Papers by Keyword: Synthetic Diamond

Abstract: In the rock-drilling industry, double layer polycrystalline diamond-hardmetal (Dia-HM) inserts for cutting tools are subjected to elevated levels of wear due to the high power involved in the process. A research performed by focusing on the wear mechanism has shown that the complexity of the actual industrial operation can be reproduced in laboratories. The present work developed a methodology to calculate the theoretical values of wear of drilling tools. The main parameter selected for this methodology was the amount of disaggregated rock. The information acquired through this methodology gives one a complete perspective about the application of Dia-HM inserts to be used in drilling tools.

Abstract: Polycrystalline SiC-diamond composites have been fabricated by high pressure and high temperature, HPHT, sintering using a Si infiltration method. However, infiltration of liquid silicon around the diamond particles results not only in SiC but also in free silicon, which causes deterioration of the composite properties. In this work, a novel sintering procedure was developed to avoid the formation of free silicon in the composite structure. A disc composed of a mixture of graphite and silicon was first press-molded at room temperature. The disc was then placed above the diamond powder inside a high pressure chamber used for the HPHT sintering process. This arrangement permitted to preferentially form liquid Si in a C solution, which infiltrates in between the diamond particles. Using this procedure, free silicon formation is inhibited and the SiC-diamond composite forms a rigid structure with improved properties.

Abstract: This paper described the preparation method for composing high-grade synthetic diamond by water atomizing using FeNi30 powder catalyst.The FeNi30 powder was corroded by the 100Mpa super high-pressure water atomizing technique and selecting organic RY corrosion inhibitor. Contrast test of the original FeNi30 powder and the treated FeNi30 powder on synthetic diamonds were conducted under super high-temperature and high-pressure using cubic press. The result shows that after the FeNi30 powder was corroded,the FeO phase and Fe3O4 phase could not longer be found by X-Ray analysis.Furthermore,the oxygen content of the powder increased up to 100PPM under the natural condition for one year. After the powder was mixed with graphite powder, diamond could be made by isostatic pressing method. Its color became darker and its TTI value increased slightly. However, its penetrability was still different from the high-grade synthetic diamond made by gas atomizing FeNi30 powder catalyst.

Abstract: This paper presents an analysis of diamond-like carbon thin film deposited using homebuilt microwave chemical vapor deposition. Two different deposition conditions were investigated, namely, with and without microwave power. Post deposition analysis included Raman spectroscopy, scanning electron microscope (SEM), energy dispersed X-ray (EDX), four-pointprobe resistivity measurements and refractive spectroscopy. Substrate with pretreatment was observed to have thin film formation. Samples with diamond paste pretreatment show better quality compared to SiC treated samples as suggested by Raman spectral. The presences of sp3 and sp2 peaks were identified in the Raman spectral. The overall resistivity is low due to the graphite content.

Abstract: In an abrasive tool the abrasive is the main part undertaking grinding work, thus, the grinding effects mainly depend on the types and properties of the abrasive. The strength and fracture property of the abrasive grain in a synthetic diamond abrasive tool have a direct influence on the operational performance of the tool. Generally, it is expected that the strength and protrusion height of the grain are as same as possible. The strength and fragmenting property of the abrasive grain hinge on its crystal shape and regularity and completeness, internal vice, impurity content and impurity distribution pattern. The abrasive grains must be sorted and classified to make their grain sizes and their properties consistent with each and all. In this paper, the author discusses the basic properties and related performances of synthetic diamond abrasives. Elementary discussion is made separately on improving the vibration sorting, introducing the magnetic separation, applying the heavy liquid separation, exploring the floatation technology and using the selective fragmentation principle. In addition, here are presented the basic methods for precise sorting of synthetic diamond abrasives and their general principles. Practices have proved these methods effective and feasible.

Abstract: The electronic and structural properties of nickel-vacancy complexes in diamond were investigated by a total energy ab initio methodology. These results are discussed in the context of the electrically active centers, commonly found in synthetic diamond.