ENGG851: Testing of a New Lubricant in Metal Forming - Engineering Research Assessment Answers

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Assignment Task

This assessment continues the work you conducted in Assessment One. Use the format provided in the Assessment Two Example to guide you in the look, feel and requirements of your submission. The assessment involves: i) Write an abstract for your research (this abstract will take the form of one suitable for a journal article). It should take the following form: a. TOPIC: Outline topic area b. SIGNIFIGANCE: Why is your research important? c. METHODOLOGY: How are you conducting your research? d. FINDINGS: What came from your research? (Create your own finding – make it up) e. CONCLUSION: As a result we recommend..... The abstract should be no longer than 200 words. While the abstract is the first activity it should be the very last thing that you write. If you try and write this first you might struggle. You won’t have any findings (as you are not undertaking any real research), so pretend that you did the experiment and mention your findings. ii) You need IMPROVE and resubmit your Introduction Chapter from Assessment One. You should use the feedback from the marked version and make all the necessary improvements. If you need to slightly change the wording of your research question, you may do so. The markers will have greater expectations compared to assessment one.

Literature survey

Solid lubricants has natural ability of low friction and low wear under specific conditions. Basic solid lubricants are of two categories. Soft coatings for surface hardness less than 10 GPa and hard, for higher than 10 GPa [Wan, Q., et al.2015; Holmberg, A. Matthews, 2011; Yuxia Caoa b., Lingzhong Dua, Chuanbing Huanga, Wei Liua, Weigang Zhang 2011]. Most oxides are highly lubricious and can be used to generate fairly low friction at high temperatures. Crystal–chemical model was proposed by Erdemir. He clasified lubricious oxides as per operational limits and lubrication performance (A. Erdemir, Tribol 2000). Certain solids like boric acid and HBN in powder form are used in mixed state with greases or oils to achieve improved lubrication under extreme temperature and pressure conditions (Y. Kimura, T. Wakabayashi, K. Okada, T. Wada, H. Nishikawa, 1999). Regardless of the type, no coating exit that can work under for all application conditions. Depending on the test environment, sliding conditions and temperature, durability of tribological , performance the solid lubricant coatings vary. To overcome variations in durability and performance, multi-layer novel coating architectures, nano-structures, micro surface texturing are being researched (C. Donnet , A. Erdemir, 2004). The natural oils are used as lubricants due its triacylglycerol structure, which is long polar fatty acids chains and are useful for boundary lubrication. It works by adhering to metallic surfaces, create a thin monolayer, and remain closely packed. Thus it remains effective for wear and friction reduction[Lundgren, S.M., Persson, K., Mueller, G., Kronberg, B., Clarke, J., Chtaib, M., Claesson, P.M 2007; Fox, N.J., Tyrer, B., Stachowiak, G.W ; and Lundgren, S.M., Ruths, M., Danerlov, K., Persson, K 2008]. Green solid lubricants are a new class of ‘‘powder lubricants’’ consisting of lamellar crystal structures with low interlayer friction. Example, boric acid (H3BO3) and hexagonal boron nitride (hBN). [Erdemir, A. 1990, Reeves, C.J., Menezes, P. L., Jen, T. C., and Lovell, M. R, 2012]. Lamellar powder lubricants are known for their crystal structure, in which atoms lying on the same layer are closely packed and strongly bonded together by covalent bonds, and the layers are relatively far apart due to the weak Van der Waals forces. When entrained between sliding surfaces, the lamellar powders can adhere to the surface, forming a protective boundary layer that minimizes contact between opposing surface asperities to prevent wear. The protective boundary acts as a lubricant in sliding contacts by accommodating relative surface velocities. These powder lubricants can lubricate in extreme conditions such as high or low temperatures and pressures. (Deshmukh, P., Lovell, M., Sawyer, W.G., Mobley A. 2006 Clauss, F.J,1972). Boron nitride (hBN) powder is soft, white, and lubricious with attractive performance enhancing attributes similar to other lamellar solids, making it an attractive alternative to other inorganic solid lubricants. It is also environmentally friendly and inert to most chemicals (Peterson M.B., 1987; Duzcukoglu, H., Sahin O. S. 2011). Boron nitride is synthesized from boric oxide or boric at temperatures ranging between 800 and 2,000? C. Boron nitride is a stable compound which does not breakdown to form other hazardous materials under normal operation; thus, it is safe to handle and feasible to use in industrial applications. High-purity, commercial-grade boron nitride powder does not contain free boron, but retains it in the form of a nitride or borate, which has no hazardous effects or limitations on its use. (Lelonis, D.A., Tereshko, J.W., Andersen, C.M. 2007). Boron compounds are safe, and no regulations exist regarding their use, transport, storage, or disposal. Due to these reasons boron nitride is an environmentally friendly substance with no limitations on its operational use. (Clayton G.D., Clayton F.E., Allan R.E., Patty F.A, 1991). From ecological sustainability point of view, better lubricant is canola oil. It is used in place of traditional petroleum-based oil or grease. (Sharma B.K., Liu Z. , Adhvaryu A., Erhan S.Z.2008). Surface tension and viscosity of canola oil is similar to the functional fluids for use in industrial applications such as metal-forming and metal-stamping operations. It is also used as an automotive lubricant for bearings and gears ( Xiaodong Z., Xun F., Huaqiang S., Zhengshui H. 2007). Canola oil is inexpensive, readily available, environmentally friendly chemical. It is derived from rapeseed plants, having high oleic acid (80 %). It surpasses petroleum-based Group I lubricants at ambient temperature. ( Rushcow J., Smith M.A. 2005). Pin-on-disk studies show boric acid and molybdenum disulfide with micron-sized and nano-sized particles added to canola oil forming a homogenous colloidal mixture, leading to improvement in wear reduction and friction [Lovell M., Higgs C.F., Deshmukh P., Mobley A ,2006; Erdemir A., 1990; Duzcukoglu H., Sahin O.S 2011; Duzcukoglu H., Acaro M 2010; Erdemir A. 1995]. Carrier fluid with particle additives remain in the contacting pin–disk interface without degrading over time [1, 40, 53]. Nano-sized particulate mixtures by themselves or in combination with submicron-sized particles provides improved tribological performance [Deshmukh P., Lovell M., Sawyer W.G., Mobley A , 2006; Duzcukoglu H., Sahin O.S , 2011]. Boric acid when mixed with distilled water is used for abrasive machining of alumina. It is also used in grinding fluids , cutting and corrosion protection, friction reduction , and as fungicide and bactericide [Sulhan 1961; Schuster, 1975; Rawlinson and White, 1984; Ritschel and Lorke, 1984; Jin et al., 1986; Johnson, 1986; Yakusheva, 1989; and Branneen et al., 1990]. The boric acid powder with canola oil lubricant forms a mixture which demonstrates lubrication performance, Kabir work micrometrescale (100–700 mm) boric acid particles were added to canola oil. The optimum composition of the boric acid–canola oil lubricant mixture, requires series of experiments at different volume fractions of canola oil with a constant particle size distribution(BY MICHAEL R. LOVELL, M. A. KABIR, PRADEEP L. MENEZES1,2 AND C. FRED HIGGS 2010). To study the relative tribological performance of different sized boric acid powder additives with lubricant "canola oil", pin-on-disc experiments carried out by MICHAEL to see friction and wear behaviour. By experiments, it was seen that a colloidal solution of 20 nm particles in canola oil gives optimum frictional and wear performance. Nano-sized particles were shown to offer the best tribological performance in canola oil when compared to micron- and submicron-sized particles in canola oil. Particle additives that are larger than the asperities carry a portion of the load between the contacting asperities, resulting in a decrease of friction; however, these larger particles are also more abrasive causing higher wear rates and a rougher final surface finish (Carlton J. Reeves Pradeep L. Menezes, Michael R. Lovell, Tien-Chien Jen). Boron nitride which has Hexagonal structure if formed by pressing and sintering at an elevated temperature of 2000 ?C. CaB2O4 is used to help crystallization. This material " Boron nitride" is used as coating to provide sealing for turbo jet engines used in aeroplane. Friction coefficients for sintered hBN in atmosphere condition increase as temperature rises from room temperature to room temperature to 400 ?C.( Yuxia Caoa, Lingzhong Dua, Chuanbing Huanga, Wei Liua, Weigang Zhanga,2011). Nano meter sized Boron nitride particulate mixture performed better compared to submicron and micron-sized combinations for reducing the wear performance and friction, and provides smoother surface finish. Tribological performance of canola oil with micron- or submicron-sized particles gets considerable enhanced with nano-sized particles. The wear and friction reduced by more than 40% and reached 70 % with nano particles (Carlton J. Reeves , Pradeep L. Menezes , Michael R. Lovell, Tien-Chien Jen 2013). Friction is also important while working with hot metal, a layer on the work piece is detrimental to die life and constitutes to a loss of metal. The frictional forces retards cooling effect. Recording the variations in die surface temperatures , when billets with different thicknesses were forged, the insulating effect of scale is demonstrated by Kellow et. al (M. A. Kellow, A. N. Bramley and F. K. Bannister, 1969).Using ring test coefficients of friction is obtained Kunogi [ M. Kunogi , 1969and H. Kudo1955] . In this method internal diameter change is compared, as friction factor changes the internal diameter. As friction increases, the internal diameter of the ring will increase by less until at some point there will be a reduction in bore with a reduction in height. Thus, when upsetting identical specimens under different conditions, the change in the internal diameter will be a measure of the effect of those conditions on interfacial friction. This method was later improved by( Male and Cockcroft ). In spite of considerable developments and research, large no of research papers published in past 25 years, no solid lubricant exits which can give low friction and reduce wear for brooder use conditions like temperatures and environments. Solid lubricants has some major shortcomings. Except for soft metals, solid lubricants mostly have low thermal conduction , hence heat cannot be carried away arising due to sliding.

Method for investigation:

In the present investigation, I will be using boron nitride powder as additives mixed with canola oil. This procedure will involve using a pin-on-disk tribometer ( Figure 1) to determine its feasibility as a biolubricant. The boric acid is very effective to give low shear strength and low friction values. Boric acid has very low shear strength only 23 MPa (Barton et al. 2004), The frictional coefficient is eveln lower than 0.02 at room temperature -10deg to 45 deg centrigrate. This is due to laminar structure of boric acid ( figure 2 ) Particle size of boron nitride powder will be used as additives with the base oil. I propose to use four hBN particle sizes were considered namely 70 nm, 0.5 micro m, 1.5 micro m , and 5.0 micro m. By using scanning electron micrographs the particle size will be verified ( Figure 3 ). hBN particles by 5% in weight will be mixed with 10 mL of canola oil. Particles are mixed with canola oil using a mixture, which generates vortex , and helps in quick mixing to yield a homogenous colloidal mixture. Pin-on-disk tribometer, an oxygen-free electronic copper (C101) 99.99 wt% copper pin need to be fabricated to slide against a 2024 aluminium disk to obtain the friction and wear properties of the lubricants. The copper pin diameter will be 6.35 mm and 50 mm length with a hemispherical tip. The aluminium disk diameter of 70 mm , 6.35 mm thick with polished surface roughness of Ra, value of 0.3 ± 0.05 micro m. Specified testing parameters to be used are given in table no 1. The friction force and linear wear loss measurements will be acquired for each test using a dual axis force transducer and a high-precision ball screw actuator with encoder. It will record the vertical displacement of the pin. The tribometer will be configured for a data acquisition rate of 10 Hz. Before starting the experiment, all test specimens must be cleaned with a acetone, and hexane solution in an ultrasonic cleaner. During each of the tests, the disk will be fully submerged inside the lubricant mixture, thus pin–disk interface will be continuously lubricated. Minimum three repeats need to be performed to insure repeatability and accuracy of the results. The analysis of the results will be done to see the important role that the boron nitride particles play in filling the inter-asperity valleys. In the case of the aluminium disk, the coefficient of friction is low because the copper pin is harder than the aluminium disk, allowing abrasive wear to occur and thus plastic deformation of the disk material. Here, the copper pin deforms the aluminium disk, creating a series of grooves as it establishes a wear track. The wear track allows the 70-nm hBN particles to remain in the contacting (pin–disk) interface, providing adequate lubrication. We can also study a mixture of 7 per cent by volume which was found to outperform by Kabir. Figure 4 shows the scematic of mechanism of friction reduction with lubricant composed of oil and mixed with particles of differnt scales.