Keywords: closed field magnetron sputtering, unbalanced magnetron sputtering, NiAl thin films, wear, mechanical properties, surface finish, surface roughness, nickel, aluminium, steel, nanoindentation, glass substrates, hardness, elastic modulus, nanotechnology
Characterisation of mechanical and wear properties of NiAl and Ni-Al-N thin films deposited by closed field unbalanced magnetron sputter ion plating
NiAl and Ni-Al-N thin films with a thickness of approximately 1 μm have been deposited onto glass and stainless steel 316 substrates using closed field unbalanced magnetron sputter ion platting process. A CSM scratch tester was used to determine the critical load, the coefficient of friction and wear rate of the films. XRD analysis confirmed the presence of β-NiAl phase. EDAX revealed nearly equal atomic composition of Ni and Al at 300 W for Ni and 400 W for Al targets, respectively with the Ni-Al-N thin films showing a nickel rich NiAl phase. AFM indicated a smooth surface finish with surface roughness ≤ 100 nm. Nanoindentation for coatings on glass substrates displayed hardness and elastic modulus of 7.7 GPa and 100 GPa respectively. Hardest coatings obtained were at 10% of N content. Scratch test of coated samples gave critical load, friction of coefficient and wear rate of 24 N, 0.24 and 1×10−6 mm3/m respectively on steel.