Effect of Organic Compounds on Electrodeposition of Iridium

• Published in: Hyōmen gijutsu Vol. 44; no. 12; pp. 1173 - 1174
• Main Authors: KITADA, Katsutsugu, SAITO, Yumiko
• Format: Journal Article
• Language: English; Japanese
• Published: Tokyo The Surface Finishing Society of Japan 01.01.1993; Japan Science and Technology Agency
• Subjects: I-E Curves; Iridium Deposits; Organic Compounds
• ISSN: 0915-1869; 1884-3409
• DOI: 10.4139/sfj.44.1173

Superior hardness, heat resistance and chemical resistance make iridium electroplates attractive for functional materials e.g. of electrochromic elements. In experiments with sodium iridium (III) hexabromate baths, oxalic acid displayed a stabilizing effect and extended the coating life by a factor of 10. Electroplate cracking was greatly reduced as well. Additions of EDTA4Na were found to retard iridium deposition. The baseline plating bath contained 0.052 mol/dm exp 3 the sodium-iridium complex salt, 0.65 mol/dm exp 3 oxalic acid. Its pH was adjusted to 5 by adding an approximately 2.5N aqueous solution of sodium hydroxide. The organic compounds were added in an amount of 0.02 mol/dm exp 3 . The current density was 1.5 mA/cm exp 2 , the bath temperature 85 deg C. The substrate was brass with a gold plate 1 mu m thick.