Microtribological studies of Al 2O 3, Al 2O 3TiC, polycrystalline and single-crystal MnZn ferrite, and SiC head slider materials

Abstract

Surface topography, friction, scratching, wear and nanoindentation behavior of head slider materials were studied using atomic force/ friction force microscopy (AFM/FFM). Materials studied include polycrystalline Al 2O 3, Al 2O 3TiC (70-30 wt.%), polycrystalline MnZn ferrite, single-crystal MnZn ferrite and polycrystalline SiC. Al 2O 3 is not used for construction of head slider but it was studied for comparisons with Al 2O 3TiC. SiC is a candidate slider material. The Al 2O 3TiC specimen exhibits the highest coefficient of microscale friction followed by polycrystalline MnZn ferrite, Al 2O 3, single-crystal Mn ferrite, Al 2O 3, single-crystal MnZn ferrite and SiC. Two phase Al 2O 3TiC exhibited higher microscale friction than a single phase Al 2O 3 and polycrystalline MnZn ferrite exhibits microscale friction than a single-crystal MnZn ferrite. The local variation in friction force for Al 2O 3, polycrystalline and single-crystal MnZn ferrite was found to correspond to the lcoal surface slope (first derivative of the surface roughness profile). For Al 2O 3TiC and SiC specimen, the local variation in friction force at the scratches corresponds to the local surface slope. However, local variation over entire region corresponds to the different phases present on the specimen surface. Thus friction force imaging can be used for structural mapping of the surfaces. Directionality effects in the friction were studied on a microscale for the Al 2O 3 specimen. Macroscale friction values for all samples are higher than microscale friction values as there is less ploughing contribution in microscale friction measurements. Microscratching/wear studies indicate that scratch and wear resistance of SiC and Al 2O 3 are higher than that of the other specimens. However, Al 2O 3 specimen shows the presence of porous holes on the surface that affect the wear performance. Al 2O 3 specimen exhibits superior microscratch and microwear resistance than Al 2O 3TiC. Wear evolution for single and two phase materials was studied in detail. Nonoindentation hardness values found to be generally higher than that of microhardness data. Based on these measurements, coefficient of friction, microscratch and microwear resistance of singe phase materials are superior to that of two phase materials.