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立方氮化硼(cBN)特性综述 总被引:4,自引:0,他引:4
氮化硼是由氮原子和硼原子所构成的晶体,化学组成为43.6%的硼和56.4%的氮,具有四种不同的变体:六方氮化硼(hBN)、菱方氮化硼(rBN)、立方氮化硼(cBN)和纤锌型氮化硼(wBN)。文章对cBN的晶体结构、物理机械特性、光学性质、电学性质、热学性质、化学性质以及cBN晶体中杂质物相与hBN中B2O3含量的关系等做了简要的综述性描述,以便我们对cBN的基本特性有一个初步的了解。 相似文献
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立方氮化硼(cBN)是在碱金属、碱土金属及它们的氮化物、硼化物、硼氮化物等触媒参与,在高压高温条件下由六方氮化硼(hBN)转变而成的。文章就一些添加物,例如,Si、B2O3、AIN、VB族等价杂质、wBN、尿素、水等对hBN转变为cBN所产生的影响做一简要综述。 相似文献
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由于PcBN材料优异的性能,使PcBN刀具在制造加工行业有着独特的优势。目前PcBN复合片主流的制备方法为高温高压一次烧结法。按照结合剂种类,PcBN材料分为金属型、陶瓷型和金属+陶瓷型。金属+陶瓷型PcBN综合了金属型和陶瓷型的性能优点,被广泛的研究。PcBN的结合剂也由单一体系发展为现在的多元化体系,并涌现出一些新型结合剂,结合剂材料也成为PcBN材料性能优劣的关键因素。文章介绍了PcBN的分类,概述了PcBN材料的优异性能和应用,最后对PcBN材料的国内外研究现状与进展进行了阐述,为后面的研究者提供了一些经验。 相似文献
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wBN通常是在动态超高压高温条件下由六方氮化硼(hBN)直接转变而成的.文章就静态高压高温条件下wBN的合成问题、高压下wBN转变为类石墨型氮化硼的规律性及其机制、高压高温下对wBN向cBN的转变以及Si3N4在该转变过程中对cBN颗粒生长的影响等进行叙述. 相似文献
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超高速陶瓷cBN砂轮的关键技术 总被引:1,自引:0,他引:1
超高速磨削技术已经是现代磨削技术发展的热点.实现超高速磨削加工,必须要有线速度高的砂轮,基于陶瓷cBN砂轮的优点多,陶瓷cBN砂轮广泛应用在高速磨削加工,文章就实现超高速陶瓷cBN砂轮的关键技术进行了简单介绍. 相似文献
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在高压高温下触媒是使hBN向cBN转变所不可或缺的材料。从已经知道的信息得知,众多的研究者经过不断探索,已用碱金属、碱土金属,如镬、锂及其氮化物Li3N、Mg3N2和Ca3N2等都合成得到了cBN,并研究了它们的转化过程的影响。由于这方面所涉及的技术信息比较丰富。因此文章仅就其中一些具有代表性、典性的结果做了简要综述。 相似文献
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钎焊立方氮化硼砂轮作为电镀立方氮化硼砂轮的替代产品,具有优越的性能特点.文章总结了国内外学者在焊立方氮化硼的钎机理、工艺方案以及钎料选择等方面的研究内容,并对钎焊立方氮化硼砂轮的研究需要解决的几个关键问题做出了阐述. 相似文献
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硝酸钾结晶生长特性的研究 总被引:3,自引:0,他引:3
利用5LMSMPR结晶器,通过改变停留时间、过饱和度和搅拌速度等因素,对硝酸钾结晶的粒度分布、平均粒径、主粒径、成核及生长速率等动力学特性进行了研究,并在结晶温度25℃、过饱和度2℃、搅拌速度400r/min和停留时间10~50min条件下,建立了硝酸钾晶体生长动力学模型:B°=6.19×1022G2.02。研究结果表明:当停留时间大于30min、搅拌速度为400r/min时,晶体的平均粒径和主粒径较大;过饱和度的减小也会使晶体粒径增大,但其影响较小。 相似文献
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Vasant R. Choudhary Anil K. Kinage 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1998,72(2):176-182
The kinetics of the hydrothermal synthesis of gallosilicate (MFI) zeolite (under autogeneous pressure at 180°C) from a gel containing a source of silica (Na-trisilicate or fumed silica), gallium nitrate, templating agent (TPA-Br or TPA-OH), deionized water and sulfuric acid have been thoroughly investigated in order to understand the influence of various synthesis parameters (viz. gel composition, source of silica, template, method of gel preparation and pH of gel) on the crystallization kinetics and crystal size/growth of the zeolite. The zeolite samples were characterized for their crystallinity by XRD and crystal size and morphology by SEM. The crystallization rate and crystal size of the zeolite were found to be strongly influenced by the above synthesis parameters. © 1998 SCI 相似文献
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分析磷酸中固形物、阴离子和阳离子等杂质对磷酸二铵产品总养分的影响。阐述调整产品总养分的措施,主要采取锥形槽式沉降法和平底槽式沉降法澄清磷酸,以降低含固量,提高产品总养分;采用配浆法提高含固量和添加硫酸、石膏的方式降低产品总养分。并对其可行性、有效性和准确性进行探讨。 相似文献
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《Diamond and Related Materials》2007,16(3):421-424
A sp2 bonded boron nitride (sp2 BN) surface layer is sometimes observed on top of cubic boron nitride (cBN) grains for BN films deposited using ion-assisted PVD techniques. Understanding the formation of such surface layer gives a clue to the cBN growth mechanisms. In the current study, the microstructure and phase composition near the top surface of several BN films were investigated in order to clarify the formation mechanism of such a surface layer. All the films investigated were synthesized using ion-assisted PVD techniques, but with different deposition parameters. It was found that such a surface layer is not necessarily present in some of the cBN growth, and its presence depends on the bombardment of ion energy during deposition. The cBN growth mechanisms are discussed based on these observations. 相似文献
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Dapeng YangXiaorui Ji Hongshi LiuYing-ai Li Tiechen ZhangPinwen Zhu 《Diamond and Related Materials》2011,20(2):174-177
In this paper, various cubic boron nitride (cBN) crystal morphologies were synthesized using hexagonal boron nitride (hBN) as raw materials and Li3N, LiH, and LiNH2 as catalysts/additives under high pressure and high temperature (HPHT).These crystal shapes contain thick-plate, spherical, octahedral or hex-octahedral, flat cone and flaky hexagonal morphologies. The reasons of various crystal shapes synthesized can be summarized as follows: various catalysts/additives take on distinct properties under HPHT, which have crucial effects on the cBN crystal morphologies synthesized. Catalyst Li3N tends to grow cBN with thick-plate morphology, catalyst LiH would induce the growth of cBN tending to integrated octahedral morphology, and catalyst LiNH2 would play diverse roles for cBN crystal morphologies in various systems. 相似文献