Tribology in Industry

1-8

Authors: N. Radhika

LM25 aluminium alloy reinforced with 15 wt% SiO2 metal matrix composite was fabricated by liquid metallurgy technique. Microstructure of the fabricated composite specimen was observed using inverted metallurgical microscope and result showed uniform distribution of reinforcement particles in the matrix. The dry sliding wear behaviour of LM25/SiO2 composite was analyzed by conducting experiments using pin-on-disc tribometer. Taguchi’s method was used for designing the number of experiments and L16 orthogonal array was developed for wear analysis. Optimization of parameters like applied load (10 N, 20 N, 30 N, 40 N), sliding velocity (0.5 m/s, 1 m/s, 1.5 m/s, 2 m/s) and sliding distance (500 m, 1000 m, 1500 m, 2000 m) was done using Signal-to-Noise ratio analysis and Analysis of Variance. ‘smaller-the-better’ characteristic was chosen to analyze the dry sliding wear behaviour. Results found that load (69.17 %) had the highest impact on wear rate followed by sliding velocity (18.04 %) and sliding distance (1.5 %). The regression equation was developed and it was validated with confirmatory experiment. Scanning Electron Microscope analysis was done to observe the mechanism of the worn out composite specimen and found more delamination at the load of 40 N.

20-30

Authors: K.A. Najar, N.A. Sheikh, M.A. Shah

An experimental investigation has been carried out to study the influence on the performance characteristics of a cutting tool material notably known as cemented tungsten carbide (WC-Co). A comparison has been documented between nanocrystalline diamond (NCD) and microcrystalline diamond (MCD) coatings deposited on two cemented tungsten carbide (WC-Co) substrates with the architectures of WC-Co/NCD and WC-Co/MCD, using hot filament chemical vapor deposition (HFCVD) technique. In the present work, the friction characteristics were studied using ball-on-disc type linear reciprocating micro-tribometer, under the application of 1–10 N normal loads, when sliding against smooth alumina (Al2O3) ceramic ball for the total duration of 20 min, under dry sliding condition. Nanoindentation tests were also conducted using Berkovich nanoindenter for the purpose of measurement of hardness and elastic modulus values. However, the average value of friction coefficient (COF) corresponding to MCD and NCD coatings decrease from ~0.37–0.32 and ~0.30–0.27, respectively when the load is increased from 1–10 N. However, for conventional WC-Co substrate the average COF increases from ~0.60–0.75, under the same input operating conditions. The wear tracks formed on the surfaces of NCD, MCD and WC-Co, after sliding were characterised using Raman spectroscopy and scanning electron microscopy (SEM) techniques. Therefore, the results will serve breakthrough information for the designer to design the cutting tool or mechanical component using this novel coating procedure.

45-49

Authors: G.R. Igtisamova, N.O. Kovalev

The paper considers improvement of screw dies of mobile coiled tubing unit injector through the change in screw die's design parameters with further mounting of metal-ceramic based friction material. Comparison of designs of unit injector screw dies was carried out and reliability evaluation of an improved coiled tubing transporter unit was executed.

63-72

Authors: F.O. Kolawole, S.K. Kolawole, J.O. Agunsoye, S.A. Bello, J.A. Adebisi, O.C. Okoye, S.B. Hassan

Characterization of synthesized cassava leaf nanoparticles (CLNPs) was carried out using SEM/EDX and Gwyddion software, XRD and TEM for cassava leaves (CL) ball milled at 36, 48, 60 and 72 hours. The morphological study was done using SEM and the Gwyddion software was used to determine the particle sizes from the SEM images. The particle size range for the un-milled cassava leaves (CL) was between 1.88 + 0.09 to 19.53 + 0.98 µm. After milling for 36, 48, 60 and 72 hours the average particle sizes were 4.96 + 0.25, 3.51 + 0.18 µm, 86.90 + 4.35, 74.50 + 3.73 nm respectively. Crystallite size of 23.94 + 1.20 nm was obtained by XRD using Scherrer equation after milling for 72 hours and the XRD results revealed the presence of compounds such as SiO2, CaCO3, Ca2(SO4)2H2O and CaC2O4(H2O). Furthermore, TEM was used to determine nanoparticles after milling for 72 hours and the particle size ranged from 9.16 + 0.46 to 58.20 + 2.91 nm for cassava leaf nanoparticles (CLNPs) and EDX results showed trace element of O, Si, Ca, K, Fe and S in the CL milled for 72 hours . FTIR was also carried out to determine the nature of bond that exist in the organic compounds in CLNPs and GCMS analysis was used to reveal the organic compounds that were present in CLNPs. Anti-Corrosion coatings reduces corrosion activities to the bearest minimum.

82-89

Authors: P. Novotny

A solution of radial slide bearing dynamics and tribology incorporating the influences of real surface roughness contacts or the influence of surface roughness on bearing lubrication is presented in this paper. Finite difference method for Reynolds equation discretization, finite element method for calculation of elastic deformations, Gauss-Seidel’s method for iterative solution of discretized equations or Newmark’s algorithm are the methods employed in the proposed solution approach. The coupled structural-fluid solver considering mixed lubrication conditions of the radial bearings is the result. The proposed algorithms are presented for highly loaded radial slide bearing of internal combustion engine.

100-109

Authors: H. Mohassel, F. Malekabadi, M. Jebreili, M. Zehsaz, F. Vakili-Tahami

We have investigated the influence of post-shot peening on Mo-coating as compared to substrate steel 16MnCr5 (according to ZFN-413 A). Shot peening of carburized steel discs with and without Mo-coating was performed by using Shot size S230, Almen intensity 0.42 mm ’A’ and exposure time 96 sec. Tribological properties were analyzed, using pin-on-disc tribometer apparatus, under dry sliding conditions at different specific applied loads, sliding velocities and distance. Typical standardized methods were used for studying of surface integrity parameters (micro-hardness, topography and surface roughness). Surface morphology of the Mo-coating specimens with and without Shot Peening before and after wear was evaluated by Scanning Electron Microscopy. The results showed that shot peening after Mo-coating has considerable effect on improving wear resistance and because of having low friction coefficient has showed better wear behavior and tribologi cal properties over that of the un-peened Mo-coating.

120-128

Authors: M.F. Abd Al-Samieh

The mechanism of oil film with a thickness in the nanoscale is discussed in this paper. A polar lubricant of propylene carbonate is used as the intervening liquid between contiguous bodies in concentrated contacts. A pressure caused by the hydrodynamic viscous action in addition to double layer electrostatic force, Van der Waals inter-molecular forces, and solvation pressure due to inter-surface forces is considered in calculating the ultrathin lubricating films. The numerical solution has been carried out, using the Newton-Raphson iteration technique, applied for the convergence of the hydrodynamic pressure. The results show that, at separations beyond about five molecular diameters of the intervening liquid, the formation of a lubricant film thickness is governed by combined effects of viscous action and surface force of an attractive Van der Waals force and a repulsive double layer force. At smaller separations below about five molecular diameters of the intervening liquid, the effect of solvation force is dominant in determining the oil film thickness.

136-143

Authors: S. Bhaumik, S.D. Pathak

The wear and surface morphology between steel (EN24, 22-24Rc)-steel (EN 31, 58-60Rc) contacts was investigated in presence of friction modifiers based (micro-graphite/nano particles- multi wall carbon nano tubes and zinc oxide) mineral oil. Though a decrease in wear was observed (upto a certain concentration of nano friction modifiers) but a weight-gain in pins after the tests was observed for all tests with ZnO nanoparticles while weight loss was observed in tests with multi wall carbon nano tubes and graphite particles based oil samples. Surface characterization of the worn surfaces showed more surface deteriorations in case of mineral oil (no friction modifiers) and mineral oil with graphite as compared with nano particles/tubes based lubricants. The occurrence of a tribo film due to the deposition of nano particle and the formation of a modified layer on the pin surfaces are likely to be responsible for the reduction of coefficient of friction and better surface roughness. Apart from investigating the wear behaviour between two steel surfaces under micro and nano particles based lubricant and analysing the surfaces of the samples a part of the work was also focussed on the weight gain after tribo tests with ZnO nano particle additions.