“…It was believed that the increased strength was mainly attributed to the improved interfacial bonding strength, which led to the effective load transfer from the matrix to the fibre, and also the PyC interface had an ability to deform and debonding and thus to accommodate the thermal mismatch stresses between the fibre and the matrix [12]. Meanwhile, PyC coating also acted as a diffusion barrier to prevent degrading fibre–matrix reactions and protected the fibre from the loss of fibre strength [35]. Figure 8 (a) Typical stress–strain curves recorded by the tensile test for the C f with and without PyC coating, (b) image of the sample had gone through the tensile test.…”
The microstructure of high strength PAN-based T700 carbon fibre (C f ) with pyrolytic carbon (PyC) coating was characterised. Effects of PyC coating on the surface of carbon fibres, interface characteristics, and mechanical properties of C f /AZ91D composites were evaluated. The results showed that the carbon fibres with PyC coating had higher surface roughness and higher graphitisation which were beneficial to ease hazardous interface reaction. C f -PyC/ AZ91D composites with an optimal PyC coating that is about 150 nm thick and has low texture exhibited ultimate tensile strength of 416 MPa, which demonstrated 35% improvement compared with the C f /AZ91D composites. The increase of mechanical properties of C f -PyC/AZ91D composites could be ascribed to a synergistic effect of the rough C f surface interlocking, an optimum interfacial bonding between fibres and matrix, and protection of fibres from a corrosive attack of the aluminium element in the matrix.
“…It was believed that the increased strength was mainly attributed to the improved interfacial bonding strength, which led to the effective load transfer from the matrix to the fibre, and also the PyC interface had an ability to deform and debonding and thus to accommodate the thermal mismatch stresses between the fibre and the matrix [12]. Meanwhile, PyC coating also acted as a diffusion barrier to prevent degrading fibre–matrix reactions and protected the fibre from the loss of fibre strength [35]. Figure 8 (a) Typical stress–strain curves recorded by the tensile test for the C f with and without PyC coating, (b) image of the sample had gone through the tensile test.…”
The microstructure of high strength PAN-based T700 carbon fibre (C f ) with pyrolytic carbon (PyC) coating was characterised. Effects of PyC coating on the surface of carbon fibres, interface characteristics, and mechanical properties of C f /AZ91D composites were evaluated. The results showed that the carbon fibres with PyC coating had higher surface roughness and higher graphitisation which were beneficial to ease hazardous interface reaction. C f -PyC/ AZ91D composites with an optimal PyC coating that is about 150 nm thick and has low texture exhibited ultimate tensile strength of 416 MPa, which demonstrated 35% improvement compared with the C f /AZ91D composites. The increase of mechanical properties of C f -PyC/AZ91D composites could be ascribed to a synergistic effect of the rough C f surface interlocking, an optimum interfacial bonding between fibres and matrix, and protection of fibres from a corrosive attack of the aluminium element in the matrix.
“…It may be concluded that these materials are inert under low-strain rate deformation, but need a significant amount of mechanical work, for example under highstrain rate plastic deformation, to drive the reaction [25]. It is obvious that further work is warranted in order to determine the products of the possible reactions between Al and carbon fibers [26,27] and between magnesium and carbon fibers [28] are desirable.…”
“…Compared with the initial carbon fibers in preforms, the strength parameters of fiber in the composites will decline due to the damage in the preparation process [35] (such as crack and oxidation). The accurate definition of the mechanical properties of carbon fibers after CVI treatment will play an important impact on the prediction of the mechanical properties of C/C composites.…”
Section: Characterization Of Carbon Fiber After CVI Processmentioning
Numerical simulation with progressive damage criterion is implemented to investigate the effect of porosity on the bending properties of 2D cross-ply carbon/carbon (C/C) composites. The mechanical properties of Pyrocarbon matrix regarding the change of porosity are calculated by using Mori-Tanaka approach. Combining with the stiffness degradation scheme, the ultimate bending strengths are calculated in Abaqus though a user-defined subroutine (USDFLD). Delamination is modelled by inserting cohesive elements between two adjacent plies. A good agreement is obtained when the FEM results are compared to three-point bending experiments. The FEM results show that the bending strength decreases greatly with the increase of porosity. When the porosity reaches up to 18%, the bending strength is decreased by 57%. The major fracture behaviors are interlamination delamination and continuous crack damage in 90˚ plies. With the increase of porosity, more severe interlamination delamination will be slightly aggravated. In addition, the increase of porosity will also accelerate the damage in 90˚ plies.
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