Electrochemical behavior of Cu-Zn-Al shape memory alloy after surface modification by electroless plated Ni-P

The electrochemical behavior of Cu-Zn-Al shape memory alloy (SMA) with andwithout electroless plated Ni-P was investigated by electrochemical methods, in artificial Tyrode'ssolution. The results showed that Cu-Zn-Al SMA engendered dezincification corrosion in Tyrode'ssolution. The anodic active current densities as well as electrochemical dissolution sensitivity ofthe electroless plated Ni-P Cu-Zn-Al SMA increased with NaCl concentration rising, pH of solutiondecreasing and environmental temperature uprising. X-ray diffraction analysis indicated that aftersurface modification by electroless plated Ni-P, an amorphous plated film formed on the surface ofCu-Zn-Al SMA. This film can effectively isolate matrix metal from corrosion media and significantlyimprove the electrochemical property of Cu-Zn-Al SMA in artificial Tyrode's solution.

Evaluation of residual stress and corrosion behaviour of electroless plated Ni-P/Ni-Mo-P coatings

Single Ni-P and Ni-Mo-P coatings as well as duplex Ni-P/Ni-Mo-P coatings with the same compositions were prepared by electroless plating.The residual stresses of the coatings on the surface and cross sections were measured by nanoindentation and AFM analysis,and the corrosion behaviour of the coatings in10%HCl solution was evaluated by electrochemical methods,to establish the correlation between the residual stresses and corrosion behaviour of the coatings.The results showed that the single Ni-P and duplex Ni-P/Ni-Mo-P coatings presented residual compressive stresses of241and206MPa respectively,while the single Ni-Mo-P coating exhibited a residual tensile stress of257MPa.The residual compressive stress impeded the growth of the pre-existing porosity in the coatings,protecting the integrity of the coating.The duplex Ni-P/Ni-Mo-P coatings had better corrosion resistance than their respective single coating.In addition,the stress states affect the corrosive form of coatings.

Surface characteristics of electroless nickel plated electromagnetic shielding wood veneer

Wood is a kind of porous natural material with very poor electro-conductivity, and it has almost no function of electromagnetic shielding. The method of electroless nickel plating was used to produce wooden material with electrical and effective electromagnetic shielding properties. Ni-P alloy layer was obtained on wood surface. The surface feature of plated wood veneer was observed by SEM and the surface composition and microstructure of the layer under different conditions were investigated by EDS and XRD respectively. Meanwhile, the relevant surface resistivity and electromagnetic shielding effectiveness were measured. Correlations of the phosphorous content in the layer to the structure of Ni-P alloy, electro-conductivity and electromagnetic shielding of plated veneers were discussed. SEM photos showed that the surface of electroless nickel plated veneers were covered with Ni-P alloy layer entirely, which made wood veneers more like metal. At the same time, the results showed that with the decreasing of the phosphorous content in the layer, the microstructure of Ni-P alloy layer transformed to be microcrystalline and electro-conductivity and electromagnetic shielding effectiveness were improved. When the phosphorous content was less than 2.37wt pct in the layer, the microstructure of Ni-P alloy layer was microcrystalline structure and its sur- face resistivity and electromagnetic shielding effectiveness were nearly 0.5Ω/□ and 55-60dB respectively.

Characterization and Properties of Electroless Nickel Plated Poly (ethylene terephthalate) Nonwoven Fabric Enhanced by Dielectric Barrier Discharge Plasma Pretreatment

In order to develop a more economical pretreatment method for electroless nickel plating, a dielectric barrier discharge （DBD） plasma at atmospheric pressure was used to improve the hydrophilicity and adhesion of poly （ethylene terephthalate） （PET） nonwoven fabric. The properties of the PET nonwoven fabric including its liquid absorptive capacity （WA）, aging behavior, surface chemical composition, morphology of the surface, adhesion strength, surface electrical resistivity and electromagnetic interference （EMI）- shielding effectiveness （SE） were studied. The liquid absorptive capacity （WA） increased due to the incorporation of oxygen-containing and nitrogen-containing functional groups on the surface of PET nonwoven fabric after DBD airplasma treatment. The surface morphology of the nonwoven fibers became rougher after plasma treatment. Therefore, the surface was more prone to absorb tin sensitizer and palladium catalyst to form an active layer for the deposition of electroless nickel. SEM and X-ray diffraction （XRD） measurements indicated that a uniform coating of nickel was formed on the PET nonwoven fabric. The average EMI-SE of Ni-plating of PET nonwoven fabric maintained a relatively stable value （38.2 dB to 37.3 dB） in a frequency range of 50 MHz to 1500 MHz. It is concluded that DBD is feasible for pretreatment of nonwoven fabric for electroless nickel plating to prepare functional material with good EMI-SE properties.

Electrolessly Plated Ni-Zn(Fe)-P Alloy and Its Corrosion Resistance Properties

The autocatalytic deposition of Ni-Zn(Fe)-P alloys has been carried out on substrate of carbon steel from a bath containing nickel sulfate, zinc sulfate, sodium hypophosphite, sodium citrate and boric acid. The effects of pH and the molar ratio of NiSO_4/ZnSO_4 on the deposition rate and the composition of deposits have been studied. It was found that the presence of zinc sulfate in the bath has an inhibitory effect on the alloy deposition. The structure and the surface morphology of Ni-Zn(Fe)-P coatings were characterized with XRD and SEM, respectively. The alloys plated under the experimental conditions consisted of an amorphous phase coexisting with a crystalline cubic Ni phase(poly-crystalline). The surface morphology of the coating is dependent on the deposition parameters. The corrosion resistance of the Ni-Zn(Fe)-P deposits was examined via mass loss tests and anodic polarization measurements, respectively. The results show that the surface morphologies of the deposits and the corrosion resistance of the deposits have been improved. The results of mass loss tests almost accord with those of anodic polarization measurements. The corrosion mechanisms of Ni-Zn(Fe)-P alloys in ~NaCl and NaOH solutions were investigated by means of EDX. The deposit immersed in an NaCl or an NaOH solution contains more content of oxygen and less contents of the metals(except Fe) than that placed in air, which shows that the NaCl or NaOH solution can accelerate the oxidation of the deposit.

Preparation and characterization of bimetallic Pt^Ni-P/CNT catalysts via galvanic displacement reaction on electrolessly-plated Ni-P/CNT

Platinum-based bimetallic catalysts have broad applications in polymer electrolyte membrane fuel cells and water splitting. In this work,galvanic displacement reaction was employed to prepare Pt^Ni-P/CNT catalysts using electrolessly-plated Ni-P/CNT. These catalysts were extensively characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Catalytic activities towards methanol oxidation and hydrogen evolution reactions were evaluated and benchmarked with a commercial Pt/C catalyst. Uniform dispersion of Pt on Ni-P particles led to high Pt utilization, and the electrochemical surface area of Pt^Ni-P/CNT with 12.1% Pt loading was found to be 126 m2 gà1, higher than that of a commercial Pt/C(77.9 m2 gà1). The Tafel slopes for the Pt^Ni-P/CNT catalysts were also found to be smaller than that of Pt/C indicating faster kinetics for hydrogen evolution reaction.

Electroless nickel plated graphite fibers and surface behavior in G_(r(Ni))/6061Al composite

The electroless nickel plated graphite fibers reinforced aluminum matrix composites (Gr(Ni))/Al) were produced by squeeze casting, and the microstructure of Gr(Ni)/Al composite and surface behavior of Ni-P coating were studied. The optimum process of electroless Ni-P plating included: burning to get rid of glue→degreasing→neutralization→acidulating→sensitizing→activation→electroless plating. The surface analysis results show that the electroless nickel plating can diffuse into the graphite fiber surface during the squeeze casting, and the Ni-P coating and aluminum alloys can produce brittle phase NiAl3 or NiAl. The X-ray diffraction(XRD) results indicate that Al4C3 is so little that no Al4C3 peaks are found, and the harmful Al4C3 can be decreased by the electroless plating Ni-P coating. The coating improves the interfacial bonding of continuous graphite fibers reinforced aluminum matrix composites.

Pd-ZSM-5复合膜的制备及其氢气分离性能

为了能够在大孔氧化铝载体表面得到透氢性能良好的钯膜,利用二次生长法在多孔Al_(2)O_(3)载体上生长出一层连续完整的ZSM-5沸石分子筛修饰层,通过化学镀过程在ZSM-5沸石分子筛修饰的载体上沉积一层钯膜,从而得到Pd-ZSM-5复合膜。利用扫描电子显微镜(SEM)对载体、ZSM-5沸石分子筛修饰后的载体和Pd-ZSM-5复合膜的形貌进行详细分析,并通过X线能量色散光谱(EDX)对Pd-ZSM-5复合膜的表面和截面元素分布进行了研究。而且,为了确定该Pd-ZSM-5复合膜的H_(2)渗透性能,在623~773 K范围内,研究了操作温度、操作时间和测试压力对Pd-ZSM-5复合膜透氢性能的影响。研究结果表明,ZSM-5沸石分子筛修饰层能够有效改进载体的表面粗糙度和降低其表面孔径,有助于Pd膜的沉积。所制备的Pd-ZSM-5复合膜表面完整、致密,Pd膜层厚度约为5μm, ZSM-5沸石修饰层厚度约为3μm。当操作温度为773 K、渗透压力为0.1 MPa时,Pd-ZSM-5复合膜的H_(2)渗透通量和H_(2)/N_(2)渗透选择性分别为0.113 mol/(m·s)和468。而且,该Pd复合膜在773 K下,连续操作300 h后,其H_(2)渗透性能保持相对稳定。

热致液晶高分子膜的表面处理及化学镀铜

论文采用氢氧化钠(NaOH)溶液对Vecstar型热致液晶高分子(TLCP)膜表面进行刻蚀粗化,然后通过3-氨丙基三乙氧基硅烷(KH550)在膜表面引入氨基,利用氨基络合银离子使膜表面活化,再进行无钯化学镀铜,提升了TLCP膜与金属铜之间的黏附力。借助扫描电子显微镜(SEM)、接触角测量仪、X射线衍射仪(XRD)和剥离测试等对经表面处理及化学镀铜后的TLCP膜进行表征,探讨了NaOH溶液浓度、表面粗化温度和时间、活化溶液组成等对TLCP表面化学镀铜的影响。结果表明,经表面处理后TLCP膜表面产生均匀的孔洞,接触角下降至29.30°,亲水性大幅提高;所镀铜层呈光亮的粉色,带有金属光泽,致密平滑,纯度高,镀层厚度可达2.78μm,与TLCP膜间的附着力等级达到了5B。

Electroless Ni-P plating on Mg-Li alloy by two-step method

Pretreated Mg-Li alloy sheets were pre-plated in a NiCO3？2Ni（OH）2？4H2O solution to form a thin Ni-P alloy film and then plating in a NiSO4？6H2O solution was carried out to obtain a protective coating.The surface morphology,structure and corrosion resistance of the coating were studied.The results showed that a flat,bright and compact plating layer,which was integrated into the matrix metal,was obtained.The P content of the Ni-P coating reached 13.56%（mass fraction）.The hardness value of the Ni-P coating was about HV 549.The polarization curve showed that the corrosion potential of the Ni-P coating reached ？0.249 V（vs SCE）.A long passivation region was found on the polarization curve,and this phenomenon indicated that the coating has an excellent anti-corrosion property.

Structure and effects of electroless Ni-Sn-P transition layer during acid electroless plating on magnesium alloys

An electroless ternary Ni-Sn-P transition layer with high corrosion resistance was applied for acid electroless nickel plating on magnesium alloys. The surface morphologies and microstructure of the traditional alkaline electroless Ni-P and novel Ni-Sn-P transition layers were compared by SEM and XRD, and the bonding strengths between the transition layers and AZ31 magnesium alloys were tested. The corrosion resistance of the samples was analyzed by porosity test, potentiodynamic polarization, electrochemical impedance spectroscopy（EIS） in acid electroless solution at p H 4.5 and immersion test in 10% HCl. The results indicate that the transition layer is essential for acid electroless plating Ni-P coatings on magnesium alloys. Under the same thin thickness（-6 μm）, the electroless Ni-Sn-P transition layer possesses superior properties to the traditional Ni-P transition layer, including high amorphization, smooth and dense surface without pores, enhanced bonding strength and corrosion resistance. Most importantly, acid electroless Ni-P coatings can be successfully deposited on magnesium alloys by using Ni-Sn-P transition layer.

间歇超声搅拌辅助化学镀制备核壳型镍包铜粉

[目的]通过优化化学镀配方和工艺,提升镍包铜粉的分散均匀性和镀层品质,以增强其作为导电填料在电子浆料中的抗氧化和导电性能。[方法]先采用Pd Cl_(2)体系活化铜粉,然后在间歇超声搅拌辅助下,采用酸性体系进行化学镀镍,制备出核壳型镍包铜粉。利用扫描电子显微镜(SEM)和X射线衍射仪(XRD)分析了Ni镀层的微观形貌和晶体结构,研究了活化液组分、镀液配方和搅拌方式对化学镀的影响。通过扫描电镜观察、能谱面扫分析和热重分析,检验了在较优条件下制备的镍包铜粉的镍层包覆效果和抗氧化性能。[结果]铜粉活化的较优配方为:Pd Cl_(2)0.50 mmol/L,盐酸2.40 mol/L,聚氧乙烯20油醚2.0 g/L。铜粉化学镀镍的较优配方为:硫酸镍0.037 5 mol/L,乙酸钠0.15 mol/L,乙酸0.27 mol/L,聚氧乙烯20油醚2.0 g/L,聚乙烯吡咯烷酮1.5 g/L,还原剂溶液(次磷酸钠3.367 mol/L)滴加速率2.5 mL/h。化学镀过程中采用30 s超声振荡和30 s机械搅拌交替进行的间歇超声搅拌方式有利于制备出镀层均匀致密和颗粒分散性良好的镍包铜粉。[结论]在较优条件下制备的镍包铜粉具有镀覆率高、镍层致密、颗粒分散均匀、抗氧化性能好等优点。

电子束辐射固化制备织物基柔性电路

本研究以聚酯织物作为基材,利用辐射固化和化学镀铜方法制备织物基柔性电路。探讨了柔性电路的微观形貌、元素分布、耐久性及稳定性。实验采用工业级电子加速器配合具有电路结构的钢板“胶片”模具实现电子束选择性辐照,进而在织物上形成与设计电路图完全对应的涂料固化区(含Ag/Fe_(3)O_(4)催化剂),再通过化学镀原位沉积金属层构建织物基柔性电路。扫描电子显微镜(SEM)、能谱元素分析(EDS)和X射线衍射(XRD)结果表明:制备的织物柔性电路结构清晰,导电铜层结晶性高。织物基柔性电路在弯折测试15 000次中,电阻变化率变化低于16%,且在15~55℃的变温实验中电阻变化率未超过5%,说明其具有良好的耐久性和稳定性。本研究的织物基柔性电路为智能织物产品的开发提供了新的研究思路。

紫外辐照与壳聚糖接枝联合处理对ABS表面改性效果的影响

聚丙烯腈-丁二烯-苯乙烯(ABS)是一种应用广泛的工程塑料。将绿色环保的紫外光辐照表面修饰技术与壳聚糖接枝处理技术相结合对ABS基板表面进行改性处理,探究了紫外光辐照条件、壳聚糖醋酸溶液的浓度、改性温度和改性时间对ABS基板表面形貌、表面粗糙度、表面亲水性和表面化学性质的影响。首先使用2 g/L的二氧化钛(TiO_(2))作为光催化剂在300 W下对ABS进行光辐照处理30 min,然后利用0.75 g/L的壳聚糖醋酸溶液在70℃下改性处理30 min,通过扫描电镜(SEM)、原子力显微镜(AFM)观察ABS基板表面形貌变化,并利用表面接触角测量仪和X射线光电子能谱(XPS)分析ABS基板表面亲水性能的变化。结果表明,经过紫外光辐照和壳聚糖接枝改性处理后,ABS基板处理后表面形成少量微小孔洞,表面粗糙度较小,但是ABS基板表面亲水基团的浓度大幅增加,表面亲水性明显增强,化学镀铜层光滑平整,颜色粉红,具有金属光泽。

超级柔韧性和优异电磁屏蔽性能的PVA-co-PE纳米纤维覆铜膜

本工作通过紫外辐射诱导和化学还原反应相结合成功制备了具有多级结构的聚乙烯醇-聚乙烯(PVA-co-PE)纳米纤维覆铜膜,PVA-co-PE纳米纤维覆铜膜具有超级柔韧性能和电磁屏蔽性能,且具有多次循环压缩后性能不减的稳定性。首先通过紫外辐照引入一定量的活化羟基,然后通过静电配位和铜粒子的化学还原作用,在纳米纤维膜上实现无钯镀铜。采用傅里叶红外光谱仪(AIR-FTIR)、能量色散型X射线荧光分析仪(EDX-7000)、扫描电子显微镜(SEM)等对样品进行结构性能分析。结果表明,成功实现PVA-co-PE纳米纤维覆铜膜的制备,SEM图表明,铜颗粒均匀分布于纳米纤维膜表面,并且薄膜由亲水转变为不易浸润。通过四探针仪器和矢量网络分析仪表征了薄膜材料的导电性和电磁屏蔽性能。结果表明,覆铜膜达到导体水平,吸波值达到47.3 dB。经过多次循环压缩后覆铜膜材料电磁屏蔽性能几乎不减,说明制得的纳米纤维覆铜膜具有优异的柔韧性和吸波稳定性,其在柔性智能可穿戴元器件领域具有广阔的应用空间。

碳纳米管增强硬质合金的制备及性能研究

为改善硬质合金中增强体碳纳米管(carbon nanotubes,CNTs)的团聚问题,采用化学镀Ni方法对CNTs进行表面改性,利用气压烧结工艺制备了WC-10Co-CNTs硬质合金和WC-10CoCNTs/Ni硬质合金。对镀Ni前后CNTs的表面形貌、结构及成分进行了分析表征,并研究了CNTs和CNTs/Ni对硬质合金组织及性能的影响。结果表明,CNTs经化学镀改性处理后,表面包覆了致密的纳米Ni颗粒,团聚现象明显改善;在WC-10Co中添加CNTs或CNTs/Ni后可以有效地细化硬质合金的晶粒,降低孔隙率;和未添加的比较,添加质量分数0.1%的CNTs的硬质合金和添加质量分数0.1%的CNTs/Ni的硬质合金抗弯强度分别提高了17.5%和28.2%,热扩散系数分别提高了23.5%和42.8%。

镀铜石墨对铜基制动闸片组织及性能的影响

采用化学镀的方式在鳞片状石墨表面镀铜来改善铜基制动闸片中石墨和铜基体的界面结合,制定了化学镀铜配方及工艺,并研究了4种不同镀液温度对镀铜效果的影响。对镀铜后的石墨进行显微组织观察和能谱分析可知:随镀液温度的升高,镀铜效果先升后降,最好的施镀温度为50℃。用热压烧结法制备出镀铜石墨/铜基制动闸片(FM1)与非镀铜石墨/铜基制动闸片(FM0),并对其进行力学性能、物理性能测试以及制动测试,并采用扫描电镜和能谱仪对制动闸片在制动前后的表面形貌进行观察及分析。结果表明:与FM0相比,FM1中石墨分布更细小均匀,因此样品的致密度较高,硬度、抗压强度和热导率也随之增大。在不同制动初速度下,随制动初速度的提高,两种闸片的摩擦系数均出现先略微增高、后平稳,然后显著降低的趋势,但FM1的摩擦系数总体比FM0的摩擦系数更高且稳定,线磨损率也相对较小。在350 km/h高速制动条件下,由于摩擦热引起的材料表面软化,两种制动闸片的摩擦系数差别不大,都呈现显著下降趋势。

挠性印制电路板细线路微蚀及化学镀镍工艺研究

[目的]化学微蚀作为前处理工艺,被广泛应用在印制电路板(PCB)制造的各大环节。[方法]分别采用硫酸-过硫酸钠(用SA-SP表示)、硫酸-双氧水(用SA-HP表示)和甲酸-氯化铜(用FA-CC表示)3种体系对挠性印制电路板(FPCB)的细线路进行微蚀。通过激光光谱共聚焦显微镜(LSCM)对比了采用不同体系时的微蚀量、微蚀速率及微蚀后线路的表面粗糙度。通过扫描电镜(SEM)研究了不同微蚀体系处理前后铜线路的表面形貌,以及微蚀液对化学镀镍的影响。[结果]3种体系微蚀能力大小顺序为:SA-SP>SA-HP>FA-CC。采用不同微蚀液时铜线的表面粗糙度均随微蚀时间延长而增大。采用甲酸-氯化铜体系微蚀后铜线表面有少量氯化亚铜形成。微蚀液对化学镀镍效果的影响显著。采用硫酸-双氧水体系微蚀时镍镀层光亮,但有渗镀现象;采用甲酸-氯化铜体系微蚀时,化学镍渗镀现象严重;采用硫酸-过硫酸钠微蚀时,细线路化学镍渗镀现象得到有效控制,但镀层较暗。[结论]可尝试通过在化学镀镍液中添加光亮剂来提高镀层光亮度。

石墨烯化学镀铜对放电等离子烧结石墨烯增强铝基复合材料组织和性能的影响

通过化学镀方法得到镀铜石墨烯粉末,再通过静电自组装方法将镀铜石墨烯粉末与铝粉混合,然后经放电等离子烧结工艺制备镀铜石墨烯增强铝基复合材料,研究了不同质量分数(0.1%,0.2%,0.3%,0.4%,0.5%)镀铜石墨烯增强铝基复合材料的微观结构和性能,并与质量分数0.1%未镀铜石墨烯增强铝基复合材料进行对比。结果表明:镀铜石墨烯在复合材料中分散均匀,复合材料的相对密度均在99%以上;铝和铜发生反应生成了中间相Al_(2)Cu,但未有Al_(4)C_(3)界面相生成;镀铜石墨烯增强铝基复合材料的硬度和耐磨性能均优于未镀铜石墨烯增强铝基复合材料;随着镀铜石墨烯含量的增加,复合材料的硬度先升高后降低,磨损质量损失和摩擦因数均呈先减小后增加的趋势。当镀铜石墨烯的质量分数为0.2%时,复合材料具有优异的综合性能,其硬度为74.7 HV,磨损质量损失和摩擦因数均最小,分别为0.0023 g和0.259,磨损机制为氧化磨损。

Ta/Ta_(2)O_(5)/Cu结构制备及应用性能研究

介绍了以Ta/Ta_(2)O_(5)/Cu为结构的平板MIM电容器的制备方法和性能测试,探究金属Cu直接作为钽电解电容器阴极层的可行性。通过阳极氧化法在钽箔表面制备非晶态的Ta_(2)O_(5)薄膜,以化学镀铜、磁控溅射镀铜两种镀铜工艺制备Ta/Ta_(2)O_(5)/Cu结构,并对所得结构进行结构表征和性能测试。实验结果表明:不同镀铜方式制备的Ta/Ta_(2)O_(5)/Cu结构在电学性能测试过程中都没有表现出电容特性,正负极之间的电阻仅有0.7Ω;以金属Cu直接作为钽电容器的阴极层会导致金属铜在测试过程中被氧化成铜离子从而进入Ta_(2)O_(5)介质层中,进而导致Ta_(2)O_(5)的击穿,因此金属铜不适合直接作为钽电容的阴极层。