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<p>In this work, we tested the ability of an experimental system, involving the use of micropipettes as force transducers, to measure the coefficients of friction of several systems. Using a magnetic pipette puller, the micropipettes were produced by first heating and stretching the glass. The pipettes are then manipulated into an L-shape. This geometry allows one arm to act as the normal force transducer, and the other to act as the lateral force transducer for the purposes of friction measurements. We then analyzed the variation of the friction force of 15 micrometre polystyrene beads in contact with silicon and polystyrene in a fluid environment at increasing velocities. We also measured the variation in friction coefficient of poly(dimethyl siloxane) coated polystyrene beads in contact with a silicon surface. Our results were then compared to known values where possible, and the variation of the friction coefficient with increasing velocity was fit to a known phenomenological model. From our experiments, we have shown that our experimental technique can provide reproducible friction coefficient measurements, and these coefficients vary with velocity in a known manner. These results confirm the ability of micropipettes to act as both normal and lateral force transducers in friction experiments, and that they have the potential to be used in measuring friction coefficients of more complex materials.</p> / Master of Science (MSc)

<p>The aim of this study was to explore environmentally friendly solutions to reduce the friction present in automotive transmissions.</p> <p>A 2005 Ford Escape Hybrid transmission was used in this study to establish reasonable operating conditions for the gear surfaces.</p> <p>Background on gear operation and surface interaction was studied to understand the nature of the contact between the gear surfaces. Based on this, a mathematical model of gear interaction was developed and used to bracket the loading conditions of the gear tooth interface to be up to 1.5GPa of contact pressure with 2m/s relative sliding velocity. This information was used to aid in the identification of suitable surface engineering technologies and set the operating conditions for reciprocating tribometer based measurements.</p> <p>Additionally, tribological tests were performed on pin-on-disc samples which were treated with various surface treatments. The resulting wear surfaces were then studied using optical and Scanning Electron Microscopy (SEM) as well as Raman Spectroscopy. These techniques were used to better understand the mechanisms associated with wear and the role that the surface treatments played in reducing wear. Based on the testing performed, the best surface treatment for this application was a super finishing process. This process also met cost and environmental constraints. An in-house dynamometer was also developed to be used in the future full scale testing of a transmission.</p> / Master of Applied Science (MASc)

Friction in machining is a complex phenomenon that can directly affect cutting productivity and product quality. Currently, different coatings are developed for machining applications which can increase tool life in the machining processes. Since performing a real machining test to quantify the friction is expensive and time-consuming, developing a bench scale testing method to simulate the friction in machining can reduce the cost and help researchers and industries select a suitable coating for their specific applications. The goal of this work was to study the adhesion between the tool and workpiece material under machining conditions by simulating them using a heavy-load high-temperature tribometer. A high normal load was applied to plastically deform the workpiece material. The contact zone was then heated up using a resistance heating method. The normal load should be in the range that can generate a plastic flow on the surface of the workpiece material prior to seizure. Three groups of in-house coatings were tested to study the effects of coating deposition parameters on the coefficient of friction. The results of these tests showed that the coating with the lowest bias voltage and highest Nitrogen pressure had the best tribological performance. As a next step, three different commercial coatings were selected. Super duplex stainless steel was chosen as the workpiece material and the tribometer tests were performed. To validate the tribometer results real machining tests and tool wear analysis were performed. AlTiNOS+ WC/C was observed to be a lubricious coating which reduced the cutting force and coefficient of friction during the running-in stage. However, the low hardness of the coating provided little abrasion resistance and was removed after the first pass. AlTiNOS+ TiB2 demonstrated a good combination of hardness and lubricity associated with improved coating tribological performance as well as wear resistance. / Thesis / Master of Applied Science (MASc)