电镀金刚石线锯快速植砂工艺研究

为了提高电镀金刚石线锯的制备效率,通过金刚石微粉表面化学镀镍、钢丝基体磁化处理等方式改进上砂工艺,结合SEM、EDS及高斯计等研究不同工艺因素对电镀线锯的制备效率及耐用度的影响。结果表明:基体磁感应强度、金刚石质量浓度及上砂时间对线锯制备效率及耐用度有重要影响;采用磁化基体制备线锯的最佳上砂工艺参数为:电流密度5 A/dm2、基体磁感应强度0.6mT、上砂槽金刚石质量浓度15g/L、上砂时间30s、温度45℃。采用最佳工艺参数制备线锯的上砂时间缩减为金刚石及钢丝基体没有处理时制备线锯的上砂时间的1/20,制备效率可提高81%,同时还能保持较高的耐用度。      

金刚石微粉电镀上砂工艺研究

针对金刚石电镀制品中微粉的上砂工序进行研究。重点对影响金刚石上砂效果的几个关键因素进行了工艺试验,讨论了阴极电流密度、搅拌方式、微粉浓度及尺寸、基体放置方式对沉积效果的影响。认为当阴极电流密度为5 A/dm2,以300 r/m in的速度,采用间歇磁力搅拌方式,对于M36/54金刚石微粉,当装载量为30g/L时,45°角放置基体并定时转动的工艺参数,可使电镀制品获得好的上砂效果。并对实际生产提出了指导性建议。     

磁化率对人造金刚石微粉电镀线锯性能的影响

通过检测不同型号金刚石微粉的磁化率、灰分等指标,用于电镀金刚石线锯的制备,并进行玻璃切割实验,分析磁化率对金刚石微粉电镀线锯性能的影响规律。结果表明:金刚石微粉磁化率对金刚石线锯的切割性能有明显影响,金刚石微粉的磁化率越低,对应金刚石线锯切割性能越好,本实验最大切割深度可达到31.4mm。      

金刚石微粉表面镀覆对线锯的关键作用分析

在分析电镀金刚石线锯工艺流程的基础上,指出了金刚石上砂是电镀线锯最关键的工艺环节.探讨了各种上砂方法及特点,分析了镀覆金刚石微粉对上砂的作用.指出,采用与金刚石形成化合物结合的镀覆金刚石,如镀钛、镀钨、镀钼、镀铬和复合镀的金刚石,有利于高质量金刚石线锯的生产;避免了采用单一镍镀层产生“双极性”效应,导致镍涂层脱落的问题;具有上砂速度快,上砂容易的特点;镍镀层对镀覆金刚石颗粒迅速整体覆盖,镍镀层生长迅速,与镀覆金刚石结合牢固,出刃高;解决了无镀层金刚石以及单一镀镍金刚石与基体结合力差的问题.因此,镀覆金刚石为生产高质量金刚石线锯提供了有力的技术支持.     

金刚石线锯悬浮上砂法制作工艺的研究

悬浮上砂法的基本原理是将锯丝基体放置在上砂槽中,槽中的金刚石微粉通过搅拌悬浮在镀液中,通过金属的电沉积将悬浮在镀液中的金刚石微粉固结在芯线基体上.利用悬浮上砂法,以φ0.3 mm的高碳钢丝为基体,选取M20/30～M22/36的金刚石微粉为磨料,选用瓦特型镀液制造金刚石线锯.结果表明:随着上砂电流密度、上砂时间、搅拌速度和金刚石微粉浓度的增加,锯丝表面金刚石微粉的沉积量逐渐增加,当增加到一定值之后不再继续增加.实验得到的最佳的上砂工艺参数为:上砂电流密度5A/dm2,上砂时间4 min,搅拌速度200 r/min,金刚石微粉浓度30 g/L.     

三丝绞合电镀金刚石线锯的切割性能研究

制备了具有绞合钢线芯的三丝绞合电镀金刚石线锯,并通过与单丝金刚石线锯的对比分析,研究了三丝绞合电镀金刚石线锯的切割性能,包括力学性能、切割效率、线锯磨损等。多晶硅锭切割实验表明:在相同的切割线张力、工作台进给速度等条件下,三丝绞合电镀金刚石线锯切割时的线弓明显小于单丝电镀金刚石线锯,最大可减小23%。其具有磨损小,切割能力强,使用寿命长等优点。     

用复合电镀法制造电镀金刚石锯丝的实验研究

固结磨料金刚石线锯切割技术有望在将来广泛地应用于硅晶体等硬脆材料的切割,而高性能的固结磨料金刚石锯丝的研制是此技术发展应用的关键.本文选用以瓦特液为基础的光亮镍镀液,采用复合电镀法试制了电镀金刚石锯丝,制定了锯丝的电镀工艺,分析了上砂电流密度和上砂时间对锯丝表面金刚石磨粒密度和镀层与基体间结合力的影响.结果表明,获得表面磨粒分布均匀、结合力良好的电镀金刚石锯丝的最佳电流密度范围为1.5 A/dm2～2.0 A/dm2,其预镀、上砂与加厚镀时间依次为6 min、8 min～10 min和18 min.     

添加剂质量浓度对电镀金刚石切割线电镀形貌的影响

通过电镀实验,研究了在硫酸镍镀镍液中,添加剂浓度对电镀金刚石切割线电镀形貌的影响。以线径0.115mm的镀铜高碳钢线为基线,使用经化学镀镍磷合金增重30%、粒度尺寸为8~16μm的金刚石微粉进行上砂。实验使用的添加剂的质量浓度为0~400mg/L。研究表明:随着镀液中添加剂浓度的增加,切割线表面的金刚石的团聚现象逐渐降低。添加剂浓度较低时,对切割线表面的金刚石颗粒团聚的影响不明显,但当添加剂浓度过高时,会造成上砂困难,上砂量明显降低。本实验条件下,在满足上砂量要求的情况下,添加剂的最佳质量浓度为200~300mg/L。     

电镀工艺参数对金刚石锯丝复合镀层质量影响研究

本文进行了采用复合电镀法制备电镀金刚石锯丝试验,重点分析了上砂与镀层加厚阶段采用不同的阴极电流密度与时间,对锯丝复合镀层外观质量、锯丝表面金刚石磨粒含量和磨粒埋入深度的影响.研究结果表明,当锯丝表面固结粒度为20 μm的金刚石磨粒时,上砂与镀层加厚阶段均可采用2.0A/dm2的阴极电流密度,对应的最佳电镀时间分别为7 ...     

钎焊金刚石线锯切割单晶硅材料时的断裂行为研究

利用铜基钎料钎焊制备小直径金刚石线锯,观察线锯形貌,测试线锯力学性能,并在不同切割参数下对单晶硅材料进行切割,记录观察切割过程中的线锯受力,观察线锯断口形貌,探讨小直径钎焊金刚石线锯线锯过程中断裂行为及断裂机理。研究结果表明,线锯的断裂主要有正常疲劳断裂和非正常拉断。     

Prospects of the Use of Synergetic Approach to Solution of Problems of the Science of Nanomaterials

A synergetic approach to solution of problems of self-controlled synthesis of nanostructures and creation of self-organizing nanotechnologies is considered in connection with the superproblem of creation of materials with functional properties resembling those of biosystems. __________ Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 7, pp. 55 – 61, July, 2005.     

Kinetics of the oxidation of metals — Influence of self-diffusion of metal

The importance of the self-diffusion of a metal during its oxidation by a gas is treated for the cases of nonstoichiometric oxides having either interstitial cation or cation vacancies. We have established a general relationship for the reaction rate when a mixed diffusion process occurs. From this relationship, we have shown that the pressure dependence can be different, according to whether the rate-determining process is the self-diffusion through the metal or through the product.     

Features of formation of the structure in production of blanks of disks of heat-resistant nickel alloys

Conclusions To provide a high level of mechanical properties in wrought blanks of cast ÉP741NP and ÉP962 alloys it is necessary to form controlled structures. A necklace-type structure formed in homogenizing isostatic treatment, subsequent thermomechanical working including alternation of the operations of deformation in the (+)-area and recrystallization anneals, and final heat treatment is preferable. The temperature conditions of all stages of thermomechanical working are strictly controlled, especially the final operation of deformation and heating for hardening. To eliminate hardening cracks and distortions it is necessary to use molten salts at t=600°C as quenchants. The use of multiple production operations makes it possible to significantly reduce the structural inhomogeneity related to inhertance of the original dendritic structure. However, the structure of the final semifinished product is nevertheless characterized by a difference in occurrence of the processes of polygonization and recrystallization between the former dendritic cells and the interdendritic spaces in deformation and heat treatment.To obtain structurally homogeneous blanks for gas turbine engine parts it is necessary to use basically new methods of remelting such as vacuum double electrode remelting and electron beam remelting with an intermediate vessel.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 12, pp. 25–29, December, 1991.     

Ab-initio calculation of enthalpies of formation of intermetallic compounds and enthalpies of mixing of solid solutions

A large number of ab-initio calculations of energies of formation of intermetallic compounds have been performed in the last 15 years. The currently used methods are listed. The paper presents a review of the aluminium based compounds which have been studied. Comparisons of calculated and experimental enthalpies of formation are provided for aluminim-3d and-4d transition metal alloys at equiatomic composition. The modelling of the enthalpies of mixing of solid solutions based on a given lattice is described.     

试论洋务派教师聘任的思想

洋务派在洋务学堂的办学活动中,为了解决西学专业学科的教学困难,采用了聘请外籍教师的应急措施.他们以真才实学,合同制管理作为主导思想,并认为这种解决师资的途径只是权宜之计,并非久远.从客观上看,洋务派的教师聘任思想有深刻的历史影响.     

胫骨生物陶瓷复合材料的微结构增韧机理

扫描电镜观察显示胫骨是一种由羟基磷灰石和胶原蛋白组成的自然生物陶瓷复合材料.羟基磷灰石具有层状的微结构并且平行于骨的表面排列.观察也显示这些羟基磷灰石层又是由许多羟基磷灰石片所组成,这些羟基磷灰石片具有长而薄的形状,也以平行的方式整齐排列.基于在胫骨中观察到的羟基磷灰石片的微结构特征,通过微结构模型分析及实验,研究了羟基磷灰石片平行排列微结构的最大拔出能.结果表明,羟基磷灰石片长而薄的形状以及平行排列方式增加了其最大拔出能,进而提高了骨的断裂韧性.     

Mechanism of Nucleation of Precipitates of Carbides of Refractory Metals Under Hot Rolling of Automotive Sheet Steel

Metal Science and Heat Treatment - The problem of formation of properties in microalloyed sheet steels is considered. The cause and the possible mechanism of precipitation of carbides of refractory...     

燃煤机组锅炉烟气脱硝灰中氨含量测定

NOx是大气环境的主要污染物之一,其主要来源为火力发电机组。依靠低氮燃烧技术,远达不到排放要求。选择性催化还原脱硝(简称SCR)技术是目前效率最高、最成熟、应用最广泛的电厂烟气脱硝技术。目前,在线氨逃逸监测技术存在诸多问题,影响了氨逃逸监测数据的准确度和稳定性。在燃料种类、炉膛结构、受热面布置、过量空气量、炉膛气流分布以及脱硝催化剂类型等条件确定的情况下,控制好氨加入量及其逃逸量是保证NOx脱除率的关键所在。燃煤锅炉除尘飞灰氨含量可侧面反映脱硝氨逃逸率的状况。根据国外的文献报道,正常情况下,电除尘灰中氨含量一般在50mg/kg-100mg/kg范围内。由于国内尚无灰中氨含量的测定方法,亦无脱硝运行对飞灰含氨量影响的数据积累。本文通过大量试验,确定了灰中氨溶解条件(如溶解时间、搅拌状态、灰水比、灰样量及其稳定性等),制定了灰中氨含量测定方法。