Dear Colleagues,

Surface coating are used as a key strategy to increase the durability of various materials. By coating materials with films accompanied by excellent properties, their original low-quality can be replaced and improved. Currently, various coatings are under intense investigation to produce materials with superior performances for potential applications in the energy and transportation fields. The choice of the deposition technique to ensure high-quality functional coatings is a challenge.

In the last decade, multielement coatings have shown their potential in developing innovative materials. Their functionalization is a primordial strategy for the development of applications, meeting industrial needs. For example, tools used in machining processes are coated with hard films to increase their performance. Other coatings have shown their potential against various degradation factors such as wear, corrosion and oxidation. As such, providing functional coatings with excellent physicochemical properties has become a high priority in the metallurgy field.

We cordially invite you to submit your works to this Special Issue entitled “Advanced Multielement Coatings: Deposition, Materials and Applications”. This Special Issue aims to present experimental and theoretical research describing recent advances in the synthesis of functional multielement coatings, their composition and design, physicochemical properties obtained through the use of different techniques as well as their performances, which could lead to the development of potential applications in energies and transports.

In this Special Issue, original research articles and reviews can be proposed. Research areas may include, but are not limited to, the following:

• Production and characterization;
• Oxynitrides coatings;
• High-entropy films;
• Surface characterization;
• Magnetron sputtering (DCMS and HiPIMS);
• Arc deposition;
• Laser cladding;
• High-temperature oxidation;
• Thermal stability;
• Mechanical and tribological coatings;
• Corrosion;
• Wear;
• Nuclear industry;
• Biomedical;
• Aerospace industry.

We look forward to receiving your contributions.

Dr. Mohamed El Garah
Prof. Dr. Frederic Sanchette
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Coatings is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• thin films
• high-entropy alloys
• oxidation
• wear
• corrosion
• physical vapor deposition (PVD)

1. Title: Titanium oxynitride thin films by reactive sputtering with an independent pulsing of O2 and N2 gases

Authors: Nicolas MARTIN, Jean-Marc COTE, Jean-Yves RAUCH, Joseph GAVOILLE

Abstract: Titanium oxynitride thin films are deposited by DC reactive magnetron sputtering. A pure titanium target is sputtered in a reactive atmosphere composed of argon, oxygen and nitrogen gases. The oxygen mass flow rate as well as that of the nitrogen gas are both pulsed during the deposition time using an independent and rectangular signal for each reactive gas. A constant pulsing period P = 45 s is applied for both reactive gases and a delay time d of 34 s between O₂ and N₂ injection times is set for all depositions. Oxygen and nitrogen duty cycles are systematically and independently changed from 0 to 100% of their pulsing period. From real time measurements of the target potential and sputtering pressure, it is shown that the reactive process alternates between oxidized, nitrided and metallic sputtering modes as a function of the oxygen and nitrogen injection times. The full poisoning of the Ti target surface by oxygen and/or nitrogen can be avoided for some given ranges of O₂ and N₂ duty cycles. Deposition rates of titanium oxynitride films are substantially enhanced and can be adjusted between that of pure Ti and TiN films with a gradual transition of their optical transmittance in the visible range. These results support that titanium oxynitride compounds exhibiting absorbent to transparent behaviors can be precisely sputter-deposited by means of a two reactive gas pulsing process.

2. Title: A simple method for the prediction of the composition of multi-element coatings deposited by magnetron sputtering

Author: Alain Billard

Abstract: Magnetron sputtering is a powerful method for synthesizing metallic or ceramic coatings of more or less complex composition. The deposition of coatings comprising several metallic elements can be carried out from alloy or composite targets, but an interesting alternative consists in sputtering several targets simultaneously on a moving substrate, most often rotating. The production of multi-element alloy coatings by magnetron co-sputtering requires a rotation speed of the substrate holder sufficient to avoid the synthesis of multi-layer or composition gradient coatings and the control of the composition of the films is then dependent on the dissipated power on each target. The synthesis of multi-element coatings with a composition defined by successive approaches may then require a number of development trials which is all the greater as the number of sputtered targets increases. We propose here a simple method to obtain, from a restricted number of development tests, coatings of complex composition by magnetron co-sputtering. After a presentation of the method and the assumptions that govern it, we present examples of the development of coatings with complex composition made from 2 to 4 targets. We then present the limits of this method, when the hypotheses are not respected, in particular in the case of very specific materials, very low powers applied to at least one of the targets or in the presence of a reactive atmosphere in the intermediate regime. Finally, we propose ways to advantageously use this method for the synthesis of complex ceramic coatings by magnetron sputtering in reactive conditions, implementing an optical closed-loop control method: Plasma Emission Monitoring.