Y. Kagawa

Effect of particle size on light transmittance of glass particle dispersed epoxy matrix optical composites

Abstract The effect of glass particle size, d p , on the light transmittance of epoxy matrix composite has been studied. A glass particle has been incorporated into an epoxy matrix and light transmittances were measured at a wavelength range from 300 to 1100xa0nm. In the same volume fraction, increasing the particle size resulted in an increased light transmittance. This behavior was correlated with the normalized total surface area of the particle, 〈Sa〉, between the particle and matrix. The wavelength dependence of light transmittance of the composite was empirically expressed as a function of 〈Sa〉 and the difference between the refractive index of the particle and that of the matrix in the composite, Δnc.

Effect of interfacial properties on tensile strength in SiC/Ti–15–3 composites

Abstract Effect of interfacial properties on tensile strength in unidirectional SiC/Ti–15–3 composites was discussed with varying consolidation time of the composites. The strength of composites and extracted fibers decreases with increasing consolidation time of the composites, while the strength of matrix is independent of it. Furthermore, the interfacial shear strength increases with increasing consolidation time of the composites, while the interfacial sliding stress is independent of it. Based on these experimental results, it is clear that the rule of mixtures modified with the shear transfer mechanism at the interface, characterized by the interfacial shear strength, could estimate the tensile strength of titanium matrix composites more accurately than the conventional rule of mixtures.

Fabrication of transparent continuous oxynitride glass fiber-reinforced glass matrix composite

Unidirectional-aligned continuous SiCaAlON fiber-reinforced glass matrix composites have been fabricated and their light transmittance was measured. Optically transparent composites with the fiber volume fraction from 0.03 to 0.10 were fabricated by a hot-pressing method. The light transmittance of the composite perpendicular to the fiber axis in the wavelength range from 200 to 700 nm was measured, and found to decrease with the increase of the fiber volume fraction. This decrease is explained by the theory proposed by the authors (Hl and YK). The major source of a light transmittance loss of the composite originates from a phase change of transmitted light in the composite.

Optothermal properties of glass particle-dispersed epoxy matrix composite

Optically transparent polymers are required for the packaging of advanced optoelectric devices; if such materials are available, the communication between the outside and inside devices at near IR light (λ≈ 800 nm) becomes possible. The minimum of the required material properties for the packaging materials are (i) optical transparency at near IR wavelength region and (ii) thermal expansion coefficient close to optoelectronic devices. An epoxy material is one of the strong candidates because the material possesses good optical properties and easy to apply conventional packaging processes. However, the thermal expansion coefficients of epoxy materials are one order larger than those of optoelectronic devices and this thermal expansion mismatch induces severe damage under service condition. Thus, the pure epoxy material could not be used as the packaging material even though its light transmittance is in the required range. The incorporation of glass particles is one of the solutions to reduce the apparent thermal expansion coefficient of epoxy materials, however. The light transmittance after the incorporation is usually lost by the difference between the refractive index of the particle and that of epoxy matrix. Recently, a composite material, which has both an optical transparency and a low thermal expansion coefficient, was reported [1, 2]. The report proved that when the refractive index difference was reduced to the order of 10−3, optical transparency appears in the composite. Theoretical consideration also demonstrates a procedure for the selection of fiber and matrix to achieve optical transparency after the incorporation of a glass fiber into an epoxy matrix [3]. Reports also demonstrated the effect of refractive index difference on the light transmittance [4] and particle size on the light transmittance [5]. However, the relation between the light transmittance and thermal expansion coefficient of the glass particle-dispersed optically transparent epoxy matrix composites is not yet reported. The purpose of this paper is to show the guideline for the property design in light transmittance and thermal expansion coefficient of glass particledispersed epoxy matrix composites. Two different size glass particles were used. The particle had an average diameter of dp= 26 and 85μm. It should be noted that the size of the glass particles was much larger than the wavelength of light in the visible wavelength region. The chemical composition of the glass particle was SiO2 (60 wt %), Al2O3 (17.4 wt %),

The energy release rate for an interfacial debond crack in a fiber pull-out model

The energy release rate for an interfacial debond crack in a ceramic-matrix composite has been derived by the use of the Lame solution for an axisymmetric cylindrical fiber/matrix model. The energy release rate expression includes the important effects of compressive residual stresses and frictional sliding stress on the debonded interface in closed form. A parametric study of the energy release rate is carried out and the effects of various parameters on the energy release rate are clarified. A method of determining the critical interfacial debond length is proposed and is shown to provide more physical insight into the debonding phenomenon on the basis of the energy release rate and the fracture criterion of the interface.

Effect of wear on interface frictional resistance in fiber-reinforced composite: model experimental

The effect of abrasive wear at frictional sliding interface on shear frictional resistance in fiber-reinforced composite has been studied using W fiber-reinforced epoxy model composite. The interface shear frictional resistance decreases with the increase of fiber-matrix relative interface sliding during pushout test. Observation of the matrix surface after the test shows that abrasive wear occurs on the matrix surface caused by the rough fiber during fiber sliding, and this wear results in the decrease of the shear frictional resistance. The coefficient of friction is separated into the contribution of wear and adhesion using a simple analysis. The contribution of wear increases with the increase of fiber surface roughness, and the total coefficient of friction decreases significantly with the proceeding of interface sliding due to the reduction of the wear contribution part.

Growth behavior of short fatigue cracks in a SCS-6:Ti composite

The initiation and growth behavior of short fatigue cracks from the interfacial micro-notches in a SCS-6/Ti composite at various maximum applied stress levels were quantitatively characterized. Micro-notches in the interfacial reaction layer were induced by applying monotonic tensile loading prior to fatigue testing. The propagation and arrest behaviors of each individual crack were carefully monitored. An interface-controlled fatigue cracking model was used to predict several critical parameters which govern the growth behavior of fatigue cracks in the composite.