Thermophysical and mechanical properties of near-stoichiometric fiber CVI SiC/SiC composites after neutron irradiation at elevated temperatures

Recuperators for micro gas turbines: A review

Comparison of thermal and ablation behaviors of C/SiC composites and C/ZrB2–SiC composites

This study reports on the effects of axial thermal residual stresses, cyclic loading and presence of notches on the tensile performance of a SiC-fiber-reinforced barium–magnesium–alumina–silicate (BMAS) ceramic matrix composite. The residual stress state of the composite was experimentally measured by interrogation of the tensile curves at a uniquely well-defined common intersection point of unloading–reloading cycles in the tensile domain. Notch presence was critical on the material’s mechanical response and promoted catastrophic failure shortly after the achievement of a saturated matrix crack state. The result of cyclic loading was an increase by 20% in sustainable stress throughout loading, as compared to pure tension. Scatter in elastic properties within specimens of different notch-to-width ratios was reconciled with theoretical expectations by application of a translation vector approach in the stress–strain plane, based on the material’s residual stress state. Acoustic emission and infrared thermography provided valuable insight into damage identification, location and sequence.

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Cyclic loading of a SiC-fiber reinforced ceramic matrix composite reveals damage mechanisms and thermal residual stress state

This article is a detailed review of the measures to modify the high-temperature mechanical properties of silicon carbide ceramic matrix composites (SiC CMCs), namely toughness, high-temperature stability and wear resistance Additionally, it briefly describes the common processing methods of the SiC CMCs and their application in the high-temperature field of aerospace The advantages and disadvantages of various existing processing and molding methods for the SiC CMCs are also discussed The high-temperature mechanical properties of the SiC CMCs are mainly affected by the properties of the matrix, added phase and interface It is crucial to reduce the crystal defects of the matrix and select a suitable enhancement phase for an elevated performance Moreover, it is important to improve the bonding at the interface between the enhancement phase and the matrix This review is expected to provide useful information for the subsequent development of complex SiC CMCs for high-temperature applications

Advances in modifications and high-temperature applications of silicon carbide ceramic matrix composites in aerospace: A focused review

Modeling stress-dependent matrix cracking and stress-strain behavior in 2D woven SiC fiber reinforced CVI SiC composites

Stress-rupture tests were conducted in air, vacuum, and steam-containing environments to identify the failure modes and degradation mechanisms of a carbon fiber-reinforced silicon carbide (C/SiC) composite at two temperatures, 600 and 1200 C. Stress-rupture lives in air and steam containing environments (50 - 80% steam with argon) are similar for a composite stress of 69 MPa at 1200 C. Lives of specimens tested in a 20% steam/argon environment were about twice as long. For tests conducted at 600 C, composite life in 20% steam/argon was 20 times longer than life in air. Thermogravimetric analysis of the carbon fibers was conducted under similar conditions to the stress-rupture tests. The oxidation rate of the fibers in the various environments correlated with the composite stress-rupture lives. Examination of the failed specimens indicated that oxidation of the carbon fibers was the primary damage mode for specimens tested in air and steam environments at both temperatures.

Effect of Environment on the Stress-Rupture Behavior of a Carbon-Fiber-Reinforced Silicon Carbide Ceramic Matrix Composite

In support of NASAs Aeronautics Research Mission, the Glenn Research Center has developed and assessed various constituents for a high temperature (2700F) SiCSiC CMC system for turbine engine applications. Combinations of highly creep-resistant SiC fibers, advanced 3D weaves, durable environmental barrier coatings (EBCs), and a 2700F-capable hybrid SiC matrix are being developed evaluated. The resulting improvements in CMC mechanical properties and durability will be summarized. The development and validation of models for predicting the effects of the environment on the durability of CMCs and EBCs and other operating-environment challenges including the effect of CMAS (calcium magnesium aluminosilicate) degradation of EBCs will be discussed. Progress toward the development of CMC joining technology for 2400F joint applications will also be reviewed.

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Overview of CMC (Ceramic Matrix Composite) Research at the NASA Glenn Research Center

LibertyWorks®, a subsidiary of Rolls-Royce Corporation, first studied CMC (ceramic matrix composite) exhaust mixers for potential weight benefits in 2008. Oxide CMC potentially offered weight reduction, higher temperature capability, and the ability to fabricate complex-shapes for increased mixing and noise suppression.In 2010, NASA was pursuing the reduction of NOx emissions, fuel burn, and noise from turbine engines in Phase I of the Environmentally Responsible Aviation (ERA) Project (within the Integrated Systems Research Program). ERA subtasks, including those focused on CMC components, were being formulated with the goal of maturing technology from Proof of Concept Validation (Technology Readiness Level 3 (TRL 3)) to System/Subsystem or Prototype Demonstration in a Relevant Environment (TRL 6).In April 2010, the NASA Glenn Research Center (GRC) and Rolls-Royce (RR) jointly initiated a CMC Exhaust System Validation Program within the ERA Project, teaming on CMC exhaust mixers for subsonic jet engines. The initial objective was to fabricate and characterize the performance of a 0.25 scale low bypass exhaust system that was based on a RR advanced design, with a 16-lobe oxide/oxide CMC mixer and tail cone (center body). Support Services, LLC (Allendale, MI) and COI Ceramics, Inc. (COIC) supported the design of a mixer assembly that consisted of the following oxide/oxide CMC components mounted on separate metallic attachment flanges: a) a lobed mixer and outer fan shrouds, and b) a tail cone. TRL 4 (Component/Subscale Component Validation in a Laboratory Environment) was achieved in a cost-effective manner through subscale rig validation of the aerodynamic and acoustic performance via testing at ASE FluiDyne (Plymouth, MN) and at NASA GRC, respectively. This encouraged the NASA/ RR/COIC team to move to the next phase of component development; full scale CMC mixer design for a RR AE3007 engine. COIC fabricated the full scale CMC mixer, which was vibration tested at GRC under conditions simulating the structural and dynamic environment of a mixer. Air Force Research Laboratory (AFRL, Wright-Patterson Air Force Base (WPAFB)) provided test support by assisting with instrumentation and performing 3D laser vibrometry to identify the mixer mode shapes and modal frequencies over the engine operating range.Successful vibration testing demonstrated COIC’s new process for fabricating full scale CMC mixers and the durability of the Oxide CMC component at both room and elevated temperatures. A TRL≈5 (Component Validation in a Relevant Environment) was attained and the CMC mixer was cleared for ground testing on a Rolls-Royce AE3007 engine for performance evaluation to achieve TRL 6.Copyright © 2015 by ASME and Rolls-Royce Corporation

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Oxide/Oxide Ceramic Matrix Composite (CMC) Exhaust Mixer Development in the NASA Environmentally Responsible Aviation (ERA) Project

A novel attachment approach for positioning sensor lead wires on silicon carbide-based monolithic ceramic and fiber reinforced ceramic matrix composite (FRCMC) components has been developed. This approach is based on an affordable, robust ceramic joining technology, named ARCJoinT, which was developed for the joining of silicon carbide-based ceramic and fiber reinforced composites. The ARCJoinT technique has previously been shown to produce joints with tailorable thickness and good high temperature strength. In this study, silicon carbide-based ceramic and FRCMC attachments of different shapes and sizes were joined onto silicon carbide fiber reinforced silicon carbide matrix (SiC/ SiC) composites having flat and curved surfaces. Based on results obtained in previous joining studies. the joined attachments should maintain their mechanical strength and integrity at temperatures up to 1350 C in air. Therefore they can be used to position and secure sensor lead wires on SiC/SiC components that are being tested in programs that are focused on developing FRCMCs for a number of demanding high temperature applications in aerospace and ground-based systems. This approach, which is suitable for installing attachments on large and complex shaped monolithic ceramic and composite components, should enhance the durability of minimally intrusive high temperature sensor systems. The technology could also be used to reinstall attachments on ceramic components that were damaged in service.

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J. Douglas Kiser

Papers

Modeling stress-dependent matrix cracking and stress-strain behavior in 2D woven SiC fiber reinforced CVI SiC composites

Effect of Environment on the Stress-Rupture Behavior of a Carbon-Fiber-Reinforced Silicon Carbide Ceramic Matrix Composite

Overview of CMC (Ceramic Matrix Composite) Research at the NASA Glenn Research Center

Oxide/Oxide Ceramic Matrix Composite (CMC) Exhaust Mixer Development in the NASA Environmentally Responsible Aviation (ERA) Project

Novel Approach for Positioning Sensor Lead Wires on SiC-Based Monolithic Ceramic and FRCMC Components/Subcomponents Having Flat and Curved Surfaces