Papers by Keyword: Cubic Boron Nitride (CBN)

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Authors: Hang Sheng Yang, Norihiko Kurebayashi, Toyonobu Yoshida
Abstract: In situ sulphur doping of cubic boron nitride (cBN) films was investigated by adding H2S into a plasma-enhanced chemical vapor deposition system. It was found that the nucleation of cBN was suppressed severely with a very low H2S concentration, while cBN could be grown continuously even at a H2S concentration as high as that of the boron source after its nucleation. Accordingly, S was incorporated into cBN films meanwhile keeping the cubic phase concentration as high as 95%. And a rectification ratio of approximately 10 5 was observed at room temperature for heterojunction diodes prepared by depositing S-doped cBN films on p-type silicon substrates, which suggests the possibility of an n-type-like doping. Moreover, 1500K post annealing of cBN films in H2 atmosphere was found to be able to release the residual compressive stress evidently. Thus, film adhesion strength increased markedly, and cBN films reached a thickness over 200 nm without peeling off from silicon and quartz substrates in air after 9 months.
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Authors: Sridhar Kompella, Kai Zhang, Rajeev Pakalapati
Abstract: The use of cubic boron nitride (CBN) over conventional abrasives in ferrous and superalloy grinding has resulted in improved manufacturing throughput and beneficial mechanical properties on workpiece surfaces. However, through the innovative use of crystal synthesis techniques, the grinding performance can be further improved over existing CBN crystals. In this study, such a new CBN crystal is developed, characterized, and its grinding performance is compared to a commercially available CBN crystal. Grinding tests are conducted in AISI M2 steel and Inconel-718 superalloy using a vitrified bond configuration with applicability in a wide range of end-use applications.
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Authors: R. Cai, H.S. Qi, Guang Qi Cai
Abstract: Wheel structure has a critical influence on grinding performance especially active cuttingedge density. Experiments were carried out to find out the relationshipbetween active and staticcutting edge density. It was found that there are many more active cutting edges in grinding thanexpected based on chip thickness formulae mainly due to wheel deflection in grinding.
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Authors: Yu Mei Zhu, Zhi Hong Li, Xia Wan Wu
539
Authors: Wen Feng Ding, Jiu Hua Xu, J.B. Lu, Yu Can Fu, Bing Xiao, Hong Jun Xu
Abstract: In this paper, the disadvantages of the current CBN (Cubic Boron Nitride) grinding wheels were firstly introduced briefly, for indicating that it was very urgent and important to develop new kinds of grinding wheels with excellent performance to replace the conventional wheels. Then high temperature brazing experiments of monolayer CBN wheels with Ag-Cu-Ti filler alloy were carried out. The result shows that the filler alloy has good wetting capability towards CBN grits. The results of scanning electron microscope (SEM) and energy dispersion spectrometer (EDS), as well X-ray diffraction (XRD) analysis show that, just because during brazing titanium atoms in filler alloys segregated preferentially to the surface of the CBN to form Ti-nitride or Ti-boride layer by reaction between titanium atoms and nitride and boron atoms at elevated temperature, strong chemical joining was formed in the interface between CBN grits and filler alloys. Finally, the contrastive grinding experiments were performed between the monolayer brazed CBN grinding wheels and the electroplated ones. The results show that the brazed wheels have more excellent performance than the latter.
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Authors: F. Richter, G. Krannich, M. Kühn, S. Peter, Ch. Spaeth
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Authors: Wioletta Gorczyńska-Zawiślan, Ewa Benko, Piotr Klimczyk
Abstract: In this work cBN-TiN composites were studied. The composites were prepared by the HPHT technique (p=8 GPa, T=1750 0C). A TiN binding phase was used in two forms: as micro and nanomaterials. Thermodynamic calculations showed that formation of new phases in the cBNTiN composites was not possible in the experimental conditions which was confirmed by XRD investigations carried out. The surface morphology of nanocomposites was studied by scanning electron microscopy. The structure of these composites was compact; a TiN phase was uniformly distributed between cBN grains. Hardness was measured by the Vickers method using an indentation load of 9.81 N. The hardness of the investigated samples was dependent on the volume and grain size of the binding phase. Young's modulus of elasticity was determined, but its value was found to be dependent on the grain size of the TiN phase.
149
Authors: J.F. Chen, J.H. Cui, F. Li
Abstract: In this paper, the principle and impact factors for super-accurate grinding are analyzed and discussed. A comparative test is made to investigate the differences between advanced cubic boron nitride (CBN) slipstone and ordinary CBN abrasive corundum in performance such as grinding force, grinding temperature, metal surface metamorphic layer and so on. Based on these results, we design and manufacture a carding Laura slot super-accurate grinding machine. This new grinding machine is standard in system, compact in structure and perfect in appearance. Its fixture has a high positioning accuracy. The surface roughness of the Laura manufactured on the new grinding machine has reduced to Ra0.01μm. The productivity of the new machine increases by 25 times.
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Authors: Xun Chen, Jing Feng Zhi, I.R. Pashby
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Authors: Xi Peng Xu, Cun Ji Du
Abstract: The present study was undertaken to compare the consumed power in surface grinding of three different materials with a vitrified CBN wheel. High speed steel, stainless steel, and natural granite were used as the workpiece materials in the experiments. Two different depth of cut and workpiece velocity were combined to give different material removal rates. The spindle power was in-process monitored in each pass of grinding. The radius wear of the grinding wheel was also measured and the morphologies of CBN grains were observed during the grinding of high speed steel and granite. The power for the grinding of high speed steel was found to be the lowest under any operating parameters. For other two materials, the results became complex. At shallower depth of cut, the power for the grinding of stainless steel was higher in most cases. However, the power for the grinding of granite was higher under larger depth of cut. It was found that the grinding wheel failed much earlier in the grinding of granite as compared with the grinding of high speed steel.
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