Geopolymer-Derived Aluminosilicate Matrix Composites Reinforced with Continuous Inconel 601 Fibers: Tensile Properties and Thermo-Oxidative Behavior

Continuous-fiber composite laminates based on Inconel 601 reinforcement and a geopolymer-derived aluminosilicate matrix were fabricated using a slurry-impregnation/prepreg processing route followed by low-temperature consolidation and post-curing. The objective of this study was to evaluate the flexural and tensile properties, as well as the thermo-oxidative behavior, of this composite system. The as-fabricated laminates exhibited a bulk density of 4.05 ± 0.08 g/cm3 and an apparent porosity of 24.88 ± 0.62%. Tensile testing showed measurable mechanical properties for both unidirectional and balanced laminate architectures. The [0]8 laminates exhibited tensile strengths of approximately 327–365 MPa from room temperature to 538 °C, while the [0/90]2S laminates showed a decrease in room-temperature tensile strength, consistent with the lower fraction of load-bearing 0° fibers. Thermo-oxidative exposure in air at 538 °C for 336 h produced no measurable reduction in room-temperature flexural strength; accordingly, accelerated oxidation tests were conducted at higher temperatures to promote observable degradation. These tests indicated a transition from limited oxidation at 538 °C to more uniform oxidation at intermediate temperatures and to more aggressive, localized fiber attack at 816 °C. These results suggest that the material system, although still in its developmental stage, is a candidate for further development toward intermediate-temperature applications (approximately 300–600 °C).