Details

Autor(en) / Beteiligte

• Beck, U.
• Reiners, G.
• Lerche, D.
• Rietz, U.
• Niederwald, H.

Titel

Quantitative adhesion testing of optical coatings by means of centrifuge technology

Ist Teil von

• Surface & coatings technology, 2011-07, Vol.205, p.S182-S186

Ort / Verlag

Amsterdam: Elsevier B.V

Erscheinungsjahr

2011

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Although adhesion testing of coatings is of fundamental interest for quality assurance, it is still a challenge regarding reliable quantitative results. Because of the huge variety of coating/substrate systems in terms of materials and thickness range, adhesion tests display the same variety as coating/substrate systems. Some tests are qualitative, many are quantitative but except for the pull (DIN EN ISO 15870) and pull-off test (DIN EN ISO 4624) adhesion is not measured in terms of force per area. For optical coatings, the standardized tests according to ISO 9211-4 apply, i.e. abrasion tests (cheese cloth or eraser test) and adhesion tests (tape or cross-hatch test) with different degrees of severity. Instead of the adhesion strength, all these single-sample tests provide only quantitative information on the abrasion or adhesion resistance of a particular coating/substrate system. The centrifuge test has manifold advantages. First, it can be easily run as multiple-sample test. Second, adhesion strength is measured in absolute numbers (N/mm2). Third, the centrifuge test requires only a one-sided sample support instead of a two-sided sample clamping as the pull- and pull-off test do. Fourth, it is much easier and faster than many other tests. Fifth, the centrifuge technology additionally enables tests under defined climates or harsh environments. Last but not least, versatile test conditions (alternating loads at various load rates) important to fatigue testing can be easily realized by varying the number of revolutions. The centrifuge test was applied to the testing of optical coatings on glass and CaF2. It could be shown that there are significant advantages compared to other tests. In particular, the centrifuge test was able to discriminate the adhesion strength for coating/substrate systems until failure which all passed the standardized tests of ISO 9211-4.