用含硼T643石墨合成导电金刚石的实验

介绍了导电金刚石的合成实验方法、条件、工艺与结果。讨论了影响导电金刚石合成效果的因素。指出了进一步提高导电金刚石合成质量及性能的途径与方法。     

新型导电钢圈对合成工业金刚石顶锤温度和锤耗的影响

使用新型导电钢圈在六面顶压机上合成工业金刚石的过程中,利用新型导电钢圈的结构性先天优势,在合成电流不变的情况下,增大与顶锤接触区域附近的导电钢圈横截面积,减少大电流在顶锤与导电钢圈接触部位附近的电阻引起的发热,从而来降低加热顶锤的温度,进而达到在合成工业金刚石的过程中,降低加热顶锤锤耗,增大合成工业金刚石的经济效益。     

含硼T641石墨合成金刚石的实验

含硼金刚石是继我国普通金刚石工业生产之后发展的新品种。晶形六—八面体聚形较多,颜色呈现黑色、深黄绿色、深兰色,耐热性能比普通金刚石高约300℃,化学惰性好;导电、抗压强度和磨耗比高。这些优异性能是普通金刚石所不能及的,它作为一种新的超硬磨料品种有广泛的发展前途。本文着重对含硼石墨合成实验的结果及其在合成中的影响因素进行阐述与讨论。     

亚晶格导电通道与新型热电材料高通量筛选

介绍了硫族类金刚石体系、ABX2型类金刚石体系和Cu2Se热电材料中的亚晶格导电通道的基本特征.同时,利用近年来本组发展的高通量筛选手段和电热输运计算方法,对于类金刚石结构体系进行了新体系热电性能的预测,得到了ZT>1.0的新型热电材料.大数据方法的运用也进一步揭示了类金刚石结构体系中普遍存在的亚晶格导电通道.     

金刚石表面电镀铬新工艺

在金刚石表面化学镀Ｎｉ－Ｗ－Ｐ做导电底层,然后采用三价铬镀液在金刚石表面电镀金属铬镀层,Ｘ－射线分析表明,在高温下金刚石表面镀层中有金属铬的碳化物生成。铬碳化物的生成增强了金刚石与胎体金属之间的浸润能力,从而增强了金刚石与胎体金属之间的结合强度。     

惊人的技术进步——两种崭新的涂复技术

<正> 两种创新的涂覆技术:一种是选择性地将细小金属粉末用于织物、纤维和薄膜上;另一种是将一层金刚石沉淀在聚合物大表面上。美国Monsanto公司用金属涂覆技术生产的Flectron商品将打入国际市场。据称,这是与美国导电纤维制造商——Sauquoit工业公司共同合作生产的产品;而金刚石涂覆技术则是Monsanto公司和Diamonex公司     

法国制造出导电性能极强的金刚石半导体

法国国家科研中心固体物理和结晶实验室的科学家,将氢元素加入含有硼的P型金刚石半导体中,结果发现,被研究材料转化成了一种N型半导体,其导电性比过去用传统方法制造的金刚石半导体高出近1万倍。这一研究成果将对微电子领域产生直接影响,并为半导体的基础和应用研究提供一片新天地。法国制造出导电性能极强的金刚石半导体     

金刚石复合镀层表面缺陷的形成原因

电沉积金刚石复合镀层会出现一些缺陷,如镀层表面起伏不平,出现结瘤、沟谷及金刚石颗粒表面的过度包镶等现象。如果增加金刚石颗粒的数量、电流密度或增加镀层厚度都会加剧这些缺陷的产生。以上现象可能来自于金刚石晶体内部金属包裹体的磁性。在电沉积过程中,这些磁性金刚石产生的磁场,对阳离子从阳极到阴极的运动产生作用,同时由于金刚石对空间的占有引起了电流密度的增加,使得金刚石颗粒表面分散的金属导电质点促进了结瘤和过度包镶的形成。     

碳素

碳素在自然界有三种变体,金刚石,石墨和无定形碳。由于三种变体结构不同,性能上差异很大。金刚石因其质地坚硬可作各种砧头,经琢磨后的金刚石,可作装饰珍品。由于用途广泛人们已采用合成的方法进行生产。石墨具有导热、导电和耐蚀性,广泛用于电气、冶金、化学工业中,如化工上常用     

氯代乙酸水溶液中低电压电沉积类金刚石薄膜的研究

采用电沉积技术,在低电压(3.0 V)下分别以乙酸、氯乙酸、二氯乙酸和三氯乙酸为碳源,在FTO导电玻璃基体上电沉积类金刚石薄膜.实验考察了氯代乙酸水溶液中氯原子的取代数量对类金刚石薄膜的厚度、形貌、结构以及电导率的影响.实验结果表明,在氯原子数量不同的氯代乙酸水溶液中电化学沉积类金刚石薄膜由易到难的顺序为:氯乙酸、乙酸...     

陶瓷结合剂金刚石磨具用于陶瓷干磨的探索

对比了三种不同结合剂的金刚石磨边轮在陶瓷砖边棱干法磨削工序中的使用情况。实验表明,树脂结合剂磨具磨损快并易在陶瓷砖上产生黑痕,金属结合剂磨具易发生粘刀现象而且被磨陶瓷砖表面光洁度低,相比之下,在同样的工况条件下,陶瓷结合剂磨具既不产生黑痕,能得到较好的表面光洁度,又有较好的自锐性。说明陶瓷结合剂金刚石磨具比较适合于陶瓷砖干磨工序。     

微波烧结陶瓷结合剂金刚石砂轮研究

为了提高陶瓷结合剂金刚石砂轮的性能,采用微波烧结技术,通过一系列试验,分析了陶瓷结合剂金刚石砂轮的微波烧结温度、陶瓷结合剂含量和金刚石磨料粒度对其性能的影响。结果表明:微波烧结温度是影响陶瓷结合剂金刚石砂轮性能的最主要因素,远超其余二者;陶瓷结合剂金刚石砂轮试样的洛氏硬度和抗弯强度在740 ℃时达到极大值且气孔率较小,此时洛氏硬度为66 HRB,抗弯强度为76.5 MPa,气孔率为17.8%;由微观组织观察可知陶瓷结合剂金刚石砂轮在740 ℃时可以实现陶瓷结合剂对金刚石磨料的均匀包裹,并且气孔较少。     

Microstructural characteristics and mechanical properties of diamond grinding wheel brazed with modified Ni–Cr–W alloy using continuous tunnel furnace

A novel brazing technology using a continuous tunnel furnace with modified Ni–Cr–W filler alloy is presented to achieve brazed diamond grinding wheels with high efficiency and low thermal damage. Mechanical characterization confirms that the static pressure strength and impact toughness of the diamond brazed using the new brazing technology are 22.2% and 10.5% higher, respectively, than those of diamond brazed using conventional vacuum brazing technology, respectively. Raman spectroscopy reveals that the degree of graphitization of diamond brazed with the novel brazing technology is decreased. In addition, residual stress is reduced by 23% after brazing with new brazing technology. Scanning electron microscopy is used to observe interfacial microstructure of brazed diamond. The elemental distribution and phase composition of brazed joint are analyzed by energy dispersive spectroscopy and X-ray diffraction. The results demonstrate that metallurgical bonds are formed between diamond and modified alloy, endowing strong bonding force to diamond abrasives. Tungsten (W) can react with diamond and modified alloy to form W–C compounds and bonding phases. Besides, W combines with certain amount of Ni element to reduce graphitization degree, improve integrity and decrease residual stress of brazed diamond. Compared with commonly utilized vacuum brazed grinding wheel, grinding test indicates that service life of grinding wheel, prepared by new brazing technology, is improved. The machining efficiency is increased by 42.4% and the abrasive invalidation rate is reduced by 33.7%. In conclusion, the diamond grinding wheel, prepared by new brazing technology, exhibits superior performance.     

Grinding of alumina ceramic with microtextured brazed diamond end grinding wheels

Brazed monolayer diamond grinding wheels have advantages of a high abrasive bonding strength, high protrusion, and a large chip disposal space. However, it is difficult to prepare ordered and fine-grained brazed diamond grinding wheels. This study presents a new method for grain-arranged, brazed diamond grinding wheels with microtextures with similar performance to ordered and fine-grained brazed diamond grinding wheels. First, coarse diamond grains (18/20 mesh) were orderly brazed to fabricate the end grinding wheels. Next, a series of microtextures were ablated on the diamond grains using a pulsed laser, and two types of textured end grinding wheels—TG-G (ablated microgrooves only) and TG-GH (ablated microgrooves and microholes)—were prepared. Then, an experiment involving the grinding of alumina ceramics was performed, and the grinding characteristics and grinding mechanism were analyzed. The results indicated that compared with untextured diamond end grinding wheels (TG), the textured diamond grinding wheels (TG-G and TG-GH) significantly reduced the grinding force and the roughness of the machined surface. The local stress concentration at the microtextures promoted the formation of microcracks in the diamond grains of TG-G and TG-GH, and the self-sharpness of the grinding wheel was significantly improved. The brittle fracture mode of ceramic materials in grinding included intergranular fracture and transgranular fracture. Ironing pressure action was a key material-removal mechanism. It had an important influence on the cutting force and plasticity characteristics of the TG machined surface. For the surfaces processed by TG-G and TG-GH, the effect of ironing was weakened, while shearing played a more important role. The TG-GH grinding wheel ablated with microgrooves and microholes was superior to the TG-G grinding wheel ablated with only microgrooves, with regard to the grinding force, roughness, and self-sharpening.     

砂轮用聚酰亚胺胶粘剂的研究现状

聚酰亚胺树脂是一种耐高温、高强度的工程塑料,它可用于制造金刚石砂轮,使砂轮的耐热性得到改善。本文从耐高温性、可加工性、高粘结性、耐磨性等方面概述了聚酰亚胺作为金刚石砂轮结合剂的优越性,实践证明,聚酰亚胺胶粘剂具有优异的耐热和高温粘接性能,用其制造的金刚石砂轮耐磨性优于酚醛砂轮。     

Diamond-wheel grinding of the refractory products for the slide gates of ladles

Conclusions A technology was developed and introduced for grinding and boring the refractory periclase plates for the slide gates of steelcasting ladles with diamond tools.The most suitable tool for grinding the plates is a diamond wheel with M1 bond, a diamond granularity of 160/125, and a diamond concentration of 100%. The drills recommended for boring the plate holes are the SK type annular diamond drills.The most efficient and suitable grinding machine for the plates is the 3D756 type fitted with clamping fixtures. For boring the plate holes the recommended machine is a modified 6A12R column-and-knee type milling machine.Translated from Ogneupory, No. 5, pp. 24–27, May, 1977.     

Fabrication of New Porous Metal-Bonded Grinding Wheels by Hip Method and Machining Electronic Ceramics

Grinding wheels with different abrasive grains and different bonding materials were fabricated using hot isostatic press (HIP) sintering. Poly-crystal diamond powder of #1000 mesh size, single-crystal diamond powder of #1000 mesh size, and synthetic single-crystal diamond abrasive grains of #325 mesh size were used as abrasive grains. Cast-iron, and two different particle sizes of iron powders were used for the bonding material. The grinding capacity of these grinding wheels as well as conventional grinding wheels was evaluated by constant-pressure-grinding method to grind Al₂O₃-TiC component ceramics, which are typical electronic ceramics used for magnetic memory devices. The hardness of the bonding materials, the adhesion strength between abrasive diamond grains and the bonding materials, and the porosity of sintered body strongly relate to the grinding capacity. The porous bonded grinding wheels showed higher grinding capacity than the conventional wheels. The HIP method enables to fabricate excellent porous metal-bonded grinding wheels.     

Wear resistant CVD diamond tools for turning of sintered hardmetals

Sintered hardmetals are very hard materials that are usually machined using diamond grinding wheels and electro-discharge machining. Dry cutting with super-hard cutting tools like cubic boron nitride (c-BN), polycrystalline diamond (PCD) and chemical vapour deposition (CVD) diamond is an ecological alternative to reduce operation times and, therefore, to improve the productivity. In the present work, cylindrical forging dies of WC–27 wt.% Co hardmetal grade were turned at fixed operating parameters (cutting speed=15 m/min; depth-of-cut=0.2 mm; feed rate=0.03 mm/rev.) using CVD diamond tipped hardmetal inserts. Commercial PCD and c-BN inserts were tested for comparison. The cutting tool behaviour was studied in terms of both the tool wear and the finishing quality of the workpiece. The tool damage was evaluated using a special probe for edge roughness evaluation, together with scanning electron microscopy observations. The CVD diamond tools survived the task showing slight cratering, whereas flank wear was the main wear mode for the other superhard tools. Amongst all the tested tools, PCD presented the worst performance in terms of tool wear and workpiece surface quality. Furthermore, the operation time was reduced to one tenth with respect to conventional diamond wheel grinding.     

有序排布结构对金刚石电镀磨盘磨削性能的影响研究

文章主要对有序排布金刚石电镀磨盘和全面电镀型磨盘的磨削性能进行比较,体现有序排布结构在高效磨削、节能降耗等方面的优势。结果表明:在磨削初期,玻璃磨削量相差不大,磨削60分钟后磨削量分别为35.30g和30.70g,有序排布结构能够有效提高磨盘的磨削效率;玻璃磨削表面粗糙度与磨盘表面结构关系不大,主要与金刚石的粒度有关;但有序排布结构能够提高加压压力,有效防止玻璃崩边。     

电镀金刚石工具第二部分电镀金钢石工具实例

以典型的电镀金刚石工具为例，详细介绍了电镀金刚石工具的工艺流程与操作要点。主要介绍的工具有：钻咀（头）、磨盘、铰刀、磨头、磨轮、磨轴。同时介绍了插座式与叠装式夹具的构件规格与在上述各种电镀金刚石工具中的使用方法。