超临界流体镍基金刚石复合电铸的实验研究

介绍了超临界流体镍基金刚石复合电铸的实验方法及工艺。采用扫描电镜和显微硬度仪表征镍基金刚石复合电铸层的表面形貌和显微硬度,分析金刚石微粒的质量浓度和工作压力对复合电铸层显微硬度的影响,并与普通复合电铸层的进行对比。结果表明:超临界CO2流体独特的理化特性,可有效提高镍基金刚石复合电铸层的表面质量。工作压力为10~14MPa时,超临界CO2流体环境对金刚石微粒的分散效果良好。在工作压力10MPa,金刚石微粒50g/L时,复合电铸层的显微硬度达到9 100MPa。     

微细电铸制造技术的研究进展

介绍了微细电铸技术的基本原理,阐述了超声微细电铸、磁电微细电铸、超临界微细电铸和屏蔽模板随动式微细电铸这4种新型制造工艺的原理及研究进展,指出了今后的研究重点。     

面向微机电系统的微细电铸制造技术

鉴于微机电系统(MEMS)承载的特殊功能,其制造技术成为当前研究的热点。微细电铸以其固有的诸多技术优势,成为制造复杂结构MEMS零部件的主流技术。概述了超声微细电铸技术、超临界微细电铸技术、屏蔽模板随动式微细电铸技术、辅助交变低气压-温度梯度微细电铸技术和高压微细电铸技术五项面向微机电系统的新型微细电铸制造工艺及其研究进展,并指出了今后的研究重点。     

快速膨胀超临界溶液法制备α-细辛醚微细颗粒研究

用快速膨胀超临界溶液 (RESS)法获得了α 细辛醚的微细颗粒。考察了膨胀压力、膨胀前温度、沉降室温度、喷嘴直径等工艺条件对微细颗粒粒径的影响。结果表明 ,采用较高的膨胀压力 ,较低的膨胀前温度及沉降室温度 ,较小的喷嘴直径 ,有利于获得平均粒径较小的微细颗粒     

1987年国外电镀技术进展(下)

电铸和复合镀Shafer概述了电铸的基本原理(623)D. Shafer. SurFin'87. Chiago. k-1, Jul.Legierse提出的论文题目是频闪观测盘系统的电铸规格要求.(624)P. E. J. Legierse, Trans. Inst. Metal Fin., 65, 13(Feb).Nee获得在频闪观测盘上沉积微细铜晶粒方法的专利权.(625)H. H. Nee, US Pat. 4 673 467Malone报道了电铸镍基结构合金的进展.     

旋翼电铸片电镀工艺的研究

阐述了旋翼电铸片电镀工艺。通过对不同工艺的电铸片内应力、抗拉强度、硬度和延伸率的对比分析,选择了氨基磺酸盐电铸镍工艺,并对温度、电流密度、pH值和氯离子等影响应力的因素进行了研究。     

不溶性阳极电铸中镍离子浓度变化及其对电铸镍的影响

研究了不溶性阳极电铸中镍离子浓度变化及其对电铸镍的影响。利用EDTA配位滴定法、扫描电子显微镜、法拉第定律和硬度计等手段,对溶液中镍离子的浓度及电铸镍层的性能进行了检测。结果表明:采用不溶性阳极电铸镍,在4A/dm2、8A/dm2、12A/dm2的电流密度下电铸12h后,镍离子的浓度分别降低了19.0%、33.6%、54.2%,电流效率分别降至59.7%、51.0%、35.9%;在8A/dm2和12A/dm2的电流密度下,电铸镍层的晶粒得到细化,硬度增大。     

超声辅助电铸钨丝–镍复合层的微观结构和抗拉强度

在钨丝–镍的复合电铸过程中施加超声辅助,以改善复合电铸层的组织结构,提高其抗拉强度。电铸液组成和工艺条件为:氨基磺酸镍400 g/L,氯化镍15 g/L,硼酸30 g/L,p H=4.5,温度43°C,电流密度4 A/dm~2,超声波频率100 k Hz,超声波功率120 W。研究了超声波辅助对钨丝–镍复合电铸层表面形貌、断口形貌、结晶取向、晶粒尺寸等微观结构及其抗拉强度的影响。结果表明:超声空化伴随的微射流和冲击波能够有效避免复合电铸层表面孔隙的形成,显著细化晶粒,减少内部空洞。超声波的应用改变了镍晶体的生长方式,显著提高了(200)面的择优程度。超声条件下获得的钨丝–镍复合电铸层具有更高的抗拉强度。当钨丝体积分数为50%时,超声辅助下所得复合电铸层的抗拉强度为1 502 MPa,比无超声条件下的复合电铸层高13.8%。     

铁(镍)复合电铸模的试制

一、言前随着工业生产的飞跃发展,模具制造在工业中所起的作用日益显得重要。电铸模具在我国是一门新兴的工艺,它不仅在国防、精密仪器仪表制造和一些轻工业产品制造上解决了几何形状特殊和形腔复杂模具的制造而且缩短了开模时间。目前一般常用的电铸工艺有电铸镍、铜等。电铸镍模不但光洁度、精密度好而且硬度高。可是由于价格昂贵,不能满足工业上的需要。如果采用先电铸一薄层(约0.8～1毫米)镍,再用镀铁来电铸加厚,则不但节约了大量贵重的镍,并且缩短了电铸周期,而且对模具硬度和耐磨度均无影响。如果不先电铸镍而直接以镀铁来电铸模具,然后进行热处理来提高硬度和耐磨度的话,那末其所起作用和经济意义就更大了。     

电铸镍网工艺实践

介绍了纺织印染系统应用的多色电铸镍网圆筒的制作工艺流程、电铸铜及电铸镍溶液组成与操作条件。对电铸铜与电镀铜工艺、电铸镍与电镀镍工艺进行了比较。提出了工艺中需要注意的几个问题,包括：电铸铜时毛刺产生的原因及解决办法、氯离子的控制、镍珠和钛篮的使用、添加剂含量控制、电源选择等。     

微电铸层均匀性的影响研究

微电铸技术加工的器件往往存在铸层不均匀的缺陷,导致其质量和性能大大降低.针对微电铸的不均匀性,介绍了微电铸工艺流程,从几何因素和电化学因素两方面对微电铸层均匀性的影响进行了综述.     

SC-CO_2氛围中制备Ni/CNTs催化剂催化性能研究

碳纳米管负载金属镍催化剂可以用于甲醇常压气相羰基化反应,但是甲醇转化率及乙酸收率均不理想。本文在SC-CO2氛围中,利用SC-CO2在碳纳米管中较高的扩散性能,将金属镍粒子带入碳纳米管内腔,以提高金属镍在载体表面的分散度,从而提高催化剂的催化性能。结果显示,此法制备出的催化剂,其甲醇转化率及乙酸收率均比由普通浸渍法制备的催化剂显著提高;制备催化剂时SC-CO2最佳温度为308.15 K,最佳压强为15.0 MPa。     

The effect of heat treatment conditions on the textural and catalytic properties of nickel–titania composite aerogel catalysts

Highly dispersed nickel–titania composite aerogel catalysts have been prepared by CO₂ supercritical drying of alcogels obtained by the sol–gel process. The effect of heat treatment conditions on the textural and structural properties of the resulting aerogels was investigated by nitrogen adsorption–desorption, TG/DTA, XRD and TEM. The nickel–titania composite aerogel calcined and reduced under carefully controlled conditions exhibited an excellent catalytic performance for the liquid-phase hydrogenation of benzophenone to benzhydrol.     

超临界CO_2中对苯二酚催化加氢反应的研究

通过超临界CO2介质中对苯二酚催化加氢的研究,探讨了催化剂、超临界CO2压力等反应条件的影响,研究了Pt/C、Pd/C、Ru/C和Rh/C几种催化剂对反应转化率和主要产物1,4-环己二醇选择性的影响,结果表明:Ru/C催化剂的活性最好。研究了超临界CO2压力、反应温度、氢气压力、反应时间等对反应转化率和选择性的影响,根据产物的选择性对该反应路径进行了初步分析。     

间苯二酚-甲醛与Ni(OH)2复合气凝胶结构特性研究

以间苯二酚、甲醛、碳酸氢钠、硝酸镍为原料,采用溶胶一凝胶法和超临界干燥工艺制得间苯二酚一甲醛与Ni(OH)2复合气凝胶,对不同pH值和Ni(OH)2含量的复合气凝胶结构进行研究。通过小角X射线散射实验测量气凝胶的散射强度,分析了复合气凝胶平均粒径、比表面积和分形行为等特性。结果表明：酸性条件比碱性条件下制成的复合气凝胶粒径小,团聚现象不明显;且随着复合气凝胶中Ni(OH)2的质量分数增加,其结构复杂度增加,胶体平均粒径和比表面积均增大。     

Bright nickel film deposited by supercritical carbon dioxide emulsion using additive-free Watts bath

This paper is aimed on studying film smoothening effect of supercritical carbon dioxide emulsion (Sc-CO₂-E) on nickel film electroplated using an additive-free Watts bath. Morphology of nickel film electroplated with Sc-CO₂-E was found to be similar to that of nickel film prepared from electroless plating. Surface roughness (R_a) of nickel film electroplated with Sc-CO₂-E was lower than that of nickel film electroplated through conventional method. A minimum R_a was found for nickel film electroplated through conventional method and Sc-CO₂-E when increasing current density from 0.010 to 0.150 A/cm². The minimum R_a was 69.8 nm at 0.020 A/cm² and 14.0 nm at 0.030 A/cm², respectively for conventional and Sc-CO₂-E case. After the minimum point, increasing rate of R_a increased was lower for Sc-CO₂-E case; this was because of higher hydrogen solubility in Sc-CO₂. Grain size of nickel film electroplated with Sc-CO₂-E was found to be finer than that of conventional case.     

Supercritical fluid CO<Subscript>2</Subscript>-extraction regeneration of nickel–molybdenum catalyst for hydrotreatment

Results from studying the supercritical fluid СО₂-extraction regeneration of DN-3531 industrial nickel–molybdenum hydrotreatment catalyst in the temperature range of 323.15–383.15 K, at pressures of up to 30 MPa, and with modification of the basic extragent with such polar compounds as chloroform, methanol, ethanol, acetone, and dimethylsulfoxide (DMSO), are presented. The order of modifiers corresponds to the increase in the solubilizing ability of modified supercritical carbon dioxide (SC-СО₂) with respect to catalyst- deactivating deposits. With DMSO as the most efficient modifier, however, not only are deactivating compounds removed but nickel and molybdenum as well, considerably reducing the final activity of a regenerated sample. During extraction regeneration, the content of coke in the catalyst is reduced by two-thirds, while the specific surface area and the pore volume grow. The activity of the deactivated catalyst in dibenzothiophene hydrodesulfurization (HDS) and naphthalene hydrogenation grows by several hundred per cent after one-time SC-CO₂ treatment and is 2.5 times higher than for a sample regenerated using the traditional oxidative method.     

多功能数控微细电铸机床控制系统开发

以PLC为控制核心,开发出一种可实现微细电铸工艺实施过程自动化、工艺参数和工艺效果能实时在线监控的智能化控制系统.从电铸工艺参数控制、阴阳极间距及相对位置控制和电解液循环过滤控制三方面阐述了系统构成,并进行了实验评价.结果表明;基于该控制系统,电铸工艺参数检测、监控准确,误差小于2％;阴阳极直线进给精度低于3μm,翻转...     

Hydrogenation of vegetable oils using mixtures of supercritical carbon dioxide and hydrogen

Hydrogenation of vegetable oils under supercritical conditions can involve a homogeneous one-phase system, or alternatively two supercritical components in the presence of a condensed phase consisting of oil and a solid catalyst. The former operation is usually conducted in flow reactors while the latter mode is more amenable to stirred, batch-reactor technology. Although many advantages have been cited for the one-phase hydrogenation of oils or oleochemicals using supercritical carbon dioxide or propane, its ultimate productivity is limited by the oil solubility in the supercritical fluid phase as well as unconventional conditions that affect the hydrogenation. In this study, a dead-end reactor has been utilized in conjunction with a head-space consisting of either a binary fluid phase consisting of varying amounts of carbon dioxide mixed with hydrogen or neat hydrogen for comparison purposes. Reaction pressures up to 2000 psi and temperatures in the range of 120–140°C have been utilized with a conventional nickel catalyst to hydrogenate soybean oil. Depending on the chosen reaction conditions, a wide variety of end products can be produced having different iodine values, percentage trans fatty acid content, and dropping points or solid fat indices. Although addition of carbon dioxide to the fluid phase containing hydrogen retards the overall reaction rate in most of the studied cases, the majority of products have low trans fatty acid content, consistent with a nonselective mode of hydrogenation.     

载体制备方法对Ni催化剂催化间二硝基苯加氢反应的影响

以正硅酸乙酯为原料,采用溶胶-凝胶法,分别经乙醇超临界干燥和常规干燥制得SiO2气凝胶和干凝胶载体,并以La2O3为助剂,通过浸渍法制备了用于间二硝基苯液相加氢制间苯二胺反应的镍基催化剂,通过BET、XRD、TPR、H2-TPD和活性评价等方法对催化剂的物化性质和催化性能进行了研究.结果表明,虽然以SiO2气凝胶为载体制备的二元镍基催化剂的镍晶粒的粒度较小,但由于金属镍烧结导致它表面存在的活性位相对较少,对反应组分的吸附强度较弱,致使其活性低于SiO2干凝胶负载的二元镍基催化剂.添加La2O3助剂的三元镍基催化剂的活性总体上比二元催化剂要高,其中以SiO2干凝胶为载体制备的三元催化剂具有较高的活性比表面积和适宜的吸附强度,对间二硝基苯加氢反应表现出很高的催化活性,在2.6 MPa、373 K下反应1 h后,间二硝基苯转化率可达97.0%、间苯二胺产率达93.1%.