Erhard Theodor Schreck

Thin film thermocouple sensors for measurement of contact temperatures during slider asperity interaction on magnetic recording disks

Thin-film thermocouple sensors have been fabricated on a magnetic recording slider. Both the sensors and the reference junctions are located on the air bearing surface of the slider. The effective size of the junctions is 4 mu m, and response time is faster than 0.5 mu s. The sensitivity of these thermocouples is measured to be 7 mu V/ degrees C. The thermocouple signals obtained at the slider asperity contacts show a temperature rise of 1-5 degrees C. Incorporating the sensor dimensions and assuming asperities of 0.5 mu m width, the actual temperatures are estimated to be in the range of 90-450 degrees C. >

Calibration of micron‐size thermocouples for measurements of surface temperature

Imbedded thin‐film thermocouples can be used for the measurement of transient surface temperatures with high spatial resolution and sensitivity. To minimize environmental effects it is desirable to have close proximity between the reference junction and the sensor junction. In this article, we present and compare two calibration techniques for such thermocouples. The first technique is a steady‐state technique and uses a focused laser beam with a diameter of 3 μm as a point heat source. This technique consists of two steps. The first step is an absolute, but spatially averaged temperature measurement with a resistive temperature sensor. In the second step, the uncalibrated thermocouple junction is translated to resolve the spatial temperature profile generated by the laser spot. Both measurements are then combined to provide an absolute calibration which is independent of the thermal properties of the imbedding material and of the absorbed laser power. We used a simple sensor design which consists of a Ni...

Nanoindentation and the tribology of head-disk interface components

Nanoindentation data are presented for three different but interrelated components of the thin film disk magnetic recording system-the air bearing slider/recording head, the disk substrate, and the sputter deposited thin film disk recording medium. Hardness traces across the slider trailing edge demonstrate the hardness of the NiFe, sputtered Al/sub 2/O/sub 3/, and the ceramic Al/sub 2/O/sub 3//TiC are 8, 10 and 24-40 GPa, respectively. Lapping under non-optimum, aggressive conditions can lead to significant recession in these components which is directly related to their hardness. The hardness and modulus have been measured for a number of alternate substrate materials ranging from AlMg/NiP to glass and glass ceramic. The ability of these substrates to resist damage from slider shock forces is presented and generally increases with substrate hardness, although other criteria (fracture toughness and plasticity initiation) rue required to rationalize all the data. Finally, hardness and modulus of carbon overcoat films are presented which have been sputtered under various conditions. The process variations lead to variations in hardness, the hardness/modulus (H/E) parameter, and tribological performance in slider/disk testing. The applicability of these mechanical property parameters to the wear degradation is discussed.