PROTECTIVE COATING FOR CARBON-CARBON COMPOSITES

CARBON-CARBON (C-C) HAS AN EXTREMELY HIGH STRENGTH-TO-WEIGHTRATIO AND WOULD THEREFORE BE THE MATERIAL OF CHOICE FOR HOT STRUCTURES ON HYPERSONIC VEHICLES IF ITS OXIDATION RESISTANCE COULD BE IMPROVED. TO ACHIEVE THIS OBJECTIVE, A COATING SYSTEM WILL BE DEVELOPED IN WHICH A VERY THIN FILM OF PLATINUM SERVES AS THE FINAL LINE OF DEFENSE AGAINST OXIDATION. PLATINUM HAS A HIGH MELTING TEMPERATURE, EXCELLENT OXIDATION RESISTANCE, AND IS DUCTILE ENOUGH TO AVOID CRACKING DURING THERMAL CYCLING. TO ENSURE GOOD ADHESION, THE PLATINUM FILM WILL BE FORMED ON C-C BY ION BEAM-ASSISTED DEPOSITION (IBAD). IBAD WILL BE USED IN PHASEI TO PLATINUM COAT TWO-DIMENSIONAL C-C COUPONS; THE COUPONS WILL BE EVALUATED FOR OXIDATION RESISTANCE UP TO 2500 DEGREES FAHRENHEIT DURING THERMAL CYCLING. SUCCESSFUL PHASEI RESULTS WILL LEAD TO FABRICATION AND TESTING OF C-C PANELSWITH PLATINUM FILMS FORMING PART OF AN OXIDATION-RESISTANT COATING SYSTEM. THE PLATINUM FILM WILL BE ONE COMPONENT OF A SYSTEM INCORPORATING MATRIX OXIDATION INHIBITORS, CERAMIC SURFACE COATINGS, AND GLASSY CRACK SEALERS--RESULTING IN MULTIPLE LINES OF DEFENSE AGAINST COMPOSITE OXIDATION. CARBON-CARBON (C-C) HAS AN EXTREMELY HIGH STRENGTH-TO-WEIGHTRATIO AND WOULD THEREFORE BE THE MATERIAL OF CHOICE FOR HOT STRUCTURES ON HYPERSONIC VEHICLES IF ITS OXIDATION RESISTANCE COULD BE IMPROVED. TO ACHIEVE THIS OBJECTIVE, A COATING SYSTEM WILL BE DEVELOPED IN WHICH A VERY THIN FILM OF PLATINUM SERVES AS THE FINAL LINE OF DEFENSE AGAINST OXIDATION. PLATINUM HAS A HIGH MELTING TEMPERATURE, EXCELLENT OXIDATION RESISTANCE, AND IS DUCTILE ENOUGH TO AVOID CRACKING DURING THERMAL CYCLING. TO ENSURE GOOD ADHESION, THE PLATINUM FILM WILL BE FORMED ON C-C BY ION BEAM-ASSISTED DEPOSITION (IBAD). IBAD WILL BE USED IN PHASEI TO PLATINUM COAT TWO-DIMENSIONAL C-C COUPONS; THE COUPONS WILL BE EVALUATED FOR OXIDATION RESISTANCE UP TO 2500 DEGREES FAHRENHEIT DURING THERMAL CYCLING. SUCCESSFUL PHASEI RESULTS WILL LEAD TO FABRICATION AND TESTING OF C-C PANELSWITH PLATINUM FILMS FORMING PART OF AN OXIDATION-RESISTANT COATING SYSTEM. THE PLATINUM FILM WILL BE ONE COMPONENT OF A SYSTEM INCORPORATING MATRIX OXIDATION INHIBITORS, CERAMIC SURFACE COATINGS, AND GLASSY CRACK SEALERS--RESULTING IN MULTIPLE LINES OF DEFENSE AGAINST COMPOSITE OXIDATION.