Title: Ultrafast spectroscopy of hybrid nanosystems Author: RNDr. Pavel Galář Department: Department of Chemical Physics and Optics Supervisor: prof. RNDr. Petr Malý, DrSc. Abstract: This Ph. D. thesis is focused on physical phenomena located at the interface of hybrid nanostructure composed of polycrystalline diamond and polymer polypyrrole. The main method used in our experimental study was ultrafast laser spectroscopy that allowed us to gain new findings about electron recombination processes in polycrystalline diamond layers, polypyrrole and in their hybrid structures. The research was focused on mutual influence of both components, especially through energy and charge transfer. In the first step of our research we carried out optical characterisation of different kinds of polypyrrole and complex study of recombination processes dynamics of photoexcited charge carriers in polycrystalline diamond. The measurements were realized by the methods of time-resolved photoluminescence and transmission spectroscopy in the time scale from picoseconds to milliseconds. On the basis of the obtained results the model explaining the origin of luminescence signal related to the different kinds of electron recombination processes in non- diamond phase and on surface defects of diamond grains in polycrystalline layers was...

A polycrystalline diamond was tested as a bearing material for a tilting pad thrust bearing to be used in an electric submersible pump, which elevates process fluids from the bottom of well bores. The goal of this study was to compare the PCD to a current best of technology, which is stainless steel with an engineering polymer.This study found that PCD can handle larger loads than current technology but is limited in size due to diamond sintering and manufacturing constraints. The maximum size is Ø75mm.

A polycrystalline diamond was tested as a bearing material for a tilting pad thrust bearing to be used in an electric submersible pump, which elevates process fluids from the bottom of well bores. The goal of this study was to compare the PCD to a current best of technology, which is stainless steel with an engineering polymer.This study found that PCD can handle larger loads than current technology but is limited in size due to diamond sintering and manufacturing constraints. The maximum size is Ø75mm.

Drilling is one of the important aspects in the oil and gas industry due to the high demand for energy worldwide. Drilling time is considered as the major part of the operations time where the penetration rate (ROP) remains as the main factor for reducing the time. Maximizing ROP to lower the drilling cost is the main aim of operators. However, high ROP if not controlled may impact on the well geometry in terms of wellbore instability, cavities, and hole diameter restrictions. Accordingly, more time is needed for the other operations that follow such as: pool out of hole (POOH), casing running, and cementing. Bit wear is considered as the essential issue that influences in direct way on the bit performance and reduce ROP. Predicting the abrasive bit wear is required to estimate the right time when to POOH to prevent any costly job to fish any junk out to the surface. The two-common types of bits are considered in the research, rock bits (roller cone bits) and Polycrystalline Diamond Compact bits (PDC). This study focuses more on PDC bits because about 60% of the total footage drilled in wells worldwide were drilled by PDC bits and this is expected to reach 80% in 2020. The contribution of this research is to help reducing the drilling cost by developing new tools not to estimating the time when to POOH to surface but also to measure the wear and enhance the accuracy of prediction the bit efficiency. The work is broken down into four main stages or models to achieve the objective: The first stage; estimating of the rock abrasiveness and calculate the dynamic dulling rate of the rock bit while drilling. The second stage; estimating the PDC abrasive cutters wear by driving a new model to determine the mechanical specific energy (MSE), torque, and depth of cut (DOC) as a function of effective blades (EB). The accuracy of the predicted wear achieves 88% compared to the actual dull grading as an average for bits used in five wells. The third stage; modifying the previous MSE tool to develop a more accurate approach; effective mechanical specific energy (EMSE), to predict the PDC bit efficiency in both the inner and outer cone to match the standard bit dulling. The fourth stage; predicting ROP while PDC drilling in hole by accounting three parts of the process: rock drillability, hole cleaning, and cutters wear. The results achieve an enhancement of about 40% as compared to the available previous models. Consequently, the developed models in this study provide a novelty on understanding in more details the bit rock interface process and gain an idea of the relationship between the drilling parameters to enhance the bit performance and avoid damaging the bit. This is basically about optimisation the controllable factors such as: weight on bit (WOB), rotary speed (RPM), and flow rate. The result is the reduction in time losses and the operations cost. To ensure reliability and consistency of the proposed models, they were validated with several vertical oil wells drilled in Libya. The results from the validation of the models are consistent with the real field data. The research concludes that the developed models are reliable and applicable tool for both: to assist decision-makers to know when to pull the bit out to surface, and also to estimate the bit performance and wear.

Thesis (MScEng)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: The aerospace industry actively pursues innovation, especially in materials and their use in new applications, to improve their aircraft as well as their competitive position. Ti-6Al-4V has been available now for more than 50 years. Yet, in the new generation of aircraft using structural composites, a dramatic increase in the proportion of Ti-6Al-4V will be seen along with emerging application in automotive and chemical industries. This material possesses superior material properties compared to conventional materials such as steel and aluminium, although it is at the expense of machinability. Researchers are therefore actively searching for improved cutting technologies to improve production rates for Ti-6Al-4V. At higher cutting speeds than the industry norm of 60 - 90 m/min, machining becomes a challenge, resulting in low productivity on titanium parts. The limiting factor in the machining of Ti-6Al-4V is high tool temperatures of the order of 1000oC, caused by its resistance to absorb heat and good mechanical strength at elevated temperatures. The result is extreme temperatures that are concentrated on the cutting edge of the tool. The challenge to improve the tool life is therefore focused on removing heat from the insert. Liquid nitrogen was identified as a good candidate as coolant with the additional advantage of being environmentally friendly. The research presented investigates the use of a gravity feed enclosed liquid nitrogen cooling system to improve the tool life of the cutting inserts. The liquid nitrogen is contained on the insert rake face by means of a tool cap. To improve the effectiveness of the cooling method, a polycrystalline diamond (PCD) insert was used. This insert has a considerably higher thermal conductivity that aids in cooling the cutting edge. Tungsten carbide inserts are used for benchmark testing. The round tungsten carbide inserts with conventional cooling performed exceptionally well for machining titanium compared to square inserts, yielding exceptional tool life improvements while significantly increasing the material removal rate. Positive results were recorded with the liquid nitrogen cooling system when used with the polycrystalline diamond cutting insert. A number of far reaching performance issues are identified relating to the design of the tool cap that hindered clear scientific outputs. From a research perspective, the project makes a contribution to the knowledge base in this field. Additionally a new approach in cooling was investigated, resulting in clear indications of design changes required. / AFRIKAANSE OPSOMMING: Die lugvaart industrie streef aktief innovasie na, veral op die gebied van materiale en hul gebruike, om hul vliegtuie en kompeterende posisie in die mark te verbeter. Ti-6Al-4V is al vir meer as 50 jaar beskikbaar. ‘n Drastiese verhoging in die aanvraag na Ti-6Al-4V deur die lugvaart, motor en chemiese industrieë word verwag wanneer die volgende geslag vliegtuie wat koolstofvesel as strukturele materiaal begin gebruik, in produksie gaan. Die materiaal het beter materiaaleienskappe as konvensionele materiale soos staal en aluminium, maar dit kom egter teen die prys van masjieneerbaarheid. Ti-6Al-4V se masjienering bo die industrie norm van 60 – 90m/min is ‘n groot uitdaging. Navorsers soek daarom deurentyd na verbeterde sny tegnologieë om die produksie tempo van Ti-6Al-4V te verbeter. Die beperkende faktor vir Ti-6Al-4V masjienering is die temperatuur wat genereer word. Die weerstand van die materiaal om hitte te absorbeer en sy goeie meganiese eienskappe veroorsaak dat temperature in die beitel 1000oC bereik. Hierdie temperature word egter op die snykant van die beitel gekonsentreer. Die uitdaging is dus om hierdie temperature in die beitel te beheer. Vloeibare stikstof is geïdentifiseer as ‘n goeie kandidaat vir verkoeling met die bykomende voordeel dat dit omgewingsvriendelik is. Die navorsing wat hier uiteengesit word, ondersoek die gebruik van ‘n geslote kamer beitelverkoelingstelsel wat deur gravitasie met vloeibare stikstof voorsien word om die beitel leeftyd te verbeter. Die oppervlak van die beitel word in hierdie konsep direk aan die vloeibare stikstof blootgestel. Om die effektiwiteit van die stelsel te verbeter word van PCD beitels gebruik gemaak. Die beitel se verbeterde hittegeleidingsvermoë help om die beitel se snykant koel te hou. Tungstenkarbied beitels word gebruik om ‘n standaard te stel vir eksperimentele analise. Die ronde tungstenkarbied beitels en konvensionele verkoeling het verstommend goed presteer vir Ti-6A-4V masjienering in vergelyking met vierkantige beitels. Die materiaalverwyderingstempo is aansienlik verhoog sonder om die beitel se leeftyd in te boet. Positiewe resultate is waargeneem met die vloeibare stikstof sisteem saam met die PCD beitels. ‘n Aantal verreikende uitdagings is geïdentifiseer wat suiwer wetenskaplike afleidings bemoeilik. Hierdie probleme kan almal aan die ontwerp van die toerusting toegeskryf word. Die werk lewer egter steeds ‘n bydrae tot die kennis in die veld. ‘n Bykomende benadering vir verkoeling is ondersoek wat duidelik ontwerp-veranderings aandui.

The thesis deals with the design, construction, production and testing of cutters with polycrystalline diamond cutting edges. Polycrystalline diamond is a suitable cutting material for machining very abrasive materials such as aluminum alloys or composite materials. The design of the tool is focused on the application of the chip breaker on the front of the tool. The aim of the solution is to reduce the cutting force in the machining of the aluminum alloy used in the aerospace industry. The first part of the thesis deals with problems related to milling technology. The practical part describes the design and construction of prototype cutting tools. Three tools were designed for experimental measurement. The technology of cutting tools made from super hardened cutting materials with laser technology is presented. The experimental part of the thesis is a measurement of the cutting force according to cutting parameters and machined material.

The master’s thesis is aimed at superhard cutting materials (polycrystalline diamond and polycrystalline cubic boron nitride) and their effective utilization. It describes the characteristics and production of these materials and evaluates product ranges of the most significant producers of tools and tool materials in given area. It further compares working conditions of selected world's producers which are related to the growing utilization of these materials in machining process. The thesis also deals with the cutting power of tools and provides a technical-economic assessment of the discussed issue.

Diploma thesis is focused on cutting superhard materials (polycrystalline diamond and polycrystalline cubic boron nitride). It deals with physical, mechanical and cutting properties, production and effective use. Evaluative product range of superhard cutting materials of the prominent world producers in terms of cutting conditions and type of materials machined in turning.

The goal for this research was to reduce the current manufacturing cost of the polycrystalline diamond compact (PDC) inserts utilized in the natural gas and oil drilling industry while not reducing their current performance. Polycrystalline Diamond is added to the tungsten-carbide (WC) substrates commonly utilized in these applications because of its greater wear and thermal resistance. With the current cube cell design for the high-pressure/high-temperature apparatus, it is necessary to bond an extra WC substrate to the polycrystalline diamond insert to achieve the sizes generally ordered by the customers. The problem of bonding the extra WC substrate was solved by increasing the operating volume of the cube cell assembly and changing the heating pattern within the cell while maintaining the temperature and the pressure required for the successful diamond sintering.The new cell design was proposed and tested. The test data were captured and analyzed to prove the hypotheses. The proposed manufacturing methods resulted in reduced cost, processing time, and reduced the need for equipment and operators without diminishing the performance of the PDC insert.

The aim of the thesis is to design, conduct and assess an experiment seeking to look into the utility properties of recent tools manufactured by HAM-FINAL. The tools include polycrystalline diamond (PCD) and CVD diamond cutting edges. In the theoretical part, the attention is devoted to cutting materials with an emphasis on diamond materials, as well as to issues associated with the wearing of the cutting tools, requirements specified for precision of bores and tools used in the manufacture of precision bores. The paper further provides an overview of a selection of world’s leading manufacturers of PCD blanks, CVD diamond coatings, CVD diamond layers and reamers with PCD cutting edges.