Result of measuring the stress of chromium deposits by Brenner and Senderoff's Contractometer was as follows:
1) No matter what kind of basic metal of helix (stainless steel, steel or copper), and how thick it was (0.016-0.031cm), the stress of chromium deposit could be measured within ±5% error, provided that the adhesion of deposit was complete.
2) The tensile stress of chromium deposit of starting period was very high (over 200×10
3psi at 1μ thickness), which could be considered to be reliable because the tensile strength and adhesion in the very thin film has been reported to be about several ten times higher than those supposed.
3) The thicker the chromium deposits, the less was the stress. The thickness, depending on plating condition, at which the needle of the stress meter stops or moves backward, is called “critical thickness” of chromium deposit. Around the critical thickness the amount of cracks in chromium deposit seems to become maximum.
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