In the mechanical plating using Fe-Zn system ejection powder (Z-iron), repeated use results in finer particle size, and to maintain high deposit density on a continuous basis, it is necessary to bleed out the fraction of the powder that has a detrimental effect on plating efficiency.
In this study, the plating densities of various mixtures were evaluated in order to determine effective bleeding methods. The principal results obtained are as follows:
(1) The deposit density obtained by ejecting a fresh mixture of ZZ-48 and ZZ-48H powder is greater than that expected from a simple sum of the deposit densities of ZZ-48 and ZZ-48H.
(2) Ejection of ZZ-48 after ZZ-48H results in a slightly lower deposit density than ejecting ZZ-48H after ZZ-48.
(3) The dust fraction produced during pulverization of ZZ-48H greatly reduces the deposit density of fresh Z-iron.
(4) The presence of magnetics portion of -60 mesh fraction resulting from repeated ejection was detrimental to plating efficiency.
(5) Powder that has detrimental due to ejection can recover its deposit plating efficiency with thermal treatment.

View full abstract

Natural II a-type diamond has a high optical transmission ratio from ultraviolet (225nm) to infrared (13μm), and a study on the optical properties of diamond films synthesized by microwave plasma CVD was accordingly carried out with a view to applying the synthesized diamond films in optical parts.
Diamond films were synthesized from CH₄-H₂ and CO-H₂ reaction gas systems on quartz substrates. Film thickness was a uniform 1μm.
Raman spectroscopy showed that carbon source concentrations that did not contain non-diamond elements (amorphous carbon etc.) in the films was higher for the CO-H₂ system than for the CH₄-H₂ system. This was because the etching rate of oxygen to carbon is higher than that of hydrogen.
In terms of optical properties, the transmission ratio of diamond films containing minute amount of non-diamond elements was about 50%, and was uniform from 240nm to 2600nm. But as the amount of non-diamond elements increased, the transmission ratio at 250nm and 500nm decreased.
The transmission ratio of the diamond films in the ultraviolet and visible ranges depended on the quantity of non-diamond elements in the films.

View full abstract

In two previous papers, a new type of bath was proposed for electroless tin plating to be applied in the disproportionation of Sn(II) ion involving
2Sn(OH)₃^-→Sn+Sn(OH)₆^2-
Sn(II) Sn(O) Sn(IV)
This results in the accumulation of Sn (IV) ion in the used bath as the product of the plating operation.
This paper reports a study of the used SnCl₂-KOH system baths in which Sn (IV) had accumulated.
The following results were obtained.
1. The addition of BaCl₂ solution to the used bath caused Ba²⁺ ion to react selectively with Sn(OH)₆^2- and precipitate as BaSn(OH)₆·nH₂O.
2. After filtration of the precipitate and replenishment of SnCl₂ into the used bath, it was possible to carry out normal electroless tin plating.
3. Even after five or more reclamation cycles, the bath remained stable and compact regular tin deposits were obtained.

View full abstract

Amorphous Fe-Ni-P alloys were prepared by electrodeposition from a 1-hydroxyethane-1, 1-diphosphonic acid bath. The effects of bath composition on alloy composition and on the range of alloys obtainable in amorphous form were investigated. Because of the surface active property of 1-hydroxyethane-1, 1-diphosphonic acid, the surface of the deposited alloy was smooth and bright, and the critical concentration of phosphorus in alloys in amorphous form was relatively low. The critical P concentration was also lowered from 7.6% by weight to some 5% when the iron content of the deposit was increased to 60% by weight.

View full abstract

Amorphous Ni-Mo-W ternary alloy films were prepared by electrodeposition from a citric acid bath and their corrosion resistance was investigated by electrochemical measurement. The crystal structure of the films was influenced by the pH of the bath rather than the cathodic current density; The amorphous films were obtained between pH2.5 and 4.0. The Mo content of the amorphous films was about 20wt% or more. Their corrosion resistance was better than that of crystalline films. Electrochemical impedance spectroscopy and scanning electron microscopy showed the surfaces of the amorphous films to be flatter and more compact than those of crystalline films. This study suggests that the effective corrosion resistance of alloy films is based on the homogeneity of the surface.

View full abstract

The anodizing of aluminum was investigated in propylenediamine-fluoride solutions containing organic acid salts. Using a 0.1mol/L propylenediamine solution containing 0.2mol/L ammonium fluoride, uniform films about 10μm thick were formed, while in the above bath with the addition of organic acid salts (CH₃COONH₄:0.05mol/L, (NH₄)₂C₂O₄:0.05mol/L, (NH₄)₂C₄H₄O₆:0.2mol/L, (NH₄)₃C₆H₅O₇:0.1mol/L), thick films (about 14∼17μm) were obtained. Marten's scratch hardness tests (load 50gf) showed that the hardest film (20.2) was obtained in the bath containing ammonium acetate. The films formed in the baths containing organic acid salts yielded nearly the same results (75∼80sec) in alkali dropping tests. SEM observation showed that the surface of films formed in baths containing ammonium acetate or ammonium oxalate consisted of a mixture of small (approx. 300Å) and large (approx. 1000Å) pores.

View full abstract

The anodizing of ADC 12 aluminum die-casting alloy, ADC 12 without Cu, Fe, or Mn (M-ADC 12), cast ADC 12 (C-ADC 12), and rapidly solidified ADC 12 (RS-ADC 12) has been investigated in 10 and 30wt% H₂SO₄ solutions at 293K with a constant current density of 100A/m². Anodic oxide film formation was examined by measuring the time variations in anode potential, the amount of dissolved Al³⁺, Cu²⁺ and Fe²⁺ ions, and the volume of O₂ evolved on the anode, as well as by electron microscopic observation of the oxide film.
The steady value of the anode potential in 10wt%-solution was 35-57V, increasing in the order C-ADC 12<<RS-ADC 12=M-ADC 12<ADC 12. The metal dissolution current was 22-25A/m², independent of the kind of specimen, while the gas evolution current was 15-30A/m², increasing in the order M-ADC 12<<RS-ADC 12=C-ADC 12<ADC 12. Increases in acid concentration caused decreases in the anode potential and gas evolution rate.
The difference in the anode potential and gas evolution rate during anodizing are discussed in terms of the inhibition of ion transport and acceleration of electron transport across the barrier layer, due to the formation of composite oxide, Al(Si, Cu, Fe)Ox.

View full abstract