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Ceramic matrix composite

About: Ceramic matrix composite is a research topic. Over the lifetime, 7807 publications have been published within this topic receiving 117020 citations.


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Journal ArticleDOI
TL;DR: In this paper, the authors measured the electrical conductivity and Seebeck coefficient of the B 4 C and B 4C-W 2 B 5 composite ceramics from room temperature up to 1500 K.

36 citations

Journal ArticleDOI
TL;DR: In this paper, the feasibility of noncontact laser ultrasonic inspection of SiC/SiC flat coupons was evaluated using a Michelson interferometer and a Yag laser.
Abstract: Ceramic matrix composites (CMCs) are poised to revolutionize jet engine technology by enabling operation temperatures well beyond those possible with current superalloys, while reducing active cooling requirements and engine weight. Manufacturing of parts formed by silicon-carbide (SiC) fibers in a SiC matrix is now well advanced, with the first non-structural static components entering service in 2017 with the CFM Leap® engine that uses SiC/SiC turbine shrouds. In order to expand the scope of application of CMCs to rotating parts, such as turbine blades, much work is being conducted to understand and characterize the modes of failure of these materials at temperatures beyond ∼ 1100 ° C . In this context, the ability of nondestructively monitoring the formation and progression of damage in CMCs specimens during high-temperature mechanical testing is critical. However, the elevated temperature precludes the possibility of using sensors placed in direct contact with the specimen and therefore severely restricts the range of available NDE techniques. This paper provides the first experimental assessment of the feasibility of noncontact laser ultrasonic inspection of SiC/SiC flat coupons. An Nd: Yag laser is used to excite ultrasonic waves on one side of the specimen while a Michelson interferometer detects the signals emerging on the other side at the epicenter position. The lasers are mounted on synchronized linear stages to form C-scans as in conventional immersion ultrasonics while ablation damage to the surface of the specimen is prevented by operating the lasers at low power density. Despite the complex microstructure of the SiC/SiC material it is found that the measured waveforms are remarkably similar to those observed when conducting the same tests in aluminum specimens. Moreover, it is shown that it is possible to image interlaminar defects caused by impacts, and monitor crack opening under tensile load. Finally, very good signal stability is observed when temperature is increased from 25 to 1250 °C which confirms the feasibility of laser monitoring at high temperature and is consistent with the good thermal stability of ceramic materials.

36 citations

Journal ArticleDOI
TL;DR: In this paper, the effects of whisker orientation on toughening mechanisms were discussed based on microscopic fractographic observation and micromechanics analyses, and the results indicated that the whisker orientations are a decisive factor for the essential toughness of whiskers, and only in the case of small θ and weak interface can whisker pullout occur, and whisker has maximum toughness.
Abstract: Si 3 N 4 ceramic matrix composites reinforced by nearly unidirectionally aligned SiC whiskers have been prepared by extrusion and hot pressing. Unlike the case in traditional Si 3 N 4 ceramic matrix composites reinforced by random SiC whiskers, the mechanical properties of the composites exhibit a significant dependence on whisker orientation. In the direction of whisker alignment for SiC(w)/Si 3 N 4 composites, increments in bending strength and fracture toughness of 200 MPa and 3 MPa·m 1/2 are obtained respectively, compared to the values in the direction perpendicular to whisker alignment. Based on microscopic fractographic observation and micromechanics analyses, the effects of whisker orientation on toughening mechanisms are discussed. The results indicate that the whisker orientation, θ , is a decisive factor for the essential toughening mechanisms of whiskers. Only in the case of small θ and weak interface can whisker pullout occur, and whisker has maximum toughening effect. The results show that effects of whisker strengthening and toughening can be improved simultaneously through whisker oriented alignment. ©

36 citations

Journal ArticleDOI
TL;DR: In this article, a review of directionally solidified eutectic (DSE) composites of boride and carbide constituent phases has been presented, along with current limitations and needs for future developments.
Abstract: Borides and carbides generally have outstanding hardness, excellent wear resistance, and high melting points due to their covalent bonding. Directionally solidified eutectic (DSE) composites of boride and carbide constituent phases have been investigated since the 1970s as an approach to produce dense composite microstructures with added control over the microstructure. A variety of DSE ceramic composites have been developed and evaluated as potential materials for structural and functional applications due to their unique thermo-electro-mechanical properties. Renewed interest over the past few decades has been motivated, in part, by the needs for ultrahigh-temperature composites for aerospace applications along with low-density composites for armor applications. Some directionally solidified boride and carbide DSEs exhibit advantages in material properties over monolithic materials. This study reviews historical and recent research on processing methods, microstructure, crystallography, and material properties (mechanical, electrical, thermal properties, and oxidation resistance) of directionally solidified boride and carbide eutectic ceramic composites. Opportunities along with current limitations and needs for future developments are also reviewed and discussed.

36 citations

Patent
16 Jan 1997
TL;DR: In this article, a method of forming a breakage resistant, erosion resistant ceramic liner for a part comprising the steps of, forming a liner of a ceramic material containing pores; filling the pores with a pre-ceramic polymer resin; and, firing the liner saturated with a polymeric polymer resin at a temperature and for a time which converts the resin into a ceramic within the pores.
Abstract: A method of forming a breakage resistant, erosion resistant ceramic liner for a part comprising the steps of, forming a liner of a ceramic material containing pores; filling the pores with a pre-ceramic polymer resin; and, firing the liner saturated with a pre-ceramic polymer resin at a temperature and for a time which converts the resin into a ceramic within the pores. The liner can be mechanically attached, adhesively bonded or, a metal part can be cast onto the liner by placing the liner within the metal casting mold for the part as a sidewall or integral element thereof. The invention also includes method for producing parts and liners of fiber reinforced ceramic matrix composite by a resin transfer molding process or the like wherein fiber preforms are saturated with liquid pre-ceramic polymer resin. The preforms are then polymerized in a mold, the part removed from the mold, and then fired to transform the polymer to ceramic. The process can also be employed to form hollow parts such as manifolds.

36 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202394
2022236
2021300
2020344
2019433
2018354