| 초록 |
In the electronic industry, there has been development in polymer-coatings as protection for displaying devices, such as mobile phones. It is widely used to measure scratch resistance of coating on substrates by a pencil hardness test. However, it only provides qualitative information on the hardness of the coating layer. In this study, we have investigated various properties with different types of pencil lead in order to quantify pencil hardness test for reliability. The chemical composition and mechanical properties for different types of the pencil (F, 2H, 4H, 6H, and 8H) were measured using an X-ray diffraction and a nano-indentation, respectively. The values of nano-indentation hardness of pencil leads are in the range of 0.3 to 0.8 GPa. The higher grade of the pencil leads in terms of hardness show wider error range. The content of the clay seems to be proportional with the hardness of the pencil leads. Different crystalline phases in clays for each grade of pencil lead results in the hardness variation, and the distribution, so the content of the crystalline phases in clay consequentially effects on the deviation of hardness. From result, this variation in error range is considered as a factor affecting a pencil hardness test. |
