Tribological studies of various magnetic heads and thin-film rigid disks

Abstract

Tribological characterization of three different magnetic heads (Mn-Zn ferrite, CaTiO 3 and Al 2O 3-TiC) and two different magnetic storage thin-film rigid disks have been made. The abrasive wear characteristics of the two disks (only differing in protective overcoat; diamond-like carbon and yttria-stabilized zirconia, respectively) have been investigated using a precision dimple grinder in order to grind small and well defined wear scars on the disks. The scratch response of the magnetic heads and the rigid disks have been studied using a single tip scratch test equipment in situ in the scanning electron microscope. Finally, the friction characteristics of the six possible magnetic head/rigid storage disk couples have been tested using in situ sliding tests in a scanning electron microscope. The results from the abrasive test show that one of the disks (with a diamond-like carbon overcoat) only displays abrasive wear, while the other disk (with a zirconia overcoat) besides abrasive wear also displays extensive spalling of the magnetic coating. The scratch tests show that for all three magnetic heads the friction coefficient increases rapidly with increasing normal force until a constant value, independent of the normal force applied, is reached. For the two disks, the friction coefficient increases with increasing normal force within the entire normal force interval investigated (0–0.5 N). The in situ friction tests show that, for a given head material, sliding against the disk with the zirconia overcoat yields lower friction than sliding against the disk with the diamond-like carbon overcoat. It was also found that, for a given disk material, the Al 2O 3-TiC head yields the highest friction. All heads, with the possible exception of the Al 2O 3-TiC head, were found to be virtually unaffected by sliding against the disks. Further, it was found that scratching of the disks occasionally occurs for the following head/disk combinations: CaTiO 3/diamond-like carbon overcoat, Al 2O 3-TiC/diamond-like carbon overcoat and Al 2O 3-TiC/zirconia overcoat.