The transfer of wear debris of a nickel-zinc ferrite head to a magnetic tape was measured by autoradiography of the tape after it was worn against the irradiated ferrite head. Ferrite deposits on the tape were observed only after 5000 passes. Dots or specks on the autoradiograph of the tapes of about 200 micrometers in diameter, caused by particles of ferrite about 1 μm in diameter and mass of about 10−11 g, were measured. The average amount of ferrite deposited on the tape after 20,000 passes was about 0.6 nanogram per square centimeter; some areas showed uniform deposits of ferrite concentration of 10–20 ng/cm2. Based on our estimates of total head wear, only a small fraction (about 0.6 percent) of the total ferrite wear debris was transferred to the tape, about 0.2 percent was transferred to the tape-drive component surfaces, and the rest, we conclude, was airborne.
