropolishing of iron, stainless steel, or aluminium. But it is possible to regenerate the CrO₃ for the relatively dilute phosphoric acid bath for electropolishing of copper.
On the other hand, when the diaphragm was used, little chromic acid in the bath was reduced even after 4 hours electropolishing, and good results were obtained by further using of the bath. But, without diaphragm, chromic acid was readily reduced, and therefore good results were no more obtained after 4 hours' polishing.
Considering these results, we can say about electropolishing baths that it is more preferable to prevent the reduction of CrO₃ by using diaphragm than to regenerate CrO₃ by means of electrolytic oxidation.

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In this rescarch the tendency of corrosion of zirconium was examined, using Zr-plate (1cm×1cm) of 99.99% of purity as anode and maintaining the temperature of the cell at 20°C, other conditions being the same as in the former research.
The results are as follows:
In H₂SO₄ though the corrosion quantity is small at the range of 10-55%, the corrosion proceeds at about 5%, 60% and more.
In HCl, the corrosion quantity is large regardless to the concentration.
The corrosion hardly proceeded in HNO₃, H₃PO₄, CH₃COOH, NH₄OH and KOH.
In NaCl solution, the corrosion degree resembles that of HCl owing to the effect of Cl^- ion.
In the mixed solution of HCl and HNO₃, zirconium metal has no corrosion resistance as in aqua regia.

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