抄録
The following results were obtained in formation and morphology of galvanically substituted Au-film, which was precipitated and developed over iron surface by means of galvanic substitution of hydrochloric acid-auric chloride solution.
(1) In the earlier stage of precipitation, Au-film was developed in net-work, and then, slowly converted into plate crystals with the lapse of time. The substrate iron surface turned golden colored and was brightened in this stage, to which plate crystals of Au-film firmly adhered.
(2) When the iron surface was dipped in 0.1 or 3% hydrochloric acid-auric chloride solution, it was coated with plate crystals of Au-film within 30 or 0.5sec., respectively.
(3) The Au-film, after the lapse of time, consisted of plate and needle crystals, because the surface looked dark by irregular reflection in needle crystals.
(4) The defects of the plate crystals decreased and the growth of needle crystals were also retarded with the increase in concentration of hydrochloric acid in the solution.
(5) The defects of the plate crystals decreased, when the solution was agitated.
(6) The plate crystals, precipitated and developed over mechanically polished single iron crystals, were observed to be poly-crystals by means of electron diffraction. The microstructure of plate crystals grew in thick when they were precipitated on iron surface crystals having low values of Miller's indices, but they grew in thin when precipitated on crystals having high values.
