Metal Finishing Guide Book

2013

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Shore Hardness vs. Nanoindentation Hardness A study measuring Martens hardness of Shore A standards with the FISCHERSCOPE® HM2000 S, a nanoindentation tester shown in Figure 5, shows a very linear correlation at relatively low loads. The data in graph in Figure 6 are from indents with 50mN maximum load with loading and unloading time of 60 seconds and a creep time of 10 seconds. These testing parameters are similar to those used for soft coatings and thin films when shallow indentation depths are required to prevent substrate effects. Figure 5: FISCHERSCOPE® HM2000 S Pencil Hardness vs. Nanoindentation Hardness for the determination of the Martens In the following study the Martens hardness Hardness. was measured for a set of graded pencils used in Pencil hardness testing. The tests were carried out with the FISCHERSCOPE® HM2000 S. Figure 7 shows the results of multiple measurements on pencils of various hardness levels. The large standard deviations of the individual test series show the limitations of the pencil hardness method. Especially in the higher range, the nominal hardness (B, HB, F, H, etc.) of pencils are not a dependable indicator of their actual hardness. With a nanoindentation tester the hardness of paint coatings can be measured directly and accurately. In addition, other characteristics can be determined, such as creep and relaxation behavior, as well as the modulus of elasticity. All of these parameters provide a true indication of the paint quality. Example of Applications Nanoindentation testers available in the market have a variety of features, load and displacement ranges and resolutions. The following examples discuss two very different coatings that are commonly characterized with the FISCHERSCOPE® HM2000 S nanoindentation tester. Key features and capabilities that are essential for the nanoindentation tester in each application are described below. Mechanical characterization of lacquer coatings in automotive applications In the automotive industry, clear coatings for paint are used as protection from corrosion and external damage. These lacquers are exposed 454 Figure 6: Martens Hardness (HM) of Shore A standards performed with a FISCHERSCOPE® HM2000 S. Figure 7: Comparison of the Martens Hardness of pencils of different hardness, shown with the standard deviation of the measurements.

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