In a standard nanoindentation test of thin films, one must be careful about the indentation depth. If the penetration is too low (comparable to roughness), the resulting hardness can be much higher. If the penetration is too high, the substrate hardness will influence the coating hardness, resulting in lower values (typically). So ideal hardness measurement is around 10 % of coating thickness.
My question is: How to measure the hardness of the multilayer structure? Let's say we have a multilayer coating with TiN and AlN; both films are 20 nm thick. The total thickness is 600 nm. How deep should I indent this structure to get the correct information about the hardness of this multi-structure? And how should I change the depth when one of the coatings (i.e. AlN) is 10 nm and the other one 20 nm?
Thank you for your answers and opinions.
Try using instrumented hardness, where you can set several parameters for hardness measurement. The advantage is that the result is a graph throughout the measurement. E.g. the dependence of the speed on the depth of the imprint, etc.. you can even see the transition between the individual layers even slightly.
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Materials Science