Slurry transport is a key material handling technology in a number of industries. In oilsands ore transport, slurry pipelining also promotes conditioning to release and aerate bitumen prior to separation. Reliability of slurry transport pipelines is a major ongoing problem for operating companies due to unexpected piping failures, even when conservative maintenance strategies are employed. To date, no accurate model has been developed to predict wear rates in slurry transport pipelines, although previous studies have shown that important variables include flow rate, slurry density, and particle size distribution. This work investigates erosion wear mechanisms causing inner pipe wall wear due to sand slurry flow in a horizontal section of pipe under steady state conditions. A corresponding lumped-parameter erosion wear model is presented based on simplification of the physics of oilsands slurry flow. An apparatus was designed and developed to measure the forces acting on the pipe inner wall to monitor forces related to erosion in a laboratory-scale sand slurry loop, and preliminary results are presented with recommendations for future work. / Engineering Management

Flotation process is mineral processing technique used for separating valuable minerals from the gangue. The research presented in this thesis deals with assessing features that can help in measuring the performance (observing) bitumen flotation process and modeling damage in flotation units. A timely measure of oilsands and process stream contents can be used to observe and control the separation performance. To this end, flotation experiments were conducted and hyperspectral images of the ore and the process stream were taken to determine whether spectral information can predict the bitumen and fines content of ore samples and establish relationship a between these variables and the froth colour. Several features that appear to correspond to clay and quartz were present. Flotation cells are prone to wear damage by particles entrained in the slurry. A wear damage model was developed to predict the damage accumulated over a period of time. Particle image velocimetry experiments were conducted on physical flotation model to understand the flow behavior of the solid particles near the wall of the flotation unit. A preliminary wear test was conducted for qualitative assessment of wear. Recommendations were made for validating the damage model. / Engineering Management

In a fully automated manufacturing environment, instant detection of condition state of the cutting tool is essential to the improvement of productivity and cost effectiveness. In this paper, a tool condition monitoring system (TCM) via machine learning (ML) and machine ensemble (ME) approach was developed to investigate the effectiveness of multisensor fusion when machining 4340 steel with multi-layer coated and multi-flute carbide end mill cutter. Feature- and decision-level information fusion models utilizing assorted combinations of sensors were studied against selected ML algorithms and their majority vote ensemble to classify gradual and transient tool abnormalities. The criterion for selecting the best model does not only depend on classification accuracy but also on the simplicity of the implemented system where the number of features and sensors is kept to a minimum to enhance the efficiency of the online acquisition system. In this study, 135 different features were extracted from sensory signals of force, vibration, acoustic emission and spindle power in the time and frequency domain by using data acquisition and signal processing modules. Then, these features along with machining parameters were evaluated for significance by using different feature reduction techniques. Specifically, two feature extraction methods were investigated: independent component analysis (ICA), and principal component analysis (PCA) and two feature selection methods were studied, chi square and correlation-based feature selection (CFS). For various multi-sensor fusion models, an optimal feature subset is computed. Finally, ML algorithms using support vector machine (SVM), multilayer perceptron neural networks (MLP), radial basis function neural network (RBF) and their majority voting ensemble were studied for selected features to classify not only flank wear but also breakage and chipping. In this research, it has been found that utilizing the multisensor feature fusion technique under majority vote ensemble gives the highest classification performance. In addition, SVM outperformed other ML algorithms while CFS feature selection method surpassed other reduction techniques in improving classification performance and producing optimal feature sets for different models.

Dissertation (Ph. D.)--University of Akron, Dept. of Polymer Engineering, 2005. / "December, 2005." Title from electronic dissertation title page (viewed 09/17/2006) Advisor, Arkady I. Leonov; Co-Advisor, Joseph P. Padovan; Committee members, Joseph P. Padovan, Gary R. Hamed, Erol Sancaktar, Rudolph J. Scavuzzo, Jr.; Department Chair, Sadhan C. Jana; Dean of the College, Frank N. Kelley; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.

This thesis includes two parts. The first part reviews the history and fundamentals of surface science and tribology. The second part presents the major research outcomes and contributions. This research explores the aspects of friction, wear, and surface modification for tribological augmentation of surfaces. An effort has been made to study these aspects through gaining insights by fundamental studies leading to specific practical applications in railroads. The basic idea was to surface engineer metals for enhanced surface properties. A micro- and nano- scale experimental approach has been used to achieve these objectives. Novel principles of nano technology are incorporated into the experiments. Friction has the potential to generate sufficient energy to cause surface reactions through high flash temperatures at the interface of two materials moving in relative motion. This allows surface modifications which can be tailored to be tribologically beneficial through a controlled process. The present work developed a novel methodology to generate a functional tribofilm that has combined properties of high hardness and high wear resistance. A novel methodology was implemented to distinguish sliding/rolling contact modes during experiments. Using this method, a super hard high-performance functional tribofilm with “regenerative” properties was formed. The main instrument used in this research for laboratory experiments is a tribometer, using which friction, wear and phase transformation characteristics of railroad tribo-pairs have been experimentally studied. A variety of material characterization techniques have been used to study these characteristics at both micro and nano scale. Various characterization tools used include profilometer, scanning electron microscope, transmission electron microscope, atomic force microscope, X-ray diffractometer, nanoindenter, and X-ray photon spectroscope. The regenerative tribofilms promise exciting applications in areas like gas turbines, automotive industry, compressors, and heavy industrial equipment. The outcome of this technology will be an economical and more productive utilization of resources, and a higher end performance.

The aim of this thesis is to increase the understanding of wear in rolling/sliding contacts such as the wheel-rail contact for railroads and the roller-washer contact for roller bearings. The Stockholm commuter train network has been the subject of papers A and B in this thesis in which the wear and surface cracks on rails has been observed for a period of three years. By comparing the wear depth with the crack length, equilibrium between these two damage mechanisms was found for a lubricated rail. By using a lubricant with friction modifiers the stresses was low enough to prevent crack propagation; at the same time, the rail was hard enough to reduce the wear rate. This is probably the most favourable state in terms of rail maintenance cost. Roller bearings subjected to lubricant borne particles have been the subject of papers C, D and E in this thesis. Particles in the lubricating oil can have a significant impact on the wear in lubricated contacts. Even at low concentration levels can self-generated particles cause significant wear. The here presented results shows that filtration during run-in can significantly reduce both the mass loss and the number of self generated particles. A series of experiments has been carried out to study the wear of roller bearings by ingested lubricant borne hard particles. The form of the worn profile and the length of wear scratches correspond closely to the sliding within the contact. A count of the number of wear scratches on the rolling element surface indicates that the contact concentrates particles. A novel wear model based on the observation of a single point on the contacting surface when a concentration of particles passes through it has been developed and the necessary data for the model has been determined from the experiments. Comparison of the simulation results with the experimental results shows good qualitative agreement for the form change of the washer surfaces. / QC 20101015

The present thesis focuses on characterisation of microstructure and the resulting mechanical and tribological properties of CVD and PVD coatings used in metal cutting applications. These thin and hard coatings are designed to improve the tribological performance of cutting tools which in metal cutting operations may result in improved cutting performance, lower energy consumption, lower production costs and lower impact on the environment.  In order to increase the understanding of the tribological behaviour of the coating systems a number of friction and wear tests have been performed and evaluated by post-test microscopy and surface analysis. Much of the work has focused on coating cohesive and adhesive strength, surface fatigue resistance, abrasive wear resistance and friction and wear behaviour under sliding contact and metal cutting conditions. The results show that the CVD deposition of accurate crystallographic phases, e.g. α-Al2O3 rather than κ-Al2O3, textures and multilayer structures can increase the wear resistance of Al2O3. However, the characteristics of the interfaces, e.g. topography as well as interfacial porosity, have a strong impact on coating adhesion and consequently on the resulting properties.  Through the deposition of well designed bonding and template layer structures the above problems may be eliminated. Also, the presence of macro-particles in PVD coatings may have a significant impact on the interfacial adhesive strength, increasing the tendency to coating spalling and lowering the surface fatigue resistance, as well as increasing the friction in sliding contacts. Finally, the CVD-Al2O3 coating topography influences the contact conditions in sliding as well as in metal cutting. In summary, the work illuminates the importance of understanding the relationships between deposition process parameters, composition and microstructure, resulting properties and tribological performance of CVD and PVD coatings and how this knowledge can be used to develop the coating materials of tomorrow.

Wear particle-induced inflammation leading to periprosthetic osteolysis remains a major cause of hip implant failure. As polyethylene particles from conventional metal-on-polyethylene implants have been associated with these failures, an interest in lower wear metal-on-metal (MM) bearings has emerged. However, the biological effects of nanometer-size chromium oxide particles, predominant type of wear particles produced by MM implants, remain mostly unknown. Therefore, this study aimed to determine the cytotoxicity of nanometer-size Cr2O3 particles on macrophages in vitro, by analyzing their effects on cell mortality and cytokine release and comparing them with those of similarly-sized alumina (Al2O3) particles (known to be relatively bioinert). Results showed that at high concentrations, nanometer-size Cr2O3 particles can be cytotoxic to macrophages, inducing significant decreases in total cell numbers and increases in necrosis. Results also showed that, at high concentrations, the cytotoxicity of Cr2O3 particles was overall higher than that of Al2O3 particles, even though Cr2O3 and Al2O3 are both stable forms of ceramic materials. However, it appeared to be lower than that of previously reported conventional polyethylene and CoCrMo particles. Therefore, chromium oxide particles may not be the main culprit in initiating the inflammatory reaction in MM periprosthetic tissues.

This study considered using a relatively new method to study soil-tool wear which could drastically reduce the time and associated costs of traditional wear studies. The goal was to utilize discrete element method (DEM) simulations to recreate the results of a circular soil bin test in order to develop a relationship that could be used to predict wear under different conditions. Through the application of DEM, simulations could be used to study different materials or designs intended to result in improved wear performance.<p> Three replications of aluminum cylindrical bars were worn during 400 km of travel in a circular soil bin. Wear was quantified by measuring the change in radius of the cylinders at 18-degree intervals around their circumference. Mass data were also obtained to provide an overall average of wear occurring on the bar and to validate the radii measurements.<p> The DEM simulations were executed using EDEM software. Conditions present in the physical soil bin trials were simulated by recreating components in the soil bin and incorporating soil properties that were directly measured, using representative soil samples. Forces exerted on the bar by the soil and the relative velocities between the soil and tool were used to generate a relationship to predict wear of the bar. The wear equation was verified using a portion of the experimental data from the soil bin.<p> The wear model showed promise in predicting the amount of wear recorded in the soil bin through the application of DEM-predicted compressive forces and relative velocities between the tool and soil particles. The Archard equation for wear was modified to create a non-linear equation. Plotting the measured wear against the wear predicted from the fitted equation produced a trendline with a slope of 0.65. Although a perfect correlation would have produced a slope of 1, the model was able to predict a large portion of the wear that occurred. Refinement of the model could further be achieved with changes in the design of the geometry used in the simulation and through verification of force predictions with experimental data. Because of the variable nature of wear, additional replications of tools in the soil bin would have increased the number of data points available to create the model and reduced the impact of outlying data. With these recommended improvements, the wear model has the ability to very accurately predict the wear of a cylindrical bar.

Wear particle-induced inflammation leading to periprosthetic osteolysis remains a major cause of hip implant failure. As polyethylene particles from conventional metal-on-polyethylene implants have been associated with these failures, an interest in lower wear metal-on-metal (MM) bearings has emerged. However, the biological effects of nanometer-size chromium oxide particles, predominant type of wear particles produced by MM implants, remain mostly unknown. Therefore, this study aimed to determine the cytotoxicity of nanometer-size Cr2O3 particles on macrophages in vitro, by analyzing their effects on cell mortality and cytokine release and comparing them with those of similarly-sized alumina (Al2O3) particles (known to be relatively bioinert). Results showed that at high concentrations, nanometer-size Cr2O3 particles can be cytotoxic to macrophages, inducing significant decreases in total cell numbers and increases in necrosis. Results also showed that, at high concentrations, the cytotoxicity of Cr2O3 particles was overall higher than that of Al2O3 particles, even though Cr2O3 and Al2O3 are both stable forms of ceramic materials. However, it appeared to be lower than that of previously reported conventional polyethylene and CoCrMo particles. Therefore, chromium oxide particles may not be the main culprit in initiating the inflammatory reaction in MM periprosthetic tissues.