Fugitive Interfacial Carbon Coatings for Oxide/Oxide Composites

Abstract

The effectiveness of fugitive interfacial carbon coatings in Nextel™ 720-based composites was investigated. Dense (>90%) matrix (calcium aluminosilicate, 0°and ؎45°) composites and porous matrix (mullite/alumina, eight-harness satin fabric) composites were fabricated and tensile tested in two control conditions (uncoated or carbon-coated) and with the carbon removed (fugitive interface). Results indicated that carbon removal in dense matrix composites did not significantly change unidirectional composite strength, even after long-term exposure at 1000°C. For porous matrix composites, composite strength was independent of the fiber/matrix interface, even after exposure at 1150°C for 500 h in air.

Influence of heat treatment and fiber orientation on the damage threshold and the fracture behavior of Nextel fiber-reinforced Mullite-SiOC matrix composites analysed by acoustic emission monitoring

“…The standard oxide/oxide composite material of EADS Deutschland GmbH/Airbus Group Innovations (UMOX TM ) is used as a representative material for SiOC containing CMCs with a fugitive fiber-matrix interface [23,24]. It has proven to be promising for a combustor liner in gas turbines [5,6], hot structures in re-entry vehicles, [7] or thermal insulations [8].…”

Creep of Hi-Nicalon S Ceramic Fiber Tows at 800 deg C in Air and in Silicic Acid-Saturated Steam

“…Here, a fiber coating is applied, then volatized by oxidation during the fabrication of the CMC, leaving a very small gap between the fiber and the matrix [35,39]. Like the weak interface bond of the first approach, this gap also protects the fiber from an advancing crack in the matrix.…”

“…Load Transfer at Fiber/Matrix Interfaces with a Fugitive Coating: a) An idealized (smooth) interface would protect the fiber from the matrix crack, but no load transfer would occur, whereas b) in reality, the interface is rough and load transfer occurs while still protecting the fiber [39], reproduced with permission from Wiley.…”

“…load transfer and crack deflection) and also to shield the fiber from the oxidizing environment. It has been well documented in literature that non-oxide fiber-reinforced CMCs experience significant degradation in their desired properties at operating temperatures due to oxidation [29,32,35,[38][39][40]. This dual use of the fiber coating makes the superior strength and creep resistance of non-oxide fiberreinforced CMCs available for advanced engineering applications.…”

Fabrication technologies for oxide–oxide ceramic matrix composites based on electrophoretic deposition

“…[1][2][3][4][5][6] Significant research effort is being expended in the optimisation of CMCs, with particular emphasis on the establishment of reliable and cost effective fabrication procedures. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] Electrophoretic deposition (EPD) is the process by which charged particles in a liquid medium move under an applied potential towards an oppositely charged electrode and coagulate there to form a stable deposit. [15][16][17] EPD has been used for the production of CMCs with a variety of ceramic matrices * Corresponding author.…”