Effect of the Cl- and SO42- ions on the selective orientation and structure of Ni electrodeposits

Karayannis, HS; Patermarakis, G

dc.contributor.author	Karayannis, HS	en
dc.contributor.author	Patermarakis, G	en
dc.date.accessioned	2014-03-01T01:10:56Z
dc.date.available	2014-03-01T01:10:56Z
dc.date.issued	1995	en
dc.identifier.issn	0013-4686	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/11509
dc.relation.uri	http://www.scopus.com/inward/record.url?eid=2-s2.0-0029326141&partnerID=40&md5=f786c2e12838ed33a1cb67b13cfbd4c6	en
dc.subject	effect of Cl- and SO42- anions	en
dc.subject	Nickel electrodeposits	en
dc.subject	structure	en
dc.subject	texture axes	en
dc.subject.classification	Electrochemistry	en
dc.subject.other	Crystal orientation	en
dc.subject.other	Crystal structure	en
dc.subject.other	Current density	en
dc.subject.other	Electrochemistry	en
dc.subject.other	Electrolysis	en
dc.subject.other	Ions	en
dc.subject.other	Nickel	en
dc.subject.other	pH	en
dc.subject.other	pH effects	en
dc.subject.other	Solutions	en
dc.subject.other	Textures	en
dc.subject.other	X ray diffraction	en
dc.subject.other	Anions	en
dc.subject.other	Baths	en
dc.subject.other	Electrochemical efficiency	en
dc.subject.other	Nickel electrodeposits	en
dc.subject.other	Texture axes	en
dc.subject.other	Electrodeposition	en
dc.title	Effect of the Cl- and SO42- ions on the selective orientation and structure of Ni electrodeposits	en
heal.type	journalArticle	en
heal.language	English	en
heal.publicationDate	1995	en
heal.abstract	Nickel electrodeposits on brass substrates were prepared in vigorously stirred baths of NiCl2 1.22M and NISO4 1.22M in a wide range of current densities, 1-300 mA cm(-2), at a constant charge density 146.3 Cb cm(-2), at a constant bath temperature of 50 degrees C and at pH values 0.1 or 0.5-5. Their selective orientation and structure were studied by means of the XRD, Electron Microscopy and Optical Microscopy methods. Also, the changes in the pH of the bath solutions during electrolyses and the electrochemical efficiencies were determined. It was shown that the Cl- ions favour the successive appearance of the texture axes [110](A) and [211] while the SO42- ions favour the successive appearance of the texture axes [110](A), [110], [210] and [110](B); all the above texture axes appear in a Watt's bath which contains both the Cl- and SO42- anions. The electrochemical efficiency strongly depends on the nature of the anion, current density, the initial pH value and the corresponding texture axes kinds. In the boundaries between two successive texture axes regions the variation of the electrochemical efficiency showed abrupt changes. The changes in the pH of the bath solution (caused by the H3+O discharge process in the NiCl2 bath and by this process together with the OH- discharge on the anode in the NiSO4 bath) depend also strongly on the above electrolysis conditions. The structure of the Ni deposits also depends on these conditions and is generally well correlated to the corresponding texture axes. Generally, the structure of the Ni deposits in the NiCl2 bath is characterized as a porous, spongy, dendritic, pyramidic structure while that in the NiSO4 bath as a non porous and pyramidic spheroidised structure. A general mechanism for the Ni electrodeposition was discussed which correlates well the involved intermediates (which are different in the two baths) and the observed texture axes and also explains the variation of the electrochemical efficiency with current density and pH and the changes in the pH of the bath solutions.	en
heal.publisher	PERGAMON-ELSEVIER SCIENCE LTD	en
heal.journalName	Electrochimica Acta	en
dc.identifier.isi	ISI:A1995RD19700001	en
dc.identifier.volume	40	en
dc.identifier.issue	9	en
dc.identifier.spage	1079	en
dc.identifier.epage	1092	en