ISO 20379:2018

INTERNATIONAL ISO
STANDARD 20379
First edition
2018-02
Fine ceramics (advanced ceramics,
advanced technical ceramics) —
Measurement of thixotropic behaviour
of ceramic slurry by use of a rotational
viscometer
Céramiques techniques (céramiques avancées, céramiques techniques
avancées) — Mesurage du comportement thixotropique d’une
barbotine de céramique à l’aide d’un viscosimètre rotatif
Reference number
ISO 20379:2018(E)
©
ISO 2018

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ISO 20379:2018(E)

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ii © ISO 2018 – All rights reserved

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ISO 20379:2018(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
4.1 Evaluation of thixotropic behaviour by hysteresis measurement of flow curve . 2
4.2 Evaluation of thixotropic behaviour by time-dependence of shear stress at
constant low shear rate . 2
5 Apparatus . 2
5.1 Measuring system . 2
5.2 Basic capacity of the instrument . 2
5.3 Calibration of rotational viscometer . 3
5.4 Temperature control device . 3
6 Pretreatment of the slurry samples . 3
6.1 General . 3
6.2 Degassing . 3
6.3 Dispersion by stirring, mixing and ultrasonication. 3
7 Measurement condition . 3
7.1 Setting of ceramic slurry to rotational viscometer . 3
7.2 Temperature . 3
8 Measurement procedure . 4
8.1 Measurement of thixotropic behaviour by hysteresis measurement of flow curve . 4
8.1.1 Condition of shear rate and setting of measurement range . 4
8.1.2 Measurement procedure . 4
8.1.3 Analysis method of measurement results . 4
8.2 Measurement of thixotropic behaviour by time-dependence of shear stress at
constant low shear rate . 5
8.2.1 Setting of measurement programme . 5
8.2.2 Measurement procedure . 5
8.2.3 Analysis method of measurement results . 5
9 Test report . 6
Bibliography . 8
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ISO 20379:2018(E)

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
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ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
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This document was prepared by Technical Committee ISO/TC 206, Fine ceramics.
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INTERNATIONAL STANDARD ISO 20379:2018(E)
Fine ceramics (advanced ceramics, advanced technical
ceramics) — Measurement of thixotropic behaviour of
ceramic slurry by use of a rotational viscometer
1 Scope
This document specifies a method for measurement of thixotropic behaviour of ceramic slurry with
rotational viscometer. The slurry with high-solid loading, which is used in ceramic manufacturing, has a
generally non-Newtonian property. This method is limited to measurement of thixotropic behaviour of
high-solid loaded ceramic slurry with “coaxial double cylinder viscometer”, “cone and plate viscometer”
and “a parallel plate viscometer” as rotational viscometers.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
shear stress
force developed on the plane which is perpendicular to the shear force when there is shear applied to
the fluid
3.2
shear rate
proportion of laminar flow rate change perpendicular to the fluid flow
3.3
Newtonian property
slurry property of which the shear stress is proportional to the shear rate
3.4
non-Newtonian property
slurry property of which the shear stress is not proportional to the shear rate
3.5
viscosity
proportion of shear stress and shear rate
Note 1 to entry: The proportion is a representation of resistance to flow.
3.6
flow curve
curve showing the relationship between shear rate and shear stress
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ISO 20379:2018(E)

3.7
thixotropic behaviour
behaviour of fluid which has time-dependence of flow behaviour so that the apparent viscosity
decreases with time at controlled shear and recovers gradually with removal of the shear force
3.8
ceramic slurry
suspension of grinding ceramic powders mixed or dispersed in water or other liquid
Note 1 to entry: The suspension is used in the ceramic process, for example screen printing, slip casting, tape
casting, granule production.
4 Principle
4.1 Evaluation of thixotropic behaviour by hysteresis measurement of flow curve
Measurement of flow curve of ceramic slurry is performed using a rotational viscometer, which can
monitor shear rate and shear stress at the same time. The thixotropic behaviour is evaluated from the
magnitude of hysteresis that is indicated by the process of the flow curve.
4.2 Evaluation of thixotropic behaviour by time-dependence of shear stress at constant
low shear rate
Measurement of the flow curve of ceramic slurry is performed using a rotational viscometer, which
can monitor shear rate and shear stress at the same time. After the viscosity of ceramic slurry is
decreased by destruction of aggregated or flocculated structure in ceramic slurry at high shear rate,
the thixotropic behaviour is evaluated by measuring the recovery process of viscosity at low shear rate.
The relationship between fabrication of re-flocculated structure and time can be detected at low shear
rate. Therefore, the thixotropic behaviour is evaluated by using data from low shear rate.
5 Apparatus
A rotational viscometer has various measuring geometrics. In this document, the rotational viscometers
with defined shear rate are a coaxial double cylinder system, a cone and plate system and a parallel
plate system.
5.1 Measuring system
The measuring
...