EFFECT OF ELECTROLYSIS CONDITIONS ON THE MORPHOLOGY AND CRYSTAL ORIENTATION OF ZINC ELECTRODEPOSIT

The effect of electrolysis condition on the morphology and crystal ori entation of zinc electrodeposit was investigated by using the polycrys tal commercial low carbon Al-killed steel sheet as a base material and the sulfate bath under the current density of 50-200A/dm(2), flow rat e of 1-2m/s and bath temperature of 50-70 degrees C. Under the conditi ons where overvoltage of electrodeposit is high, such as high current density, low flow rate and low temperature, heteroepitaxy of steel/zin c decreases, so that zinc crystals become fine and random in size and growth direction. Under the high overvoltage conditions, orientation i ndexes of (0002)Zn and <(10(1)over bar 3>)Zn decrease but those of <(1 0(1)over bar 1)>Zn and <(10(1)over bar 0)>Zn increase. When zinc elect rodeposits grow heteroepitaxially, (0002)Zn and <(10(1)over bar 3)>Zn planes are preferred. From these results, zinc electrodeposits are tho ught to progress as follows: At initial stage of plating, zinc electro deposits grow heteroepitaxially at preferred orientations of (0002) Zn and <(10(1)over bar 3)> Zn. Then, random growth of zinc begins partly on the (0002)Zn and <(1(01)over bar 3)>Zn and finally random growth o f <(10(1)over bar 1)>Zn and <(10(1)over bar 0)>Zn occurs partly on the (0002)Zn and <(10(1)over bar 3)>Zn.