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[October 2004]
Interlaboratory Exercise on High Purity Alumina
The VAMAS Technical Working Area 3 (TWA3) - Ceramics - has been evaluating a question that arose in ISO TC206 when discussing conditions for flexural strength measurement (ISO 14705, BS EN 843-1, ASTM C1161). Normally, this test is performed in air, but many ceramics have strengths which are dependent on the testing rate and the humidity level.
To evaluate simple methods for determining strength in inert conditions, the Korean standards laboratory, KRISS, organised an interlaboratory exercise on a high purity alumina. Participants were asked to use either dry inert gas or pre-baked liquid paraffin to provide the inert environment, plus another condition of their choice, as well as ambient atmosphere as a baseline.
NPL's results in the UK indicate that placing the test-jig inside a plastic bag and flushing it out with argon for 30 seconds before the test is marginally more effective at excluding moisture - and is a lot less messy - than brushing with, or baking immersed in, liquid paraffin.
For more on these particular results, e-mail: roger.morrell@npl.co.uk
ENDS