Abrasion and acid resistances of Ni-W alloy plating obtained from citric acid baths were studied and they were compared with those of Ni plating and hard chrome plating.
The following results were obtained:
(1) Ni-W alloy plating, when rubbed with S15C (heat-treated), gave abrasion resistance higher than that of S15C (heat-treated) or Ni plating obtained from Watts bath. Heat-treated Ni-W alloy plating gave abrasion resistance nearly the same as that of hard chrome plating.
(2) Ni-W alloy plating gave higher abrasion resistance when rubbed with the same alloy rather than with a different alloy or metal.
(3) The abrasion in wet process (oil lubrication) was nearly the same as that in dry process.
(4) Ni-W plating obtained from citric acid baths gave specially high corrosion resistance against nitric acid.

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In general, the atmospheres for heat treatment are composed of O₂, N₂, CH₄, CO, CO₂, H₂, H₂O, etc. The process of oxidation-reduction by the bright heat treatment in these atmospheres is very complicated.
This paper discusses the oxides of plain carbon steel produced by various oxidizing gases at high temperatures.
The following results were obtained.
(1) Oxides of the specimens produced by each of O₂, CO₂, H₂O (gas), and air were much different one another in microstructures.
(2) The X-ray diffraction patterns showed that the oxides of specimens heated in H₂O (gas) contained FeO more than those heated in other gases.
(3) In general, the surface of specimens consisted of the layer of α-Fe₂O₃, or the layer of rich in α-Fe₂O₃. However, its content was gradually decreased with the increase of depth from the surface.
(4) As the results of line analysis of X-ray microanalyzer, it was shown that the oxygen content of the oxidized layer was increased in linear proportion toward the surface.

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This paper discusses the effects of the addition of carboxylic acids and inorganic salts on anodizing of aluminum in alkaline solutions.
AC Electrolysis of aluminum was made in NaOH (1.25×10^-2mol) containing a salt of 0.1mol carboxylic acid (sodium tartrate or malonate). The thickest film (as much as about 3μ by microscopy) was produced on aluminum after 30min. at current density of 1 Amp/dm².
When inorganic salts (0.05mol) were added to NaOH (0.1mol), pitting corrosion was observed after 30min. at 0.5Amp/dm² in the presence of Cl^- or ClO^-, but a film was not produced in the presence of NO₃^-.
A thick film (about 3.5μ) was formed in NaOH containing Na₂B₄O₂ to which F^- or SO₄^2- had been added.
The above experiments were also conducted for the black oxide film (formed in ferricyanide and chromate bath) which was previously reported.
In this ferricyanide-chromate system, the thickest (about 4.3μ) and hardest (12.9 by Marten's scratch hardness tester under load of 50g) film was obtained in NaOH (2.15×10^-2mol) containing tartrate. Thus, better result was obtained by the addition of tartrate than the case of its no addition in NaOH of the same concentration.
A colored film was obtained by the addition of inorganic salts, but it was not obtained in the presence of halogen ions.

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The effects of various treatment conditions such as H₂ flow rate, time, particle size etc. on Cr diffusion coating by powder method were studied. The behavior of the surface layer was discussed with respect to the weight increase of specimens by reducing reaction.
The results obtained and considerations were as follows:
(1) Since a reversible relation was found between the generating reaction of CrCl₂ and the reducing reaction for Cr deposition, the maximum value appeared in the H₂ flow rate (partial pressure of H₂) for the weight increase by the equilibrium between the both reactions.
(2) The reaction rate was higher with the decrease of Cr particle size in the diffusion agent and was determined by the step of gas diffusion. On the other hand, the rate was determined by the step of chemical reaction rate for coarse particles.
(3) Since the weight increase of specimens was caused by exchange reaction, not by reducing reaction, the specimens having higher content of iron showed smaller increase of weight.

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