Effect of Alloying Elements on the Tribological Response of Amorphous Carbon Coatings
Understand the Promising Tribological Properties of Gd- and Eu-Doped Amorphous Carbon Films.
Doping and alloying amorphous carbon (a-C) thin films are ways to tailor their mechanical and tribological properties. However, few studies have focused on doping/alloying with rare-earth elements. This study shows that a-C films containing europium (Eu) or gadolinium (Gd) can have promising tribological properties.
Join us for this webinar to see:
- Results of shear strength at the sliding interfaces for a-C films alloyed with Eu or Gd.
- Near-edge X-ray absorption fine structure (NEXAFS) spectromicroscopy data to clarify the origin of the tribological results.
- A model proposed by the researchers for the effect of Gd or Eu introduction on tribological response of a-C.
Guest Speaker Abstract
Dopants and alloying elements are commonly introduced in amorphous carbon (a-C) thin-film materials to tailor the mechanical and tribological properties. While most studies have focused on doping and/or alloying a-C coatings with metals and metalloids, the introduction of rare-earth elements into the a-C matrix is largely unexplored. Here, the friction response of a-C films containing europium ([Eu] = (2.4±0.1) at.%) or gadolinium ([Gd] = (2.3±0.1) at.%) was evaluated as a function of applied normal load in open air and at room temperature. The friction results indicated that alloying a-C films with Gd or Eu leads to a significant reduction of the shear strength of the sliding interfaces. To shed light on the origin of the promising tribological properties of Eu- and Gd-alloyed a-C films, near-edge X-ray absorption fine structure (NEXAFS) spectromicroscopy measurements were performed. The surface-analytical results indicated that no stress-assisted sp3-to-sp2 rehybridization of carbon atoms was induced by the sliding process in the near-surface region of undoped a-C, while the amount of sp2-bonded carbon increased in Eu- and Gd-alloyed a-C films. Based on the spectroscopic results, a model is proposed for the effect of introduction of Gd and Eu into the a-C matrix on the resulting tribological response.
Presenter: Filippo Mangolini, Ph.D. (Associate Professor Cockrell Family Fellowship)
Filippo Mangolini received his M.Sc in Materials Engineering from Polytechnic University of Milan. After obtaining his Ph.D. in Materials Science at ETH Zurich, he moved to the University of Pennsylvania as a Swiss National Science Foundation Fellow. He was then awarded a Marie Curie Fellowship, which allowed him to move to Ecole Centrale de Lyon. Between 2015 and 2017, Filippo was a University Academic Fellow and a Marie Curie Fellow at the University of Leeds. In January 2018 Filippo joined the University of Texas at Austin, where he is currently an Associate Professor in the Department of Mechanical Engineering.
