Protection of brittle film against cracking

• Published in: Applied surface science Vol. 370; pp. 306 - 311
• Main Authors: Musil, J., Sklenka, J., Čerstvý, R.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.05.2016
• Subjects: Amorphous structure; Bending; Brittleness; Cracks; Crystal structure; Film cracking; Magnetron sputtering; Mechanical properties; Optical properties; Protective film; Transparency; X-rays; Zr[sbnd]Si[sbnd]O film; Mechanical properties; Film cracking; Transparency; Magnetron sputtering; Protective film; ZrSiO film
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2016.02.132

•A brittle film can be protected against cracking when it is over-coated with an elastic film.•The brittle films can have either X-ray amorphous or crystalline structure.•The elastic films can have also either X-ray amorphous or crystalline structure.•The brittle films exhibit low elastic recovery We<60% and low ratio of the hardness H and the effective Young's modulus E* (H/E*<0.1).•The elastic films exhibit high elastic recovery We≥60% and high ratio of the hardness H and the effective Young's modulus E* (H/E*≥0.1). This article reports on the protection of the brittle ZrSiO film against cracking in bending by the highly elastic top film (over-layer). In experiments the ZrSiO films with different elemental composition and structure were used. Both the brittle and highly elastic films were prepared by magnetron sputtering using a dual magnetron. The brittle film easily cracks in bending. On the other hand, the highly elastic film exhibits enhanced resistance to cracking in bending. Main characteristic parameters of both the brittle and highly elastic films are given. Special attention is devoted to the effect of the structure (crystalline, amorphous) of both the brittle and highly elastic top film on the resistance of cracking of the brittle film. It was found that (1) both the X-ray amorphous and crystalline brittle films easily crack in bending, (2) the highly elastic film can have either X-ray amorphous or crystalline structure and (3) both the X-ray amorphous and crystalline, highly elastic top films perfectly protect the brittle films against cracking in bending. The structure, mechanical properties and optical transparency of the brittle and highly elastic sputtered ZrSiO films are described in detail. At the end of this article, the principle of the low-temperature formation of the highly elastic films is also explained.