Abstract
Experimental and numerical investigations have been performed on the relationships between coating parameters, residual stresses, micro-cracks and the near surface strength of electrochemically deposited hard chromium coatings. The experimental investigations included: X-ray measurements of residual and externally-applied stresses; crack density measurements using microscopy; and load-bearing measurements using ball-on-plate tests. The numerical investigations in combination with analytical conclusions focused on the influence of different crack lengths and densities on the effective elastic modulus of the chromium coating and the stress-enhancing or shielding effect of micro-crack networks respectively. The results show that the residual stresses and crack networks are influenced by the current density used during deposition. Coatings with high tensile residual stresses have low crack densities. This correlation is associated with stress relaxation by formation of micro-cracks and, to a lesser extent, to a direct reduction in residual stresses due to the deposition process. The load bearing capacity is dominated by the crack density and can be significantly increased by shot-peening-induced compressive residual stresses. Thus, optimization of hard chromium deposition parameters for applications needing high surface strength should predominantly focus on minimizing the crack density.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.