New Excimer Process Rapidly Creates Super Hard DLC Films at Low Temperatures.
New Excimer Process Rapidly Creates Super Hard DLC Films at Low Temperatures The ChallengeDiamond-like (DLC) carbon is widely used to form highly wear-resistant coatings. But current DLC coating methods suffer from various drawbacks. For example, tetrahedral amorphous carbon (ta-C) is a desirable hydrogen-free DLC material known for both its extreme hardness (>40 GPa) and low friction. But typical production methods create films with high internal stress, degrading their performance. Hagen Grüttner and colleagues in the laboratory of Professor Steffen Weissmantel at the University of Applied Sciences Mittweida set out to develop a new process that can create low-stress films and that is suitable for industrial production. Their method is based on pulsed laser deposition (PLD) using the uniquely high pulse energy of Coherent 248 nm excimer lasers.
The key to developing a successful low-temperature production method was to combine two excimer-based processes: pulsed laser deposition (PLD) and annealing. Grüttner explains, “Excimer-based PLD is a well-known industrial process for producing functional films such as high temperature superconducting films. Plus it can be used with low-temperature substrates. However, when the PLD process (or any other process) is used for ta-C, the coating layers often contain huge amounts (e.g., 12 GPa) of residual stress, which greatly compromises their mechanical strength.” Grüttner and colleagues have solved this problem and created thick (microns) ta-C coatings with as little as 0.1 GPa of residual stress…