Pulsed laser deposition (PLD) is a technique that was developed nearly 2 decades ago to deposit thin films of material on substrates to improve surface properties such as hardness, wear resistance, and lubricity. The Mound Laser and Photonics Center (MLPC) is applying this technology to a variety of coating applications including coating surfaces of molds made by rapid prototyping processes to improve performance of these tools. We are also using PLD to improve surface properties of other materials from plastics to tool steel.
PLD is performed in vacuum and uses a high peak power laser to ablate a target composed of the material that is desired for the coating. After traveling a short distance, the ablated material impinges on the substrate with sufficient kinetic energy to imbed into the surface. This results in growing a thin film (0.5 to 1.0 micrometer) on the surface of the substrate that has improved adhesion properties over other coating techniques. In addition to the improved adhesion, the coatings are fully dense and have optimized crystal structure and morphology. Perhaps the most important attribute of the PLD process is that the coating retains the stoichiometry of the target during the film growth process. Coatings grown in this manner are thin enough to cause virtually no dimensional change to the surface making them ideal for mold coating applications.
This presentation will provide a brief overview of the principles behind PLD as well as how the process can be controlled through the appropriate choice of laser wavelength, fluence, and real-time monitoring. Examples of how the technology is being used to deposit coatings such as graphite, diamond like carbon (DLC), Ni-200, gold, silicon carbide, and stainless steel will be discussed. The presentation will conclude with a discussion of commercial applications of the technique being pursued by the MLPC.