Behaviour of Plasma Spray Coatings under Disruption Simulation

THE BEHAVIOUR OF METALLIC AND CERAMIC PROTECTIVE COATINGS UNDER DISRUPTION SIMULATION WAS STUDIED AND THE DAMAGE PRODUCES WAS CORRELATED TO THEIR PHYSICAL AND STRUCTURAL PARAMETERS. PLASMA SPRAY (PS) AND VACUUM PLASMA SPRAY (VPS) ARE THE TECHNIQUES USED FOR THE PRODUCTION OF THE COATINGS. A VARIETY OF MATERIALS INCLUDING CERAMICS, REFRACTORY METALS AND COMPOSITES HAVE BEEN DEPOSITED IN A LARGE RANGE OF THICKNESSES BY PS AND VPS. COATING POROSITY AND CONSEQUANTLY, THERMAL AND MECHANICAL PROPERTIES OF THE FILMS CAN BE WIDELY MODIFIED CHANGING THE PARAMETERS OF THE PLASMA DEPOSITION. W-RE ALLOYS AND MO ARE TAKEN INTO CONSIDERATION FOR DIVERTOR PLATES, WHILE TIC, TI02 AND AL203 LOW Z CERAMIC MA- TERIALS ARE SELECTED FOR THE FIRST WALL PROTECTION. THE SUBSTRATES STUDIED IN THIS WORK ARE 316 STAINLESS STEEL, CU AND AL. AN ELECTRON BEAM GUN DEVICE WAS USED TO SIMULATE THE ENERGY DEPOSITION OF A PLASMA DISRUPTION ON THE COATED SAMPLES. TESTS WERE CARRIED OUT AT ENERGY DENSITIES RANGING FROM 1.06 TO 1.107 J/M2. THERMAL EFFECTS DUE TO THE ELECTRON BEAM SHOCKS ON COATINGS AND SUBSTRA- TE MATERIALS WERE STUDIED BY METALLOGRAPHIC AND ENERGY DISPERSIVE X-RAY ANALY- SIS (EDXA). THE DAMAGES PRODUCED IN THE SUBSTRATE BY IDENTICAL SHOCK TESTS ON DIFFERENT COATINGS WERE OBSERVED, IN ORDER TO COMPARE THE DEGREE OF PROTECTION PROVIDED BY EVERY COATING AND TO STATE THE MINIMUM THICKNESS NECESSARY TO PRE- VENT THE UNDERLAYING MATERIAL FROM MELTING. GOOD PROTECTIVE COATINGS MUST HAVE HIGH MELTING POINT, GREAT POROSITY AND LOW THERMAL CONDUCTIVITY. SUCH COATINGS ACT AS THERMAL BARRIERS, INCREASING THE SURFACE TEMPERATURE AND RA- DIATING LARGE PARTS OF THE ENERGY BACK. FOR TIC COATINGS A COMPARISON BETWEEN EXPERIMENTAL RESULTS AND NUMERICAL CALCULATION WAS DONENA-NOT AVAILABL