ULTRA 2000 OPTIMIZATION AND SCALEUP FOR THE OXIDATION PROTECTION OF CARBON-CARBON COMPOSITES

THE ABILITY TO OPERATE GAS TURBINE ENGINE COMPONENTS AT TEMPERATURES OF 1600-2000 DEG C REPRESENTS A CONSIDERABLE INCREASE IN BOTH THRUST AND FUEL EFFICIENCY FOR THESE ENGINES, AND IS CRITICAL TO MEETING IHPTET PERFORMANCE GOALS. THE STRENGTH OF CARBON-CARBON COMPOSITES (C-C), PARTICULARLY AT ELEVATED TEMPERATURES, MAKES THEM AN ATTRACTIVE POTENTIAL STRUCTURAL MATERIAL FOR GAS TURBINE ENGINE APPLICATIONS. HOWEVER, THE OXIDATION THRESHOLD OF C-C IS ONLY ABOUT 370 DEG C. OPERATION AT HIGHER TEMPERATURES IN AN OXIDIZING ENVIRONMENT ULTIMATELY REQUIRES OXIDATION-PROTECTIVE COATINGS FOR EXTENDED LIFETIMES. ULTRAMET HAS DEVELOPED A PROPRIETARY OXIDATIONRESISTANT COATING SYSTEM, ULTRA 2000, BASED ON THE HAFNIUM CARBIDE/ SILICON CARBIDE (HFC/SIC) SYSTEM THAT HAS DEMONSTRATED OXIDATION PROTECTION FOR CARBON-CARBON COMPOSITES IN ONE ATMOSPHERE OF AIR AT 1800 DEG C FOR EXTENDED PERIODS (HOURS) AND TO 1925 DEG C FOR SHORTER PERIODS. THIS COATING, DEPOSITED BY CHEMICAL VAPOR DEPOSITION (CVD), UTILIZES THE FORMATION OF HAFNIUM SILICATE TO REDUCE OXYGEN DIFFUSION THROUGH THE COATING. THIS PHASE IS SIGNIFICANTLY MORE STABLE THAN CURRENT INHIBITOR MATERIALS, ALLOWING THE USE OF C-C IN THE 1600-2000 DEG C RANGE. IN THIS PHASE I PROGRAM, ULTRAMET PROPOSES TO MOVE ULTRA 2000 INTO THE NEXT STAGE OF ITS DEVELOPMENT, INVOLVING OPTIMIZATION OF THE COATING THICKNESS AND STRUCTURE IN RELATION TO BOTH THERMAL AND MECHANICAL PROPERTIES. THIS WILL BE FOLLOWED BY INVESTIGATION OF PROCESS SCALEUP TO LARGE IRREGULAR SURFACES. ULTRAMET WILL WORK CLOSELY WITH A LEADING SMALL GAS TURBINE ENGINE MANUFACTURER, WHICH WILL PROVIDE SPECIFIC DESIGN AND PERFORMANCE INFORMATION ON A SELECTED C-C TURBINE ENGINE COMPONENT, TO BE APPLIED TO THE ULTRA 2000 OPTIMIZATION AND SCALEUP EFFORT.