| In hard disk drives, the flying height of the slider is on the order of 1 nm for achieving high recording density. At this small spacing, the slider/disk contact is likely to occur, which could cause error of data recording or slider damage. Therefore, the flying height of slider and silder/disk contacts should be well measured and controlled. In recent years, A temperature sensitive thermal contact sensor has been developed for measuring the flying height of slider and detecting slider/disk contacts. However, more researches are needed to study the thermal response of the thermal contact sensor to the different states at the head disk interface. In this dissertation, thermal effects of head disk interface are analyzed, and corresponding thermal response of thermal contact sensors is investigated. The main content of the research includes:The air bearing pressure is calculated based on the modified Reynolds equation considering the rarefied effect of air at small spacing in head disk interface. Effects of moving disk defects on the air bearing pressure are analyzed by building a time dependent pressure calculation model. The pressure close to the location of read/write elements is around 0.5~1 MPa without thermal protrusion on the slider. However, the maximum pressure reaches around 8.5 MPa with a spacing of 1 nm between the slider protrusion and the disk surface. In addition, the air bearing pressure locally increases at the presence of disk asperities, and decreases at the location of disk voids. The buoyancy force changes due to the presence of small disk defects are small, which has little effects on the flying height of the slider.A steady-state heat transfer model in the head disk interface is bulit, including the iterative calculation of air bearing pressure, temperature and thermal deformation of slider. The temperature in the head disk interface is calculated based on the energy equation, considering the temperature jump at the solid-gas interface. Effects of moving disk defects are analyzed by building a time dependent temperature calculation model. In thermal flying-height contrrol sliders, the heater causes temperature rise on air bearing surfaces. Meanwhile, the air bearing has cooling effects on the temperature of air bearing surface. The cooling effect of the air bearing increases rapidly with an increase in the heater power, because of the decrease in the slider/disk spacing and the increase in the air bearing pressure. The cooling effect of the air bearing leads to a decrease in the temperature change of the slider. In addition, the heat flux on the air bearing surface locally increases at the presence of disk asperities, but decreases at the location of disk voids.Slider/disk contacts are analyzed using thermo-elastic-plastic finite element models. The contact force and the temperature response during both slider protrusion/disk contact and slider/disk asperity contact are i nvestigated. In slider protrusion/disk contact, the contact force is around 0.5~5 m N, and the temperature is around 350~550 K. The slider/disk asperity contact could generate a contact force in the range of 0.07~0.1 m N and a flash temperature in the range of 500~1000 K, depending on contact conditions.Based on the above analysis, the thermal response of thermal contact sensors while slider/disk spacing changes and slider/disk contacts occure is investigated. When slider/disk spacing decreases due to the increase in the heater power, the temperature of thermal contact sensors increases, while the temperature change decreases. If the flying height decreases to less than 1 nm, the temperature of the thermal contact sensor decreased with an increase in heater power. As the slider protrusion/disk contact occurs, thermal contact sensors have a rapid temperature rise. Slider/disk asperity contacts could cause a high flash temperature of thermal contact sensors. For detecting disk asperities, the optimal sensor length should be in the range of 1~2 μm.
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