A new trivalent chromium black plating based on trivalent chromium and cobalt metal has been optimized both in the as plated as well as annealed conditions. The annealed coatings exhibited high hardness, good corrosion resistance and optical properties. XRD and SEM investigations confirmed the formation of intermetallic phases of Cr-Co-P which induced mechanical properties of the coatings. The corrosion resistance characteristics of coatings have been evaluated in 3.5% NaCl using potentiodynamic polarization and A.C impedance measurements. The black coatings offered a good absorption and emission properties.

Jeeva P-A

Department of Design and Automation

School of Mechanical Engineering

Vellore Campus

Narayanan S

Department of Manufacturing Engineering

Karthikeyan S

Department of Chemistry

School of Advanced Sciences

Fulltext

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Procedia Engineering

An attempt has been made to develop an eco-friendly trivalent black hard chromium process as an alternate to hexavalent chrome plating for industrial steel components. Vicker's hardness and A.C impedance studies revealed that the coatings exhibit high hardness and good corrosion than mild steel in sea water medium. XRD and SEM results confirmed precipitation of chromium on iron matrix which improved the mechanical properties on the heat treated mild steel surface coated by trivalent chromium. The optical properties of black coatings obtained by trivalent chromium and Ni-Cu-Co based electro plating baths were evaluated. © 2017 Elsevier Ltd.

Materials Today: Proceedings

An Eco- Friendly Process On The Improvement Of Hardness And Corrosion Resistance Characteristics Of Trivalent Hard Chromium Electrodeposition

An effort was made to study the characteristics of zinc coatings obtained from free-cyanide alkaline bath and a newly phosphate passivation coatings treatment has been studied. Impedance and polarization tests performed on phosphate + based passivation on electroplated mild steel resulted in an exponential increase in the corrosion resistance of the mild steel sample. Morphological studies from SEM analysis presented nodular arrangement of zinc particles and lamellar arrangement of phosphate particles that were stressed out confirming a low increase in the micro hardness value of the coated sample. XRD analysis revealed the amorphous nature of coating material and indicating the presence of phosphate ions in the coating. The results of these measurements showed that the newly developed phosphate conversion coating is a promising candidate for replacing the conventional hexavalent chromate treatments used at present. © 2017 Elsevier Ltd.

Improvement in Corrosion Resistance of Mild Steel Using Phosphate Conversion Coatings on Electro-Deposited Alkaline Zinc

New phosphate black coatings for the improvement of mechanical properties on metallic objects have been developed to extend life time of machinery. The performance of phosphate black coatings was evaluated by weight gain studies, micro hardness studies, abrasive wear resistance and corrosion resistant measurement by electrochemical methods. The surface morphology of the coatings was assessed by XRD, SEM and XPS. The absorption coefficient of the coatings was evaluated by UV-visible spectrometer. Salt spray analysis was carried out to follow up the corrosion and get an idea about the performance of black coatings in automobile parts. The mechanical properties were very much improved after heat treatment of coatings at 200°C.

Journal	Data powered by TypesetProcedia Engineering
Publisher	Data powered by TypesetElsevier BV
ISSN	1877-7058
Open Access	Yes