Characterisation of engineered surfaces by a novel four-in-one tribological probe microscope

We present a novel designed multi-function tribological probe microscope (TPM), which has been developed to provide, within one set-up arrangement, measurements of topography, Young’s modulus, hardness and friction of a surface. The measurement is based on a point-by-point scanning so values of the four measured functions are linked in space and in time. This enables us to determine whether a surface treatment is effective in influencing its mechanical or tribological properties or how local surface features affect these properties. It is capable of revealing direct correlations between surface structure and mechanical and tribological properties. The TPM is a force-controlled scanning probe which has two precision capacitive sensors, one to measure surface topography and the deformation being made under a required loading force and the other to measure the frictional force between the tip and the surface being scanned. The contact force at the tip is controlled by a magnet/coil force actuator, which applies a constant force in the range 0.01–25 mN. The topography measurement has a range of 15 μm with a resolution of 0.1 nm. The scanning area of 100 μm×100 μm is a closed loop controlled with an accuracy of 1 nm. Evaluations have been carried out on some specially prepared engineered surfaces such as plasma immersion ion implanted ultra-high molecular weight polyethylene (UHMWPE), rutile surface modified titanium–aluminium–vanadium (Ti–6Al–4V) and austenitic stainless steels (AISI 316).