Plasma enhanced chemical vapor deposition(PECVD) is being increasingly used for the fabrication of transparent dielectric optical films and coatings. This involves single-layer, multilayer, graded index, and nanocomposite optical thin filmsystems for applications such as optical filters, antireflective coatings, optical waveguides, and others. Beside their basic optical properties (refractive index, extinction coefficient, optical loss), these systems very frequently offer other desirable “functional” characteristics. These include hardness, scratch, abrasion, and erosion resistance, improved adhesion to various technologically important substrate materials such as polymers, hydrophobicity or hydrophilicity, long-term chemical, thermal, and environmental stability, gas and vapor impermeability, and others. In the present article, we critically review the advances in the development of plasma processes and plasmasystems for the synthesis of thin film high and low index optical materials, and in the control of plasma–surface interactions leading to desired film microstructures. We particularly underline those specificities of PECVD, which distinguish it from other conventional techniques for producing optical films (mainly physical vapor deposition), such as fabrication of graded index (inhomogeneous) layers, control of interfaces, high deposition rate at low temperature, enhanced mechanical and other functional characteristics, and industrial scaleup. Advances in this field are illustrated by selected examples of PECVD of antireflective coatings, rugate filters, integrated optical devices, and others.

Plasma deposition of optical films and coatings: A review

Durability of nanosized oxygen-barrier coatings on polymers

Defect-interface interactions

At present, there is neither standard test procedure nor standard methodology for assessment of toughness of thin films. However, researchers have long been trying to make such measurements, thus a spectrum of test methods have been developed, mostly each in its own way. As qualitative or semiquantitative assessment, a simple plasticity measurement or scratch adhesion test can mostly suffice. For quantitative description, however, a choice of bending, buckling, indentation, scratching, or tensile test has to be made. These testing methods are either stress-based or energy-based. This paper gives a critical review on these methods and concludes that, for thin films, the energy-based approach, especially the one independent of substrate, is more advantageous.

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Toughness measurement of thin films: a critical review

BMP-2 liberated from biomimetic implant coatings induces and sustains direct ossification in an ectopic rat model.

Quasicrystalline low-friction coatings

Progress towards standardisation of ball cratering

Coatings of three different compositions (Al65Cu20Fe15, Al64Cu18Fe8Cr8, and Al67Cu9Fe10.5Cr10.5Si3) were realized by various thermal deposition techniques. They were studied in the as-deposited state and after annealing. In view of potential applications, these quasicrystalline coatings were examined from the point of view of tribology: friction and wear. Some basic components of friction such as roughness, plowing, and adhesion have been studied in scratch testing. The friction resistance of the coating is strongly dependent on its inherent porosity, hardness, and thickness. The damage of the coatings is essentially brittle though some ductile behavior is observed. Static indentation hardness is in the range 500–600 HV0.03 (5–6 GPa), whereas the scratch hardness varies from 1.4 to 2.4 GPa depending on the percentage of porosity. Friction coefficients (measured at constant load of 20 N) were found to be typically 0.07 and 0.20 for diamond (tip radius R = 0.79 mm) and AISI 52100 (radius R = 0.79 mm) indenters, respectively.

J. von Stebut

Papers

Quasicrystalline low-friction coatings

Progress towards standardisation of ball cratering

Tribological properties of quasicrystalline coatings

Results from an interlaboratory exercise to validate the micro-scale abrasion test

The nano-scratch tester (NST) as a new tool for assessing the strength of ultrathin hard coatings and the mar resistance of polymer films