[article]
| Titre : |
Does temperature have an effect in coating thickness reading ? |
| Type de document : |
texte imprimé |
| Auteurs : |
David J. Barnes, Auteur |
| Année de publication : |
2018 |
| Article en page(s) : |
p. 14-16 |
| Langues : |
Américain (ame) |
| Catégories : |
Epaisseur -- Mesure
Essais (technologie)
Revêtements
Température
Ultrasons
|
| Index. décimale : |
667.9 Revêtements et enduits |
| Résumé : |
A simple search of the internet will tell you that the speed of sound in a material changes with temperature. Concern has therefore been expressed that temperature may have a noticeable effect on the speed of sound when taking coating thickness measurements with an ultrasonic gauge.
The method of measuring the coating thickness using ultrasonics is defined in ASTM D6132-13 as follows.
Instruments complying with this test method measure thickness by emitting an ultrasonic pulse into the coating that is reflected back from the substrate to the probe. The travel time is converted into a thickness reading. The instrument's probe must be placed directly on the coating surface to take a reading.
After verifying accuracy on a known coated part of the object or material of the same kind, the instrument probe is coupled with the coated specimen, after proper cure and conditioning according to the coating manufacturer's instructions.
It should be recognized that the accuracy of the measurements can be influenced when :
The coated object to be measured is not planar with respect to the transducer face at the point of measurement,
Coating density is not uniform, and
The substrate peak-to-valley surface profile of the coated specimen exceeds the coating thickness.
While the theory of ultrasonic measurement can be a daunting proposition to some users, gauges produced today are essentially "point-and-shoot" devices - the user simply reads the thickness, in digits off of the gauge screen; there is no opportunity for confusion or for different operators to read the numbers differently. However, the onus is on the operator to verify that the gauge is reading correctly, and if temperature might affect this, the operator needs to take note and adjust accordingly.
This article looks at the effect of temperature on the speed of sound in coating materials and the subsequent effect on coating thickness readings. |
| Note de contenu : |
- Table 1 and 2 : Sample Thickness Reading with Gauge A Calibrated at Each TEst Temperature.
- Table 3 : Sample Measured at Each Norminal Test Temperature with Gauge A Calibrated at Room Temperature |
| Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=31889 |
in JOURNAL OF PROTECTIVE COATINGS & LININGS (JPCL) > Vol. 35, N° 9 (09-10/2018) . - p. 14-16
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Does temperature have an effect in coating thickness reading ? in JOURNAL OF PROTECTIVE COATINGS & LININGS (JPCL), Vol. 35, N° 9 (09-10/2018)
