LASER-BASED IN SITU CLADDING WITH SILICON NITRIDE

THE PROPOSED PROGRAM RELATES TO THE DEVELOPMENT OF A LASER-BASED METHOD TO CLAD METALS WITH SILICON-BASED CERAMICS. THE CERAMIC LAYER IS TO BE INTIMATELY BONDED TO THE METAL SURFACE BY IN SITU CERAMIC FORMATION AND REACTION WITH THE METAL SUBSTRATE. SUCH CERAMICCLADDED METALS WILL BE LOW-COST, ADVANCED ENGINEERING MATERIALS SUITABLE FOR USE AT HIGH TEMPERATURE UNDER MECHANICAL STRESS. THE OBJECTIVE OF THE PROGRAM IS TO DEMONSTRATE THAT SIH(2) RADICALS FORMED BY CO(2)-LASER MIRPD OF ARYL SILANES WILL REACT IN SITU WITH ND:YAG-LASER HEAT-ACTIVATED METAL SURFACES. BY CARRYING OUT THIS PROCESS IN A NITROGEN-GAS RICH ATMOSPHERE, INITIMATELY BONDED COATINGS OF SILICON NITRIDE ON THE METAL SURFACE ARE EXPECTED. THE CORROSION RESISTANCE AND TEMPERATURE STABILITY PROPERTIES OF THIS CLADDED METAL, AS WELL AS SURFACE MORPHOLOGY AND CHEMICAL COMPOSITION, WILL BE INITIALLY EVALUATED IN THE PHASE I PROGRAM.