PROTECTIVE REFRACTORY ALLOY COMPOSITE COATING USING NOVEL LTAVD TECHNIQUE

THERE IS A CRITICAL NEED TO ELIMINATE THE SEVERE RESTRICTIONS IMPOSED ON THE USE OF MANY ALLOYS IN ADVANCED PROPULSION SYSTEMS DUE TO HYDROGEN EMBRITTLEMENT AND OXYGEN INSTABILITY. THE APPLICATION OF A STABLE COATING THAT COULDPROTECT THE ALLOY FROM THOSE ENVIRONMENTAL HAZARDS WOULD SUBSTANTIALLY IMPROVE THE EFFICIENCY AND PERFORMANCE OF COMPONENTS IN THOSE SYSTEMS. ONE PROPOSAL FOR ACCOMPLISHINGTHIS IS THE APPLICATION OF A ZRO2-TIC ALLOYED COMPOSITE COATING OF A POSSIBLY GRADED COMPOSITION. ZRO2 HAS A THERMAL EXPANSION COEFFICIENT APPROACHING THAT OF METALS (REDUCING THERMAL STRESS), AND THE ZRO2-TIC MATERIAL HAS PREVIOUSLY EXHIBITED LOW WEAR AT BOTH LOW AND HIGH TEMPERATURES. THIS COATING WILL BE DEPOSITED USING A NOVEL COATING APPROACH IN WHICH THE CERAMIC COMPOSITE IS USED AS THE CATHODE IN AN ELECTRIC ARC DISCHARGE MODE. THE PROPOSEDTECHNIQUE DEPOSITS MATERIALS IN AN INNOVATIVE MANNER AT VERYHIGH KINETIC ENERGIES, RESULTING IN EXCELLENT ADHESION AND A HIGH DEPOSITION RATE. IN ADDITION, THIS DEPOSITION OF MULTICOMPONENT REFRACTORY MATERIALS IS ACHIEVED WITHOUT INTRODUCING A SIGNIFICANT AMOUNT OF HEAT TO THE SUBSTRATE. THERE IS A CRITICAL NEED TO ELIMINATE THE SEVERE RESTRICTIONS IMPOSED ON THE USE OF MANY ALLOYS IN ADVANCED PROPULSION SYSTEMS DUE TO HYDROGEN EMBRITTLEMENT AND OXYGEN INSTABILITY. THE APPLICATION OF A STABLE COATING THAT COULDPROTECT THE ALLOY FROM THOSE ENVIRONMENTAL HAZARDS WOULD SUBSTANTIALLY IMPROVE THE EFFICIENCY AND PERFORMANCE OF COMPONENTS IN THOSE SYSTEMS. ONE PROPOSAL FOR ACCOMPLISHINGTHIS IS THE APPLICATION OF A ZRO2-TIC ALLOYED COMPOSITE COATING OF A POSSIBLY GRADED COMPOSITION. ZRO2 HAS A THERMAL EXPANSION COEFFICIENT APPROACHING THAT OF METALS (REDUCING THERMAL STRESS), AND THE ZRO2-TIC MATERIAL HAS PREVIOUSLY EXHIBITED LOW WEAR AT BOTH LOW AND HIGH TEMPERATURES. THIS COATING WILL BE DEPOSITED USING A NOVEL COATING APPROACH IN WHICH THE CERAMIC COMPOSITE IS USED AS THE CATHODE IN AN ELECTRIC ARC DISCHARGE MODE. THE PROPOSEDTECHNIQUE DEPOSITS MATERIALS IN AN INNOVATIVE MANNER AT VERYHIGH KINETIC ENERGIES, RESULTING IN EXCELLENT ADHESION AND A HIGH DEPOSITION RATE. IN ADDITION, THIS DEPOSITION OF MULTICOMPONENT REFRACTORY MATERIALS IS ACHIEVED WITHOUT INTRODUCING A SIGNIFICANT AMOUNT OF HEAT TO THE SUBSTRATE.