introduction
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ISO 20379-2018 “Fine Ceramics (advanced ceramics, advanced technical ceramics) using rotary viscometers to measure the thixotropy of ceramic pastes”

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This document was prepared by the Technical Committee ISO/TC 206, Fine Ceramics.

1 Range
This document specifies a method for measuring the thixotropic behavior of ceramic pastes using a rotary viscometer. Pastes with high solid loads used in ceramic manufacturing usually have non-Newtonian characteristics. The method is limited to measuring the thixotropic behavior of ceramic slurps with high solid load using “coaxial double-barrel viscometer”, “cone plate viscometer” and “parallel plate viscometer” as rotating viscometers.

2 Normative references
There is no normative reference in this document.

ISO 20379-2018 “Fine Ceramics (advanced ceramics, advanced technical ceramics) using rotary viscometers to measure the thixotropy of ceramic pastes”

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

3.1 Shear stress

The force generated when a shear force is applied to a fluid in a plane perpendicular to the shear force

3.2 Shear Rate

The ratio of layer velocity perpendicular to the change in fluid flow

3.3 Newton Attributes

Slurry properties in which shear stress is proportional to shear rate

3.4 Non-Newtonian properties

Slurry characteristic in which shear stress is not proportional to shear rate

3.5 Viscosity

The ratio of shear stress to shear rate

Note 1: Ratio is an indication of flow resistance.

ISO 20379-2018 “Fine Ceramics (advanced ceramics, advanced technical ceramics) using rotary viscometers to measure the thixotropy of ceramic pastes”

3.6 Traffic Curve

A curve showing the relationship between shear rate and shear stress

3.7 Thixotropy

The behavior of a fluid that has a time-dependent flow behavior, so that under controlled shear, the apparent viscosity decreases with time and gradually recovers as the shear force is removed

3.8 Ceramic paste

A suspension of ground ceramic powder mixed or dispersed in water or other liquids

Note 1: Suspensions are used in ceramic processes such as screen printing, slip casting, tape casting, particle production.

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