Papers by Keyword: B4C

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Authors: Kerim Emre Öksüz
Abstract: Increasing density is the best way to increase the performance of powder metallurgy materials. Conventional powder metallurgy processing can produce copper green compacts with density less than 8.3g/cm3 (a relative density of 93%). Warm compaction, which is a simple and economical forming process to prepare high density powder metallurgy parts or materials. CuSn matrix composites with %2 weight fractions of reinforcement particles were prepared using warm compaction and sintering. Micro-structural aspects were observed by optical microscope. Density, hardness and wear tests were also performed. Abrasion resistance measurements were used to study the abrasive behaviors of CuSn matrix and its composites. The effects of reinforcement and preparation methods on the microstructure and mechanical properties of composites have been investigated.
Authors: Rong Zhen Liu, Qing Wen Duan, Wen Wei Gu, Hai Yun Jin, Shao Chun Xu, Jian Feng Yang
Abstract: Silicon was infiltrated into B4C preforms to fabricate B4C based composites ceramics at 1600 °C under vacuum circumstance. In this paper, silicon infiltration process was discussed by theoretical calculation. The volume expansion caused by reactions between silicon and boron carbide was about 89.1% from the calculation. In our study, the maximum density of B4C preform for the infiltration of silicon was about 1.5g/cm3 which was larger than theoretical result. The results of mechanical behavior showed that B4C based composites had excellent mechanical properties with a density lower than 2.6g/cm3, Vickers-hardness of this material was 27.2GPa, and this material showed a flexural strength of 349MPa and fracture toughness of 3.8 MPa*m1/2.
Authors: Ying Ying Liu, Ying Jie Qiao, Ai Dong Liu, Yan Wang
Abstract: The binder system removal was studied in a laminated B4C ceramics prepared by tape casting and lamination with castor oil, polyvinyl butyral(PVB) and di-n-butyl phthalate (DBP) as dispersant, binder and plasticizer, respectively. Thermo gravimetric analysis and Fourier transform infrared spectromer was used to examine the degradation of the binder system. The degradation behavior of the pure organics, single sheet and laminated B4C body were investigated. The results indicate that nitrog4en was selected as the binder system removal atmosphere and two decomposition temperature ranges was obtained for organics. A model based on diffusion can be used to predict the binder system removal time for a certain thickness of laminated B4C.
Authors: Xuan Liu, Qiang Xu, Shi Zhen Zhu
Abstract: ZrB2-SiC-B4C is sintered at 1700°C by spark plasma sintering process. The effect of B4C content on the mechanical properties and microstructure of ZrB2-SiC based ceramics is studied. The results show that, with the content of B4C increases, the relative density and room-temperature strength decrease in the ZrB2-SiC-B4C composite. The fracture toughness rises at first and then falls down. The high temperature strength increases.
Authors: Rosa Maria da Rocha, Francisco Cristóvão Lourenço de Melo
Abstract: This paper presents results of experiments on pressureless sintering of boron carbide (B4C) with addition of titânia (TiO2) and titanium diboride (TiB2). The TiB2 powder was added as a second phase and the TiO2 powder for reactive sintering and in-situ formation of TiB2. The final concentrations of TiB2 in the composites were 0 to 10 vol%. Sintering was performed at 2050 °C/30min in argon atmosphere. TiO2 was completely transformed into TiB2 with fine equiaxed grains distributed homogeneously. Composites obtained by in-situ reaction showed a densification increase with the concentration increase, while the composites with TiB2 powder mixture showed low densification in all compositions. Relative Density of the composite with 10 vol% of TiB2 obtained in-situ was 91% (TD) compared to 86 % for B4C only. Vickers hardness was about 29 GPa.
Authors: Xian Feng Li, Bin Liu, Wen Mao Huang, Hao Wei Wang
Abstract: Particles size grading method was employed to fabricate aluminum matrix composites reinforced with 75% volume fraction B4C particles by squeeze casting. Dynamic behaviors of the composite was investigated and compared with 55 vol. % composite which were reinforced with particles of uniform size. The results showed that the flow stress increased but the fracture strain decreased with increasing reinforcement volume fraction. Furthermore, the dynamic behaviors of 55 vol. % composite were significantly affected by adiabatic heating softening which was demonstrated by the local melted matrix on the fracture surface and an increase-decrease tendency on flow stress and failure strain was obtained with increasing impact velocity. However, due to load redistribution caused by particles size grading, no melted region was found on the fracture surface and no increase-decrease tendency on flow stress and failure strain was observed for 75 vol. % composites under the same impact loading.
Authors: Zhang Jian Zhou, Chang Chun Ge
Abstract: B4C is a promising candidate for using as plasma-facing material in fusion devices. In this paper, both B4C/Cu coating FGM (Funetionally graded material) and B4C/Cu bulk FGM containing a spectrum of 0-100% compositional distributions of B4C were fabricated by atmosphere plasma spray and ultra-high pressure consolidation respectively. The microstructure of B4C/Cu FGM showed good graded composition distribution. Water quenching and high heat loading experiments using an electron beam were carried out to evaluate the high heat load resistance of B4C/Cu FGMs. The in situ plasma irradiation in a Tokamak facility showed that the B4C/Cu bulk FGM has higher physical sputtering performance than that of B4C/Cu coating FGM.
Authors: Gurpreet Singh Saini, Sanjeev Goyal
Abstract: In the present paper aluminum matrix composites were fabricated using base material AA6082-T6. SiC and B4C particulates were used as reinforcement to obtain hybrid and non-hybrid composites through the conventional stir casting process. AA6082-T6/SiC composites with 5, 10, 15 and 20 wt % of SiC; AA6082-T6/B4C composites with 5, 10, 15 and 20 wt % of B4C and AA6082-T6/(SiC+B4C) hybrid composites with 5, 10, 15 and 20 wt % of (SiC+B4C) taking equal fraction of SiC and B4C were made and the microstructure study was carried out. X-Ray diffraction (XRD) patterns revels the presence of reinforcement within the matrix along with some other compounds. The microstructure of the fabricated composites was examined with the help of Scanning electron microscope (SEM) and the micrographs revealed that the dispersion of reinforced particles was reasonably uniform at all weight percentages.
Authors: Lin Geng, Qing Wu Meng, Yan Bin Chen
Abstract: In order to improve wear resistance of titanium alloy, with pre-placed B4C and NiCrBSi powders on Ti-6Al-4V substrate, a process of laser melting-solidifying metal matrix composite coating was studied. The coating was examined using XRD, SEM and EDS. A good metal matrix composite coating was obtained in a proper laser process. There is a metallurgical interface bonding between the coating and the substrate. During laser melting-solidifying process, high energy of laser melted the pre-placed powders and a part of Ti-6Al-4V substrate, which made Ti extend into a melting pool. A reaction between Ti and B4C took place in the melting pool, which in-situ synthesized TiB2 and TiC reinforcements in the coating. The composite coating mainly consists of γ-Ni matrix, TiB2, TiC and CrB reinforcements. Microstructure of the reinforcements obtained using the laser melting-solidifying is not as same as that of reinforcements obtained using general producing methods. Due to high cooling rate of the melting pool, TiC nucleated primarily and grew up in dendrite morphology from undercooled liquid. Encircling TiC, TiB2 precipitated later and grew up in hexagonal prism morphology. TiC and TiB2 formed an inlaid microstructure.
Authors: Manickam Ravichandran, Arumugam Manikandan, Meenakshi Sundaram Omkumar
Abstract: Powder metallurgy is a popular technique to synthesize metal matrix composites with uniform distribution of the reinforcements. The present work aims to synthesize Al-B4C composites through powder metallurgy route and study their properties. The compositions of the composites are Al-5%B4C, Al-10%B4C & Al-15%B4C. Blending of powders, compaction and sintering process were carried out as per standard powder metallurgy procedure. The distributions of the reinforcements were analyzed for the sintered specimens by the help of scanning electron microscope. The effect addition of B4C in the Aluminium matrix on the properties such as density, porosity, hardness and compressive strength were discussed. Results show that addition of B4C improves the properties of Al-B4C composites.
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