Two phase alpha/beta titanium alloys are used in a wide variety of applications such as aerospace, biomedical, gas turbine engine, sport and energy. These alloys have high specific strength and specific modulus as compared to magnesium and aluminium alloys as well as excellent corrosion resistance. The Ti-6Al-4V (α+β) alloy is the most widely used and the best known of all the Ti alloys. Although there are a number of observations in the literature reporting the mechanical responses of these two phase alloys, there exists very little understanding of the mechanisms of the individual phases and the alpha/beta interface’s role in strengthening. Additionally, it has often been reported in the literature that ‘smaller is stronger’ for different metals due to the presence of a size effect. There is no real understanding of the mechanism of the size effect in the alpha-beta titanium and HCP and its dependence on orientation. Single alpha, beta and alpha-beta colony micro-pillars have been manufactured from a polycrystalline commercial Ti-6Al-4V sample using Focused Ion Beam (FIB). Alpha/beta pillar contained two alpha lamellae separated by a thin fillet of beta phase. A nano-indenter was then used to conduct uniaxial micro-compression tests on Ti alloy single crystals, using a diamond flat tip as a compression platen. By controlling the crystal orientation along the micro-pillar using Electron Back Scattering Diffraction (EBSD) different slip systems have been selectively activated. The advantage of the micro-compression method over conventional mechanical testing techniques is the ability to localize a single crystal volume which is characterisable after deformation. This study makes a contribution to knowledge in several key areas, including an understanding of the mechanical response of different crystals at micro/submicro-scale, the effect of phase interfaces on deformation, and an understanding of the strengthening mechanism in two-phase Ti alloys, the orientation size effect in HCP metals and the CRSSs for each phase in Ti-6Al-4V. Therefore, in order to evaluate the behaviour of these alloys for future applications, it is imperative that the microstructural features and characteristics be quantified and examined on a small scale. The results showed that the beta phase in between alpha lamellae caused strengthening deformation. When the surface normal is parallel to the [0001] of the single alpha crystal, the material deforms with difficulty in the [0001] direction of the single alpha phase. The mechanical responses of the alpha, beta, and alpha/beta crystals not only depended on the size of the pillars, but also on the crystallographic orientation, the initial dislocation density and the relationship between the two phases in the case of α/β crystals. Extensive electron microscopy investigation revealed that the anisotropy in basal and prismatic slip systems can be directly correlated with the transmission of dislocations across the single crystal, the beta laths, and the accumulation of residual dislocation content near the interfaces and in the single beta phase. This information is essential in order to better model mechanical deformation in these materials. In addition, dislocation analysis indicated that the deformation of individual grains conformed to the Schmid factor (SF) analysis where slip primarily occurs on those slip systems where the resolved shear stress (SF) values are highest. The results presented in this thesis bring to light several concerns for designing with titanium alloys and identify a number of phenomena of strong scientific interest. They will allow for the development of realistic models for the mechanical behaviour and provide a comprehensive analysis that can contribute to the theoretical development of the design and enhancement of the titanium allows. Moreover, the role of crystallography in plastic deformation provides a novel insight into the nature of the orientation size effect in HCP. This work points towards the need for further investigations into the higher and lower temperature deformation behaviour of Ti-64 to fully understand the phenomena identified within this study.

Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Mining Engineering and Metallurgy, 1878. / by Takuma Dan. / B.S.

Oil is a major source of energy around the world. With the decline of light conventional oil, more attention is being paid to heavy oil and bitumen, as a good alternative to light oil for energy supplies. Heavy crude oils have a tendency to have a higher concentration of metals and several other elements such as sulfur and nitrogen, and extraction of these heavy oils requires more effort and cost. The Toe-to-heel Air Injection catalytic upgrading process In-situ (THAI-CAPRI) is an integrated process which includes recovery and upgrading of heavy oil and bitumen using an air injection process, and horizontal injector and producer wells. Since the process works through a short distance displacement technique, the produced oil flows easily toward the horizontal producer well. This direct mobilized oil production and short distance are the major properties of this method which lead to robust operational stability and high oil recovery. This technique gives the possibility of a higher recovery percentage and lowers environmental effects compared to other technologies like steam based techniques. A catalyst plays a crucial role in the THAI-CAPRI technique to be successfully conducted. However, heavy coke can be formed as a result of the thermal cracking of heavy oil occurring in the THAI-CAPRI process, and a catalyst resistant enough to use in CAPRI needs to be developed. Therefore, there is a need to understand the pore structure to achieve a high catalyst quality, to obtain a structure that directly affects the fluid behaviour within a disordered porous material. In this study, novel experimental techniques were used to obtain greater accuracy results, for the information obtained from gas adsorption curves by using a combination of data obtained for two adsorptives, namely nitrogen and argon, both before and after mercury porosimetry. This new method allows studying the effect of pore-pore co-operative during an adsorption process, which significantly affects the accuracy of the pore size distributions, obtained for porous solids. A comparison, between the results obtained from the characterisation of a mixed silica-alumina pellet and those obtained from pure silica and alumina catalysts, were presented to study the effects of surface chemistry on the different wetting properties of adsorbates. The pore networks within pellets invaded by mercury following mercury porosimetry have been imaged by computerized X-ray tomography (CXT). It was noticed that the silica-alumina catalyst had a hierarchical internal structure, similar to that for blood vessels in the body. To validate the findings of the pore geometry characterisation obtained from the new method, several techniques, such as cryoporometry, gas sorption isotherms, and mercury intrusion experiments, were considered. Further, a novel well design consisting of two horizontal injectors and two horizontal producers was used in different well configurations, to investigate the potential for improved efficiency of the THAI process on the heavy oil recovery. A 3D dimensional simulation model, employing the CMG-STARS simulator, was applied in this simulation. Two horizontal injectors and producers were designed in this project, instead of horizontal injector and producer were used in the Greaves model (the base case model), to investigate the effect of the extra injector and producer on the performance of the THAI process. It was found that the locations of the well injections and the well productions significantly affected the oil production. For the study of the effectiveness of the catalysts in the oil upgrading process, the CAPRI technique has been simulated to investigate the effect of several parameters, such as catalyst packing porosity, the thickness of the catalyst layer and hydrogen to air ratio, on the performance of the CAPRI process. The TC3 model used by Rabiu Ado (2017), which was the same model used in the experimental study of Greaves et al. (2012), was also used in this study. The Houdry catalyst characterised by the experimental work was placed around the horizontal producer in this simulation.

The accepted design techniques for bulk solids handling equipment are frequently overlooked during the installation of industrial process plants. As a result, flow unreliability is often observed in silos in the form of flow stoppages, product bulk density variations, formation of rat-holes, flushing, flooding and product segregation. In most cases when these problems are detected in silos, they are the result of a discharge pattern known as core flow, where localised flow channels promote the preferential draw of material from certain zones of the silo, with the rest of the material remaining stagnant. Coal handling is not the exception and process equipment is not always designed to cope with the often variable characteristics of the coal, which is frequently processed in a large variety of forms, with particle sizes ranging from fine dust to a top size several inches and other parameter like moisture content varying from completely dry to dripping wet. In order to solve the problems caused by core flow, the discharge behaviour of the silo needs to be modified to produce a uniform movement of all the material, to achieve a flow pattern known as mass flow. Static inserts have been proved to be an effective method of modifying the discharge patterns in silos, but their use and design procedures are not well understood or are well hidden behind patents and trade secrecy. This research project aims to produce practical guidelines for the design and positioning of static insert to improve flow in silos. The work presented in this thesis follows an experimental approach where the performance of an insert is first evaluated at bench scale in a 3 litre model silo and then validated at semi-industrial scale in a 400 litre test rig. The bench scale model allows the evaluation of numerous changes in insert morphology and positioning at relatively low costs, facilitating the development of practical rules for their design. Following this approach a design procedure for inverted cone inserts is proposed as a modification of a method developed by J. Johanson [Johanson, 1965]. A performance comparison was undertaken both at bench and semi-industrial scales with inserts designed following Johanson’s method and the modified method proposed by the author. The results showed that both inserts were capable of producing mass flow in an otherwise core flow silo, but the modified insert produced more consistent results, particularly with lower heights of powder bed. This experimental approach was also followed to develop a novel type of insert called open double cone which maximizes the area of influence of the insert inside the silo facilitating flow. For this insert, three design procedures where proposed with each of them producing inserts capable of achieving mass flow in the bench scale model. The main difference between the inserts produced by the three procedures, was the size of the insert in relation to the volume of the silo hopper. In a similar way, two procedures were also proposed for the design of double cone inserts, with the resulting inserts capable of achieving mass flow in the bench scale silo. Then, a prototype of an inverted cone designed with the modified method, a prototype of the open double cone and a prototype of a double cone were tested in the semi-industrial scale test rig. The results at both scales showed that the open double cone and the double cone inserts outperformed the inverted coned, by producing more uniform velocity profiles across the silo and also producing more consistent flow rates. Although the performance between the open double cone and the double cone was very similar, the open double cone was more consistent in producing flatter velocity profiles and also the double cone was more prone to produce slightly off centre discharges. The procedures proposed for insert design provide the tools needed to apply insert technology to industrial processes. This is demonstrated with the design of double cones which successfully eliminated rat-holing problems in conical silos from an industrial pneumatic conveying system. The bench scale methodology is also employed to try to solve flow unreliability issues experienced in an industrial coal silo. For this case, a bespoke type of insert was developed to respond to the complex geometry and mode of operation of the silo. The proposed insert produced very positive results at bench and semi-industrial scales, laying the bases for a solution for the full scale silo.

Thousands of employees in small and medium-sized enterprises (SMEs) in Indonesia’s tin mining industry are working in dangerous environments without an adequate safety and health protection programme. Occupational safety (OS) has become a primary focal point when it comes to preventing dangerous incidents. Such incidents can lead to serious injuries and fatalities, particularly given that mining involves dangerous and high-risk activities, for example, in onshore tin mining, working in muddy areas with heat, humidity and a risk of landslide. Studies addressing the health and safety domain in Indonesia and the mining sector have the least number of ergonomics applications. The research examined the existing OS of a state-owned tin company, namely PT Timah, in Indonesia. The company has a relatively good level of experience in practising tin mining operations, and also employs occupational safety programmes. For approximately a decade, this company has collaborated with 16 private onshore SMEs which work in more than 400 locations under the PT Timah cooperation scheme. Despite applying OS and a health programme in the main company, the same programme has not been included in the tin mining operation cooperation scheme that regulates the rights and obligations of SMEs. This thesis examines the possibilities of using a well-established ergonomics approach and adapting it so that it is more frequently accepted and embraced in Indonesia. The research is focused on the participatory ergonomics (PE) approach as applied to SMEs. Postal data reviews, interviews and observation methods were used to examine the current status of OS in the Indonesian tin mining industry. The scenario-based design (SBD) method was used to investigate the acceptability of PE, while the two-round Delphi technique was applied to reach a consensus on the practical implementations of PE solutions. There is positive acceptance of PE among workers in Indonesian tin mining companies. Regular working safety dissemination through a kinship approach and specific safety training is recommended for resolving communication, cultural and knowledge issues related to OS. In addition to this, a consensus was reached on proposed solutions regarding the implementation of PE within the Indonesian tin mining industry, such as evaluation of the remuneration and bonus system, employing the train-the-trainer programme, and the OSH reporting system.

Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Mining and Metallurgy, 1937. / MIT copy bound with: Investigation of E.G. Herbert's magnetic hardening of metals / by Farmer L. Current [1937] / Includes bibliographical references (leaf 37). / Stuart Verne Cuthbert, Jr. / B.S.

Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Mining Engineering and Metallurgy, 1885. / by Hugh MacRae. / B.S.

Filamentary carbon deposition on 20Cr/25Ni/Nb austenitic stainless steel from 1000-5000 ppm C2H4 in 1%CO/ bal. CO2 at 600°C has been investigated. This filamentary carbon deposition is catalysed by metallic nickel-rich particles formed intrinsically from the alloy during the early stages of oxidation. Samples were analysed using electron microscopy techniques. A simple model has been proposed to explain the formation of nickel-rich particles within the subsurface oxide layer. Furthermore, in this project the effect of COS, H2S and CH3SH on carbon deposition were examined. Addition of sulphur species suppressed the deposition process but the effect was dependent on the concentration of C2H4 and the sulphur species. This suppressing effect of sulphur on carbon deposition was explained in term of the role played by the adsorbed sulphur in reducing the rate of the key steps of the growth process of a filament.

Thesis--University of Missouri, School of Mines and Metallurgy, 1883. / The entire thesis text is included in file. Holograph [Handwritten and illustrated in entirety by author]. Title from title screen of thesis/dissertation PDF file (viewed September 24, 2008)

Thesis (M.S.)--Middle East Technical University, 2004. / Keywords: Air Cannons, Sampling, Quality Control, Sample Increment, Size Distribution.