Papers by Keyword: Cubic Boron Nitride

Abstract: The article summarizes the results of the of the titanium alloy surface morphology and chemical composition study after grinding with a wheel of cubic boron nitride on a ceramic bond. The titanium alloy was treated using the method of cut-in grinding in the finishing mode using a synthetic water-soluble lubricant-cooling liquid that does not contain mineral oil. The research was carried out using the FEI Versa 3D LoVac electron microscope. Digital photos of the titanium alloy surface at different magnifications are given. Individual objects’ morphology allows us to identify them as wear products of abrasive tools. The chemical composition of the selected objects was studied by local x-ray spectral analysis. CBN crystals are partially or completely pressed into the treated surface and covered with a layer of the treated material. On the surface of CBN crystals, there are chemical elements that are part of the abrasive tool bond.

Abstract: A brief review of the characteristics and properties of cubic boron nitride (cBN) is presented, including different processing methods. The influence of bonding substances, as well as other ceramic composites, is also discussed. Finally, it is highlighted the great practical importance of the cBN as a ceramic with elevated hardness in substitution for the diamond in cutting tools.

Abstract: Titanium has been evaluated in a broad range of aerospace, biomedical and sports equipment applications due to its unique combination of high mechanical strength, light weight and good biocompatibility. However, Ti implants are often subject to wear in specific areas. Therefore, the improvement of mechanical properties, such as hardness, wear resistance, bearing capability of implants is a key point to broaden the application fields of titanium. Cubic boron nitride (cBN) is a well-known superhard material possessing high chemical stability and biocompatibility. However, cBN suffers from poor machinability and sinterability. Attempts to process boron nitride by laser treatment into intricate shapes are extremely difficult, expensive and time-consuming tasks squeezing its applicability. In this work, manufacturing of Ti/cBN cellular structures and solid parts of high strength and good wear resistance by selective laser melting was performed. In Ti/cBN composite powder, the boron nitride provides the excellent mechanical properties, and titanium promotes the laser absorption improving the process of densification. The parametric study of consolidation process has been performed and the microstructural features along with mechanical properties are examined.

Abstract: In the present study austempered ductile irons (ADI) with an upper and lower bainitic structure with nanosized particles of cubic boron nitride cBN (50nm) are studied. The austempering modes include austenization at 900^оС during an hour and isothermal retention at 280^оС from 0.5 to 6 hours and at 380^oС from 0.5 to 6 hours. The samples microstructure is investigated by means of an optical metallography, scanning electron microscopy and X-ray analysis. Tests for hardness, impact toughness and wear are performed. The influence of nanosized additives on the kinetic of the bainitic transformation and on the morphology of the obtained bainitic structure is studied. It is established that the changes of the bainitic cast irons microstructure under influence of the nanoparticles of cBN lead to the cast irons impact toughness and wear resistance increase. The research is aimed at expanding the scope for new ADI applications in the industry.

Abstract: Cubic boron nitride (cBN) particle-dispersed-aluminum (Al) matrix composites were fabricated from the powder mixture composed of cBN, pure Al and Al-5mass% Si alloy in liquid and solid co-existent state by spark plasma sintering (SPS) process. Al/cBN composites were well consolidated by heating at a temperature range between 798 K and 876 K for 1.56 ks by SPS. Microstructures of the composites produced were examined by scanning electron microscopy and the reaction between the cBN particle and the Al matrix was not detected. The relative packing density of the Al/cBN composite was higher than 99 % in a volume fraction range of cBN up to 45 %. The thermal conductivity of the composite increased with increasing the cBN content in the composite in a volume fraction range of cBN between 35 and 45 vol. %. The highest thermal conductivity of 305 W/mK was obtained for Al matrix composite containing 45 vol.% cBN particles.

Abstract: Cubic Boron Nitride (cBN) has wide application prospect in the field of high performance cutting tool, for its outstanding mechanical properties. In this paper, the cBN coating was synthesized on cement carbide by chemical vapor deposition nanocrystalline diamond interlayer in radio frequency magnetron sputtering system. The SEM, FTIR and AFM were used to investigate the microstructure, purity and morphology of the cBN film. The research was carried out on the effect of the deposition parameters on the cBN content in the film. High temperature and high pressure locally in the substrate is an important factor of transformation of cubic phase BN from hexagonal phase BN. There is a narrow optimization parameters window in cBN synthesis by ion bombardment assist radio frequency magnetron sputtering method. The good quality of cBN film can be obtained by a combination of moderate substrate bias voltage and gas pressure, high substrate temperature and a certain N₂ partial pressure.

Abstract: The ultra–precision cutting of steel materials is possible but needs modifications of machine tools or the workpiece material. One approach of actual research is the development of cutting materials that gives the opportunity for direct cutting of surfaces with ultra–precision quality. Binderless–cBN is here one of the most promising materials. The paper shows results of experimental studies with binderless–cBN as cutting material while turning stainless steel. Various investigations were carried out to determine the wear mechanisms. Furthermore, measurements are shown regarding the surface quality. The achieved results show the high potential ofbinderless–cBN as cutting material for the machining of steel.

Abstract: This research paper focuses on grinding of materials used for tools (100Cr6 (CSN 4 14109), X210Cr12 ( CSN 4 19436) and epoxy resin) using grinding wheels from cubic boron nitride and diamond. The disadvantage of grinding of difficult-to-machine materials is higher wear of grinding wheels. The modern grinding wheels are able to achieve high accuracy of dimensions and high surface quality with a smaller wear of grinding wheels then grinding wheels from conventional materials. Correctly selected technological conditions are one of the most important matters to achieve the required surface quality. The main aim of this research is to determine the influence of technological conditions to quality of surface after planar grinding. The research determines the influence of the grain type of grinding wheels, feed rate and cutting depth on the quality of functional surfaces.

Abstract: Hard turning is a turning operation performed on hard materials (hardness more than 45 HRC) in order to reach surface roughness close to that obtained in grinding. The development of this technology was accompanied by the development of new cutting materials such as cutting ceramics, cubic boron nitride and polycrystalline diamond. Especially cubic boron nitride has found its use in hard part turning operations because of its characteristics. However, new cutting materials result in new questions, which researchers are trying to solve. The major consideration for a user of this relatively new technology is the quality of parts produced and how the new cutting material will behave during machining. This paper aims to document and describe the process of wear on the cutting edge of a tool made from cubic boron nitride of a different grade and with a different geometry of the cutting edge, and its influence on surface roughness and quality. Wear was documented by a digital microscope with measurement option. Surface roughness was measured by a roughness meter. A notable observation from this research is that the flank wear of the cutting tool has a large impact on the quality of machined parts (especially surface finish and surface integrity) [1].

Abstract: As a superhard material, next to diamond, the cubic boron nitride (cBN) is of great interest owing to its efficiency in machining ferrous alloys. In nature, only the hexagonal, hBN, exists. In practice, high pressure and high temperature (HPHT) synthesis has to be used to produce small cBN crystals. For larger size machining inserts, the powder-like cBN crystals need to be sintered at specific HPHT conditions using a metallic binder. The present work investigates the sintering of cBN inserts using a Si3N4 binder agent. The results disclosed relatively high hardness for the inserts and revealed their effectiveness in machining high strength steels.