Chromium electrodeposition from Cr(VI) low concentration solutions

Abstract

This work presents a study of a hard chromium plating process using low concentration H 2 CrO 4 baths. In particular, the effect of different values of CrO 3 /H 2 SO 4 ratio on coating properties such as adhesion, hardness, surface roughness, apparent density and microstructure were considered. To increase the solution conductivity, avoiding long deposition times and low throwing power typical of dilute solutions, the behaviour of various inorganic compounds was investigated. Specifically, the compounds suitable for obtaining brighter coatings with lower surface roughness values than those obtained using Fink's solutions were Na 2 SO 4 and Al 2 (SO 4 ) 3 9 18H 2 O. A bath composition was identified, with a limited use of Cr(VI) in a solution able to produce coatings with a better surface roughness than those of conventional industrial baths.

Soft magnetic properties of Ni–Cr and Co–Cr alloy thin films electrodeposited from aqueous solutions containing trivalent chromium ions and glycine

“…However, it is quite difficult to obtain Cr alloys at room temperature due to the high T m and the mechanical hardness. On the contrary, in a conventional electroplating process, metallic Cr films can be synthesized by electrodeposition from an aqueous solution containing hexavalent chromium ions (Cr 6+ ) under the condition of room temperature and atmospheric pressure [1][2][3]. However Cr 6+ ions are known to toxic and carcinogenic substances, hence, in recent years, the solution containing trivalent chromium ions (Cr…”

Chromium electrodeposition using electrolytes based on trivalent chromium compounds: a review

“…Çâè÷àéíî, ùî íåãàòèâíèé åôåêò â³ä âèêîðèñòàííÿ åëåêòðîë³ò³â õðîìóâàííÿ íà îñíîâ³ ñïîëóê øåñòèâàëåíòíîãî õðîìó ìîaeå áóòè ïåâíîþ ì³ðîþ çí³âåëüîâàíèé øëÿõîì çíèaeåííÿ êîíöåí-òðàö³¿ õðîìîâîãî àíã³äðèäó ó ðîç÷èí³ òà îïòèìàëüíèì ï³äáîðîì ñêëàäó ³íøèõ êîìïîíåíò³â åëåêòðîë³òó òà ðåaeèì³â åëåêòðîë³çó [14][15][16][17][18][19][20]. Âò³ì îñòàòî÷íå ðîçâ'ÿçàííÿ ïðîáëåìè «øåñòèâàëåíòíîãî õðîìó» ó ãàëüâàíîõ³ì³÷íèõ òåõíîëîã³ÿõ ìîaeëèâå ò³ëüêè ïðè ïîâí³é â³äìîâ³ â³ä éîãî âèêîðèñòàííÿ.…”

Influence of CH3SO3H and AlCl3 in direct and pulse current electrodeposition of trivalent chromium

“…Since 1933, many patents and papers have been issued for deposition of chromium alone and then as an alloy with elements like nickel, manganese, irons, cobalt and molybdenum. [1][2][3][4][5][6][7][8][9][10] Considerable research has been conducted to study Cr(III) plating, including the effects of the plating bath chemistry on plating thickness, brightness, hardness, and corrosion resistance [11][12][13][14][15][16][17] and the effect of current wave forms on chromium deposit structure, distributions, brightness and hardness. [18][19][20][21][22] Trivalent chromium electroplating was first used only for decorative purpose due to thickness limitations.…”