Multilayered MAX Phase Coating for High-Speed Missile Control Surfaces and Fins

Missile defense interceptors experience very high axial and lateral accelerations as well as extremely stressful aerothermal environments during endoatmospheric operation. To maximize performance, control surfaces (e.g. fins, strakes, canards) must be a low-density, lightweight, and rigid structure that can operate at high temperature in an oxidative environment. The MAX phase ternary carbide Ti3SiC2, or titanium silicon carbide, is a material of interest for missile control surfaces because it forms a tenacious protective oxide in high temperature oxidizing environments, has high stiffness, behaves plastically, is resistant to thermal shock, maintains its strength at high temperature, and is easily machinable. Multilayered coatings of Ti3SiC2 and SiC have demonstrated oxidation resistance and self-healing characteristics up to 1500°C and during thermal cycling. The multilayered coating can be combined with a lightweight and strong substrate, such as a carbon/carbon (C/C) composite, the molybdenum alloy TZM, or the niobium alloy C103 as an alternative to the steels and nickel-based superalloys that are typically used. C/C, TZM, and C103 are strong, lightweight structural materials that maintain their desirable properties at high temperatures, but they have a low oxidation threshold. A protective multilayered Ti3SiC2/SiC coating would prevent oxidation of the structural substrate and enable a low-density lightweight structural material for missile control surfaces. In recent research, Ultramet developed initial processing conditions to deposit multilayered Ti3SiC2/SiC coatings onto carbon-based substrates and performed preliminary oxidation testing. In this project, the processing conditions and interlayer coatings will be optimized to create a strongly adhered multilayered Ti3SiC2/SiC coating on metallic substrates such as TZM and C103, and the coatings will be further characterized in a high temperature oxidative environment. Additionally, a control surface design will be modeled to examine the thermomechanical performance of the materials under high-speed missile operational loads. Subscale prototype control surface specimens will then be fabricated and characterized in preparation for full-scale component fabrication and testing in Phase II.