SCRATCH HARDNESS MEASUREMENT

The images of the scratch tracks of three metals (Cu110, Al6061 and SS304) after the tests are shown in FIGURE 1 in order to compare the scratch hardness of different materials. The mapping function of the NANOVEA Mechanical Software was used to create three parallel scratches tested under the same condition in an automated protocol. The measured scratch track width and calculated scratch hardness number (HSP) are summarized and compared in TABLE 1. The metals show different wear track widths of 174, 220 and 89 µm for Al6061, Cu110 and SS304, respectively, resulting in a calculated HSP of 0.84, 0.52 and 3.2 GPa.

In addition to the scratch hardness computed from the scratch track width, the evolution of coefficient of friction (COF), true depth and acoustic emission were recorded in situ during the scratch hardness test. Here, the true depth is the depth difference between the penetration depth of the stylus during the scratch test and the surface profile measured in the pre-scan. The COF, true depth and acoustic emission of Cu110 are shown in FIGURE 2 as an example. Such information provides insight into mechanical failures taking place during scratching, enabling users to detect mechanical defects and further investigate the scratch behavior of the tested material.

The scratch hardness tests can be finished within a couple of minutes with high precision and repeatability. Compared to conventional indentation procedures, the scratch hardness test in this study provides an alternative solution for hardness measurements, which is useful for quality control and the development of new materials.