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M50 steel was implanted with nitrogen at elevated temperatures ranging from 260 [degrees]C to 420 [degrees]C using plasma-based ion implantation. The effect of implantation temperature on surface microstructure, hardness, and wear resistance was investigated. It is observed that nitrogen penetrates very deeply from the surface as a result of implantation and thermal diffusion at elevated temperatures. The amount of nitrides and their distribution depth as well as the hardness and the wear resistance in the surface layer increase with the processing temperature. As the implantation temperature increases, the wear mechanism changes from adhesive wear to abrasive wear. Index Terms--Elevated temperature ion implantation, plasma-based ion implantation (PBII), structure, wear.

Very hard and wear-resistant layers are formed after energetic nitrogen insertion into stainless steel. Here, a systematic investigation of the influence of the microstructure is presented. Nitrogen implantation was performed in austenitic, martensitic, and ferritic steels with the samples investigated with respect to formation of expanded phase, nitrogen depth distribution, hardness, and wear. Microstructure strongly affects the diffusion in austenite and has negligible effect in the case of martensitic/ferritic transformations. Index Terms--Microstructure, nitrogen implantation, stainless steel, wear.

To synthesize good diamond-like carbon (DLC) films on the inner surface of a cylinder, [C.sub.2][H.sub.2] plasma should be generated uniformly in the cylinder. In this study, glow discharge [C.sub.2][H.sub.2] plasma was generated by a high pulsed bias voltage applied on the cylinder, and ions were accelerated and implanted into the sample by the same bias. The effect of pulse frequency of the bias and working pressure on the discharge characteristics was investigated. In addition, the ball-on-disk test and Raman spectroscopy were used to characterize the as-deposited DLC films. The test results show that wear resistance of samples increases with the applied voltage, and the friction coefficient of DLC films lies in the range of 0.15-0.20. Index Terms--Diamond-like carbon (DLC) film, inner surface modification, plasma immersion ion implantation (PIII), wear resistance.

The wear behavior of helical scan recorder heads is studied using the micro-indentation technique, where Vickers micro-indentations are spatially distributed on the head surface to provide a scale for wear measurement as a function of position. Atomic Force Microscopy is used to measure the wear rates with high accuracy. The maximum wear occurs in the trailing pole piece of the head. The MP tape proved to be more abrasive than the [Gamma] [Fe.sub.2][O.sub.3] tape. Chemical analysis of films forming in the glass region indicated iron oxide transfer from the tape to the head surface.

The dynamic load head-disk interface durability is experimentally investigated using 50 percent TPC sliders and super-smooth disks. Severe head-disk contact conditions are applied and disk-synchronized head loading motions are performed in order to see the effect of repeated dynamic load head-disk contacts. Readback signals are recorded and analyzed, and the disk surfaces of the head-disk contact area are examined after 100,000 repeated contacts. The results are compared with those of our previous study. We find that the dynamic load head-disk interface durability of 50 percent TPC sliders and polished disks is superior to that of 70 percent taper-flat sliders and textured disks, and the experimental results suggest that better dynamic load head-disk interface reliability can be achieved with good head-loading velocity control, even though head-disk contact may occur during loading.

In this paper, we report on the durability performance of two commercial Hi-8 video tapes, a metal evaporated (ME) tape and a metal particle (MP) tape. Mechanical and physical changes in the surface of the tapes have been correlated to recording error measurements. Modified and adapted commercial Hi-8 recorders have been used for all the mechanical measurements and for sample generation whilst X-ray photo-electron spectroscopy (XPS) and scanning electron microscopy (SEM) have been employed in the surface characterisation. The durability of the tapes was assessed through cycling tests and it was found that the MP tape exhibited far greater durability than the ME tape.

This paper reports experimental results of a comparative study for mechanical and tribological properties of permalloy (NiFe) and magnetically soft high moment FeTaN sputtered thin films. It was observed that the hardness, elastic modulus and wear resistance of FeTaN films are all superior to those of NiFe permalloy films. AFM observations on unworn films and worn surfaces of a wear scar revealed that pit formation may contribute to wear damage mechanisms for low load abrasive wear.

A technique for evaluating the wear of Diamond Like Carbon (DLC) coating on the alumina encapsulation portion of coated pseudo contact thin film inductive sliders is presented. The tested parts were subjected to a chemical etch and were examined via Scanning Electron Microscope (SEM) techniques. Film voids and wear over the trailing edge were clearly revealed. Data regarding prime coated, prime uncoated heads and heads that have experienced CSS and sweeping actuation tests are presented. Prime sliders coated with approximately 150[Angstrom] of DLC were shown to contain small amounts of porosity and scratches, while heads without coating were uniformly etched. The amount of DLC wear on both CSS and sweeping heads was inconsistent and varied from near complete removal to slightly increased scratches. Inconsistency in wear is attributed to the variability among the heads' flying characteristics.

Two different types of microcracks in thin film head alumina were observed : cracks initiated at the alumina edges growing toward the head pole tips and cracks initiated at the head pole tip area and growing towards the leading edge of the alumina. Thermally induced cracks may cause degradation of magnetic head read/write performance due to the damage of the pole tip gap or corrosion of the head pole tips. Data from Ultrasonic AFM (UFM) indicate the difference in the subsurface structure of the observed cracks of the alumina.

A novel experiment was designed to promote the understanding of the mechanism of disk wear caused by particulate contamination. Obtained results suggest that the slider picks up particles and accumulates them on its surfaces as it flies above the disk. The instability of the flying slider, especially that induced by track seeking, leads to slider-disk impact which releases the accumulated particles. This results in abrasion amongst the slider, the contaminants, and the disk. The investigation also indicates that the outer two surfaces in a disk-stack and the corresponding sliders have higher likelihood of capturing flying particles. A Model has been proposed to explain the observed phenomena.

A flat-head/bump-disk apparatus, consisting of a 70% catamaran head made of [Al.sub.2][O.sub.3]-TiC material without leading taper, and a BK-7 borosilicate crown glass disk, has been built to investigate the measurement accuracy of a flying height tester. Compared with existing flying height tester calibration standards, this apparatus allows one to estimate the amount of elastic deformation occurring at the bump/disk interface, relax the strict requirements of head rail and disk surface flatness, and eliminate manual load/unload operations. With this apparatus, good agreements have been obtained between profilometer measured bump heights and flying height tester measured head/disk separations under 60 nm.

A commercial Hi-8 VCR was instrumented to measure the friction force between the rotary heads and tape, rms head output and signal dropouts to sub-[[micro]seconds] durations. Streaming mode experiments at design tension using metal evaporated (ME) and metal particle (MP) tapes were performed in which the tapes were subjected to repeated play/rewind cycling. Long wavelength waviness of the ME tape surface and a large number of sharper asperities on the MP tape surface affected the magnetic and tribological performance of the tapes. The friction force and head output generally increased, and the dropout frequency (number of dropouts/min) generally decreased as the tapes were worn smooth. Head-to-tape spacing and dropout frequency decreased more for MP tape, as compared to ME tape. On the ME tape surface, damage initiated at high points or bumps, which resulted in weakening of the metal coating at these locations. Cracks initiated at these locations grew (driven by longitudinal tension) laterally across the tape width and connected localized damage areas at tape failure after 840 play/rewind cycles. MP tape performance improved gradually through 1000 play/rewind cycles. Based on this study, ME tape is less durable than MP tape, and reduced waviness of the ME tape surface could further improve ME tape performance.

In previous work, carbon coated [Al.sub.2][O.sub.3]/TiC sliders showed much better wear properties on lubricated carbon disks than the uncoated sliders [1]. In this paper, drag tests were conducted in a vacuum chamber to monitor the tribochemistry at the head-disk interface to understand the fundamental mechanisms related to the wear at the head disk interface.

The alteration of carbon bonding resulting from the continuous frictional heating between a magnetic head slider and a rotating thin film rigid disk has been investigated. This change of carbon bonding from diamondlike amorphous carbon phase to graphite phase was inspected by Scanning Auger Microscopy (SAM). As near and direct contact recording are being considered for future high density disk drives, this phase transformation of the protective carbon overcoating could result in failure of the head-disk interface.

The disk surface texture was assessed in both the radial and tangential directions to estimate the size and number statistics of real contact spots at the head-disk interface and the friction force between head and disk surface. It was demonstrated that textured disks having similar characteristics in the radial direction happen to show different profile features in the tangential direction. The relatively large values in wave peak undulation and its tangential spacing in the tangential direction reduced the frictional force in CSS tests. It was also indicated that the friction force increases with apparent radius of curvature of the significant wave peaks determined by rolling a virtual circle over the macroscopic profile in the tangential direction.

In order to reduce the decrease of head output level during running, the wear recession formed on a composite material and MIG heads with various ferrite crystallographic orientations was investigated. It was found that wear recess depends mainly on the wear rate ratio of materials, and that the decrease in output level was in proportion to the spacing loss due to the formation of a level difference at the interface between the metal and the ferrite core. However the decrease measured using different kind tape from the running tape was also effected by the unfitness between head and tape. We also found that the damage caused to ME tape depends on the ferrite orientation of the head.

Key aspects for continuous contact recording technology were investigated experimentally. A slider with 0.7 mN contact force was used. Slider jump height and head positioning error were negligible with a low stiction media. Wear of head protective layer was predicted to be several nm through the drive lifetime. Mechanical spacing estimated from PW50 was 8 nm. These results proved feasibility of continuous contact recording scheme. Index Terms--Contact recording, dynamic stiction force, positioning error, slider jumping, wear of head protective layer.

A drag test with a speed alternating between two levels was developed to create wear tracks on disk surfaces. This approach reduces the uncertainty involved in the contact start/stop (CSS) test of thin carbon overcoats. The wear tracks were identified with an optical surface analyzer as regions with higher values of the absorption ratio calculated from reflectivity data of both P- and S-polarized lights. Calibrated with scanning micro-ellipsometry, the absorption ratio was converted to a wear depth. The amount of wear in a drag test increased with time, and a low-flying head resulted in more wear than a high-flying head. The 45-angstrom nitrogenated carbon film sputtered at a lower temperature exhibited a smaller wear depth. The higher wear resistance of the low-temperature sputtered film is supported by less wear in a nanowear test, a lower Raman G-peak position, and less frequent crashes in CSS tests. Index Terms--Carbon film, disk drive, drag, ellipsometry, tribology, wear.