Gananath D. Thakre

Effect of cylindricity on the tribological performance of heavily loaded slow-speed journal bearing:

Theoretical and experimental studies have been conducted to analyze the effect of cylindricity on performance of a heavily loaded slow-speed journal bearing. The design of experiments has been employed to quantify the effect of bearing clearance and cylindricity on the wear. Since the initial experimental results did not establish any definitive trend, the effect of running-in was considered and the sliding distance required for reaching steady wear was estimated by conducting tests on lubricity tester employing conformal block and disc configuration. Further experiments incorporating the running-in were then conducted on journal bearing test rig. The wear coefficient was determined using the steady wear data obtained experimentally on the lubricity tester. A mathematical model was formulated to estimate wear of the bearing incorporating the actual cylindricity. The theoretical and experimental results corresponded well indicating a strong dependence of wear on the bearing cylindricity at the contact zone.

Derivatizing L-histidine to develop a novel additive for a polyol-based biolubricant

Two novel histidine Schiff base esters, HSE-A and HSE-B, were synthesized using a two-step reaction. The synthesized compounds were characterized using carbon, hydrogen, nitrogen analysis, Fourier-transform infrared and nuclear magnetic resonance spectroscopy. The antioxidant and anticorrosion properties of these additives were assessed using the universal oxidation test (IP-306) and standard accelerated corrosion testing procedure, which revealed that both additives have good antioxidant and anticorrosion properties. Lubricity test carried out in a four-ball test machine indicated that both additives could reduce wear when compared with the pure polyol base oil. Overall, the HSE-A additive is more effective than the HSE-B additive as an antioxidant/antiwear/anticorrosion biolubricant additive.

Halogen-free ammonium–organoborate ionic liquids as lubricating additives: the effect of alkyl chain lengths on the tribological performance

Novel halogen and phosphorus free ionic liquids containing chelated organoborate anions having different alkyl chain lengths and tetrabutyl ammonium cations have been studied as anti-wear and friction reducing agents under elasto-hydrodynamic/mixed lubrication conditions for steel–steel contacts. The synthesized ionic liquids were found to be quite stable at room temperature and showed a remarkable improvement in the friction-reducing and anti-wear properties of the PEG 200 lube base. The effect of alkyl chain lengths on the tribo-performance of the synthesized additives was systematically studied.

Development of new ecofriendly detergent/dispersant/antioxidant/antiwear additives from L-histidine for biolubricant applications

Two novel overbased Ca salts of histidine Schiff base esters Ca-HDS-L and Ca-HDS-M were synthesized following a three-step reaction sequence. The histidine Schiff base (HDS) was synthesized first by imine coupling of histidine with salicylaldehyde. Then its phenolic group was esterified using lauroyl chloride and myristoyl chloride to obtain HDS-L and HDS-M, respectively. Finally in the third step, their respective overbased salts Ca-HDS-L and Ca-HDS-M were synthesized by reaction with Ca(OH)2. All the synthesized compounds were characterized using FT-IR, NMR, CHN and TG analysis. Panel coker federal test (FTM 3462), blotter spot test (ASTM D7899), universal oxidation test (IP-306) and four ball test (ASTM 4172A) were used for the evaluation of detergent, dispersant, antioxidant and antiwear activity, respectively, of the synthesized additives in polyol base oil. Both the additives are active but overall Ca-HDS-L is more effective as detergent and dispersant while Ca-HDS-M is more effective as antioxidant and antiwear multifunctional biolubricant additive.

Experimental study on the efficacy of MoS2 microfluids for improved tribological performance

This paper reports the synthesis and tribo-performance investigation of microfluids developed using silane functionalized µ-molybdenum disulphide (µ-MoS2) particles for improved tribological performance. The functionalized µ-MoS2 particles were characterized by analytical techniques like Fourier-transform infrared, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The µ-MoS2 particles were then blended with mineral base oil in varying concentrations. The lubrication characteristics in terms of anti-friction, anti-wear, and extreme pressure properties of the µ-MoS2 particle blended microfluids were evaluated under different lubrication regimes. The results showed an excellent improvement in anti-wear, anti-friction, and extreme pressure properties. The tribo-performance of the MoS2 microfluids strongly depends on the compatibility and concentration of particles with base oils. Functionalization of the µ-MoS2 particles by trichlorooctadecylsilane allows forming stable dispersion in base oil. The MoS2 microfluids can be used as lubricants in advance tribological applications.

Capacity of thiourea Schiff base esters as multifunctional additives: synthesis, characterization and performance evaluation in polyol

A novel thiourea Schiff base ester TSBE was synthesized following a two step reaction. At first, thiourea and salicylaldehyde were reacted in ethanol to obtain thiourea Schiff base TSB. In the second step, esterification of TSB was done with lauroyl chloride catalyzed by 4-(dimethylamino)pyridine (DMAP) in N,N-dimethylacetamide (DMAc) solvent to obtain the final product TSBE. The synthesized compounds were characterized using CHN analysis, FT-IR and NMR. The antioxidant properties of this additive were assessed via the universal oxidation test (IP-306) and rotary bomb oxidation test (ASTM D2272) while antifriction and antiwear properties were evaluated in terms of the average friction coefficient and average wear scar diameter respectively by doing the four ball test (ASTM D4172). Studies revealed that TSBE had good antioxidant properties. Tests carried out by a four ball test machine indicated that the additive TSBE could reduce the friction to 45.6% and wear to ∼20% when compared with the pure polyol base oil.

A parametric investigation on the microelastohydrodynamic lubrication of power law fluid lubricated line contact

A parametric study of microelastohydrodynamic lubrication contact between rough cylinder and plane lubricated with non-Newtonian power law fluid is carried out. A Gaussian rough surface is considered and modeled using stochastic approach. A theoretical solution of pressure distribution, fluid film thickness, and friction for given speeds, material properties, slide-to-roll ratio, and power law index, is obtained by solution of Reynolds equation using finite element method techniques. An isotropic roughness pattern is considered and results are obtained for wide range of operating parameters. The results indicate that the shear-thickening fluids provide thicker lubricant films as compared to shear-thinning fluids. The minimum fluid film thickness is observed to decrease with an increase of load and it increases with an increase of speed and material parameter. Slide-to-roll ratio has a marginal influence of the minimum film thickness. Under certain operating conditions, softer materials with shear-thickening lubricants yield thicker lubricant films than the harder materials lubricated with shear-thinning fluids. The coefficient of friction too is influenced by the rheology of lubricants with shear-thinning fluids providing larger values of coefficient of friction than the shear-thickening fluids.

Synthesis and tribological behavior of fatty acid constituted tetramethylguanidinium (TMG) ionic liquids for a steel/steel contact

In the present study a number of fatty acid constituted ionic liquids having tetramethylguanidinium ion as a cationic counterpart were synthesized by neutralization of 1,1,3,3‑tetramethyguanidine (TMG) with fatty acids having varying degree of alkyl chain and olefinic bonds. The structure of the synthesized ionic liquids was thoroughly characterized using a number of analytical tools such as TGA, FT-IR, 1H and 13C NMR spectroscopy. The tribo-properties of the obtained ionic liquids as high performance anti-friction and wear reducing additives were studied in different dosage to mineral base oil under condition of mixed/boundary lubrication. It was found that the anti-wear and friction reduction properties of blends were improved with increasing the alkyl chain in constituted fatty acid ionic liquids.

Friction Reduction Capabilities of Silicate Compounds Used in an Engine Lubricant on Worn Surfaces

Effects of magnesium silicate and alumina dispersed in engine lubricant on friction, wear, and tribosurface characteristics are studied under boundary and mixed lubrication conditions. Magnesium silicate and alumina, henceforth called as friction reducing compounds (FRC), were dispersed in engine lubricant in very low concentration of 0.01% weight/volume. Four-ball wear test rig was used to assess friction coefficient and wear scar diameter of balls lubricated with and without FRC based engine lubricant. Scanning electron microscopy (SEM) equipped with Energy Dispersive X-ray (EDX) was used to analyse the tribosurface properties and elemental distributions on worn surfaces of the balls. Test results revealed that FRC based engine lubricant increases friction coefficient but marginally reduces wear scar diameter of new balls, whereas, test on the worn-out balls running on FRC based engine lubricants shows 46% reduction in friction coefficient compared to the new balls running on engine lubricants without FRC. Investigations on tribosurfaces with respect to morphology and elemental distribution showed the presence of Si and O elements in micropores of the worn surfaces of the balls, indicating role of FRC in friction coefficient reduction and antiwear properties. These FRC based engine lubricants may be used in the in-use engines.