A Wide Range Measuring System for Thin Lubricating Film: From Nano to Micro Thickness

This paper introduces a newly developed lubricating-film-thickness measuring system, which implements the multi-beam intensity-based (MBI) scheme proposed recently by the authors. Some details about the software of the testing system and instrumentation of the MBI approach are discussed. For efficient determination of the fringe order range of measured points, a simple counting strategy was suggested. It is shown that this measuring system can provide a measurement range from nano to micrometers and a high resolution on the nanometer level. Besides being able to detect ultra-thin lubricating film thickness, the system can also measure tiny local variations in film thickness on a nano-scale in the conventional EHL regime. The capability of the system is demonstrated by the determination of film thickness in the range of 1nm to 2.542m with a standard deviation of 0.89nm. In addition, some analyses are given for further understanding the optical EHL and the testing system in this paper.     

The Effect of Heat Treatment on Sliding Wear Behaviour of a Zinc-Based Alloy Containing Nickel and Silicon

This investigation deals with the observations made pertaining to the sliding wear behaviour of a zinc-based alloy containing nickel and silicon in partially lubricated condition. Wear tests were conducted over a range of applied pressures and sliding speeds. The effect of microstructural changes brought about through T6 heat treatment involving solutionizing followed by artificial ageing on wear behaviour was also investigated. The wear rate increased with pressure. The slope of the wear rate versus pressure plots was low initially up to a specific pressure. This was followed by a higher slope beyond the (specific) pressure. In some cases, the rate of change in wear rate, i.e. the slope, decreased at still higher pressures. Moreover, the (specific) pressure decreased with sliding speed in general. Increasing sliding speed caused the wear rate of the as-cast zinc-based alloy to increase up to a sliding speed of 2.68m/s. The trend reversed at a still higher speed of 4.60m/s. However, increasing wear rate with speed was noted for the heat-treated alloy over the entire speed range. Heat treatment led to reduced wear rate up to a sliding speed of 2.68m/s. An opposite trend was observed at a higher speed of 4.60m/s in this case. Specimen seizure was noted at speeds above 2.68m/s in the case of the as-cast alloy whereas seizure took place only at 4.60m/s for the heat-treated alloy samples. Frictional heating increased with pressure and speed. The specific response and changing mode of distribution of various phases were thought to be responsible for the typical wear behaviour of the alloy in specific material and test conditions. The predominance of parameters like thermal stability and cracking tendency over each other is suggested to lead to the varying wear behaviour of the alloy in different (material and sliding) conditions. The wear response of the samples has been substantiated through characteristics of their wear surfaces, subsurface regions and debris.     

Time-of-Flight Trigger Based on a Time-to-Amplitude Converter

A time-of-flight trigger based on a time-to-amplitude converter and differential discriminator is described. The trigger has a short decision time (60 ns) and high (100%) efficiency of useful event selection.     

Time-of-Flight Characteristics of Scintillation Counters with Fine-Mesh Photomultipliers

The characteristics of the time-of-flight system of scintillation counters with the -527 and R5505 fine-mesh-dynode photomultipliers for high-magnetic-field environment were measured. Scintillation counters with thin plastic scintillators 1, 3, and 5 mm thick were designed to operate in comparatively strong stray magnetic fields of up to several kilogauss. The measurements were carried out in beams of the U-10 proton synchrotron (Institute of Theoretical and Experimental Physics) with proton, ⁺-meson, and ^–-meson momenta of 0.63, 1.03, and 1.28 GeV/c. For counters with scintillator sizes of 1 × 20 × 154 mm (BI-408) and 3 × 20 × 200 and 5 × 20 × 200 mm (Kuraray and SCSN-81), time resolutions of 45–180 ps were obtained. The time resolution of the scintillation counters, in which scintillators 20 mm thick and -527 photomultipliers were used, was found to be 50–80 ps.     

Effect of temperature on tribological performance of a silicon nitride ball material with a linear perfluoropolyalkylether

The effect of temperature in rolling contact performance of a hot isostatically pressed (HIP) silicon nitride ball material with a linear perfluoropolyalkylether (PFPAE) was studied using a ball-on-rod type rolling contact fatigue tester. The test temperature ranged from ambient to 343°C for a period of 24 h at a stress of 5.5 GPa using thin dense chrome (TDC)-coated T-15 bearing races. The lubricant and its decomposition products, specifically acid fluoride and acids, attacked Si₃N₄ balls at all test temperatures resulting in corrosion pitting. The presence of metal fluoride on all the Si₃N₄, transferred from the races, was detected by X-ray photon spectroscopy (XPS). The thickness of the oxide layer formed on the balls, as determined by Auger electron spectroscopy (AES) increased with temperature. The changes in physical properties of post-test lubricant showed that the lubricant was stable at temperatures up to 288°C. The change in viscosity was constant up to 288°C and with a significant change above 288°C. The FTIR analysis of 316 and 343°C post-test lubricant showed the presence of carboxylic acid. The total acid number (TAN) increased linearly up to 288°C and accelerated at 316 and 343°C. The study indicates that the use of Si₃N₄ balls with a linear PFPAE results in an incompetent tribo system.     

Low-Stress Abrasive Wear Behaviour of a 0.2% C Steel: Influence of Microstructure and Test Parameters

A low (0.2%) carbon steel has been subjected to heat treatment to form varying quantities of ferrite plus martensite in its microstructure. This was achieved by holding the samples in the two-phase (ferrite plus austenite) region at three different temperatures (750, 780, and 810°C) for a specific duration followed by quenching in ice water. In another exercise, the steel was also subjected to annealing treatment by austenitizing at 890°C followed by furnace cooling for comparison purposes. The samples were subjected to low-stress (three-body) abrasion tests using an ASTM rubber wheel abrasion test apparatus at different wheel speeds (150, 273 and 400rpm corresponding to linear speeds of 1.79, 3.26 and 4.78m/s respectively) for different sliding distances at a fixed load of 49N. Crushed silica sand particles of size ranging from 212 to 300 m were used as the abrasive medium. The wear rate of samples decreased progressively with sliding distance until a (nearly) steady-state condition was attained. This was considered to be due to abrasion-induced work hardening of subsurface regions as well as the greater tendency of protrusion of the harder martensite/pearlite phase at longer sliding distances, thereby providing greater resistance to wear. Decreasing wear rate with increasing treatment temperature 750–810°C could be attributed to the greater volume fraction of the hard martensite phase in the samples containing ferrite plus martensite. The lower wear rate observed in the case of the samples containing ferrite plus martensite over the annealed ones comprising ferrite and pearlite was attributed to the higher bulk hardness of the former. Increasing linear speed from 1.79 to 3.26m/s led to an increase in wear rate. This could be attributed to greater tendency of the abrasive particles to create deeper scratches and scouping (digging). A reduction in wear rate with a further increase in the linear speed from 3.26 to 4.78m/s could be due to a change in the mechanism of wear from predominantly sliding to rolling of the abrasive particles in view of the increased plastic deformability characteristics of the specimens due to higher frictional heating. The present investigation clearly suggests that it is possible to attain a desired combination of bulk hardness and microstructure (consisting of ferrite plus martensite) leading to optimum abrasion resistance in low-carbon steels. The quantity of the two phases in turn could be varied by suitably controlling the heat-treatment temperature.     

A Solar Spectromagnetograph

A new solar spectromagnetograph for measuring the full magnetic-field vector and line-of-sight velocities is described. A new version of a polarization analyzer ensuring parallel measurements of six polarization components of spectral lines is considered. The spectromagnetograph allows the use of any algorithms for obtaining the magnetic fields vector, in particular, the Babcock algorithm and the Fourier transform technique. The sensitivity of the instrument for the longitudinal and transverse magnetic field is 3–5 and 20–30 G, respectively, and 10 m/s for the line-of-sight velocities.     

The FOZAN-II Fast-Response Chemiluminescent Airborne Ozone Analyzer

The design of the FOZAN-II dual-channel automatic fast-response (1 s) chemiluminescent ozone analyzer for a M55 Geophysicahigh-altitude aircraft is described. Its measured concentrations range is 10–500 g/m³; relative error, 10%; operating temperature range, –95+40°C; and its operating pressure range, 1100–30 mbar (0–22 km). The device has a built-in reference ozone generator (relative error of <6%) allowing one to autocalibrate the device in flight. Solid-state chemiluminescent sensors manufactured with the use of a coumarin 307 dye and a cellulose-acetate-based substrate have an operation lifetime exceeding 25 h, are highly sensitive, and are rugged. Results obtained during one of the flights near the South Pole in September 1999 are presented.     

Detection of the Increment of an Instantaneous Phase in a Long-Base Laser Meter of Small Vibrations

A phase meter for processing signals of a laser meter of small displacements and vibrations at long base distances is described. Vibrations of objects are transformed into small increments of a signal phase at an RF carrier, which are detected by the phase meter and are outputted as signals proportional to microvibrations in the acoustic range. At a given carrier frequency f _c = 10.7 MHz, vibrations are detected within a band f = 3 kHz. Such vibrations produce phase fluctuations of 10^–42, which correspond to magnitudes of 1 nm for a laser wavelength 10 m.     

Adhesion and Friction Evaluation of Textured Slider Surfaces in Ultra-Low Flying Head-Disk Interfaces

To achieve extremely high-density magnetic recording of 1Tbit per square inch using conventional technologies, the distance between the recording slider and the rotating disk needs to be less than 5nm. For successful operation, disk and slider surfaces must also be extremely smooth with root-mean-square roughness values of few angstroms. However, ultra-low flying super smooth head-disk interfaces may be exposed to a significant amount of intermittent contact, adhesion, stiction and friction that can cause the interface to collapse. In order to circumvent such problems, many novel techniques have been proposed, such as laser zone texturing, contact pads and surface microtexturing. A reliable method to reduce adhesion and friction in ultra-low flying head-disk interfaces is to control the area of contact and roughen the interface, which allows the slider to fly at sub-5nm with minimal contact. A technique known as preferential texturing provides a unique roughening of the air-bearing surface, where parts of the surface are removed, i.e., subtractive texturing process. In this paper, the effect of preferential texturing (roughening) of slider air-bearing surfaces on the adhesion and friction forces are investigated using quasi-dynamic models. The simulation results show that surface texturing reduces adhesion and friction by reducing the effective area of contact between the slider and media surfaces and by preferentially roughening the interface. The simulation results of friction compare favorably with experimental data.