Papers by Keyword: Cubic Boron Nitride (CBN)

Abstract: PcBN–Al composites（PAC）have been synthesized by pressure infiltration(PI) and a general mixing method(GM)[1-3] with a wide grain sizes range of 4-25 um and a wide temperature range of 1200-1600°C at 5.0 GPa,respectively.Hardness ranged between 30and 40 GPa, while the flank wear (Vb) reached 0.12mm when it finished 4000m in cutting test ofPAC synthesized by PI method. Hardness ranged between 25 and 35GPa, while the flank wear (Vb) reached 0.14 mm when it finished 4000mof PAC synthesized by GM method. The homogeneity of PcBN–Al synthesized by PI have been improved compared with GM. PI is a superior method to synthesize PAC in the field of mechanical properties.

Abstract: Cubic boron nitride (cBN) has significant technological potential for use in high-temperature high-power electronic applications. And S and Zn were reported to be potential n-and p-type dopants. In this study, influences of vacancies, S and Zn impurity atoms on the electronic properties of cBN were investigated by first-principle approaches. The computation results are in good agreement with our experimental approach.

Abstract: Cubic boron nitride (cBN) grains treated with hydrochloric acid, nitric acid and sulphuric acid were investigated, respectively. The results indicated that the surface treatment technique with hydrochloric acid was an excellent method for improving the properties of cBN grains. After hydrochloric acid treating, cBN grains with clean surface and satisfied strength were obtained. Moreover, the bonding strength between cBN grains and vitrified bond was increased significantly for application in vitrified bond grinding tools.

Abstract: Preparation of high wear-resistant ceramic parts was studied in this paper. The mechanical property was measured by the three-point bending tester, and the microstructures were analyzed with the scanning electronic microscope (SEM). The experimental results showed that vitrified bond CM2 was suitable for the preparation of high wear-resistant ceramic parts because of its lower refractoriness, and higher bonding strength sintering at 850oC. Moreover, containing 8- 12μm CBN abrasive grains, the ceramic parts reached higher strength and higher wear resistance than other samples.

Abstract: Selecting Si3N4 as binding agent and Al2O3–Al–Y2O3 as sintering additives, the sintered compact of polycrystalline cubic boron nitride (PcBN) was studied . By modifying the ratio of each component and the parameters of the sintering process, the compact sintered at 4.5 GPa and 1650 °C showed good mechanical properties.The phase constitution, microstructure of the sintered compact were characterized by XRD and SEM respectively. The degree of phase transformation of Si3N4 , the chemical reaction during the sintering process, and the sintering mechanism of the additives were discussed . The best relative density is more than 97 % , the flexural strength is more than 650 MPa, the Vickers hardness Hv is more than 8.7 GPa.

Abstract: The cBN-cBN direct bonding structure of some cBN compacts made by the method of the direct conversion of the pyrolytic-BN (pBN) or wurtzite-BN (wBN) to cubic-BN at the pressure of 7GPa and temperature 2000 °C and the cBN compact made by the method of sintering the cBN powder along with polyvinylidene chloride (PVDC) at the condition of 5.5GPa and 1600 °C has been studied. The XRD, SEM, TEM analysis and the wear resistance on the ductile cast iron machining has been investigated. While the XRD analysis of the above cBN samples showed that all samples consist only of cBN, and the SEM observation showed that they all have the cBN-cBN direct bonding structure, A STEM analysis showed the existence of the impurities at the cBN crystal boundary. The starting materials and the sintering method affect the degree of these impurities.

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.

Abstract: Controlling the shape of cBN has been met with limited success. This work mainly reports a hydrothermal route to synthesize cBN nanocubes with oriented growth along [100] direction. XRD, TEM and SEM are applied to characterize the structure properties. Regular cubes of cBN have perfect quality and good uniformity. The square symmetry illuminates that cBN cube is a single crystal bounded mainly by the less stable {100} facets. This special morphology is determined by the ratio(R) between the growth rates along [100] and [111] direction.

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.

Abstract: The development of China as the world's manufacturing house is best exemplified in the industry of diamond superabrasives. Diamond is indispensable in the creation of industrial infrastructure, including the construction of roads and building of houses. The diamond market was previously dominated by countries outside China. However, a "great leap forward" has taken in China with rapid expansion in Chinese diamond-making capabilities from the enlargement of the equipment (cubic presses) and improvements in diamond yield and product quality in the end of last century. In the new millennium, China outpaced the rest world combined in the total diamond output, became the largest producer in the world indubitably. This paper presents the progress in recent years based on the statitics, and also an outlook of the future development of the Chinese superabrasives industry based on the Chinese macroeconomics and the recent data of the end-users as well as their future development trend.