Chemical bonding states and solar selective characteristics of unbalanced magnetron sputtered Ti x M 1−x−y N y films

• Published in: RSC advances 2016, Vol.6 (43), p.36373-36383
• Main Authors: Rahman, M. Mahbubur, Jiang, Zhong-Tao, Munroe, Paul, Chuah, Lee Siang, Zhou, Zhi-feng, Xie, Zonghan, Yin, Chun Yang, Ibrahim, Khalil, Amri, Amun, Kabir, Humayun, Haque, Md Mahbubul, Mondinos, Nick, Altarawneh, Mohammednoor, Dlugogorski, Bogdan Z.
• Format: Article
• Language: English
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/C6RA02550A

Transition metal nitride Ti x M 1−x−y N y (M = Al or AlSi) based thin films are evaluated as solar selective surfaces by correlating their spectral selective features with their crystal structure and chemical bonding state including mechanical strength. Ti 0.5 N 0.5 , Ti 0.25 Al 0.25 N 0.5 , and Ti 0.25 Al 0.2 Si 0.05 N 0.5 films were synthesized on AISI M2 steel substrates via closed field unbalanced magnetron sputtering technology. These were investigated using XRD, SEM, XPS, UV-Vis, FTIR and nanoindentation techniques. Analysis of the optical properties showed the solar absorptance, in the visible range, of the Ti x M 1−x−y N y films improved significantly from 51% to 81% with AlSi-doping and an increase of solar absorptance of up to 66% was recorded from films doped with Al. Moreover, the Al doping can reduce the thermal emittance in the infrared range from 6.06% to 5.11%, whereas doping with AlSi reduces the emittance to ca. 3.58%. The highest solar selectivity of 22.63 was achieved with TiAlSiN films. Mechanical studies showed enhanced hardness by ∼32%; enhanced yield strength by ∼16% and enhanced plastic deformation by ∼110% of Al and AlSi doped TiN matrix.