Effects  of Additives on Chromium Coating in Trivalent Chromium Bath

Please enable javascript in your browser.

Ebrahimi, Ghasem | 2012

561 Viewed

Type of Document: M.Sc. Thesis
Language: Farsi
Document No: 42843 (07)
University: Sharif University of Technology
Department: Materials Science and Engineering
Advisor(s): Dolati, Abolghasem
Abstract:
In this work, effects of different additives on trivalent Chromium bath and Chromium coating has been investigated. Malonic acid wich had been used as a complexing agent of the bath improved current efficiancy and coating quality obviously. Effects of Magnesum, zinc, Tin, Aluminium sulfates, Molybdic acid, TiO2 nano particles, Sodium hypophospite, formaldehead and mixtures of these compositions on hexavalent Chromium concentration of the bath were also studied. Concentration of Cr6+ ion decreased by 18 ppm due to adding these materials. Using Ti/ TiO2/ RuO2 Anode also could decrease Cr6+ concentration by 78 ppm. Remarkable results had been recorded in current efficiency and coating quality by adding aluminium sulfate and Sodium hypophosoite. The most value of achieved current efficiency was 25 percent. Using PVP, apparently, enhanced hardness and the thickness of deposit. Designed bath was stable for even one month and high quality coat was gained after this period
Keywords:
Chromium Coating ; Hexavalent Chromium ; Trivalent Chromium Bath

No TOC