Ceramic Matrix Composites: Mechanical Behavior
Sponsored by: MS&T Organization
Program Organizers: Narottam Bansal, NASA Glenn Research Center; J. P. Singh, U.S. Army Research Laboratory; Jacques Lamon, CNRS; Sung Choi, Naval Air Systems Command
Thursday 8:00 AM
October 20, 2011
Room: C112
Location: Greater Columbus Convention Center
Session Chair: Yutaka Kagawa, The University of Tokyo
8:00 AM Invited
Mechanical Performance of Discontinuous Carbon Fiber-SiC Matrix Composites for Wear Components of High-Speed Train Applications: Yutaka Kagawa1; 1Research Center for Advanced Science and Technology, The University of Tokyo
Discontinuous carbon fiber-dispersed SiC matrix composites fabricated by melt infiltration process (CF/SiC) have been expected to use light weight frictional components for brake disk applications in high-speed transportation trains, e.g., Shin-Kansen trains etc. The used CF/SiC composite contains 20 to 40 vol% quasi in-plane randomly distributed discontinuous carbon fibers in SiC matrix. Basic mechanical properties of CF/SiC composites, strength, toughness, impact resistance, damage tolerance, and wear damage etc., are examined and these properties are evaluated in terms of required properties for the brake applications. Application of hybrid structure, i.e., CF/SiC and monolithic SiC laminate, on the mechanical properties are also evaluated. Merits and demerits for applications of the composites are discussed based on a set of experimental results. Candidate application field of the composites in Japan will be also discussed.
8:40 AM Cancelled
Development of a Laser Test Facility for Thermomechanical Characterization of CMCs: Mark Novak1; Frank Zok1; 1UC Santa Barbara
High-temperature aerospace components, such as leading edges and combustor liners, are subjected to simultaneous thermal and mechanical loads in service. The inability to fully reproduce service conditions with standard laboratory test methods (e.g. isothermal furnace tests or room temperature mechanical tests) has motivated the development of a laser heat flux test facility that incorporates a ring-on-ring mechanical test stage. An array of instrumentation and analytical tools, including quantitative thermal imaging and non-contact full-field strain measurement via digital image correlation, provides an information-rich thermomechanical test for materials characterization and selection. Engineering solutions to specific challenges of laser heat flux testing, namely beam shaping and high-temperature imaging, are described. The measurement of thermal expansion, deformation in a thermal gradient, and a high-temperature biaxial flexure test are used to demonstrate the capabilities of this facility.
9:00 AM
High-Temperature Interlaminar Tension Test Method Development for Ceramic Matrix Composites: Todd Engel1; 1Hyper-Therm High-Temperature Composites, Inc.
Ceramic Matrix Composite (CMC) materials are an attractive design option for various high-temperature structural applications. However, 2D fabric-laminated CMCs typically exhibit low interlaminar tensile (ILT) strengths, and interply delamination is a concern for some targeted applications. Currently, standard test methods only address the characterization of interlaminar tensile strengths at ambient temperatures, which is problematic given that nearly all CMCs are slated for service in elevated temperature applications. This work addresses the development of a new test technique for the high-temperature measurement of CMC interlaminar tensile properties.
9:20 AM
Biaxial Flexure Testing of Advanced C/SiC and SiC/SiC Composites: John Shaw1; Michael Rossol1; Mark Novak1; Frank Zok1; 1University of California, Santa Barbara
The thermomechanical response of ceramic matrix composites with protective coatings is difficult to probe experimentally due to the effects of cut edges. New test methods are required to capture the true response of the coated composites under various loadings. The present talk will focus on the use of biaxial flexure tests to impose multi-axial stresses in C/SiC and SiC/SiC composites both at ambient and elevated temperatures. The test obviates the edge effects since none of the cut edges are located within the stressed zone. When combined with high-resolution strain mapping by digital image correlation and advanced pyrometry techniques, such tests provide a rich information set from which insights into mechanisms and mechanics can be gleaned.
9:40 AM Break
10:00 AM
Notch Sensitivity of C/SiC and SiC/SiC Composites: Michael Rossol1; John Shaw1; Frank Zok1; 1University of California Santa Barbara
The talk will focus on the effects of stress concentrators (including notches and holes) on the deformation and fracture response of woven C/SiC and SiC/SiC composites at ambient and elevated temperatures. Full field strain mapping via digital image correlation is performed to characterize the local material deformation in the vicinity of the stress concentrators. Salient aspects of strain mapping in regions of high gradients and at elevated temperature will be described. The measurements are combined with numerical simulations to assess proposed constitutive models for the inelastic response of these composites and to identify appropriate failure criteria.
10:20 AM
Identification of Damage Modes in Ceramic Matrix Composites Using Acoustic Emission Signal Pattern Recognition
: Jacques Lamon1; Nathalie Godin2; Mohamed R'Mili2; Pascal Reynaud2; Gilbert Fantozzi2; 1CNRS; 2INSA de Lyon/MATEIS Laboratory
Identification of damage mechanisms and kinetics is a big issue with a view to predicting the lifetime of ceramic matrix composites (CMC). For this purpose, monitoring of acoustic emission (AE) is a powerful tool. AE consist of transient waves resulting from the sudden release of stored energy. Damage of CMCs involves several phenomena at various length scales including matrix cracking, fiber debonding, fiber failures. The objective of the present paper is to propose a quantitative approach to damage identification based on signal analysis by pattern recognition. An unsupervised classification method was used to differentiate the signals generated during reference fatigue tests on SiC/SiC samples at high temperature. The library of signals that had been built was then used to identify the damage modes generated during fatigue test at different temperatures. For this purpose a supervised classification method was developped. Promising results were obtained. Application to lifetime prediction is discussed.
10:40 AM
Staggered Lamination Design for Enhancement of Mechanical Resistance of Ceramic-Metal Composite: Osayande Ighodaro1; Okenwa Okoli2; Ben Wang2; 1FAMU-FSU College of Engineering, High Performance Materials Institute (HPMI) Florida State University; 2High Performance Materials Institute (HPMI), Florida State University
Ceramic-metal laminated composites are being employed for enhancement of desirable fracture characteristics of ceramic materials. A method has been described whereby the plane of the ductile metallic phase is partially metallic and partially ceramic. The locations of this phase are also staggered across the planes. This design enables more ceramic constituent proportion in the composite thereby reducing loss of modulus introduced by the ductile phase. The locations of the ductile phase (aluminum) were first fabricated in the ceramic (alumina) preform as slots using carbon as fugitive material. The slots were then filled by molten aluminum via pressureless infiltration. The modulus of rupture (MOR) of the fabricated specimens exhibited relatively higher stiffness and graceful fracture in addition to high strengths than the conventional ceramic–metal laminated composite.
11:00 AM
Effects of the Mode of Target Support on Foreign Object Damage in MI SiC/SiC and Oxide/Oxide CMCs: David Faucett1; Sung Choi1; 1NAVAIR
Foreign object damage (FOD) phenomena of a prepreg MI SiC/SiC and an oxide/oxide ceramic matrix composites (CMCs) were assessed using spherical steel ball projectiles in an impact velocity range of 100 to 350 m/s. CMC test coupons were ballistically impacted at a normal incidence angle while supported in three different configurations of full support, partial support, or cantilever support. Surface and subsurface impact damages, typically in the forms of craters, fiber breakage, delamination, and cone cracks, were characterized with respect to the mode of target supports. Effects of the support mode were also determined through residual strength measurements to better assess the severity of impact damage. Some analytical considerations of impact force with respect to the support mode will be also discussed utilizing impact events recorded during impact.
11:20 AM Student
Sintering and Mechanical Behavior of Doped Cr3C2-NiCr Cermets: Commercial vs Steric Entrapment Method Produced 3Y-TZPs: Ali OZER1; Yahya TÜR1; Waltraud KRIVEN2; 1Gebze Institute of Technology; 2University of Illinois at Urbana-Champaign
8 wt% of 3Y-TZPs which were purchased from a commercial source and produced by steric entrapment method by PEG as steric entrapment agent were examined for doping to 75 wt% Cr3C2-25 wt% NiCr cermet. Sintering behaviors were evaluated by measuring relative densities via Archimedes technique and also employing SEM. XRD studies were made to determine the phases present. Primary crystallite sizes of dopants were investigated by XRD software following FWHM method. Results showed that since 3Y-TZP produced by steric entrapment method (StEM) has had a significantly low primary crystallite size determined by XRD, the dispersion was relatively more homogenouos than the purchased 3Y-TZP produced by solid state calcination(SSC) followed by grinding to a certain particle size range. Microhardness, elastic modulus and transverse rupture strength tests were carried out to evaluate the effects of different dopants. SEM analysis was conducted to characterized the fracture surfaces of doped composites, as well.
11:40 AM Cancelled
In Situ Deformations Measurement during Multi-Materials Microwaves and Conventional Heating: Saunier Sébastien1; 1Ecole des Mines de Saint-Etienne
Today the raw materials control, the cutting cost and the manufacturing become economical and ecological issues. Indeed for many applications the research of the good material in the good place, becomes a major interest for many applications. Moreover, the association of a brittle material with another brittle or ductile material is potentially interesting, what is already the case in cermet composites. The powder metallurgy processes constitute a viable solution for the realization of such materials, at profitable cost compared to conventional processes such as joining, welding or surface treatment. Nevertheless, the success to obtain a well assembly requires the control of materials properties: differential green density, shrinkage rate mismatch, coefficient of thermal expansion, physical or chemical interface adhesion. The objective of this work is to monitor the co-sintering of bi-layered materials, ceramic-ceramic (Al2O3 - ZrO2, Al2O3 – WC-Co) or ceramic-metal (Al2O3 - 316L). In this work we used two thermal treatment methods : Conventional and microwaves heating. We endeavored to show the difficulties and the solutions brought at the various stages of the sintering: the setting in layer, the sintering cycle (heating and cooling rates). A special tool, using CCD camera, has been developed for both sintering methods. This not only tracks the shrinkage, as in a dilatometer, but also the presence of cracks, and the deformations of both the part and those at the interface.