Analysis of low temperature viscosity data for three NBS standard glasses

Abstract

The low te mpe r ature viscos iti es of three glasses es tabli shed as. viscosit y sta nd a rds a t th e Nati onal Bureau of Stand ard s are re ported. Th e data overla p res ults which a pp ear on th e published certificates be tween 10" a nd 10" poise and prese nt exte nsive meas ure ments up to 10 '0" poise. The meas ure me nts were made usin g both the fib er-e lo ngation and bea m-be ndin g me thods. No evide nce of an Arrheniu s be hav ior was found for a ny of th e three glasses, even though th e meas ure me nts co vered a na rro w ran ge of te mperatures. An a nalys is of th e inhe re nt meas ure ment unce rtaint y associa ted with each meth od indicates th at th e fiber-elongation meas ure ments are more prec ise th a n the beam-be ndin g meas ureme nts. Ana lys is of th e data a nd its un ce rtai nt y by th e Fulc her Equation supports th e co nc lusions of th e e rror anal ys is.Key word s: Bea m-be ndin g; fib e r·elongation; Fulcher eq uation; glass viscosity; sta nd ard referen ce mate rial ; viscos it y; viscosity sta nd ard.

Sintering Characteristics of Nano-Ceramic Coatings

“…Thus with increasing temperature the decreasing viscosity results in a very high densification rate, much higher than the rate of densification of crystalline materials. The viscosity of silica is 10 -7 Pa s at 800 °C [30]. The sintering rate is also faster for bodies with smaller particles or pores, colloid diameters comparable to conventionally crushed powders, sinter typically orders of magnitude faster.…”

Composition dependence of glass transition temperature and fragility. II. A topological model of alkali borate liquids

“…Such vanishing of the topological degrees of freedom can be associated with the Vogel temperature T 0 ͑x͒ at which the viscosity of a supercooled liquid diverges. 1,48,76,77 In Fig. 3 we compare our model result of Eq.…”

Fabrication of optical fiber of zinc tin borophosphate glass with zero photoelastic constant

“…Viscosity η was calculated using the equation η = W • τ=K, where W is the loaded weight (g), τ is the time (s) needed for 100-µm-depth penetration, and K is an apparatus-dependent constant, determined using a standard glass sample (SRM717) with a known relationship between viscosity and temperature. 6) Intermediate values of viscosity were measured by the fiber elongation method 4) using a cylindrical glass rod with length L = 6-8 mm and diameter 2r = 3.2-4.1 mm. A weight (m = 1.2-4.9 g) for suspension was attached to one end of the preform rod using ceramic paste.…”

“…The glass elongation speed (dL=dt in mm=s) for each composition and temperature was recorded as a function of isothermal heating time at a certain temperature in the furnace. Then, η was estimated in the measured region from the equation η = mgL=[3π(dL=dt)r 2 ], 4,6) where g is gravitational acceleration.…”