前处理工艺对镁合金化学镀Ni-P质量的影响

采用扫描电镜和性能检测的方法,分析了表调、活化和浸锌等前处理工艺对镁合金化学镀Ni-P质量的影响.结果表明,表调可使晶界凸出于α-Mg基体,降低镁合金的表面粗糙度,提高化学镀层的结合强度.活化及浸锌后,促进了化学镀的进行.按表调、活化、一次浸锌、退镀、二次浸锌的工艺进行前处理后实施化学镀,得到的Ni-P镀层致密、平整,与基体结合力强,有效提高了镁合金表面耐蚀性及显微硬度.     

锡青铜化学镀 Ni-P 合金工艺及镀层性能

目的在锡青铜基体上化学镀Ni-P合金镀层,提高锡青铜的耐磨性和耐腐蚀性。方法以酸性含锌活化液活化锡青铜试样,在相同的条件下实施化学镀,并对镀态试样进行不同温度(250,400,500℃)下的热处理。对比基体、镀态试样和热处理试样的性能,研究热处理温度对锡青铜化学镀Ni-P合金层微观结构、显微硬度、耐磨性和耐腐蚀性的影响。结果锡青铜表面形成了Ni-P合金镀层,并且镀层无孔隙缺陷,与基体结合良好,沉积速率较快,为10.00μm/h。经热处理后,镀层的微观结构由非晶态向晶态转变,在500℃热处理的镀层显微硬度最大,耐磨性最好。镀态镀层和经250℃热处理的镀层在10%HNO3溶液和10%H2SO4溶液(10%均为体积分数)中的耐腐蚀性明显好于锡青铜基体,镀态镀层在两种介质溶液中的腐蚀速率分别为0.225,0.146 mg/(cm2·d)。结论采用酸性含锌活化液活化锡青铜基体,可以在锡青铜表面制备出化学镀Ni-P合金镀层,且镀覆效果较好。这表明紫铜化学镀Ni-P合金工艺同样适用于锡青铜。     

镀液配方及化学镀工艺对Ni-P合金镀层性能影响

通过Ni-P合金镀层硬度、耐蚀性与表面含磷量的关系,分析了镀液镍次比、pH值、络合剂、缓冲剂以及施镀温度、施镀时间、时效温度对Ni-P合金化学镀层含磷量的影响,探讨了提高镀层表面硬度、耐磨性、耐蚀性的方法.     

镁锆合金表面Ni-P非晶化学镀工艺研究

镁锆合金是一种轻质、高阻尼的新型合金,但耐蚀性极差.采用化学镀方法,系统研究了Mg-0.57Zr合金表面Ni-P非晶化学镀的预处理及施镀工艺.研究结果表明:1)采用复合酸洗,有利于提高镀层与基体的结合力、镀层的沉积均匀性和金属光泽度;2)直接化学镀镍比预浸锌后再化学镀镍的工艺方案,更利于提高镀速、降低镀层孔隙率;3)采用所推荐的化学镀工艺,获得了与基体结合力高、孔隙率低、耐蚀性较好的Ni-P非晶镀层,其平均镀速为11.44 μm/h,镀层硬度比合金基体提高10.7倍.     

27SiMn化学镀Ni-Ce-P工艺研究

以液压支架立柱常用材料27SiMn为基体,在Ni-P化学镀的基础上加入稀土硫酸高铈.通过正交试验对施镀工艺参数进行优化,以镀速为评定指标,获得了化学镀Ni-Ce-P的最优工艺配方,并对最优工艺条件下得到镀层的形貌进行了分析.结果表明:含有40 mg/L硫酸高铈的最优配方下的镀速为33.38 μm/h;相对于二元Ni-P镀层,加入稀土得到的镀层胞状结构更细小,表面更加平整、致密.     

PVC塑料上微波辅助化学镀镍

研究了在微波辅助下PVC塑料上沉积Ni-P合金的工艺,以及镀液的主要成分对沉积速率和镀层性能的影响,确定了镀液的最佳配方,且与常规镀进行了比较。结果表明,利用微波加热可显著提高化学镀Ni-P合金的镀速、降低施镀温度,可以在PVC塑料上获得表面平整致密、与基体结合良好、耐蚀性良好、具有银白色金属光泽的镍磷镀层。     

ZLl01A合金化学镀Ni-P研究

为提高ZL101A合金的耐蚀性能,可直接化学镀Ni-P或电镀Cu后化学镀Ni-P在其表面施加镀层.利用恒电位仪、盐雾实验、扫描电镜和显微硬度计等,研究了两种工艺处理后镀层的性能.结果表明,两种工艺得到的镀Ni-P样品均具有优异的耐蚀性和较高的硬度,对Al合金基体都具有很好的保护作用;其中带镀Cu中间层的化学镀Ni-P层更致密,具有更好的耐蚀性和硬度.     

还原剂对镁合金表面化学镀Ni-P合金性能的影响

通过镀速测量、SEM、EDS等方法研究了AZ31B镁合金的化学镀Ni-P合金工艺。结果表明:镁合金表面化学镀Ni-P合金的最佳还原剂为次磷酸钠,还原剂的最佳浓度为20 g/L。所制备的镀层耐腐蚀性能良好。     

镁合金表面Ni-P/Ni镀层的制备与性能研究

在镁合金表面先化学镀Ni-P层,再电镀Ni,获得高耐蚀性Ni-P/Ni镀层,并用静态腐蚀浸泡法研究了化学镀时间和电镀时间对所得镀层在5%NaCl溶液中的耐蚀性能的影响。结果表明,先化学镀40 min,再电镀15 min所得的Ni-P/Ni镀层具备高耐蚀性能,电化学测试结果表明,此种镀层在酸性和碱性溶液中都具有较好的耐蚀性能。在200℃热处理24 h后,Ni-P/Ni镀层的耐蚀性提高,同时外层Ni层的显微硬度从HV460增大到HV550。镀层侧面的SEM照片显示,镀层均匀致密,与基体结合良好,化学镀层与电镀层之间没有明显的界限。     

Mg-12Li-2Al-2Zn合金化学镀镍工艺的研究

研究化学镀液pH值、温度及施镀时间对Mg-12Li-2Al-2Zn合金表面镀镍层组织形貌和性能的影响.结果表明:在镁锂合金表面进行化学镀镍的最佳工艺参数是:pH=7±0.2,温度(80±2)℃,施镀时间50 min.在此工艺条件下,所获镀层厚度13～15μm,显微硬度435 HV左右,镀层结构为Ni-P非晶态.     

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.     

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.     

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.     

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。