Investigation of Bias Voltage and Relative Humidity on Wear and Pit Formation at the Head–Disk Interface

Wear and pit formation of a thermal-flying height-control (TFC) slider was studied as a function of bias voltage and environmental relative humidity (RH; 5%-85%). Burnishing tests were performed by applying an “over-push” heater power to the heater element, causing slider-disk contacts. The experimental results showed that both bias voltage and RH have a large effect on the power-to-contact change and the wear of the slider. Atomic force microscopy (AFM) was used to study the wear and pit formation as a function of bias voltage and RH. The wear of the slider surface was found to be less at the positive disk bias voltage compared with the negative disk bias voltage at all RH conditions. Pit formation was observed on the slider in the vicinity of the read-write transducer area when a positive bias voltage was applied to the disk at high RH conditions (85%). Pit formation was not observed at low RH.