This part of ISO 7884 specifies a method of determining the an-nealing point and the strain point of a glass by beam bending. These values have been found useful for specifying the cooling programme in the production of glassware. The annealing point and strain point include a well-defined temperature decrease during the measurement.At temperatures corresponding to the annealing and strain points, the viscosity of glass is highly time dependent. Hence, any viscosities that might be derived or inferred from measurements carried out according to this part of ISO 7884 cannot be assumed to represent equilibrium structural con-ditions. Therefore, the insertion of the strain point into the VFT-equation (see ISO 7884-1) is always impossible. The inser-tion of the annealing point causes in some cases marked failures.NOTE —The annealing and strain points by beam bending can also be determined using devices as specified in ISO 7884-4, but these devices are more expensive and the procedures lead to some viscosity-temperature and viscosity-time relationships besides the fixed points. In this part of ISO 7884, however, the device and procedure are restricted to the fixed-point determination.note:* 1 dPa·s = 1 dN·s/m = 1 P(P is the symbol for poise)
BS 7034-7-1988由英国标准学会 GB-BSI 发布于 1989-01-31,并于 1989-01-31 实施。
BS 7034-7-1988 在中国标准分类中归属于: Q30 陶瓷、玻璃综合,在国际标准分类中归属于: 81.040.10 原材料和未加工的玻璃。
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