Abstract
Kinetics of etching of MgO crystals have been studied in H2SO4, HNO3 and HCl. The effects of etching time, acid concentration and temperature on the growth of hillocks, on the selective etch rate and on the rate of overall dissolution are demonstrated. It is observed that etch rates are independent of time, but are determined by the temperature and concentration of the acid. The etch rate-concentration curves show maxima which are characteristic of an acid. The values of activation energy for the processes of dissolution, selective etching and hillock growth and the corresponding frequency factors are computed. It is established that the process of dissolution in concentrated H2SO4 is diffusion controlled, while in H2SO4 with concentrations below 18 N and in HNO3 and HCl it is reaction rate controlled. The pre-exponential factor is found to be a function of acid concentration. The results are discussed from the standpoint of chemistry. A comment on the data published on MgO by previous workers is made.
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Sangwal, K., Arora, S.K. Etching of MgO crystals in acids: kinetics and mechanism of dissolution. J Mater Sci 13, 1977–1985 (1978). https://doi.org/10.1007/BF00552905
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DOI: https://doi.org/10.1007/BF00552905