Joining of oxide-oxide ceramic matrix composites – A review

Oxide–oxide ceramic matrix composites are attractive for high-temperature structural applications, but their industrial use in complex assemblies requires reliable joining technologies. This review critically compares glassceramic bonding, brazing, adhesive or polymer-derived routes, and mechanical fastening for ox–ox CMCs, focusing on processing conditions, thermo-mechanical compatibility, joint strength, ageing resistance, thermal cycling, and flame exposure. Reported apparent shear strengths range from 2 to 5 MPa for conventional active brazes, 7–18 MPa for glass-ceramic joints, and up to 49 MPa for Ti-based brazed butt joints, showing the strong influence of joint geometry and filler infiltration. SiO₂–Al₂O₃–CaO–MgO and SiO₂–Al₂O₃–TiO₂–Y₂O₃ glassceramics showed stable interfaces after ageing at 850–930 ◦C and survived direct flame exposure at 900 ◦C. Overall, glass-ceramic joining currently offers the best balance between oxidation resistance, thermo-mechanical compatibility, and durability, whereas brazing provides higher strength but greater sensitivity to CTE mismatch and residual stresses