Papers by Keyword: Diamond

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Authors: Arthur Vo-Ha, Mickaël Rebaud, Davy Carole, Mihai Lazar, Alexandre Tallaire, Véronique Soulière, Jose Carlos Pinero, Daniel Araújo, Gabriel Ferro
Abstract: This work deals with the localized epitaxial growth of SiC on (100) diamond substrate using the Vapour-Liquid-Solid (VLS) transport. An epitaxial relationship of grown SiC with the seed was succesfully achieved when inserting a silicidation step before the VLS growth. This silicidation consists in the formation of a SiC intermediate layer on the diamond substrate by solid-state reaction with a silicon layer deposited at 1000 or 1350 °C. On the 1350°C formed SiC buffer layer, p-doped 3C-SiC(100) islands elongated in the <110> directions were obtained after VLS growth. For the 1000°C buffer layer, the SiC deposit after VLS growth is much denser but mostly polycrystalline. Interfacial reactivity and diffusion are considered to explain the obtained results.
Authors: Yi Qing Yu, Yuan Li, Xi Peng Xu
Authors: Hong Hua Su, Yu Can Fu, Yan Chen, Jiu Hua Xu, Wen Feng Ding
Abstract: Monolayer brazed diamond tools, which are high bonding strength at the interface between brazing alloy and grits, are becoming the active field in which improvements in processing and advanced products can be anticipated. Some researchers proposed brazing diamond methods with Ni-Cr and Ag-Cu-Ti alloy, but there is a shortage of the comparative study of the characteristics of the brazed diamond tools fabricated with the different brazing alloy. In this paper, machining performance experiments have been carried out, including contrast tests about tool life and machining efficiency for thin-walled monolayer brazed diamond core drills fabricated with Ni-Cr and Ag-Cu-Ti alloy. The results show that the Ag-Cu-Ti alloy can improve the machining performance. Wear mechanism of diamond grits was studied in those drilling processes. The results show that the low ratio of grit breakdown of the core drill using Ag-Cu-Ti alloy is the key factor of its longer life. Furthermore, based on the experimental results, the areas of the grits wear flat increase the feed force, and decrease the machining efficiency.
Authors: Chong Mu Lee, Kyung Ha Kim
Abstract: Diamond-like carbon (DLC) films have been deposited by radio frequency plasma enhanced chemical vapour deposition (rf-PECVD) with different Ar-CH4 mixtures. Nanocrystalline diamond films have been deposited by microwave plasma-enhanced chemical vapour deposition (MPCVD), using Ar-H2-CH4 mixtures. X-ray photoelectron spectroscopy (XPS) and nanotribological investigation (by scanning force microscopy) have been used to compare the mechanical properties and structures of these films. Highly orientated and non-orientated microcrystalline diamond films and MPCVD-produced amorphous carbon have also been studied by way of comparison. The diamond films exhibit a linear relationship between roughness and the coefficient of friction. The DLC and amorphous carbon have higher friction coefficients than the best performing diamond film, but may more easily be deposited as smooth coating. Possible applications for these various carbon-based films include microelectromechanical components, for which smooth, hard coatings are required.
Authors: Margareta K. Linnarsson, J. Isberg, Adolf Schöner, Anders Hallén
Abstract: The boron diffusion in three kinds of group IV semiconductors: silicon, silicon carbide and synthetic diamond has been studied by secondary ion mass spectrometry. Ion implantation of 300 keV, 11B-ions to a dose of 21014 cm-2 has been performed. The samples are subsequently annealed at temperatures ranging from 800 to 1650 °C for 5 minutes up to 8 hours. In silicon and silicon carbide, the boron diffusion is attributed to a transient process and the level of out-diffusion is correlated to intrinsic carrier concentration. No transient, out-diffused, boron tail is revealed in diamond at these temperatures.
Authors: Jonathan P. Goss, R. Jones, S.J. Breuer, Patrick R. Briddon, Sven Öberg
Authors: Ana Lúcia Diegues Skury, Sérgio Neves Monteiro, Guerold Sergueevitch Bobrovinitchii, Marcia G. de Azevedo
Abstract: It is still in focus the problem of obtaining high quality polycrystalline materials by means of sintering fine diamond powders. The most important task of this problem is the consolidation or improvement of the processed polycrystalline diamond. It is worldwide recognized that the plastic deformation of the diamond particles performs the most important role on the diamond powder consolidation. In some cases, the contact and shear tensions reconstruct the compact structure. In this work the sintering process used a mixture of micro and nanodiamonds. The sintering process was carried out in a toroidal high-pressure device. The effects of nanodiamond addition and sintering conditions on the microstructure and mechanical properties sintered diamond bodies were studied. The sintering parameters were pressure of 6.8 GPa and a temperature of 1850 K, and these conditions were maintained for 1 minute. Homogeneous sintered bodies were obtained, which have a Vickers' hardness over 40 GPa, and fracture toughness around 7.1 – 7.9 MPa.m1/2.
Authors: Dong Xu Li, Jing Lu, Dong Li Yu
Abstract: Diamond with inorganic coating such as silicon coatings was used to promote applications. Different kinds of silicon structures were found in the coatings. In this paper, first principle calculation was used to study the stability of cubic silicon and hexagonal silicon coatings deposited on diamond substrate. The simulation data suggest that the single layer hexagonal silicon coating form easily under low temperature due to the low lattice mismatching and thermodynamic temperature. However, the stronger bonding of Si-C bonds between substrate and coating direct the formation of cubic silicon coatings, as well as Si-Si bonds inner coatings, in agreement with experiments.
Authors: K.Eric Drexler
Abstract: Proposed advanced mechanosynthetic systems [1] require molecular tools able to bind and transfer reactive moieties with high reliability at 300 K (failure rates << 10–10 per transfer operation). Screening of a large number of candidate tools at the AM1 level enabled the identification of a structure, DC10c, that is calculated (at the B3LYP/6- 31G(d,p) level) to meet these stringent requirements when used to transfer carbon dimers to any of a target class of graphene-, nanotube-, and diamond-like structures [2]. The favorable energy of transfer (exoergic by a mean energy ≥ 0.261 aJ per dimer) results from avoidance of the generation of high-energy radical sites during dimer release by means of π-delocalization to form a strained aromatic ring on the binding face of the empty structure. These energies are compatible with transfer-failure rates ~ 10–24 per operation at 300 K, and overall failure rates << 10–10.
Authors: Ying Wu, Ming Qing Sun, Zhuo Qiu Li
Abstract: Many efforts have been directed to the micro structure and performance evaluation of Electroplated Diamond Film. The indentation method has become extensively utilized in the evaluation of materials’ mechanical. Nano indentation devices, such as MTS-XP, are very useful, but on the other hand, are not affordable for many research institutions. This paper presents an effective and economic method for testing and evaluating micro-cracking performance of Electroplated Diamond Film on Instron 5848 MicroTester by considering the relative hardness values, and the need to evaluate the maximum strength for brittle materials in practical applications. The design of the test system, the evaluation methods, the test results, and the discussions are presented.
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