ICMCTF 2026 Session IA2-1-WeM: Surface Modification of Components in Automotive, Aerospace and Manufacturing Applications I

The lifetime of components operating in harsh environments subjected to repetitive contacts in high performance manufacturing operations, gas turbines and automotive engines can be extended by the application of advanced multilayer coating systems. These coating systems need to combine high hardness with resistance to fracture. The cyclic nano- or micro-scale impact test has been shown to be a convenient test method to rank coating resistance to fracture, with coating performance in the test with typically a 1:1 correspondence to the application performance.

In this presentation we will provide an overview of the technique and describe several recent technical developments including (1) higher data acquisition for multi-metric analysis of every impact (2) inclined impact to combine shear and compression forces (3) impact at elevated temperature (4) spatially distributed impact, and show how these are being used in testing (i) thermal barrier coatings (TBCs) in gas turbines (ii) DLC coated steel components in automotive engines (iii) PVD coated steel and coated WC-Co cutting tools.

The multi-metric analysis reveals significantly more about the deformation and wear behaviour in the test than the impact depth alone, showing that in some cases the % dissipated energy in cyclic impact can act as an “early warning signal” for failure as it can be sensitive to the initiation and growth of sub-surface crack networks before crack coalescence and fracture occurs. To simulate applications where cyclic impact events are not perpendicular to the surface inclined impact tests have been performed which have, for example, revealed markedly different effects on the durability of DLC coatings and TBCs. Reasons for these differences will be discussed. To replicate the spatial distribution of multiple impacts that occur when a coated component is subjected to solid particle erosive wear the method has been adapted to produce controlled impacts at different statistically-distributed locations on the sample surface. Tests on the TBCs 7YSZ and gadolinium zirconate clearly showed that the spatially-distributed micro-impact test could replicate differences in erosion resistance and also reproduce the main damage mechanisms and surface morphology that occur.

Magnesium and aluminum alloys are extensively used in the automotive, aerospace and other industries due to their robustness, lightweight, and excellent weight-to-strength ratios. The manufacturing of lightweight structural components for aircraft and various types of vehicles leads to improved fuel efficiency and lower greenhouse gas emissions. However, long term exposure to moisture, pollution, salt and other harsh environments make them susceptible to corrosion. Common mitigation strategies involve surface treatments like ion implantation and protective coatings that can enhance the corrosion resistance of common metals.

In the first part of this talk, an overview of plasma-based coating methods for corrosion protection will be presented. For decades, low pressure plasma systems were employed in the deposition of thin coatings on steel, aluminum and other metals. While the coatings provided significant improvement in corrosion protection, vacuum chambers are often limited in volume, making it difficult to treat large or irregularly shaped parts efficiently.

In recent years, atmospheric pressure plasma systems are preferred for scalable, continuous, and flexible surface treatments. In the second part of this work, the plasma-assisted, large area deposition of dense, organosilicon coatings on Al 6061, AM60 and AZ91D Mg alloys using atmospheric pressure plasma jets will be presented. For the deposition process, clean dry air was used as the plasma generating gas, along with 2 types of siloxane precursors. The process was fully automated, as the plasma jets were moved over the substrates at constant speed with the assistance of a robotic system.

Results from the analysis of coatings with thicknesses ranging from 200nm to 1200nm will be shown. The electrochemical characterization involved immersion of the Mg alloy substrates in a 3.5wt.% NaCl solution, whereas the aluminum substrates were exposed to highly corrosive HCl solutions. Multi-scale image characterization and chemical analysis was performed using scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectrometry (EDS) and scanning transmission electron microscopy system. More information correlating the plasma process parameters to the elemental composition, thickness and corrosion resistance of the coated metals will be presented.

Overall, large area plasma deposition enables uniform, scalable application of anti-corrosion coatings on metal surfaces, making it ideal for industrial components like automotive and aircraft panels. Its atmospheric operation allows integration into continuous production lines, reducing costs while enhancing durability and surface protection.

With the increasing demand for efficiency and sustainability in aerospace applications, the development of lightweight parts represents a critical challenge. This study presents an integrated approach that covers the entire process chain, from alloy and powder development to the production of functional components, made possible through close collaboration between a research institute and industrial partners. Bronze coatings are applied onto aluminium substrates using a laser powder based Directed Energy Deposition (DED) process, aiming to combine low weight with enhanced wear resistance for the production of sliding bearings.

The metallurgical interaction between aluminium and copper-based alloys is highly complex. In addition to differences in physical properties such as thermal expansion, melting point and diffusion behaviour, brittle intermetallic phases tend to form at the interface. These phases often act as crack initiation sites and can lead to delamination.

In this work, bronze coatings are deposited on aluminium substrates using a powder-based Directed Energy Deposition (DED) process. Prior to the deposition, the aluminium substrates undergo appropriate surface preparation, and post-deposition heat treatments are applied to optimise adhesion and coating properties. The resulting microstructure and phase formation at the interface are investigated. Furthermore, this study identifies critical process parameters that affect coating quality and discusses strategies to mitigate interfacial defects.

This study demonstrates the potential of laser-powder-based DED process for the fabrication of lightweight, wear-resistant sliding bearings, and provides valuable insights into the application of copper-based coatings on aluminium substrates for a variety of applications, particularly in the aerospace sector.

Magnesium–aluminum alloys are increasingly utilized in areas requiring lightweight materials, such as the automotive industries and humanoid robotics, due to their advantageous properties. However, their relatively low strength, hardness, and corrosion resistance limit their broader engineering applications. To address these shortcomings, surface modification techniques such as plasma electrolytic oxidation (PEO) are employed to form protective oxide layers that enhance surface performance. In previous studies, sodium phosphate (Na3PO4) solutions were commonly used as electrolytes, while other electrolyte systems have been less frequently investigated. In this study, aluminate–silicate mixed electrolytes with varying concentrations were utilized to fabricate PEO coatings. The surface morphologies were examined using scanning electron microscopy (SEM), and elemental contents were quantified through energy-dispersive X-ray spectroscopy (EDS), the phase compositions were identified by X-ray diffraction (XRD). Furthermore, potentiodynamic polarization, hardness, and indentation tests were conducted to assess the coatings’ performance. The results revealed that the addition of silicate to the aluminate electrolyte enhanced the coating growth rate. Moreover, coatings produced from electrolytes with different concentrations exhibited distinct surface morphologies, as well as varying corrosion and indentation resistance.

The persistent challenges in the field of PVD coatings—both in established and emerging applications—can be effectively addressed through close collaboration along the entire value chain. This paper highlights key milestones achieved through the long-standing partnership between Plansee Composite Materials and Oerlikon Surface Solutions, which has now spanned more than two decades. Substantial support from the Austrian Christian Doppler Research Association has enabled a strong collaboration between industry and a broad network of scientists from leading Austrian research institutions: Montanuniversität Leoben, the University of Innsbruck, and Technische Universität Wien.

Initiated in 2000, this collaboration was guided by clear objectives to advance the development of TiAl- and AlCr-based nitride coatings. Plansee contributed through innovations in target materials design, while Oerlikon provided the industrial platform for PVD coating processes. This paper provides an overview of systematic investigations on how variations in composition influence the properties of PVD-deposited thin films, ultimately leading to the industrial implementation of novel AlCrB- and AlCrSi-based hard coatings. These achievements were realized by establishing fundamental concepts, evaluating new coatings in both laboratory settings and industrial PVD systems, and consistently integrating findings into iterative development cycles.

To address new applications in machining, forming, and high-temperature environments, the research scope expanded beyond nitrides to include borides and carbides, with particular emphasis on enhancing oxidation resistance without compromising hardness.

The outcomes of this collaboration led to the development and successful market introduction of several coating solutions that contribute to a more sustainable and environmentally responsible economy.