Optimization of Plating Parameters for Low Contraction Chromium Electrodeposits

Abstract

Electrodeposition of low contraction (LC) chromium has been investigated in order to deposit a high tensile strength and crack-free chromium coating. The plating parameters--current density, chromic acid/sulfuric aced ratio, and chromium(III) concentration--were varied and a systematic study was performed. A chromic acid concentration of 250 g/l and a bath temperature of 85 C were maintained constant throughout the study. The deposit is crack-free having a typical columnar microstructure of fibrous grains with a <211> preferred orientation. On the basis of mechanical properties of the deposits, optimum plating conditions were found, i.e., 97 amperes per square decimeter current density, 100/1 acid ratio, and 4.0 g/l chromium(III) concentration. With the optimum plating conditions, a tensile strength of 87,000 pounds per square inch and hardness of 760 KHN were obtained from the deposit. Keywords: Chromium; Electrodeposition; Electroplating; Knoop hardness number; Plating; Metal coatings; Current density; Low contraction; Crack-free; Sulfuric acid.

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Document Details

Document Type
Technical Report
Publication Date
Oct 01, 1989
Accession Number
ADA220379

Entities

People

  • F. J. Nelson
  • M. D. Miller
  • S. K. Pan

Organizations

  • United States Army Armament Research, Development and Engineering Center

Tags

Communities of Interest

  • Weapons Technologies

DTIC Thesaurus Topics

  • Chromic Acid
  • Chromium
  • Coatings
  • Crystal Structure
  • Current Density
  • Electrodeposition
  • Electroplating
  • Hardness
  • Materials
  • Mechanical Properties
  • Mechanics
  • Microstructure
  • Military Research
  • Security
  • Tensile Strength
  • X Rays
  • X-Ray Diffraction

Fields of Study

  • Materials science

Readers

  • Surface Engineering/Surface Coating Technology.