The modelling of shear stress transfer in Hi-Nicalonα-Si3N4 ceramic-matrix composites by the use of micro-indentation tests

The CNTs/Si3N4 ceramic matrix composites were prepared by the reaction bonded processing. The phase compositions, chemical compatibility, mechanical properties, and microwave attenuation properties of the composites were investigated. XRD analysis shows the composites consist mainly of the α- and β-Si3N4, with a trace of unreacted silicon. The SEM micrograph displays the fractured surface of the composites studs with intact CNTs, indicating that CNTs and Si3N4 are chemically compatible. The composites with 1.0wt.% CNTs have a strength of 280 MPa, hardness of 8.2 GPa and toughness of 2.3 MPa·m0.5. The average value of the transmission attenuation reaches 6 dB at X band, indicating the composites have a potential for application in electromagnetic adsorbing or shielding.

Download Full-text

Processing of Non-Oxide Ceramic Matrix Composites: An Overview

Advances in Science and Technology ◽

10.4028/www.scientific.net/ast.50.64 ◽

2006 ◽

Vol 50 ◽

pp. 64-74 ◽

Cited By ~ 5

Author(s):

Roger R. Naslain

Keyword(s):

Shear Stress ◽

Thin Layer ◽

Ceramic Matrix Composites ◽

Ceramic Matrix ◽

Oxide Ceramic ◽

Matrix Composites ◽

The Matrix ◽

Low Shear Stress ◽

Compliant Material ◽

Low Shear

Ceramic matrix composites (CMCs) comprise a fiber reinforcement embedded in a ceramic matrix, the two main constituents being bonded through an interphase, which is a thin layer of a compliant material with a low shear stress, arresting and deflecting the matrix microcracks formed under load. Non-oxide CMCs, such as C/C ; C/SiC or SiC/SiC, are fabricated from a suitable precursor of the matrix, following a gaseous (CVI-process), a liquid (PIP and RMI processes) or a slurry (SI-HPS) routes. Each of these routes is briefly depicted focusing on fundamental aspects and its advantages and drawbacks discussed. Possible extensions of the processes to new composites are suggested. Finally, a comparison of these techniques, in terms of processability and composites properties is presented.

Download Full-text

A micromechanical vibration damping model of fiber-reinforced ceramic–matrix composites considering interface debonding

Proceedings of the Institution of Mechanical Engineers Part L Journal of Materials Design and Applications ◽

10.1177/1464420720969711 ◽

2020 ◽

pp. 146442072096971

Author(s):

Longbiao Li

Keyword(s):

Shear Stress ◽

Ceramic Matrix Composites ◽

Ceramic Matrix ◽

Vibration Damping ◽

Dissipated Energy ◽

Interface Debonding ◽

Matrix Composites ◽

Fiber Reinforced ◽

Stress Dependent ◽

Damping Model

A micromechanical vibration damping model of fiber-reinforced ceramic–matrix composites is developed considering interface debonding. The relationship between the stress-dependent composite damping and interface debonding is established. Effects of material properties and damage-related parameters on the vibration damping of fiber-reinforced CMCs are discussed. Experimental vibration damping with interface debonding of C/SiC composites is predicted. When the vibration frequency increases from f = 1–5 Hz, the vibration damping decreases due to the increasing dynamic interfacial shear stress and low frictional dissipated energy in the debonding region. The composite vibration damping decreases with increasing fiber volume, matrix crack spacing and interface shear stress, and increases with fiber radius and fiber elastic modulus. When the interface debonding energy increases, the vibration damping decreases when the interface partial debonding and approaches the same value when the interface complete debonding, and the vibration stress for complete interface debonding increases.

Download Full-text

Modelling of Hysteresis Behavior of Ceramic Matrix Composites

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.795.180 ◽

2019 ◽

Vol 795 ◽

pp. 180-187

Author(s):

Xue Feng Teng ◽

Duo Qi Shi ◽

Xiao Guang Yang

Keyword(s):

Shear Stress ◽

Sliding Friction ◽

Hysteresis Loops ◽

Ceramic Matrix Composites ◽

Friction Stress ◽

Ceramic Matrix ◽

Static Friction ◽

Matrix Composites ◽

Hysteresis Behavior ◽

Macro Scale

Under cyclic loading, the fiber-reinforced ceramic matrix composites exhibits hysteresis behavior due to the friction stress. When the matrix/fiber debonding occurs, the shear stress is transferred by friction stress on the debond surface. The friction stress is derived from the equilibrium equation of debond fiber in the unit cell. The result indicates that friction shear stress of a single debond fiber can be described by bilinear law due to the static friction and sliding friction. The nonlinear characteristic of friction stress at macro scale attributes to the distribution of the fiber pullout length. The hysteresis loops arise due to the friction stress and the shape is dominated by the evolution of friction during loading/unloading process. The model decoupled the shear stress into two independent terms: the first term represents the shear stress on well bond interface and the second term represents friction shear stress on debond interface. The method developed in this paper is employed to study the hysteresis behavior of C/SiC composite subjected to arbitrary cyclic load. The hysteresis behavior of C/SiC composite is predicted and compared with experimental data.

Download Full-text