Predictive, Miniature Co‐Extrusion of Multilayered Glass Fiber‐Optic Preforms

Abstract

A miniature co‐extrusion technique, to produce a concentric multilayered glass fiber‐optic preform of ~3 mm diameter, is modeled and experimentally demonstrated. A three‐dimensional, incompressible, noncavitating, and nonisothermal Computational Fluid Dynamics (CFD) model, similar to one developed in our previous work, is used to predict the dimensions of an alternating four‐layer glass stack feed required to produce the desired layer dimensions in a multilayered‐glass preform extrudate, using a miniaturized and thus more economical co‐extrusion. Strong agreement in the cross‐sectional geometrical proportions of the simulated and experimentally obtained preform supports the prowess of the predictive modeling. Nevertheless, some small deviations between the simulated and experimentally obtained dimensions indicate topics for future rheological study. Performing the co‐extrusion process under vacuum helps to minimize the inter‐layer defects in the multi‐layered fiber‐optic preform. The miniature co‐extrusion potentially removes the need for a postextrusion draw‐down prior to fiber drawing, avoiding devitrification issues possible in non‐oxide novel glass compositions.

Mid-infrared sources for biomedical applications based on chalcogenide glass fibres

“…Additional physical characterisation of the glasses reveals important information such as composition (EDX), crystallisation (XRD), onset glass transition temperature (Tg) and an assessment of viscosity-temperature behaviour that is used to determine glass preform extrusion and fibre drawing conditions and which once again provides key information simulation activities that support the experimental work [11,12].…”

Numerical simulation of the Ge28Sb12Se60 fiber extrusion process

“…suggested 3D CFD model of the glass pipe coextrusion process; based on the use of the model, it is possible to determine the stable part of the preform, in terms of constant core/cladding layer geometry. Moreover, Bhowmick et al 13 . used CFD modeling to predict the dimensions of an alternating four‐layer glass stack feed in a miniature coextrusion technique to produce a concentric multilayered glass fiber‐optic preform.…”

“…For example, Bhowmick et al 12 suggested 3D CFD model of the glass pipe coextrusion process; based on the use of the model, it is possible to determine the stable part of the preform, in terms of constant core/cladding layer geometry. Moreover, Bhowmick et al 13 used CFD modeling to predict the dimensions of an alternating four-layer glass stack feed in a miniature coextrusion technique to produce a concentric multilayered glass fiber-optic preform. Trabelssi et al, 14 using computational simulations, found that at high viscosities of the glass during extrusion of glass preforms, slip occurs at the die/glass interface on the die swell.…”

Co-extrusion of zirconia core-shell rods with controlled porosity in the core

“…In the co-extrusion process, two or more feedstocks are extruded simultaneously. There are two basic possibilities of feedstock arrangement for ceramic co-extrusion: i) the multi-channel or multi-billet extrusion [16,[23][24][25], and ii) co-extrusion of a preform, which is often referred to as feed rod, with serial [20,[26][27][28] or parallel [3,4,19,29,30] ordering of feedstocks in the feed rod. Recently, Kastyl et al [4] have reported on bimaterial core-shell rods composed of dense zirconia toughened alumina (ZTA) core and dense alumina shell that exhibited a combination of high surface hardness of alumina with high fracture force in bending that even exceeded the value of monolithic ZTA.…”