Attaining a controlled graded distribution of particles in polymerizing fluid for functionally graded materials

Abstract

The precise control on concentration profile of dispersion in functionally graded material (FGM) is essential for obtaining a desired material. A suitable simulation of parameters and an appropriate model that describes the motion of particles in the fluid can predict various aspects those are needed to produce FGM, by gravity sedimentation or centrifugation technique. Simulation was conducted to observe the changes in concentration profile, while using the following equations applicable to polymerizing fluid, and to determine the terminal velocities (V m ) of particles;}/(18 0 e btc ) for centrifugation, where D is the diameter of the spherical particle, s the density of solid particles, l the density of fluid, the viscosity of fluid, g* the acceleration due to gravity, s is the volume fraction of particles, and t c is the elapsed time of curing of thermosetting resin. b is a constant, r is the radius, and is the angular velocity. This simulation demonstrates that the time of centrifugation/sedimentation, particle size, distribution of particle size, and centrifugal/gravitational forces can be effectively utilized to attain a desired concentration profile in graded materials. Simulation also revealed that there exist the possibility of two graded profiles, namely low concentration profile and high concentration profile, in one sample of graded material, made either by centrifugation or sedimentation. Low concentration profile is more sensitive to particle size distribution as compared to high concentration profile. The present simulation method is also sensitive to concentration-measuring methods.

Mode-3 spontaneous crack propagation along functionally graded bimaterial interfaces

“…Similar to the multitude of applications, there are a variety of manufacturing techniques that can produce functionally graded materials. These include controlled exposure to ultraviolet (UV) radiation (Lambros et al, 1999), using laser melt injection (Hosson and Ocelik, 2003), centrifugal molding Watanabe et al, 2005), dynamic shock compression (van Zyl et al, 2005), spark plasma sintering Jiang et al, 2005), pressureless sintering (Pine and Bruck, 2006) and by controlled suspension of particles in polymer matrices (Hashmi, 2006;Kirugulige and Tippur, 2006;Kitey and Tippur, 2005). From the above mentioned examples it is clear that the concepts of manufacturing and applications of FGMs are well established.…”

Simulation of compositional profile in functionally graded materials

“…3 and 4, simulation was performed. Volume fraction of multiparticle system (V mp ri ) at certain position r i in the sample was estimated using the following relations [19]:…”

“…Using Eq. 3, a modified equation of particle velocity in concentrated suspensions that takes into account the viscosity variation due to cross linking reaction of resin has been demonstrated appropriate for moving particles in polymerizing fluid [19]. According to this equation, the maximum terminal velocity v m of particle in a polymerizing fluid under gravitational force was estimated as given below:…”

Studies on dry sliding wear behaviour of functionally graded graphite particle-filled glass-epoxy composites

“…FGMs composites have been manufactured by a variety of processes technique including centrifugal moulding, suspension of particles in polymer matrix, pressure less sintering, spark plasma sintering and laser melt injection. [32][33][34][35][36][37][38] In most of the aforementioned manufacturing processes, micron-to nanometre-sized particles are significantly distributed in the matrix (either a molten metal or polymer) to obtain the desired inhomogeneous material property variation in the composite.…”