Mechanical Properties of Fibre Reinforced Geopolymer Composites Exposed to Operating Fluids

Geopolymers are amorphous aluminosilicate materials which combine low temperature, polymer-like processing with high temperature stability and fire resistibility without toxic smoke generation. For larger expansion of geopolymer composites in aircraft industry, it is necessary to know how it behaves in contact with operating fluids. The specimens were divided into groups exposed to fuel, hydraulic oil, jet oil, and salt mist. Hot/Wet condition until saturation was also applied for one group. Mechanical testing was performed by means of tension, compression, in-plane shear, flexion and interlaminar shear on both reference non-treated and exposed specimens. The largest decrease in all measured strength values was caused by the salt mist. As the most significant, in-plane shear strength was decreased by 85 % by this environment. Operating fluids and hot/wet conditions decreased the shear strength approx. by 15 %. Geopolymer composites are an interesting alternative to existing polymeric and ceramic matrix materials and offers high potential for cost-efficient applications dealing with temperatures up to 1 200°C.