Determining critical loads for ultra-thin overcoats using a depth sensing nanoindentation multiple sliding technique

A new technique to determine critical loads in accelerated wear tests on ultra-thin overcoats for magnetic hard disks is presented. This technique is referred to as the depth sensing nanoindentation multiple sliding wear test with a ramped load. The test is conducted on 20 nm SiC, carbon and nitrogenated carbon overcoats produced by dc magnetron sputtering. A well defined and highly repeatable critical load is determined for each of these overcoats by the new technique developed in this work. It was found that the nitrogenated carbon has the highest critical load, while for the SiC and C the critical loads are similar. In addition, an increasing trend in the critical load with increasing of nitrogen content is observed for the CN films