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碳化硼陶瓷具有高硬度、高熔点和低密度的特点,是优异的结构陶瓷,在民用、宇航和军事等领域都得到了重要应用。本文中综述了碳化硼结构陶瓷的优异性能和制备新方法,重点介绍了自蔓延高温合成法(SHS),碳管炉、电弧炉碳热还原法,激光化学气相反应法,溶胶-凝胶碳热还原法等合成碳化硼粉末的主要方法以及碳化硼成型和烧结的常用方法,简述了碳化硼抗弹陶瓷材料的发展应用和研究现状。 相似文献
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碳化硼陶瓷专用粉末的制备 总被引:2,自引:0,他引:2
碳化硼是一种重要的工程材料 ,其硬度仅次于金刚石和立方氮化硼 ,具有耐磨性好、比重小、耐酸碱、较好的中子吸收性能等特点 ,被国内外广泛应用于耐火材料、工程陶瓷、核工业等领域。本文从碳化硼工程陶瓷的生产工艺特点介绍了其对碳化硼粉的特殊要求以及专用碳化硼粉的制备工艺。1 碳化硼陶瓷烧结1 1 烧结过程烧结是减少气孔、增强颗粒之间结合力、提高机械性能的工艺过程 ,是一种或几种固体粉末经过成型 ,加热到一定温度后开始收缩 ,在低于熔点强度下变成致密的、坚硬的烧结体的过程。烧结过程是一个物质的传递过程。粉末体的表面能是烧… 相似文献
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Graphite and boron carbide composites made by hot-pressing 总被引:1,自引:0,他引:1
Composites consisting of graphite and boron carbide were made by hot-pressing mixed powders of coke carbon and boron carbide.
The change of relative density, mechanical strength and electrical resistivity of the composites and the X-ray parameters
of coke carbon were investigated with increase of boron carbide content and hot-pressing temperature. From these experiments,
it was found that boron carbide powder has a remarkable effect on sintering and graphitization of coke carbon powder above
the hot-pressing temperature of 2000° C. At 2200° C, electrical resistivity of the composite and d(002) spacing of coke carbon
once showed minimum values at about 5 to 10 wt% boron carbide and then increased. The strength of the composite increased
with increase of boron carbide content. It was considered that some boron from boron carbide began to diffuse substitutionally
into the graphite structure above 2000° C and densification and graphitization were promoted with the diffusion of boron.
Improvements could be made to the mechanical strength, density, oxidation resistance and manufacturing methods by comparing
with the properties and processes of conventional graphites. 相似文献
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We report the synthesis of boron carbide powder via the reaction of hexagonal boron nitride with carbon black. The reaction between hexagonal boron nitride and carbon black completed at 1900 °C for 5 h in vacuum. The particle sizes of the synthesized boron carbide powder were about 100 nm from transmission electron microscopy. The possible reaction mechanism was that hexagonal boron nitride decomposed into elemental boron and nitrogen even when there was no carbon at a relatively low rate, and introduction of carbon into hexagonal boron nitride powder facilitated the decomposition process; the boron from the decomposition of boron nitride reacted with carbon to form boron carbide. 相似文献
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M. Akkaş 《Materialwissenschaft und Werkstofftechnik》2021,52(1):32-42
In this study, composite samples were produced by reinforcing boron carbide and silicon carbide particles in different rates by weight into copper-nickel powder mixture using powder metallurgy method. The prepared powder mixtures were cold pressed under 600 MPa pressure and pelletized. The pelletized samples were then sintered in an atmosphere-controlled furnace. Scanning electron microscopy to determine the microstructure of the produced samples and x-ray diffraction method analysis to determine the phases forming in the structure of the produced samples were used and microhardness was taken to determine the effect of boron carbide and silicon carbide on hardness. In addition to that, the mechanical properties the transverse rupture strength were investigated using three-point bending tests. The corrosion tests were performed potentiodynamic polarization curves of the samples in 3.5 % sodium chloride solution. The highest hardness value was measured as 162 HV 0.05 in the sample reinforced with 10 % boron carbide. As the amount of silicon carbide increased, the corrosion resistance of the composite increased. Moreover, as the amount of boron carbide increased, the corrosion resistance of the composite decreased. Load-contact depth values were examined, copper-nickel+10 % silicon carbide has the highest peak depth of 48.12. 相似文献
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A novel method, based on the combustion of boric acid–sucrose xerogel was developed to synthesize nanocrystalline boron carbide
powder. This xerogel was pyrolyzed at 1273 K. Boron carbide was obtained by heating this precursor at 1823 K. The yield of
boron carbide was improved by the use of a novel graphite crucible designed for this purpose. The xerogel and the precursor
were characterized by using Fourier transform infrared spectroscopy. The constituent phases were identified by using X-ray
diffraction while their elemental composition was established with the help of chemical assay. The microstructure of the final
product was examined with the help of scanning electron microscopy and transmission electron microscopy. This study demonstrates
that the yield of boron carbide would be enhanced to about 48% while the free carbon content in the final product could be
reduced to about 6 wt%. These are significant improvements over similar studies reported so far on the gel-based preparation
of boron carbide. 相似文献
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Numerical simulation was carried out using ANSYS/LS-DYNA on empty and boron carbide filled stainless steel tubes and zircaloy rod for studying their elastic wave propagation during tensile impact. While empty stainless steel tubes and zircaloy rod showed perfect one dimensional wave propagation, presence of boron carbide powder increased the stress underwent by the tube as the tensile stress wave approached the powder. Furthermore, the wave propagation time of boron carbide filled tube increased in comparison with the empty tube. Experimental results compared well for the plateau region of the strain-time history of the boron carbide powder filled tube. For the empty steel tube and zircaloy rod there was good comparison of strain amplitude. 相似文献
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Boron carbide nanoparticles were produced using commercially available boron carbide powder (0·8 μm). Mechanical milling was used to synthesize Al nanostructured powder in a planetary ball-mill under argon atmosphere up
to 20 h. The same process was applied for Al–4 wt % B4C nanocomposite powders to explore the role of nanosize reinforcements on mechanical milling stages. Scanning electron microscopy
(SEM) analysis as well as apparent density measurements were used to optimize the milling time needed for completion of the
mechanical milling process. The results show that the addition of boron carbide particles accelerate the milling process,
leading to a faster work hardening rate and fracture of aluminum matrix. FE-SEM images show that distribution of boron carbide
particles in aluminum matrix reaches a full homogeneity when steady state takes place. The better distribution of reinforcement
throughout the matrix would increase hardness of the powder. To study the compressibility of milled powder, modified heckel
equation was used to consider the pressure effect on yield strength as well as reinforcing role of B4C particles. For better distribution of reinforcement throughout the matrix, r, modified heckel equation was used to consider the pressure effect on yield strength as well as reinforcing role of B4C particles. 相似文献
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Polyvinyl borate (PVBO) was prepared by the condensation of poly(vinyl alcohol) (PVA) and boric acid, and used as a precursor for boron carbide. Boron carbide powder was synthesized by the pyrolysis of the PVBO precursor in air at 600 °C for 2 h, followed by heat treatment in Ar flow at 1300 °C for 5 h, which is a relatively low temperature compared with conventional carbothermal methods. Pyrolysis of the PVBO precursor resulted in submicron-size particles of B2O3 dispersed in a carbon matrix. In addition, the pyrolysis temperature governed the carbon content in the pyrolyzed product of the PVBO precursor, which led to the synthesis of crystalline boron carbide powder with little free carbon. 相似文献
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O. M. Syzonenko P. I. Loboda A. D. Zaichenko Ye. V. Solodkyi A. S. Torpakov M. S. Prystash V. O. Trehub 《Journal of Superhard Materials》2017,39(4):243-250
The influence of high-voltage electrical discharge on the distilled water–boron carbide powder dispersion system has been studied, making it possible to clarify the relationship between the discharge parameters and the powder dispersion and structure. It is shown that the necessary conditions for effective dispersion of the boron carbide powder are the compression wave pressure amplitude at least ca. 100 MPa and the specific processing energy about 20 MJ/kg. 相似文献
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Studies were carried out to extract elemental boron from boron carbide scrap. The physicochemical nature of boron obtained through this process was examined by characterizing its chemical purity, specific surface area, size distribution of particles and X-ray crystallite size. The microstructural characteristics of the extracted boron powder were analyzed by using scanning electron microscopy and transmission electron microscopy. Raman spectroscopic examination of boron powder was also carried out to determine its crystalline form. Oxygen and carbon were found to be the major impurities in boron. Boron powder of purity ~ 92 wt. % could be produced by the electroextraction process developed in this study. Optimized method could be used for the recovery of enriched boron (10B > 20 at. %) from boron carbide scrap generated during the production of boron carbide. 相似文献