The use of chemical etching for the detection of defects in monocrystalline and polycrystalline material was investigated. Slow defect delineation was studied using a HF-HNO3-CH3CO2H solution, with CH3CO2H concentrations of more than 50%. Micro-pit delineation etchants were also developed. The latter etchants revealed defects which had extremely small defect energies, and exhibited a good preferential etching ability. Micro-pit etching was applied to electromagnetic cold-cast material, and revealed features which conventional etchants failed to expose. The high sensitivity of micro-pit etching was explained in terms of the ratio of defect etching rate to bulk etching rate. Monochromatic light-induced current measurements indicated that the micro-pits were electrically active.

Y.Kashiwagi, R.Shimokawa, M.Yamanaka: Journal of the Electrochemical Society, 1996, 143[12], 4079-85