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Cerablak™ on ceramics & composites

Refractory ceramics are used extensively in energy, aerospace, and chemical/metal processing industries.  Although most ceramics are chemically-resistant and thermally stable, the surfaces are often porous which leads to ingress of gaseous/liquid species.  Sealing of ceramic surfaces with Cerablak™ films can offer better durability and can limit the leakage of gases desirable for many applications.  Ceramic matrix composites (CMCs) are a new class of advanced ceramic materials intended for high temperature applications demanding high degree of toughness and high strengths.  Cerablak™ can be used as an interface coating on ceramic reinforcements (to induce debonding), protective coating on fibers, or as a matrix material.  The low density, non-wetting properties, and suitable dielectric properties make Cerablak™ an ideal choice for many high-temperature applications.

  • Low-cost solution-based processing

  • Matrix for oxide CMCs-high density, high strength

  • Unidirectional Cerablak™/alumina Nextel 610 CMC ~90 ksi (RT-UTS), 30% strain (alumina filler)

  • >93% density in 2-ply CMC panels with Nextel 610 fabrics

  • Non-bonding interface coatings for oxide/SiC CMCs

  • Protective EBCs for SiC/SiC, C/Sic, and C/C CMCs

  • Excellent fiber strength retention properties (Nextel 610 & 720)

  • Hermetic surface coatings; effectively smoothens surfaces

SEM micrographs of uncoated (left) and coated (right) porous ceramic bodies, showing sealing of pores by Cerablak™ Enhanced surface planarization is induced.
Stress-strain curve showing 0.3% stress and some degree of nonlinearity, corroborated by the fiber pullout seen in the SEM micrograph.
Cerablak™ coatings can protect graphite against oxidation (800°C, 2hr anneal in air).
Excellent fiber strength retention properties have been demonstrated with Cerablak™ coatings on Nextel 610 and 720 fibers annealed to 1100°C. Debonding at fiber/coating interfaces has been observed in minicomposites. TEM evidence demonstrating the thermal stability of Cerablak™ films produced on Nextel 610 fibers and annealed to 1200°C for 100 hours in air is shown on the left.

SEM micrograph of fracture surface of a relatively dense Cerablak™/alumina matrix composite with Nextel 610 reinforcement showing some degree of fiber pull-out even through no interface coating was utilized
Applied Thin Films, Inc.
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