Abstract
The authors examined the changes in number of crack meshes, crack width, plateau size, etc. of a part of chromium deposit, which had been subjected to sucsessive electrolytic etching. The examination was conducted by a serial photomicrography. The following results were obtained. The increase in number of crack meshes and the decrease in plateau size of chromium deposit electrolytically etched were proportional to a certain unit thicness of the deposit; this phenomenon reveals that the presence of cracks of chromium deposit was separated by unit thickness of the deposit, which is referred to as the “thickness of unit crack layer”, hereinafter. The “thickness of unit crack layer” was thinner when the cracks were more dense, but was thicker when the cracks were sparser. Moreover, it was related with the “critical thickness” observed in the measurement of the stress of chromium deposit. When the etching was further promoted, each of the number of crack meshes and plateau size tended to a constant value, at which the thickness was several times as large as that of the “thickness of unit crack layer”.
