Investigation of tribological and read-write performance of textured sliders
Slider surface texturing is a promising new way to improve the tribological performance of future hard disk drives with very low flying heights. In this study, proximity recording sliders with a design flying height of 6 nm at 20 m/s were textured using oxygenated plasma etching. In order to protect the read-write element, texturing of sliders was performed after positioning a mica mask over the read-write element. The tribological and read-write performance of the slider before texturing was compared with the tribological and magnetic performance of the same slider after texturing. It was found that no degradation of the read-write performance occurred and that the tribological performance of the slider was improved after texturing.
Study on the Correlation Between Dynamical Behavior and Friction/Wear Mechanism Under the Effect of Grooves
In this work, the interfacial friction and wear and vibration characteristics are studied by sliding a chromium bearing steel ball (AISI 52100) over both multi-grooved and single-grooved forged steel disks (20CrMnMo) at low and high rotating speeds in order to reveal the effect mechanism of groove-textured surface on tribological behaviors. The results show that the grooves modify the contact state of the ball and the disk at the contact interface. This consequently causes variations in the normal displacement, normal force, and friction force signals. The changes in these three signals become more pronounced with increasing groove width at a low speed. The collision behavior between the ball and the groove increase the amplitude of vibration acceleration at a high speed. The test results suggest that grooves with appropriate widths could trap wear debris on the ball surface while avoiding a strong collision between the disk and the ball, resulting in an improvement in the wear states.
Evolution of carbide precipitates in Hastelloy N joints during welding and post weld heat treatment
Abstract The effects of welding and post weld heat treatment (PWHT) on the morphology, composition and lattice parameter of the precipitates in the welding joints of Hastelloy N alloy have been investigated. Joint samples were prepared using a gas tungsten arc welding process with ERNiMo-2 fillers, and then solid-solution treated at 1100 °C for 20 min. After welding, eutectic M6C carbides can be observed in the heat affected zones (HAZ) and weld zones (WZ). These eutectic M6C carbides become spheroidized during the following PWHT. The concentration of Si decreases during the transformation from the primary ones to eutectic ones, and then increases during the spheroidizing process. The total concentration of Si + Cr in M6C carbides remains stable during welding and PWHT. At the same time, the heat leads to the outward diffusion of Mo from the M6C carbides, which results in a decrease of the lattice parameter.