Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 21 for “"polycrystalline diamond"”.
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The Effect of Average Grain Size on Polycrystalline Diamond Films
The work function of hydrogen-terminated, polycrystalline diamond was studied using ultraviolet photoelectron spectroscopy. Polycrystalline diamond films were deposited onto molybdenum substrates by electrophoresis for grain sizes ranging from 0.3 to 108 microns. The work function and electron …
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The Solid Particle Erosion of Polycrystalline Diamond at High and Low Temperatures
Polycrystalline diamond (PCD) is formed by sintering together micron sized diamond grits at high temperatures and pressures in the presence of a metal catalyst, usually cobalt. Combining the hardness of diamond with the toughness of a polycrystalline microstructure, a material is produced with …
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Investigation on removal mechanism in catalytic aided electrical discharge machining of polycrystalline diamond
… process that has become famous in machining of Polycrystalline Diamond (PCD). PCD is typically used as a cutting tool for aerospace and automotive industries as the material has high hardness (~80GPa) and strength (~60Gpa). However, low electrical conductivity (~10−13 S/m) and high melting …
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Fracture in polycrystalline diamond. Investigating cracking and toughness behaviour using a miniature double torsion technique
… propagation of cracks in four grades of polycrystalline diamond (PCD) employing a miniature double torsion (DT) technique. The extremely high stiffness and relatively low toughness of the PCD material make controllable crack propagation and fracture parameter studies very difficult. …
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Parameter analysis of copper-nickel-tungsten prepared via powder metallurgy process for electrical discharge machining of polycrystalline diamond
Polycrystalline Diamond (PCD) tools have an outstanding wear resistance. The electric conductivity of PCD caused by the conductive binding material (Cobalt) makes it possible to machine PCD tools with EDM. Electrode used in EDM of PCD must have better porosity, electrical and thermal conductivity. …
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An investigation into the characterisation of the spalling behaviour of Polycrystalline Diamond Compact(PDC) cutters under impact loading conditions
… the identification of the spalling mechanisms of polycrystalline diamond compact (PDC) cutters and the effect of stress wave shape on the degree of spalling was performed using the split-Hopkinson pressure bar (SHPB) apparatus. The PDC cutters were loaded under specific impact conditions and their …
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The application of the soft impression technique to evaluate flow stress, creep and frictional deformation of polycrystalline diamond and cubic boron nitride
… - e.g. the measurement of the flow stress of diamond single crystals at temperatures up to 1500°C (Brookes, 1992). In this work, the technique has been extended further in order to form a basis for the comparison and evaluation of ultra-hard materials. Three main aspects of the performance of …
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Electrical characterisation of defects in wide bandgap semiconductors.
… different wide bandgap semiconducting materials (polycrystalline diamond and GaN) which have both recently attracted a great deal of attention because of their potential applications in the fields of power electronics and optoelectronics. Raman spectroscopy, I-V and C-V measurements were carried …
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Investigation of Structure and Properties of Low Temperature Deposited Diamond-Like Carbon Films
… is a novel method for fabrication of diamond-like carbon (DLC) films on metal substrates. In this work, DLC was electrochemically deposited on different substrates based on an anodic oxidation cyclization of acetylene in liquid ammonia. Successfully anodic deposition was carried out …
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The effects of properties, microstructure and phase transformation on the erosion of hard materials
… zirconias, sialon, cubic boron nitride and polycrystalline diamond, and these have a range of microstructural, physical and mechanical properties. The damage modes are described for the two types of erosion and the results are critically discussed. It has been shown that different properties …
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Nanoscale engineering of spin-based quantum devices in diamond
… quantum system: optically active defects in diamond, known as color centers. Color centers have a variety of advantageous characteristics, including long-lived quantum phase coherence in their electron spin degrees of freedom, available highfidelity control and readout at the single-spin …
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Tool selection and kitting : technical and organizational issues
… performance as compared to a 1180 point angle polycrystalline diamond (PCD) cutter with a single margin design that was previously used. For this specific application, changing to the proposed WC cutter resulted in savings of approximately 66% per airplane in tool costs alone and a 62% …
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The effects of hardness, toughness, microstructure and thermomechanical heating on the erosion of ceramic and ultrahard materials
… the soft stabilised zirconias to the very hard polycrystalline diamond composites. The four erodent particles used were: soft, friable silica, sharp alumina, tough silicon carbide and very hard, synthetic industrial diamonds. The steady state erosion rates of the different target/erodent …
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The performance of ultra-hard cutting tool materials in maching aerospace alloy TA48
… performance of cubic boron nitride (CBN) and polycrystalline diamond (PCD) cutting tool materials and compared to various coated and uncoated tungsten carbide grades when cutting titanium alloy workpieces. Two important experimental techniques were employed during the course of this work, …
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Investigation of stagnation-flow diamond-forming flames using advanced laser diagnostics
… in atmospheric-pressure, stagnation-flow diamond-forming flames. In these flames, a rich acetylene/oxygen/hydrogen mixture accelerates through a nozzle and impinges on a water-cooled molybdenum substrate, stabilizing a flat-flame approximately 1 mm below the substrate. A thin, …
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Mechanical Stiffness and Dissipation in Ultrananocrystalline Diamond Films
Tetragonal sp3-bonded diamond has the highest known atomic density. The nature of the bond and its high density enable diamond to have superior physical properties such as the highest Young’s modulus and acoustic velocity of all materials, and excellent tribological properties. Recently, conformal …
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Analytical Modeling and Diagnosis of Penetration Rate Performance of PDC Bits
… metal and then scaled up as a full scale polycrystalline diamond compact (PDC) bit model. The models compared well with laboratory test results by predicting penetration rate performance based on the strength and internal friction angle of the rock, confining pressure, and cutter and bit …
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Machinability study of particle reinforced aluminium metal matrix composites
… turning of round composite bars, using polycrystalline diamond (PCD) inserts has been selected as the test method. The test conditions included cutting speeds varying from 75 to 700m/min and feed rates from 0.1 to 0.4 mm/rev with constant depth of cut of 0.5 mm. The main wear mechanism …
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Assessment and Modelling of Wear prediction and Bit Performance for Roller Cone and PDC Bits in Deep Well Drilling
… 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 …
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Electro-thermal nanoprobes for nanometrology and nanofabrication
… cantilever whose tip is coated in a thin film of polycrystalline diamond to protect the tip from wear and reduce debris buildup. The tip of a conventional scanning probe changes unpredictably over time due to wear, damage, and the accumulation of debris; this is a significant hurdle preventing the …
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