Glass melting batch preparation

Sample Preparation. Two methods were used to produce sodium silicate glass samples for this study. The primary method used conventional glass melting techniques to produce compositions ranging from 12 to 21 wt. % Na20. Batch ingredients, African sand, sodiiam carbonate, and sodium nitrate, were melted at 1600 C for six hours in platinum crucibles, poured into patties and fine ground into 1 1/2" diameter discs with thickness of one to four millimeters. These anhydrous discs were fully hydrated in a one cubic foot autoclave under saturated steam conditions and stored in controlled relative hiimidity desiccators at room temperature. 

It is well known that corrosion of refractories used in the superstructure of glass melting furnaces can occur due to reaction with components of raw batch (also known as batch carryover) such as silica sand and soda ash and also from vapor phase species, such as NaOH. While there is a standard test available from ASTM for corrosion of refiectories from vapors (C987), there is no standard test available for testing corrosion from batch carryover. The ASTM standard, C987, requires the use of either alumina or platinum crucible for melting batch components that produce vapors, such as sodium carbonate. For the purpose of this study, the authors chose to prepare crucibles directly from the fusion-cast AZS and vibro-cast AZS products. 

All ingredients of the emulsion base formulation (Table 1) were accurately weighed for the batch size. The drug and parabens premixed in water were then added to the previously melted emulsion base at 50 2°C and stirred until completely mixed. The samples prepared were cooled to room temperature and stored in glass containers. 

Formation of a glass is a rather simple process. The appropriate batch is prepared, placed in a crucible, heated to form a crystal-free melt, and cooled to room temperature. The sample is examined to determine if it contains crystals, using methods ranging from casual visual examination, to X-ray or electron diffraction. If no crystals are detected, the sample is deemed to be a glass if crystals are detected, it is described as either partially- or fully- crystallized, depending upon the extent of crystallization. 

Melt polycondensation is the most used procedure for the preparation of polyesters such as PBSu or PESu from butylene or ethylene diols and dicar-boxyllc acids. Poly(propylene alkylanedicarboxylate) polyesters can be also prepared by the two-stage melt polycondensation method (esterification and polycondensation) using proper amounts of aliphatic acids and 1,3-PD in a glass batch reactor using a procedure described in detail in Ref. [9]. The esterification reaction progress is monitored by measuring the amount of water produced as a by-product and removed by distillation. Other reaction conditions are included in Scheme 4.4. 

The metallic glass a-Zr2 d (batch identification RCB-5) had been produced by a previously-described helium atmosphere melt-spinning method from a stoichiometric crystalline alloy. The amorphous deuteride was prepared by slowly reacting 2 to 3 cm strips of the glassy ribbon with approximately one atmosphere of D2 gas over a total period of six days. 

Glass with composition (wt<%) 8.25 CaO-I7.75 Na20-74.00 SiOj prepared from conventional batch (type I) or from alkoxides (type II). Differences in viscosity remain even after melting at high temperature (1375°C) for 150h. From Yoldas [58]. 

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