COATINGS FOR HIGH TEMPERATURE POLYMER COMPOSITES

摘要

New erosion and thermo-oxidative coatings for polymer matrix composites (PMCs) used in gas turbine engine applications up to 280°C were prepared and evaluated. T650-35/PMR-15 graphite fiber composites were plasma spray coated using a system comprised of a soft bondcoat and a hard topcoat. The bondcoat was made up of zinc with up to 5% polyimide added to improve the compatibility between the PMC and the topcoat. A design of experiments approach was used to study coating durability (measured by weight loss and tensile adhesion tests) as a function of weight % polyimide in bondcoat, aging time and thermal cycling time, thus the number of cycles in air. Various damage types were identified, quantified, and then correlated to potential mechanisms. Mathematical modeling with the damage quantifiers was attempted for performance and durability prediction. The most critical parameter controlling damage was the number of thermal cycles that the sample saw during aging. The addition of polyimide to the bondcoat provided a modest improvement in tensile properties after aging.