电沉积Ni-Cr合金工艺研究

含有一定量Cr的Ni-Cr镀层具有良好的耐磨、耐腐蚀性能.选取柠檬酸钠作为配位剂,用动电位扫描法研究了电沉积Ni-Cr合金时的阴极行为,同时对镀层的耐腐蚀性进行了试验.试验结果表明:镀液中加入配位剂柠檬酸钠可以提高阴极极化;pH值、阴极电流密度、配位剂对镀层中铬含量影响较大,在一定范围内增大pH值,增加配位剂的用量,提高电流密度,有利于提高镀层中铬的含量,最佳工艺条件为pH值为2.5,阴极电流密度为25A/dm2,镀液中柠檬酸钠的含量为35g/L,镀层中铬质量分数为20%左右时,Ni-Cr合金镀层的耐腐蚀性能最好.     

2种配位剂对镁合金化学镀镍锡磷合金的影响

在镁合金上以硫酸镍和锡酸钠为主盐沉积了镍锡磷镀层.探讨了在碱性镀液中,以柠檬酸钠和碳酸钠为配位剂对化学镀镍锡磷镀层性能的影响.结果表明:此三元合金镀层为非晶态,含2.48%Sn,8.51%P,平整致密;柠檬酸钠与镍生成了稳定常数大的配位化合物,有利于镀层的快速生长;锡元素的加入增强了二元镍磷合金的耐蚀性.     

配位剂对电沉积Fe-Ni-Cr合金电化学行为的影响

利用线性电势扫描法和循环伏安法分别讨论了配位剂对Fe2 、Ni2 、Cr3 单独电沉积和Fe-Ni-Cr合金共沉积电化学行为的影响,并采用SEM和XRD技术对合金镀层表面形貌和结构进行了表征.实验结果表明,有配位剂存在时,Fe2 单独沉积电势向正方向移动,Ni2 单独沉积电势向负方向移动,且两者析出电势均在-0.85V附近;在简单铬离子水溶液中,不能沉积出金属铬,有配位剂存在时,Cr3 溶液可以得到金属铬;在合金镀液中,没有配位剂存在时,不能得到Fe-Ni-Cr合金镀层,有配位剂存在时,可以得到晶粒平均尺寸为87nm的光亮致密的Fe-Ni-Cr合金镀层,说明配位剂能与Cr3 在电极表面形成电活性配合物,使Cr3 容易在电极上放电,另一方面说明Ni、Fe的析出对Cr的沉积有诱导的作用,使铬在合金镀液中沉积电势正移,实现Fe-Ni-Cr合金共沉积.     

三价铬镀液中配体的作用

三价铬镀铬液中的配体对镀液的稳定性和沉积速度影响极大,从三价铬镀液的化学和电化学特性分析入手,介绍了镀液中所加配体(如羧酸、羟基羧酸、氨基羧酸及其盐)的作用:(1)与三价铬离子形成活性配位离子加快电沉积速度;(2)抑制Cr3 的羟桥化反应;(3)可以掩蔽杂质金属离子,减少杂质金属离子对镀层质量的干扰,使电镀能持续进行;(4)可以稳定镀液.特别指出,只有选用能形成活性配位离子的配体,使电镀能持续进行,才能获得性能良好的厚铬镀层.     

Sb—Zn合金的电沉积及其耐腐蚀性能

以柠檬酸为络合剂和硼酸为缓冲剂的酸性镀液中电沉积Sb—Zn合金,循环伏安实验表明该合金的起始共沉积电位在约-0．805V（vs．SCE）,并且沉积过程受扩散控制。借助扫描电镜（SEM）、能谱分析（EDS）和X射线衍射（XRD）研究了沉积条件对合金镀层组成和结构的影响。结果表明,Sb—Zn镀层的组成受镀液pH值或阴极电流密度影响较大;镀态镀层含非晶态相和SbZn（Pbca）相。腐蚀极化实验表明在3．5wt％NaCl溶液（pH7．0）介质中,Sb—Zn镀层可以作为阳极性镀层起到防止碳钢腐蚀的作用（牺牲阳极镀层）;并且该镀层中锌含量越高,其耐腐蚀性能越优异。     

阴离子膜不锈钢阳极锌锰合金电沉积的研究

研究了锌锰合金电沉积的工艺条件,镀液稳定性,镀层中锰含量和阴极电流效率的规律。采用阴离子膜作阳极隔膜,不锈钢作阳极,紫铜板为阴极,研究了硫酸盐－柠檬酸体系锌锰合金电沉积的工艺条件,讨论了阴极电流密度,镀液中锰离子的浓度,镀液中锌,锰离子的摩尔比,增效剂、电沉积温度等因素对镀层中锰含量和阴极电流效率的影响规律,探索了提高阴极电流效率的途径,改善了镀液的稳定性。本文所选工艺条件为：MnSO4.H2O 30-50g/L,ZrSO4.7H2O:5-10g/L,柠檬酸钠（二水）100－150g/L,增效剂0．083g/L,表面活性剂适量,ic 1.5-3.0A/dm^2,pH值5．6,t25-30℃。该工艺可得含锰量为50％左右的锌锰合金镀层,阴极电流效率约60％。镀液在该工艺条件下连续施镀90min镀层组成稳定。     

锌酸盐体系Zn-Fe合金电镀阴极电流效率的研究

对碱性锌酸盐体系电镀Zn-Fe合金阴极电流效率的影响因素进行了系统的研究,并分析了镀层中铁原子的引入对Zn-Fe合金电镀阴极电流效率的影响原因及合金镀层中铁含量与阴极电流效率的关系,以期通过控制镀液组成及工艺条件在一定程度上提高阴极电流效率.增加电镀液中锌铁离子总摩尔浓度,提高镀液中锌铁离子摩尔比,降低铁离子浓度,适当控制阴极电流密度,升高镀液温度均可提高锌铁合金电沉积的阴极电流效率.添加剂ZFA的加入使Zn-Fe合金电镀的阴极电流效率降低.合金镀层中引入Fe明显降低了电沉积的阴极电流效率,镀层中的Fe含量从0升高至0.73%,合金电沉积的阴极电流效率却从79.48%降低至68.23%.这是由于碱性溶液中,氢气在金属Fe上析出的过电势明显小于在金属Zn上的过电势,使析氢容易进行引起的.     

Fe-Ni-Cr合金电沉积工艺参数对镀层铬含量的影响

为了在铁基上获得耐腐蚀性能好的、光亮致密的Fe-Ni-Cr合金镀层,在氯化物-硫酸盐混合体系中,研究了在铁基上电沉积Fe-Ni-Cr合金的工艺,确定出电沉积铁镍铬合金的最佳工艺条件:阴极电流密度14 A/dm2,镀液温度30℃,pH值2.0,镀液中CrCl3·6H2O浓度为25g/L.结果表明,合金镀层中Cr含量越高,镀层耐蚀性能越好,在最佳工艺条件下,镀层中Cr的含量接近6%,Fe的含量为54%,镀层光亮致密且耐蚀性好.     

电镀不锈钢工艺及镀液稳定性的研究

为了提高电镀不锈钢镀液的稳定性能,采用蓄电池耐腐蚀隔膜材料将石墨阳极与电镀液隔离,阳极区电解液中不加Fe2 和Cr3 盐,连续电镀30 min,阴极区Fe3 质量分数为0.35g/L,未加隔膜时为1.10g/L,累计电镀120 min,Fe3 降至0.18g/L.该工艺克服了镀液中Fe3 持续升高和由此引起的电镀试片发黑问题,镀出的双层镍-非晶态不锈钢防护装饰镀层试件经16 h连续喷雾,并经保温8 h的铜加速醋酸试验,保护等级在9级以上,外观无明显变化.     

刷镀铁工艺研究与应用

刷镀铁与刷镀镍相比具有成本低、硬度高的优点.研究了刷镀铁镀液中主盐、配位体、缓冲剂、抗氧化剂、表面活性剂等添加剂的种类、浓度及电压、pH值、阳极等工艺条件对镀层性能的影响,确定了镀液配方和工艺.结果表明,在优化的镀液配方及工艺条件下,可获得了良好的镀铁层,镀层硬度为450～500 HV.采用铁屑和三氯化铁配制镀液,成本低、配制速度快、浓度易控制、对环境无污染、所得镀层硬度高、结合力好.     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.