Laser Coatings


     We did quite a lot of work on laser based surface protective coatings on various types of materials like tool steel, graphite, and tool bits. Our first work was on molybdenum coating on AISI 4130 steel for which we made use of an intermediate layer based on chromium. Both the coatings (chromium and molybdenum) were prepared by laser melting a preplaced powder layer using a fiber laser. First, a chromium layer was deposited on steel and then a molybdenum layer on top of the chromium layer. It was found that there was a gradual increase in the hardness from the substrate to the top of the molybdenum coating. This work was published in Surface Coatings and Technology in 2009.

     Although some work has been done by Bourell D.L. on carbon-carbon composites, it appears that we are the first research group to demonstrate the feasibility of producing laser based surface coatings on graphite. We successfully deposited titanium, zirconium, and niobium coatings on graphite. Due to lack of facilities for oxidation analysis, the coatings produced on graphite could only be characterized using scanning electron microscope, x-ray diffraction, and secondary ion mass spectroscopy. It was interesting to note that all the three coatings were fully dense. This work was presented at the International Congress on Applications of Lasers and Electro-Optics (ICALEO), Orlando, Florida in 2009. A similar work on W-TiC cermelt coatings on graphite was presented at the International Conference on W, Refractory & Hardmaterials VII, Washington DC in 2008.

Details of all the coatings, experimental data, and characterization results will be posted soon.

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An SEM image showing molybdenum-on-chromium coating on steel.

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SEM images showing niobium coating on graphite (A) and its structure at higher magnification (B).