ISO INTERNATIONAL STANDARD 7884-6 First edition 1987-12-15 INTERNATIONAL ORGANIZATION FOR STANDARDIZATION ORGANISATION INTERNATIONALE DE NORMALISATION MEKAYHAPOAHAN OPTAHW3ALMHO CTAHAAPTM3ALWM Nl inrerrr Doc Bect Glass - Viscosity and viscometric fixed points - Part 6 : Determination of softening point Referencenumber ISO 7884-6: 1987 (E) Copyright lntern No reproduction or networking permitted without license from IHS Foreword ISo (the International Organization for Standardization) is a worldwide federation.of national standards bodies (Iso member bodies). The work of preparing International Standards is normally carried out through iso technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, govern- mental and non-governmental, in liaison with Iso, also take part in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the ISo Council. They are approved in accordance with ISo procedures requiring at least 75 % approval by the member bodies voting. International Standard ISO 7884-6 was prepared by Technical Committee ISO/TC 48, Laboratoryglasswareandrelatedapparatus. Users should note that all International Standards undergo revision from time to time and that any reference made herein to any other International Standard implies its latest edition, unless otherwise stated. InternationalOrganizationforStandardization,1987 Printed in Switzerland Copyright International Organization for Standardization No reproduction or networking permited without license from IHS Not for Resale INTERNATIONAL STANDARD ISO7884-6:1987(E) Glass -- Viscosity and viscometric fixed points Part 6 : Determination of softening point 0 Introduction 3 Reference International Standard ISo 7884, Glass Viscosity and IEC Publication 584-1,Thermocouples - Part1:Reference viscometric fixed points, consists of the following separate tables. parts : Part 1 : Principles for determining viscosity and viscometric 4 Definition fixed points. For the purposes of this part of ISo 7884, the following defini- Part2:Determinationofviscositybyrotationviscometers. tion applies. Part3： Determination of viscosity by fibre elongation softening point, Vt2 : Approximately the temperature above viscometer. which the glass is capable of most forming operations. Part 4 : Determination of viscosity by beam bending. NOTES Part 5: Determination of working point by sinking bar A viscosity of about 107,6 dPa-s* may be assigned to the softening viscometer. point for glass of density Q = 2,5 g/cm3 and surface tension Part 6 : Determination of softening point. α=300mN/m.(Forglasseswith othervalues of density or surface tension, see iso 7884-1.) Part 7: Determination of annealing point and strain point by 2 The softening point is also called the Littleton temperature. beam bending. Part8: Determinationof (dilatometric) transformation Principle temperature. Determination of the temperature at whicha round fibre of the glass, nominally 0,65 mm in diameter and 235 mm long with 1 Scope specifiedtolerances,elongates underits own weight at a rate of 1 mm/min when the upper 100 mm of its length is heated in a specified furnace at the rate of (5 ± 1) oC/min. This part of iSO 7884 specifies a method of determining the softening point of a glass. It has been found useful as a control NOTE - In principle, the device used in this method corresponds to a test to indicate changes in composition, for specification ac- fibre elongation viscometer (see ISo 7884-3).Closely defined re- ceptance and for providing information in research and quirements for the test specimen, procedure and apparatus lead to a development work with glass. good repeatability of the specified temperature point.The related viscosity value, however, is of less certainty. 2 F