Structure and Properties of ZnO Coatings Obtained by Atomic Layer Deposition (ALD) Method on a Cr-Ni-Mo Steel Substrate Type.

Marcin Staszuk,Antonín Kříž,Mariusz Król,Marcin Basiaga,Daniel Pakuła,Dominika Mysłek,Łukasz Reimann

doi:10.3390/ma13194223

Marcin Staszuk, Antonín Kříž + Show 5 more

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https://doi.org/10.3390/ma13194223

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Abstract

This paper aimed to investigate the structure and physicochemical and tribological properties of ZnO coatings deposited by ALD on 316L stainless steel for biomedical applications. To obtain ZnO films, diethylzinc (DEZ) and water were used as ALD precursors. Zinc oxide layers were deposited at the same temperature of 200 °C using three types of ALD cycles: 500, 1000 and 1500. The structure and morphology of ZnO coatings were examined using SEM and AFM microscopes. The XRD and GIXRD methods were used for the phase analysis of the obtained coatings. To determine the resistance to pitting corrosion, potentiodynamic investigations and impedance spectroscopy were conducted in a Ringer solution at a temperature of 37 °C. The obtained results showed that the number of ALD cycles had a significant impact on the structure, morphology and corrosion resistance of the ZnO layers. It was found that after increasing the coating thickness of the ZnO on the material, its electrochemical properties determining the corrosion resistance also increased. Moreover, on the basis of the ball-on-plate tribological investigations, we found a significant reduction in the friction coefficient of the samples with the investigated coatings in relation to the noncoated substrates.

Highlights

Zinc oxide is a semiconductor, most often n-type, from groups II–IV
The analysis showed that the grain size and structure changed with the increase of the number of atomic layer deposition (ALD) cycles
The ZnO layer applied to the steel substrate improved the resistance to corrosion damage of the tested material, which was indicated by a decrease in the value of the corrosion current by one order of magnitude in relation to the uncoated sample and by an over 10-fold increase in the material resistance in the case of 1500 cycles

Summary

Introduction

Zinc oxide is a semiconductor, most often n-type, from groups II–IV. In the case of this oxide, the band gap energy (Eg ) is 3.3 eV at room temperature. The sp hybridized orbitals are created by s orbitals and p cations (Zn++ ), (O− − ) anions, and they bind and antibind. The binding energy of exocytone is 60 meV at room temperature; ZnO is widely used in electronics, optoelectronics and photovoltaics as a semiconductor layer due to these properties [1,2,3]. Zinc oxide has demonstrated protective, regenerative, slightly antibacterial and anti-inflammatory properties. The subject of zinc oxide as a biomaterial is relatively new. Due to its electrical, slightly antibacterial and protective properties, is a material suitable for use in modern

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