No abstract

Two additive free calcium stearate greases have been developed for the requirements of lubrication in automotive components. Two compositions of calcium stearate greases have been prepared by adding 12% and 15% by weight calcium stearate soap in the 450-neutral base oil. Greases have been prepared using the dry technology. The effects of the compositions of calcium stearate soap on the tribological properties of greases have been investigated with the aid of four-ball tester, SRV-Optimol tester, scanning electron microscope (SEM), and transmission electron microscope (TEM). The tribological properties of the additive free greases have been compared with similar application intended commercially available greases containing additives. The structure examinations (before and after weld tests on four ball tester) of the additive free calcium stearate greases have been done using TEM. The FTIR analyses of both synthesized additive free greases have been carried out to study the degradation in greases after weld tests on four-ball tester. It has been observed based on the present investigations that the additive free calcium stearate greases show comparable tribological behavior with commercial greases containing additives.

The effect of various film profiles on the load carrying capacity of adiabatically lubricated fixed pad thrust bearing is analyzed in this work. One dimensional film thickness profiles such as taper, polynomial, catenoidal, exponential and truncated cycloidal are employed here to predict the load carrying capacity of the fixed pad thrust bearings. Results are computed for various levels of speeds (5m/s, 15m/s, 25m/s) at two levels of viscosity (0.5Pas, 0.05Pas). The shape of the film profile do influence the load carrying capacity of the thrust bearings and the polynomial film thickness profile has the maximum influence when compared to other film profiles.

The investigation is aimed at a study of the relations between powder properties, sintering treatments and the densification and microstructure development in urania pellets. Urania powders for this study were prepared from ammonium diuranate by decomposition and reduction at various temperatures, namely, 400°, 600°, 900°, 1200° and 1500°C. Pellets prepared from these powders were sintered at temperatures in the range of 1200° to 1700°C with different soaking periods.The influence of (i) sintering temperatures, (ii) soaking periods at different temperatures, (iii) intermediate soaks at varying time periods at various temperatures, (iv) reheating of prepared sintered pellets and (v) rates of heating during sintering, on the density and microstructure development of pellets was studied in this investigation.The study revealed that urania pellets of specified density and grain development can be prepared by first attempting to achieve 'densification and then continuing the thermal treatments to attain the desired grain size and microstructure.

The objective of this study is to investigate the enhancement of tool life and wear resistance with a physical vapour deposition (PVD) process applied using aluminium chromium nitride (AlCrN) and titanium nitride (TiN) coating on carbide inserts. Flank wear experiments are carried out on a computer numerically controlled (CNC) machine under wet conditions with both the coated inserts. Effectiveness of the coating on the tool life and its resistance to flank wear are observed at various cutting parameters such as cutting speed and feed rate by following the principle of design of experiments (DOE). It is inferred that AlCrN coated carbide tools perform nearly 70% better than the TiN coated carbide tools under high cutting speed and feed rate. AlCrN coating also enhances the durability of tool for metal cutting and thereby improves tool life even under harsh cutting conditions. A response surface methodology (RSM) is utilised to arrive at the optimum value for the various parameters which are responsible for improving the wear resistance and tool life.