Surface Morphology and Hardness Analysis of TiCN Coated AA7075 Aluminium Alloy

• Published in: Journal of the Institution of Engineers (India) Series C Vol. 100; no. 1; pp. 221 - 228
• Main Authors: Srinath, M. K., Ganesha Prasad, M. S.
• Format: Journal Article
• Language: English
• Published: New Delhi Springer India 08.02.2019; Springer Nature B.V
• Subjects: Aerospace Technology and Astronautics; Aluminum base alloys; Engineering; Hardness; Heat treating; Heat treatment; Industrial and Production Engineering; Lattice parameters; Mathematical analysis; Mechanical Engineering; Morphology; Original Contribution; Surface hardness; Titanium carbonitride; Unit cell; Surface hardness; SEM; XRD; PVD-coatings; TiCN; AA7075
• DOI: 10.1007/s40032-017-0427-1
• ISSN: 2250-0545

Successful titanium carbonitride (TiCN) coating on AA7075 plates using the PVD technique depends upon many variables, including temperature, pressure, incident angle and energy of the reactive ions. Coated specimens have shown an increase in their surface hardness of 2.566 GPa. In this work, an attempt to further augment the surface hardness and understand its effects on the surface morphology was performed through heat treatments at 500°C for different duration of times. Specimen’s heat treated at 500°C for 1 h exhibited a maximum surface hardness of 6.433 GPa, corresponding to an increase of 92.07%. The XRD results showed the presence of Al 2 Ti and AlTi 3 N and indicate the bond created between them. Unit cell lattice parameters in the XRD data are calculated using Bragg’s law. The SEM images exhibit increasing crack sizes as the heat treatment time is increased. From the studies, the heat treatment duration can be optimized to 1 h, which exhibited an augmented surface hardness, as further increases in durations caused a drop in the surface hardness. The heat treatment effectively modified the surface hardness. Equations providing the relationships that temperature and time have with the reaction parameters are presented.