Wear Testing: An Overview
ScanningWearTM testing is a feature enabling research into wear resistance of coatings and films at the nanoscale. The capability is standard on all Hysitron TS and TI series instruments enabling a complimentary technique to nanoindentation and scratch.
The wear patterns are created by raster scanning the sample with a given force, predefined by the user. A scan can consist of a single pass or multiple passes over the same area within one test. By applying a known force and selecting the number of passes over which this force is applied, the amount of material that is removed during the wear scan can be measured post-test using the in-situ imaging technique.
ScanningWear enables the ability to wear at different loads and carry out several wear experiments on one sample as shown in the figure below (left). This experiment involved several individual wear tests carried out at increasing loads and number of passes on a DLC film coating on a hard drive.
The precise position that in-situ SPM imaging provides also enables nano-machining and nano-patterning on surfaces as shown below (right). In this study two wear patterns were nanomachined in Lanthanum oxide. One pattern consisted of a 5 μm x 5 μm square, the other 1.25 μm x 5 μm rectangle. The patterns were placed less than 1 μm apart and resulted in removing the oxide layer to selectively reveal the substrate.
(Left) ScanningWear test on DLC (Diamond-Like Carbon) coating on a computer hard disk drive with 15 μN, 30 μN and 45 μN loads and 1, 5, 10 passes respectively. (Right) Wear tests, 5 μm x 5 μm square and 5 μm x 1.25 μm rectangle less than 1 μm apart in LaO coating.
ScanningWear testing produces wear tracks such as those in the figure above (left), however for reciprocating wear tests which enable wear along one single wear track over several thousand cycles, TriboImageTM is a seperate product available from Hysitron. For more details please refer to the TriboImage product page or contact Hysitron.