Development of BN/SiC Duplex Fiber Coatings for Fiber-Reinforced Alumina Matrix Composites Fabricated by Directed Metal Oxidation

Fareed, A. S.; Schiroky, G. H.; Kennedy, C. R.

doi:10.1002/9780470314234.ch13

Cited by 12 publications

(6 citation statements)

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“…The desirable properties of BN, either in hexagonal or pyrolitic form, have been exploited in a variety of applications, including corrosion-resistant coatings and ceramic components, debonding layers in ceramic-matrix composite materials, , and coatings on nuclear fuel elements . In the majority of these applications, BN is deposited via chemical vapor deposition (CVD) processes in which the precursors of choice are boron trichloride and ammonia .…”

Section: Introductionmentioning

confidence: 99%

Flow-Tube Investigation of the High-Temperature Reaction between BCl₃ and NH₃

McDaniel

Allendorf

1998

J. Phys. Chem. A

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The reaction between BCl 3 and NH 3 to produce dichloroboramine (Cl 2 BNH 2 ) and HCl was probed using a flow-tube reactor interfaced to a molecular-beam mass-sampling system. A composite method that couples the detailed simulation of the fluid mechanics and chemical reactions occurring in the flow tube to an algorithm for nonlinear least-squares optimization was used to extract the kinetic parameters from the experiment. The rate constant for this gas-phase reaction is k (cm 3 mol -1 s -1 ) ) 4.21 × 10 11 exp[-(8350 cal mol -1 )/(RT)] with an estimated uncertainty of 10-15% over the temperature range 670-920 K. The results indicate that surface reactions involving BCl 3 and NH 3 occur in the flow tube, but their contributions to the observed chemical behavior of the system can be quantified and therefore do not affect the kinetic measurements reported here. In addition, the low-energy barrier to this gas-phase reaction has important implications for the chemical vapor deposition of boron nitride from BCl 3 and NH 3 .

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Section: Introductionmentioning

confidence: 99%

Flow-Tube Investigation of the High-Temperature Reaction between BCl₃ and NH₃

McDaniel

Allendorf

1998

J. Phys. Chem. A

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“…The alumina matrix was then infiltrated at approximately 900–1000 °C using a direct metal oxidation process. More details about the processing technique can be found elsewhere ( Fareed et al ., 1993 ). The BN inner layer in the coating was introduced to provide the weak fibre/matrix interface, while the outer SiC layer was deposited to protect the BN from the effects of the oxidizing environment at elevated temperature as well as during matrix infiltration.…”

Section: Methodsmentioning

confidence: 99%

Identification of weak interfaces in composites using transmission electron microscopy

Perez‐Rigueiro

Herrero

LLorca

2000

Journal of Microscopy

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A new experimental technique was developed to identify crack paths with a resolution of nanometres in fibre‐reinforced composites. Cracks were introduced through Vickers indentations on one side of the sample prior to starting the thinning process. Indentations were placed close to the fibres in order to get enough cracks at the fibre/matrix interface in the electron‐transparent region of the thinned sample. The technique was used in a Nicalon‐fibre Al2O3 matrix composite prior to and after a heat treatment at 1200 °C for 1 h. The analysis of the crack paths allowed the identification of the weakest interface in each condition.

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“…Individual thicknesses of BN and SiC coating layers can play a pivotal role in the resulting mechanical properties of the composite [6]. In general, optimal SiC coating thicknesses fall in the 2-4 m range.…”

Section: Role Of the Bn/sic Fiber-matrix Interfacementioning

confidence: 99%

“…Advanced performing techniques such as braiding and 3-D weaving can be used for complex shaped components. Following preform fabrication, a BN/SiC duplex coating [6] is applied on the fibers by chemical vapor infiltration (CVI). The inner BN layer provides a weak fiber-matrix interface, which is essential in order to achieve the desired composite toughness and non-catastrophic failure.…”

Section: Composite Fabricationmentioning

confidence: 99%

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Silicon Carbide and Oxide Fiber Reinforced Alumina Matrix Composites Fabricated Via Directed Metal Oxidation

Fareed

Handbook of Ceramic Composites

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Directed metal oxidation was used to fabricate a variety of fiber-reinforced ceramic matrix composites. Reinforcements included silicon carbide and oxide based fibers. SiC f /Al 2 O 3 components successfully completed engine and rig tests with operating temperatures between 1000 and 1400• C. Replacement of ceramic grade (CG) Nicalon TM fibers with reduced oxygen containing Hi-Nicalon TM fibers resulted in enhanced properties, particularly residual strengths following elevated temperature exposure. Oxide based fibers offer the advantage of a closer coefficient of thermal expansion match with the alumina matrix. Aluminum oxide and mullite based fibers were evaluated as reinforcements. The oxide-oxide composites exhibited a significant drop in strength as test temperatures approached 1000• C. In contrast, composites reinforced with silicon carbide fibers retained over 80% of their room temperature strength and fracture toughness at temperatures as high as 1200• C in air.

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Development of BN/SiC Duplex Fiber Coatings for Fiber-Reinforced Alumina Matrix Composites Fabricated by Directed Metal Oxidation

Cited by 12 publications

References 0 publications

Flow-Tube Investigation of the High-Temperature Reaction between BCl₃ and NH₃

Flow-Tube Investigation of the High-Temperature Reaction between BCl₃ and NH₃

Identification of weak interfaces in composites using transmission electron microscopy

Silicon Carbide and Oxide Fiber Reinforced Alumina Matrix Composites Fabricated Via Directed Metal Oxidation

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Development of BN/SiC Duplex Fiber Coatings for Fiber-Reinforced Alumina Matrix Composites Fabricated by Directed Metal Oxidation

Cited by 12 publications

References 0 publications

Flow-Tube Investigation of the High-Temperature Reaction between BCl3 and NH3

Flow-Tube Investigation of the High-Temperature Reaction between BCl3 and NH3

Identification of weak interfaces in composites using transmission electron microscopy

Silicon Carbide and Oxide Fiber Reinforced Alumina Matrix Composites Fabricated Via Directed Metal Oxidation

Contact Info

Product

Resources

About

Flow-Tube Investigation of the High-Temperature Reaction between BCl₃ and NH₃

Flow-Tube Investigation of the High-Temperature Reaction between BCl₃ and NH₃