Phosphoric Acid Bath Research Articles

ニッケル鋼, ケイ素鋼, マンガン鋼の電解研摩

Electropolishing of various metals in phosphoric acid-chromic acid bath was investigated. In this paper, the result of the studies of electropolishing effects on nickel steels, silicon steels and manganese steels in the above bath are reported as follows:1) Electropolishing of the above metals in the phosphoric acid-chromic acid bath which was applied to carbon steels, copper alloys and auminium alloys, are good with low bath voltage and low anode current density, 2) On castings of these metals, however, electropolishing effect is not good without for the crystlline textures are coarse, but it is improved after heat treatment of the castings.3) It is very easy to polish nickel steels.4) Silicon in silicon steel seems to be oxydized to silica and dissolved as colloid at the anode in the above bath, and then the silicon steel being polished.5) Manganese steels should be treated at low current density and in short treating time in order to prevent the slective dissolution of manganese carbide.

ニッケル浴における陽極酸化皮膜の電極電位について

In the nickel plating bath the electrode potentials of aluminium plates anodized in the phosphoric acid bath, oxalic acid bath and sulphuric acid bath, are measured.The results are as follows:i) The electrode potential is enhanced slightly by the anodizing and is always negative disregarding of the electrolyte used in the anodizing.ii) The highest potential is obtained by using the phosphoric acid bath for anodizing.iii) The electrode potential of the plate anodized in the phosphoric acid bath is lowered markedly by immersing into the nickel plating bath. This phenomenon is probably originated from the inherent action of the active layer produced by anodizing, which seems to be effective to improve the adhesive property of the electro-deposite.iv) The potential-current density curve bends near the 20mA/dm2, such bend is most marked in that anodized in the sulphuric acid bath.

アルミニウムの陽極酸化膜への有機皮膜の付着性について

To find out the difference between the adhesive property of electro-plating and of organic coating to metal surface, the acetyl cellulose films as organic are coated on the anodized aluminum plates under various anodizing conditions, and each adhesive strength is measured.The results of the measurment are as follows.1) The adhesive strength of the coating on aluminum plate anodized in phosphoric acid bath at room temperature is several times greater than the others. However, the strength falls with anodizing temperature rise.2) The coatings on the aluminium plates anodized in sulphuric or oxalic acid bath and etched by sodium hydroxide have almost the same or slightly less adhesive strength as the above.3) Such tendency of the adhesive property of organic coating is the same as that in the case of electro-plating of anodized aluminum.

アルミニウムへの電着における素材の純度の影響について

As base metals 3 kinds of aluminium plates of different composition (99.9% Al, commercial aluminium, and 52S) are used in the experiments.Specimens are made by plating the anodized and plate mentioned above. The examination of the adhesive property of these specimens shows that the low grade aluminium has the best adhesive property.The cause of the difference in the adhesive properties is investigated, and the following results are obtained:i) The electron-microscopic observation of the oxide film shows that the inherent pores are slightly larger for the higher purity aluminium than the lower one. When the phosphoric acid bath is used, no relation exists between the adhesive property and pore size. The cell structure of the oxide film is more uniform and continuous in the high purity aluminium, while the low grade aluminium has many defects in the oxide film.ii) The anodized surface of low grade aluminium macro or micro-scopically rough.iii) The nucleation during initial plating is selective as a rule, and the higher the purity of aluminium is, the higher is the selectivity.iv) In the case of nickel bath, the lower the grade is, the higher is the electric potential, and the easier is the plating operation. This agrees with the well known fact that the nobler the metal is, the easier is the plating operation. The potential rises due to the anodizing, and the highest possible potential becomes almost as high as that obtained by using iron plates.

The vibrating electropolishing process of aluminium in phosphoric acid solution (1st Report)

This study is concerning with the electropolishing process with the vibrating anode in phosphoric acid bath based on the patents-(Jap. Pat. No. 128891, 190520, T-Nakayama)In these experiments the static method and the vibration method have been used symmetrically.(1) As a whole, the electropolished surface produced by the static method has always shown uneven surface, its reflectivity being up to 80%, but the vibration method gave an extremely smooth surface and its reflectivity reached to 90%.(2) In the vibration method, the concentration of phosphoric acid to obtain electropolished surface is higher than that in the static method, but it has been possible to perform electropolishing up to a higher concentration than that in the static.(3) Upon increase of the current density, the surface condition has changed in the order as follows:A (etched surface)-B (insufficient polished surface)-C (electropolished surface)-D (rough surface)-E (burned surface).The similar results can be obtained with each concentration as well as with both the static and the vibration method.(4) With the identical concentration of phosphoric acid, the vibration method produced electropolished surface in a higher current density than the static method, and electropolished surface also can be obtained untill reaching to a higher current density than that of the static.(5) With the same temperature, electropolished surface can be obtained at a higher current density of the vibration method than that of the static, producing electropolished surface untill reaching a higher current density.(6) While the static method produces electropolished surface in short time in comparison with the vibration method, the vibration method produces electropolished surface until reaching to a longer electrolysis time than the static.

アルミニウムの陽極酸化膜への電着について (第4報)

During the anodizing of aluminium the surface state varies by oxidation and dissolution.The appearance is not always the same according to the kind of electrolyte; for example, in the case of using sulphuric acid bath, the surface shows an extremly irregular appearance, and in the case of using phosphoric acid bath, it consists of the collection of pits, which are very much like those etched by sodium hydroxide. The observations of the forming-points of nuclei by instantaneous electroplating of such surfaces revealed the followings:In the case of using sulphuric acid bath, the nuclei are formed starting from the defects on the surface, having nothing to do with the state of oxidized surface, and in the case of using phosphoric acid bath, they are formed mostly around the pits on the surface. The sections across the surface also show that these nuclei have settled mostly on the protrusions from the surface.

燐酸-クロム酸糸電解研磨浴の老化および再生に関する研究

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.