Effect of addition of Cu into ZrOx film on its properties

The article reports on the effect of addition of Cu into the ZrO2 film on its structure, physical and mechanical properties. The ZrO2 and Zr-Cu-O films were reactively sputtered using a dc unbalanced magnetron from Zr (99.9) and ZrCu (90/10 at.%) targets in Ar+O-2 mixture at the substrate temperature T-s = 300, 400 and 550 degrees C and total sputtering gas pressure p(T) = 1 Pa on steel, Si(100) and glass substrates. The structure of films was characterized by an X-ray diffraction (XRD) and mechanical properties, i.e. microhardness H, effective Young's modulus E* = E/(1 - v(2)) and elastic recovery W-e, were measured using a microhardness tester; E and v are the Young's modulus and the Poisson ratio, respectively. The film brittleness was characterized by the formation of cracks during the diamond indenter impression into it. 5 girt thick ZrO2 films prepared in the oxide mode of sputtering are crystalline (m-ZrO2) and exhibit relatively (i) high hardness H approximate to 16 GPa and (ii) low ratio H-3/E-*2 approximate to 0.11 GPa. The Zr-Cu-O films with low (52 at.%) Cu content exhibit (i) crystalline structure, (ii) higher H, (iii) lower (- 1.5 GPa) macrostress cr and (iv) higher ratio H3 / E, 14 GPa. On the contrary, the Zr-Cu-O films with high (24 to 44 at.%) Cu content exhibit (i) X-ray amorphous structure, (ii) lower H approximate to 11 GPa and lower ratio H-3/E*(2) approximate to 0.075 GPa. A special attention was devoted to the investigation of cracking of Zr-Cu-O films under high (0.5 and 1 N) loads of the diamond indenter. The relations between the film cracking and properties of the film and the substrate were used to assess the toughness of the Zr-Cu-O film, It was found that the film toughness increase with increasing H-3/E*(2) ratio. It was shown that the addition of Cu to ZrO2 film can improve its toughness. (c) 2005 Elsevier B.V. All rights reserved.