| 초록 |
There has been development in functional coatings for displaying devices to improve their hardness and wear protection. Despite many studies evaluating coating resistance, a pencil hardness test is still used to measure the scratch hardness for research and production; however, this only provides qualitative information on the coating layer hardness. In this study, we have investigated various properties of different types of pencil leads in order to quantify the pencil hardness test reliability. The chemical and mechanical properties for different types of the pencils (F, 2H, 4H, 6H, and 8H) were measured using a micro hardness tester, a nano-indentation, and a pin-on-disk tribometer, respectively. The content of the clay was proportional with the hardness of the pencil leads. Both the nano-indentation and Vickers hardness value are in the range of 300 to 800 MPa. The peaks of Al2(Al2.8Si1.2)O9.54 (Mullite) appear on 4H, 6H, and 8H leads. A higher proportion of clay contains a higher mullite phases that result in a higher standard deviation and margin of error for lead hardness. From these results, the variations in error ranges are considered to be a factor affecting the pencil hardness test. |
