Abstract
This paper presents the synergy of the effect of two surface engineering technologies—magnetron sputtering (MS-PVD) and atomic layer deposition (ALD) on the structure and properties of 316L steel. Recent studies indicate that PVD coatings, despite their thickness of a few micrometers, have many discontinuities and structural defects, which may lead to pitting corrosion after time. Applying an ALD layer to a PVD coating seals its structure and contributes to extending the service life of the coating. Investigations of the structure and morphology of the produced layers were carried out using a scanning electron microscope (SEM) and atomic force microscope (AFM). In addition, the structure of the coatings was investigated on the cross-section using a scanning-transmission electron microscope S/TEM. The tribological properties of the materials studied were determined by the ball-on-disc method. The corrosion resistance of the tested materials was determined by the electrochemical potentiodynamic method by recording the polarization curves of the anodes. Additional information about the electrochemical properties of the tested samples, including the quality, their tightness, and their resistivity, was obtained by electrochemical impedance spectroscopy (EIS). In addition, the main mechanisms of corrosion and tribological wear were determined by SEM observations after corrosion tests and after tribological tests. The study showed that the fabrication of hybrid layers by MS-PVD and ALD techniques allows obtaining coatings with electrochemical properties superior to those of layers fabricated by only one method.
Highlights
316L austenitic steel has excellent corrosion and mechanical properties, thanks to its chromium and nickel content, which makes it suitable for a variety of industrial and biomedical applications
A Park System XE-100 (Suwon, Korea) atomic force microscope was used to study the morphology of the studied samples
The evaluation of the degree of corrosion resistance first consisted of corrosion tests of atomic layer deposition (ALD)-coated samples at varying numbers of process cycles
Summary
316L austenitic steel has excellent corrosion and mechanical properties, thanks to its chromium and nickel content, which makes it suitable for a variety of industrial and biomedical applications. Many materials exhibit better properties than this steel, e.g., antibacterial properties, and yet this steel is used much more frequently. The main factor that determines the use of 316L steel as a biomedical material is its price and availability. When used for long periods in conditions that do not allow for regular maintenance (e.g., as an implant in the human body), the passive layer, which determines corrosion resistance, becomes brittle and vulnerable to the external environment. One of the ways to improve its corrosion resistance and to increase its biocompatibility is to apply thin films showing the desired properties
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