Date of Award

7-2-2013

Thesis Type

masters

Document Type

Thesis

Divisions

eng

Department

Faculty of Engineering

Institution

University of Malaya

Abstract

The effects of intermediate TiO2 coating layer on the adhesion strength improvement of TiN coating were studied. Ti/TiO2/TiN coatings were deposited by D.C magnetron sputtering on high speed steel (HSS) and stainless steel (SS) substrates. A series of dense and uniform coating films, 844.1 – 926.4 nm thickness, were deposited at discharge power of 150 W and substrate temperature ranging from 50 to 250 °C. The duration time for depositing Ti coating layer was 2400 s and for TiN and TiO2 coating layer were 3600 s each. The as-deposited coating films were heat treated (annealed) for 1 hour at 400, 500 and 600 °C. The adhesion strength of Ti/TiO2/TiN coatings were evaluated by scratch testing and the coating hardness values were measured using micro-hardness tester. X-ray diffraction (XRD) analysis revealed anatase TiO2 phase. The results from the scratch test discovered that Ti/TiO2/TiN coating exhibits higher adhesion strength compared to Ti/TiN and single layer TiN coating. The maximum adhesion strength of 1417.19 mN was observed for Ti/TiO2/TiN coating deposited on HSS substrate. It is also observed that Ti/TiO2/TiN coatings deposited at higher deposition temperature exhibits higher values of critical load. The adhesion strength of Ti/TiO2/TiN coating also increases as the TiO2 coating thickness increases. The adhesion strength of Ti/TiO2/TiN coating deposited on HSS decreases with the increases of substrate surface roughness. It was also observed that annealing Ti/TiO2/TiN coating at 500 °C yielded highest adhesion strength and coating hardness. The annealed coating at 600 °C revealed film delamination and exhibited lowest adhesion strength.

Note

Dissertation (M.Eng.) - Faculty of Engineering, University of Malaya, 2013.

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