Mechanical surface properties

Development of coating techniques such as PVD and CVD, plasma spray, anodic oxidation, chemical and galvanic deposition created a huge demand to characterize mechanical properties of surfaces. Amongst the properties that are of great interest to be measured are coating adhesion, scratch resistance, coating hardness, elastic modulus and viscoelastic properties. Such measurements are performed not only to develop new coatings and improve the deposition process but also for product quality control.
This talk will introduce the principles of the main techniques (i.e. nano-indentation and scratch) used to evaluate the mechanical surface properties in the nano- and micro-meter scale, the major industries in which these techniques are successfully applied, and the best practices when conducting the experiments.

Coatings bring advantages for functional surfaces on different relevant mechanical performances: better scratch resistance and higher wear resistance for a longer lifetime, lower friction coefficient for a reduced energy consumption. The physical phenomena involved at the surfaces under stress conditions represent a key part in understanding the performances of some coatings. Scratch testing characterizes the scratch resistance and adhesion of coatings. Tribology testing characterizes the wear resistance and friction of surfaces in relative contacts. The unique combination of mechanical testing with 3D-profilometry (confocal microscopy and white-light interferometry) provides new insights into the visualization of surface damages occurring in scratch testing (plastic deformation and delamination of coatings) and tribology (wear and deformation from particles, 3^rd bodies, ..). Applications on different materials and in different industries are shown.

Surface engineering approaches that can prevent wear have become crucial for sustainability and cost reduction. Wear tests used to study these surfaces must represent the real field conditions and this is a big challenge. We have solved these challenges using precision measurements that were designed to simulate wear conditions in gas turbine, windmills, electric vehicles & railways. I will describe some of these case studies and help you understand on how to choose the wear test methods.

Atomic Force Microscopy (AFM) is a versatile technique that not only can image surfaces with a resolution in the nanometre range but also generates 3D data for critical dimensions, roughness, step height and defect analysis. Despite being a contact probe measurement, by operating with forces from the sub-nanonewton up to the millinewton range the system can be used to both non-destructively image samples but also to perform nanomechanical testing of materials in the kPa to GPa range, including mapping of elastic modulus and surface adhesion.

This talk will introduce the basic principles of AFM, show examples of measurements of common industrial samples, and also show how compact AFM systems can be integrated with nanoindenters, hardness testers and 3D optical profilometers to enhance information gathered from these techniques.