Tribology in Industry

109-116

Authors: A. Mukhopadhyay

Ethylene Propylene Diene Monomer (EPDM) rubber emerges as a dominant elastomer for major engineering applications. The major properties of EPDM are its outstanding heat, ozone and weather resistance ability. It has a good resistance to polar substances and steam condition too. In automobiles EPDM rubber has a common use as seals. This includes door seals, window seals, trunk seals and sometimes hood seals. Frequently these seals are the source of noise due to the movement of the door versus the car body. This is due to friction between the EPDM rubber parts and the mating surfaces. Thus, the contact iteration between the rubber sealing and the indenting object must be known to optimize the performance of rubber sealing. However, it is need less to mention that the behaviour of any viscoelastic material is very difficult to be predicted. In the present work various tribo-characteristics of EPDM rubber of different hardness have been evaluated utilizing the available laboratory test facilities in the Jadavpur University, Kolkata, India. Compression tests have been carried out using ‘Instron’ to determine the flow behaviour of EPDM rubber of different hardness both in dry as well as under different conditions of lubrication. The flow behaviour like load -vs.- elongation curves, true stress -vs.- elongation curves and true stress -vs.- true strain curves have been drawn from the experimental data. Abrasive wear behaviour has been evaluated using a two-body abrasion tester and the pattern abrasion has been appraised through SEM/EDAX study. Experimental results reveal that the hardness of EPDM rubber has significant effect on the flow behaviour and wear characteristics. The hardness, again, depends on the proportion of carbon black (CB) content. Thus it can be stated that the flow behaviour can be governed by controlling the CB concentration in the EPDM rubber. Based on the experimental results conclusion has been drawn accordingly. Some of the important tribo-characteristics of EPDM have been highlighted. Light has also been shed on various possible areas of further researches those should be undertaken in the future to come.

127-133

Authors: S. Baskar, G. Sriram

The friction and wear behavior of journal bearing material has been investigated using pin on disc wear tester with three different lubricating oils i.e. synthetic lubricating oil (SAE20W40), chemically modified rapeseed oil (CMRO), chemically modified rapeseed oil with Nano CuO. Wear tests were carried out at maximum load of 200 N and sliding speeds of 2 – 10 m/s. The results showed that the friction and wear behavior of the journal bearing material have changed according to the sliding conditions and lubricating oils. The journal bearing material has a lower friction coefficient for CMRO with Nano CuO than other two oils. Higher wear of journal bearing material was observed in SAE 20W40 and CMRO. Worn surfaces of the journal bearing material with three lubricating oils were examined using scanning electron microscope (SEM) and wear mechanisms were discussed.

144-154

Authors: U.A. Zia, A.A. Baqai, W. Akram

Frictional wear is one of the most common causes of material failure. One of the most common techniques to overcome this is to lubricate the surfaces in contact using an optimum amount of appropriate lubricant. Same technique is utilized in the present case to overcome the problem of frictional wear between two parallel surfaces subjected to high acceleration. The lubrication solution proposed is a modification of “Numerical model for mixed lubrication” presented in 1990s. Present research is an extension of author’s previous work in the same. Here the smooth surfaces of the previous research have been replaced with rough surfaces having same surface roughness value. Also in order to study the effect of temperature the viscosity of lubricant is taken for different temperatures. Keeping in view the problem constraints as explained in section 3, certain modifications are proposed in the model of mixed lubrication. Outcome of the research is a graphical pattern showing the lubricant film thickness required at different positions between the contacting surfaces. Different grades of Krytox are used for the solution as it is nonflammable, anticorrosive Perfluoropolyether based grease, commonly used for high temperature cases. The results obtained by the numerical model are compared and found well-in-accordance with the experimental data available and with the analytical predictions made by scholars in the past, which verifies the applicability of the model chosen for solution.

163-171

Authors: H.M. Mobarak, M. Chowdhury

Increasing environmental awareness and demands for lowering energy consumptions are strong driving forces behind the development of the vehicles of tomorrow. Without the advances of lubricant chemistry and adequate lubricant formulation, expansion of modern engines would not have been possible. Considering environmental awareness factors as compared to mineral oils, vegetal oil based biolubricants are renewable, biodegradable, non-toxic and have a least amount of greenhouse gases. Furthermore, improvement in engine performance and transmission components, which were impossible to achieve by applying only lubricants design, is now possible through diamond like carbon (DLC) coatings. DLC coatings exhibit brilliant tribological properties, such as good wear resistance and low friction. In this regard, tribological performance of a-C: H DLC coating when lubricated with Canola vegetal oil has been investigated by the help of a ball-on-flat geometry. Experimental results demonstrated that the a-C: H DLC coating exhibited better performance with Canola oil in terms of friction and wear as compared to the uncoated materials. Large amount of polar components in the Canola oil significantly improved the tribological properties of the a-C:H coating. Thus, usage of a-C: H DLC coating with Canola oil in the long run may have a positive impact on engine life.

181-187

Authors: M. Kandeva, D. Karastoianov, B. Ivanova, V. Pojidaeva

Friction and wear of 10 types Ni chemical coatings, with and without heat treatment, containing nano-diamond particles of various size – 0;5 nm; 100 nm; 200 nm and 250 nm, are studied in the paper. Procedure and laboratory device for friction investigation in starting regime were developed. Experimental results for the influence of the particle size on the static friction force and the change of friction coefficient have been obtained. Abrasive wear has been studied by means of the procedure developed by the authors for the study of above coatings under conditions of dry friction on surfaces with fixed abrasive. The obtained results are related to the parameters linear wear, wear rate and wear-resistance. A part of this study is connected with the tasks on the 7 FP Project „Acom In (Advanced Computing Innovations)” coordinated by the Institute of Information and Communication Technologies at the Bulgarian Academy of Sciences, and the other part is carried out under the Project ДУНК-01/3 “University R&D Complex for innovation and transfer of knowledge in micro/nano-technologies and materials, energy efficiency and virtual engineering” funded by the Bulgarian Ministry of Education and Science.

195-203

Authors: K.K. Alaneme, B.O. Fatile, J.O. Borode

The mechanical and corrosion behaviour of Zn-27Al alloy based composites reinforced with groundnut shell ash and silicon carbide was investigated. Experimental test composite samples were prepared by melting Zn-27Al alloy with pre-determined proportions of groundnut ash and silicon carbide as reinforcements using double stir casting. Microstructural examination, mechanical properties and corrosion behaviour were used to characterize the composites produced. The results show that hardness and ultimate tensile strength of the hybrid composites decreased with increase in GSA content. Although the % Elongation somewhat decreased with increase the GSA content, the trend was not as consistent as that of hardness and tensile strength. The fracture toughness of the hybrid composites however, increased with increase in the GSA content of the composites. In 3.5 % NaCl solution, the composites were resistant to corrosion with some of the hybrid composite grades containing GSA exhibiting relatively superior corrosion resistance to the grades without GSA. In 0.3M H2SO4 solution, the composites were generally a bit more susceptible to corrosion (compared to 3.5 % NaCl solution), but the effect of GSA content on the corrosion resistance of the composites was not consistent for the Zn-27Al alloy based composites.

211-219

Authors: P.C. Mishra

Performance characteristics of a rough elliptic bore journal bearing are studied. The bearing bore of isotropic roughness orientation is characterized by stochastic function and the film geometry is quantified to elliptic shape. There after the Reynolds equation and energy equation are descretized for pressure and temperature respectively. A finite difference model is developed to evaluate hydrodynamic pressure and oil temperature. Solution to this model is done using effective influence Newton-Raphson method. Performance parameters such as load bearing ability, friction, flow-in and side leakages are computed and discussed.