Papers by Keyword: Diamond

Abstract: This study presents the development of an advanced 215.9 mm drill bit with an optimized material distribution to enhance wear resistance, durability, and operational efficiency in highly abrasive formations. A comprehensive scanning electron microscopy (SEM) analysis of the powders used in the drill bit's construction was conducted using the TESCAN Mira 3 LMU system. The analysis included tungsten carbide–cobalt (WC–Co) and diamond-containing composite powders. The results revealed that WC–Co powders exhibit high density and uniform particle distribution, making them suitable for load-bearing components, while diamond-containing powders ensure superior cutting performance and wear resistance. Based on these findings, a rational material allocation was implemented: WC–Co-based materials were used for structural elements, and diamond-containing powders were applied in cutting and undercutting inserts. Process was optimized to prevent thermal degradation of the polycrystalline diamond compact (PDC) inserts. The developed drill bit was designed for rotary drilling with an axial load range of 20–80 kN, rotation speeds of 80–250 rpm, and a drilling fluid flow rate of up to 40 L/s. The proposed design is particularly suited for the geological and technical conditions of Kazakhstan’s oil and gas fields, contributing to reduced drilling costs and increased efficiency.

Abstract: In this study, we present positron lifetime calculations for diamond, including the defect-free bulk, vacancies and vacancy clusters, as well as grain boundaries, using Two-Component Density Functional Theory. Our results show a positron bulk lifetime of 103 ps and a mono-vacancy lifetime of145 ps, which is in agreement with experimental data. We calculated positron lifetimes for vacancy clusters from 2 up to 40 missing atoms, resulting in lifetimes between 168 to 365 ps. From these results, we derived a function that correlates the cluster size with the respective positron lifetime.Furthermore, we computed the positron lifetime of 124 ps for a grain boundary, which is between the bulk and mono-vacancy lifetime. Our results will be used to interpret measured positron lifetime spectra in diamond.

Abstract: Direct diamond deposition on a steel surface has been considered very difficult. Recently, we found that high-quality diamond films can be deposited on the surface of stainless-steel X5CrNi 18-10 by drilling multiple regularly arranged pits without interlayers or seeding. The following two hypotheses (A) and (B) can be considered as the reason why a high-quality diamond film can be deposited: (A) unoxidized Cr and Ni exposed to the stainless-steel X5CrNi 18-10 surface prevent carbon diffusion into interior of the stainless-steel, resulting diamond core generation, (B) Surface geometry with regular roughness contributes to stress relaxation and delamination prevention. In the present study, those hypotheses have been examined by quantum chemistry calculation and experimental. For the quantum chemistry calculation, energy barrier and kinetic energy for a carbon atom intrudes into a model cluster has been calculated with an ab-initio computational chemistry software package, Gaussian. The calculation result has supported hypothesis (A). For the experiment, X5CrNi 18-10 stainless-steel substrates with different surface characteristics are prepared by using various mechanical machining methods and used in the direct deposition process for diamond with in-liquid plasma CVD. The experimental result has supported both hypothesis (A) and (B).

Abstract: Diamond and Silicon Carbide (SiC) are promising wide band-gap semiconductors for power electronics, SiC being more mature especially in term of large wafer size (200 mm). Nitrogen impurities are often used in both materials for different purpose: increase the diamond growth rate or induce n-type conductivity in SiC. The determination of the nitrogen content by secondary ion mass spectrometry (SIMS) is a difficult task mainly because nitrogen is an atmospheric element for which direct monitoring of N^± ions give no or a weak signal. With our standard diamond SIMS conditions, we investigate ¹²C¹⁴N^- secondary ions under cesium primary ions by applying high mass resolution settings. Nitrogen depth-profiling of diamond and SiC (multi-) layers is then possible over several micrometer thick over reasonable time analysis duration. In a simple way and without notably modifying our usual analysis process, we found a nitrogen detection limit of 2x10¹⁷ at/cm³ in diamond and 5x10¹⁵ at/cm³ in SiC.

Abstract: Carbide tools with mono/multilayer coating such as TiN, TiC, TiAIN, TiB₂ and Al₂O₃ on inserts of WC-Co generated key success for machining of ferrous materials without coolant/lubrication. So far dry machining of aluminium, manufacturing industries such as automobile and aerospace engineering are facing considerable challenges. Exploration of correct cutting tool for machining of aluminium still persists in the present day context. This paper experimentally investigated the affinity and performance of different cutting tool materials available in local tool shopping center along with the diamond coated tool insert prepared and developed in our own HFCVD reactor for machining of aluminium in dry condition. Finally it is revealed that, due to the low chemical affinity, small magnitude of cutting force, chemical inertness and remarkable anti-welding characteristics, diamond coated tool displayed improved performance as compared to other tools.

Abstract: In this work, using polymer 3D printing, we obtained ceramic parts of complex shape with the topology of a triple periodic minimal surface (TPMS), of the “Schwarz primitive” type. The technology of manufacturing ceramic products from a diamond-silicon carbide composite ("Ideal") with the geometry of TPMS by pressing is described. The properties of 3D ceramics are similar to those of a monolithic material.

Abstract: This paper introduces the characteristics of sapphire and sapphire digging bits in LED field. The segment matrix design principle of bit and the rule of diamond selection are put forward. In addition, this paper analyzes the function of different metal powders and diamond parameters in the segment matrix. The results show that the finer grained (for example 80/100 mesh) diamond should be used with the concentrations of 30-60%. In the segment matrix, tin element can make the matrix more brittle and then the bit is sharper. Copper, silver and nickel element can enhance the matrix toughness and strength, cobalt and tungsten element can increase abrasive resistance. All of the above designs enable the sapphire bit to high sharpness and long life. A 4-inch sapphire bit was prepared for drilling sapphire crystal, the efficiency is increased by 8% than the Taiwan drill bit with the same specifications, the life is equal to Taiwan's drill bit, and the defect rate of sapphire bar is less than 0.5%, which satisfies the requirement of customers.

Abstract: Diamond/aluminum matrix composite with high thermal conductivity is of great significance to solve the heat dissipation problem of large-scale integrated circuits and high-power components. This paper reviews the current research status of diamond/aluminum matrix composites, and analyzes the effects of the preparation and processing of the composites, the interface bonding between diamond and aluminum matrix, the reinforced diamond and matrix alloy elements on the properties of the composites.

Abstract: Diamond is arguably the best candidate material for heat dissipation applications, especially in high-power electronic devices. Silicon carbide (SiC) is a kind of wide band gap material, which can be used in applications of silicon (Si) components to reach the performance limits. In this paper, thin diamond films were successfully deposited on C-face and Si-face of 6H-SiC substrates respectively using MPCVD at temperatures from 800 to 1050 °C. SEM images indicated the growth quality comparison of the two faces of SiC. The diffraction peaks of the diamond (111), (220), and (311) crystal planes can be observed by XRD measurement, and the intensity of the diamond diffraction peaks grown on the C-face is stronger than that on Si-face. The growth process was analyzed by Raman spectrum. FWHM of diamond Raman spectra on Si-face and C-face are 6.07cm^-1 and 5.47cm^-1 respectively. All above measurement results show that the diamond grown on the C-face has higher crystal quality than that on Si-face of SiC.

Abstract: A monocrystalline diamond substrate was bonded with a Si substrate employing a direct bonding technique. The diamond and Si surfaces were functionalized with hydroxyl (–OH) groups and subsequently bonded by the thermal dehydration reaction across the bonding interface. When a diamond (111) surface was treated with a mixture of H₂SO₄ and H₂O₂, it generated an atomic bond of C–O–Si with an oxygen-plasma-irradiated Si substrate. The bonding technique of diamond using the H₂SO₄/H₂O₂ mixture is expected to contribute to the future integration of diamond and semiconductor substrates because it allows low-temperature bonding in atmospheric air with negligible crystallinity damage.