2023 Bill Sproul Award and Honorary ICMCTF Lecture Recipient

Purpose

The Bill Sproul Award and Honorary ICMCTF lectureship is to recognize the achievements of a mid-career researcher who has made outstanding scientific and/or technological contributions in areas of interest to the Advanced Surface Engineering Division (ASED) of the AVS, with an emphasis in the fields of surface engineering, thin films, and related topics.

Biography

Paul Mayrhofer is a University Professor of Materials Science at the Institute of Materials Science and Technology, and chairs the Materials Science Division at the University TU Wien, Vienna, since 2012. He received a Dr. in 2001 and a Habilitation in 2005 in Materials Science at the University of Leoben. Paul spent his post-doc and Erwin-Schrödinger-Fellowship at the University of Illinois at Urbana-Champaign, RTWH Aachen, and Linkoping University. Paul is currently Dean of Academic Affairs for Materials Science, Mechanical Engineering, and Mechanical Engineering – Management at TU Wien. Editor for Short Communications of Vacuum, and on the Editorial Board of Surface and Coatings Technology.

Paul has pioneered age hardening within hard ceramic thin films based on ternary nitrides and borides and is fascinated by phase transitions in general. His research activities focus on the development and characterization of vapor phase deposited nanostructured materials by a combination of computational and experimental material science. He won the prestigious START prize of the Austrian Science Fund and served scientific societies in numerous appointed and elected positions. Paul is an elected member of the Austrian Academy of Sciences. He is active in the ASED, where he has served as Division Chair in 2020. He was Editor of the ICMCTF Proceedings in 2007, 2008, and 2009, and the Program and General Chair of ICMCTF in 2012 and 2013. He also served as the Chair of the ASED Sessions at the AVS International Symposium and Exhibition (2008–11, 2016–17). Paul is a Fellow of AVS for Seminal contributions in the development of vapor phase deposited nanostructured materials and self-hardened protective coatings of ternary nitrides and borides. He has published more than 300 SCI-listed papers in the general field of thin film materials science, with >15,000 citations to these (h-index of 65; GS), and holds 13 patents regarding hard coatings.

Abstract

“Strategies for the Development of Robust and Stable, but also Functional Ceramic Coatings”

Monday, May 22, 2023 – 10:00 AM (PT)
Room: Pacific E

For mechanically dominated load profiles, nitrides are preferred, while oxide materials offer better protection against high-temperature corrosion. Thus, when mechanical and thermal loads are combined, the nitrides used should also have excellent temperature and oxidation resistance. How to develop such nitride materials that can withstand both high mechanical and thermal loads will be the focus of this presentation. In addition, we will also discuss the excellent supercapacitor properties of transition metal nitrides.

Using transition metal nitride coatings, we will discuss important guidelines for material development to improve strength, fracture toughness, and stability. In particular, the stability (emphasis on phase stability to composition and temperature, but also to oxidation) of nitrides is a highly interesting task. For example, while the face-centered cubic (fcc) structure of TiNx has a relatively large homogeneity range, the fcc structure of other transition metal nitrides (such as MoNx and TaNx) is extremely sensitive to small chemical variations, even if only the vacancy concentration changes. We will use these model systems to explore the possibilities of alloy and structural developments.

Among the many alloying elements that have been studied for (Ti,Al)N-based coatings, tantalum is one of the most versatile, capable of simultaneously increasing strength, fracture toughness, thermal stability, and oxidation resistance. This can be further improved when alloyed with Si and reactive elements.

The concept of high entropy is also very beneficial for hard ceramic thin films. We will see that, for example, (Hf,Ta,Ti,V,Zr)N and (Al,Cr,Nb,Ta,Ti)N easily outperform their commonly used binary or ternary constituents in terms of thermal stability and thermomechanical properties. In addition, all of the highly entropic ceramic sublattice thin films studied were relatively insensitive to variations in deposition parameters-which is good because their properties are at a high level.

With superlattice coatings, we will discuss how such nanolamellar microstructures can also simultaneously improve strength and fracture toughness.

However, we will also investigate the performance of electrochemical supercapacitors, which strongly depends on chemical stability, accessible surface area, and electrical conductivity. Transition metal nitrides are also excellent candidates for this purpose, but must have a very open-pore microstructure. Glancing angle deposition enables the fabrication of such zigzag-structured electrodes based on γ-Mo2N, combining excellent electrochemical energy storage capabilities with excellent mechanical flexibility.

The individual concepts allow the materials to be designed to meet the ever-growing demand for further coatings tailored to specific applications.