Experimental Study of the Outside Vapor Deposition Process

Abstract

Outside vapor deposition has been studied experimentally, and the deposition process parameters have been examined. The system consisted of an industrial-type burner and a cylindrical bait rod. The following aspects of this process were studied: 1) the temperature prome of the bait rod surface, 2) the deposition efficiency measured in terms of the mass of deposited SiO,, and 3) the size distribution of the deposited particles. The maximum bait rod surface temperature was, as expected, at the stagnation point. The temperature on the surface dropped rapidly along the axis of the bait rod away from the stagnation point; this is expected to innuence the thermophoretic deposition rate. The particle size distribution shows that the particle diameters are near 0.2 pm and above.

Deposition of SiO2Nanoparticles Produced in a Turbulent H2/Om2Flame

“…Turbulence Many studies emphasized thermophoresis as dominant mechanism for particle deposition (e.g., Bautista et al 1990;Graham & Alam 1991;Tandon et al 2005). However, all of these experimental, analytical, and numerical studies were performed for laminar flames only.…”

“…However, their model needed measured particle velocities as input. Graham and Alam (1991) summarized some older work on the OVD process and studied experimentally the deposition efficiencies for variations of carrier gas flow rates, burner-cylinder distances, and fuel equivalence ratios. They suggested optimum operation parameters for their process, which resulted in a deposition efficiency of 83% for burner-cylinder distance of 5.5D, with D being the diameter of the target.…”

Experimental Study of SiO2Soot Deposition using the Outside Vapor Deposition Method

“…This method is still the subject of many review papers (Blankenship and Deneka 1982;Schultz 1980;Wang et al 2008) and of various detailed theoretical works (Filippov 2003;Hong and Kang 1998;Kang and Greif 1993;Tandon et al 2003;Tandon and Murtagh 2005;Tandon and Balakrishnan 2005;Wu and Greif 1996). However, it appears that only few experimental data have been reported in the literature (Cho et al 1998;Graham and Alam 1991) since the OVD process is subject to industrial and intellectual property rights. The report of a detailed experimental study on the fabrication of silica preforms using the OVD method is thus highly desirable in order to try to fill this lack in the literature.…”

Effects of flame temperature and SiCl4 concentration on particle characteristics for synthetic silica glass

“…Frenkel derived an equation about viscous flow sintering model between two particles of equivalent size: (4) where x is the radius of the interface, r is the original radius of the spheres, x/r is the interface increasing rate,γ is the surface tension, t is the time, and η is the viscosity. The sintering rate is inversely proportional to the particle size r. Consequently, particle size control is crucial, which can guide us to choose the parameters in the production.When the particle size is large, the deposition temperature should be increased to decrease the value ofη.…”

“…In overview, the SiO 2 particles generate in an oxy-hydrogen diffusion flame for the hydrolysis and oxidation reactions of SiCl 4 [1] , transport with the flame flow, and deposit on a rotated target to consolidate to glass finally [2,3] . The bulk glass properties depend on the size and morphology of the particles, since control of which plays an important part in synthetic silica glass production [4] .…”