This study provides information about the surface morphology of sputtered yttria-stabilized zirconia (YSZ) thin films from the AFM spectral analysis using the power values of the power spectral density (PSD) function at varying annealing temperatures. We obtained information about fractal features of films such as fractal dimension, correlation length, and surface roughness by interpreting fractal and K-correlation models. The PSDs of the films exhibit an inverse power-law variation at high spatial frequency, which points to the existence of the fractal components in the film’s surface. The annealing temperatures up to 900 °C resulted in a decrease in fractal dimension from 2.60 to 2. The surface roughness increased from 0.10-13.92 nm (obtained from the root mean square) and from 0.04 to 3.95 nm (obtained from the K-correlation model). The films annealed from 500 to 800 °C show fine grain size morphology with Hurst exponent values from 0.40 to 0.53, indicating a homogeneous spatial roughness distribution. While the film annealed at 900 °C has large aggregate grains morphology, suggesting the inhomogeneous spatial distribution of roughness. In contrast, normal self-affine behaviour is observed at lower annealing temperatures. The growth of a sample annealed at the temperature of 900 °C is more likely to be ruled by the step-edge barrier-induced mound growth and inhomogeneous spatial distribution of roughness.

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In the present research, diamond-like carbon (DLC) thin films were applied on steel substrates by means of pulsed-direct current (DC) plasma-enhanced chemical vapor deposition (PE-CVD). The effects of bias voltage and deposition pressure on the films’ structure and properties were investigated. The Raman spectra of the films revealed features typical of G and D bands, indicating the formation of a DLC phase. The results demonstrate that the sp3 carbon fraction or the so-called diamond-like character of the DLC films increased with increasing bias voltage. Moreover, an increase in the bias voltage resulted in a decrease in the film thickness from 800 to 200 nm. Also, the DLC films prepared at a higher deposition pressure showed a higher fraction of sp2-bonded carbon – that is, graphitic domains. Furthermore, it was found that the variation in the bias voltage and deposition pressure also affected the internal stress values of the DLC films in a way that they increased from 1 to 11 GPa when the bias voltage was increased from 475 to 675 V. The effectiveness of DLC films formed on the steel substrates can pave the way for developing a new class of advanced materials to enhance the performance of stainless steel for biomedical applications.

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A series of diamond-like carbon thin films was applied on AISI 316L stainless steel substrates through a pulsed-direct current plasma-enhanced chemical vapor deposition technique to study the effects of working parameters (bias voltage and deposition pressure) on the microstructure and biocorrosion resistance of films. Raman spectra indicated that under low bias voltage and higher deposition pressure, the films possess a higher amount of sp2 structure, lower internal stress and an improved biocorrosion resistance due to a smooth and defect-free morphology. The lamellar sp2 structure blocked a penetration of corrosive entities. The oxygen content of locally corroded areas (∼11·9 wt.%) was much higher than that of non-corroded areas (2·6 wt.%) corroborating galvanic corrosion between carbide and nitride phases. Moreover, by increasing the deposition pressure from 20 to 40 Pa, the internal stress decreased from 1·03 to 0·82 GPa. The results confirmed that it is possible to tailor the properties of the coatings such as structural composition and particularly biocorrosion resistance by the control over the working parameters. Such anticorrosive diamond-like coatings could benefit biomedical implants used for tissue regeneration.