Thin films scratch test

J. Oroshnik and J. W. Croll, Thin film adhesion testing by the scratch method, Surface Science Symp., New Mexico Section, Am. Vac. Soc., Albuquerque, NM, April 22, 1970. 

The scratch tests are very similar to the nanoindentation tests and can be considered side by side. In both teclmiques, a prime tip is used for the adhesion measurements by dragging across the measuring surface under an increasing load, which results in an indentation. Scratch and indentation tests are suitable for the analyses of the coatings and thin films [100]. Sharp diamond indenters are usually used for the adhesion and scratch resistance determination between the substrate and coating. These techniques can fail for the analyses of hard coatings on soft substrates due to no detectable failures as a result of small critical loads. Therefore,... 

Scratch tests have been used to evaluate the adhesion of thin films to a ceramic substrate. 

In early work on the test, it was argued that the critical load was determined only by the properties of the interface, the radius of the stylus and the hardness of the substrate. On this basis, the scratch test would give a measure of fundamental adhesion (see Adhesion - fundamental and practical). However, there are many reports of dependency on the thickness and mechanical properties of the thin film, even several of those upon which supposedly similar styluses were used. 

A simple form of the scratch test is used for assessing paint adhesion (see Paint constitution and adhesion). The scratch test, as described in this article, is perhaps best regarded as a useful comparative method of characterizing thin film adhesion. The test variables used should be carefully characterized and caution exercised in comparing results obtained in different laboratories. 

Scratch test D E PACKHAM Assessment of thin film adhesion... 

Laugier, M.T., 1981. The development of the scratch test technique for the determination of the adhesion of coatings. Thin Solid Films 76, 289—294. 

Laugier, M.T., 1984. An energy approach to the adhesion of coatings using the scratch test. Thin Sohd Films 117, 243-249. 

As mentioned earlier, one of the main purposes of reinforcing thin sol-gel silica films is to improve their wear and scratch resistance, and for this reason scratch tests are usually performed to measure the scratch resistance and the fi iction coefficient of the coating [33,35,40,41]. These tests are usually conducted by using nanoindentation equipment or pencil scratch tests, but traditional wear tests using a tribometer can also be found in the literature [5,42]. Impact and erosion resistance [43] are also mechanical properties of sol-gel coatings that can be improved by the addition of fillers. 

Sarin VK (1995) Micro-scratch test for adhesion evaluation of thin films. In Mittal KL (ed) Adhesion measurement of films and coatings. VSP, Utrecht, p 175... 

V.K. Sarin, Micro-Scratch test for adhesion evaluation of thin films, in K.L. Mittal (Ed.), Adhesion Measurement of Films and Coatings, VSP BV Publishing, 1995, p. 175. 

The main value of salt-spray tests is in the evaluation of the effectiveness of phosphate coatings in restricting the spread of rust from scratches or other points of damage in a paint film. This feature is of particular interest to the motorcar industry, as vehicles are often exposed to marine atmospheres and to moisture and salt when the latter is used to disperse ice and frost from road surfaces. Great care is needed in the interpretation of a salt-spray test, as it has been found to favour thin iron phosphate coatings more than is justified by experience with natural weathering. In the motorcar industry the present custom is to use zinc phosphate coatings on the car bodies and all other parts exposed to the outside atmosphere. 

W. Heinke, A. Leyland, A. Matthews, G. Berg, C. Friedrich and E. Broszeit, Evaluation of PVD nitride coatings, using impact, scratch and Rockwell C adhesion tests. Thin Solid Films 1995, 270, 431-438. 

Burnett, P.J., Rickerby, D.S., 1988. The scratch adhesion test an elastic-plastic indentation analysis. Thin Solid Films 157, 233—254. 

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