刷镀工艺参数对镍镀层显微组织与耐磨性能的影响

为了提高电刷镀镍层的耐磨性能,系统研究了刷镀工艺参数对镍镀层显微组织和耐磨性能的影响。结果表明:镀笔移动速度、刷镀电压对镍镀层的组织和耐磨性能有着重要影响;镀笔移动速度为10 m·min~(-1)和刷镀电压为12 V时,镀层的组织致密均匀、胞状晶粒团的尺寸较小,晶粒细小,镀层的耐磨性能较高,此时镀层的磨损量为0.002 g;镀笔移动速度过小和刷镀电压过大都会使镀层组织恶化,磨损量增加。     

碳纳米管/镍复合镀层硬度研究

在瓦特镀镍溶液中加入碳纳米管,研究球磨处理、搅拌分散形式、分散剂对碳纳米管在镀液中均匀稳定分散的影响,采用恒电流电沉积工艺制备了碳纳米管／镍复合镀层。结果表明：碳纳米管球磨后加入到镀液中,并通过超声分散,可以得到稳定的复合电镀液;碳纳米管与镍能很好地共沉积。当阴极电流密度为2．5A／dm^2、镀液温度为45℃、碳纳米管加入量为0．8～1．2g／L时镀层显微硬度达到最大值。     

纳米SiC/Ni复合镀层的制备及其摩擦磨损性能

用电沉积方法在316L不锈钢表面制备了纯镍镀层和纳米SiC/Ni复合镀层,考察了电镀时间、SiC质量浓度、电流密度和镀液温度对复合镀层中纳米SiC含量的影响,表征了镀层的表面形貌和SiC纳米颗粒的尺寸;最后研究了镀层的摩擦磨损性能。结果表明:复合镀层中纳米SiC的含量随着电镀时间延长、电流密度增大、镀液温度升高以及SiC质量浓度的增大先升高后降低,且最佳工艺参数为电镀时间30min,SiC质量浓度20g·L-1,电流密度2A·dm-2,镀液温度60℃,镀液pH4.5,搅拌速度300r·min-1;与纯镍镀层相比,纳米SiC/Ni复合镀层的晶粒更细小,组织更致密,具有更好的摩擦磨损性能,摩擦因数降低了7%以上,磨损率降低了50%。     

激光电刷镀Ni基镀层表面形貌及相结构研究

进行了脉冲和连续Nd^2＋：YAG激光电刷镀Ni及n—Al2O3／Ni试验，利用SEM分析了镀层表面形貌，采用X射线衍射仪分析了镀层的相结构。结果表明：与普通电刷镀镀层相比，激光强化电刷镀镀层晶粒明显细化，其中镀层的晶粒尺寸减小了约5nm，且激光的连续性对Ni镀层晶粒尺寸的影响较大。激光未对Ni镀层和n-Al2O3／Ni复合镀层的晶体结构产生明显影响，但使镍晶粒在（111）晶面具有优先生长现象。     

镍、硼、碳纳米管复合镀层的性能研究

用化学复合镀的方法,把碳纳米管作为第二相加入到化学镀镍、硼镀液中得到复合镀层;改变还原剂二甲胺硼烷在镀液中的相对浓度,得到各种镀层表面成分;利用摩擦磨损实验机、电化学综合测试仪、X射线光电子能谱（XPS）和扫描电子显微镜等分析复合镀层的摩擦磨损性能、耐腐蚀性能、表面形貌特性。结果表明：通过化学复合镀的方法得到镍、硼和碳纳米管复合镀层,其平均厚度为7~8μm;随着二甲胺硼烷在镀液中的相对浓度增加,镀层的摩擦因数减小,磨损量和腐蚀电流也减小,说明随着二甲胺硼烷在镀液中浓度的增加,其耐磨性和抗腐蚀性逐渐提高;复合镀层中主要含有N i,C,O 3种元素,其中N i以单质的形态出现,B以N i2B化合物的形态出现,元素C以碳纳米管形式沉积在镍硼基体中。     

Al2O3增强镍-磷-钨复合镀层的制备及性能

为了提高镍-磷-钨合金镀层性能,制备了Al2O3增强的镍-磷-钨复合镀层;探讨了镀液中Al2O3颗粒尺寸、搅拌方式、电流密度、镀液中Al2O3、Na2WO4的含量和pH值等对镀速、镀层中Al2O3的质量分数及镀层外观质量的影响;确定了复合电沉积最佳工艺条件;并对镀层的硬度、耐磨性能、抗高温氧化性能、耐腐蚀性能、表面形貌、相结构和化学成分等进行了测试.结果表明:在超声波振荡搅拌下,加入纳米Al2O3,控制电流密度为2A·cm-2,镀液中Al2O3和Na2WO4的含量分别为50g·L-1和6g·L-1,pH值为5.0时,镀速和镀层中的Al2O3质量分数最大,镀层质量最佳;加入微米和纳米Al2O3镀层的综合性能均高于未加入Al2O3的镀层.     

提高电刷镀镀层沉积速度的方法

在传统电刷镀中，镀层沉积速度比较慢，本文运用流镀的方法，通过提高电流密度和补充镀液离子的方法，对传统电刷镀技术进行改进，设计了新型镀笔，采用镀液循环装置补充镀液。研究了时间和极间距对镀层沉积速度的影响，进行了快速镍刷镀试验，并用SEM对镀层的表面和侧面形貌进行观察和分析。试验结果表明：沉积速度是传统电刷镀的几十倍；表面形貌较为粗糙，晶粒较大；侧面形貌镀层明显，底部为较细的结晶晶粒，具有较好的镀层质量。     

喷射电沉积纳米晶镍机理及工艺研究

采用极化曲线、循环伏安法研究了喷射电沉积制备纳米晶镍的阴极极化行为及其机理。并根据电化学测试结果,选取一定范围内的电流密度,利用扫描喷射电沉积在45钢基体表面制备了纳米镍涂层。用扫描电镜、X射线衍射仪和显微硬度计研究了电流密度对镍涂层表面形貌、微观组织结构、晶粒尺寸及表面显微硬度的影响,并进行了耐磨性试验。结果表明,喷射电沉积可以显著提高镍沉积的极限电流密度,并在高的过电位下促进晶体的形核,有利于获得纳米晶镍镀层;随着电流密度的增大,纳米晶镍的平均晶粒尺寸先变小再变大,当电流密度为130A/dm2时涂层最致密,平均晶粒尺寸最小,表面显微硬度也最高;经过喷射电沉积后,试样耐磨性能有了较大的提高。     

铁-纳米ZrO2复合电镀层的组织与性能

采用氯化物低温镀铁工艺,选择纳米ZrO2作为第二相粒子,以不对称交流一直流电源电镀法制备了铁-纳米ZrO2复合镀层;研究了工艺参数对镀层组织结构和镀层硬度、耐磨性能的影响.结果表明:采用此方法可获得内应力小、致密的复合镀层,镀层为α-Fe体心立方结构;当镀液中ZrO2纳米粒子含量为30 g/L,pH值为1,搅拌转速为300 r/min,阴极电流密度为20 A/dm2,施镀温度为30～40℃时,ZrO2粒子在镀层中弥散分布,镀层的平均硬度值达到800 HV.镀铁层中复合适量的ZrO2纳米粒子,能有效地降低粘着磨损,提高镀层的耐磨性能.     

晶粒尺寸对GH4169镍基合金疲劳小裂纹扩展的影响

采用光学显微镜、扫描电镜、拉伸及疲劳试验机等研究了热处理对GH4169镍基高温合金显微组织和力学性能的影响,重点研究了晶粒尺寸对其疲劳小裂纹扩展的影响。结果表明:采用固溶加双时效的热处理工艺能够提高试验合金的力学性能,随着固溶温度升高,合金中晶粒尺寸变大,强度下降,疲劳寿命延长;小裂纹阶段占疲劳寿命的80%,晶粒尺寸对疲劳小裂纹扩展速率的影响不明显,但随着晶粒尺寸增大,长裂纹的扩展速率下降。     

Dry friction and wear characteristics of nickel/carbon nanotube electroless composite deposits

Ni/carbon nanotube (Ni/CNTs) composite coatings were deposited on carbon steel plate by electroless deposition. The friction and wear properties were examined under dry sliding conditions using the ball-on-disk configuration. For reference, carbon steel plate was coated with Ni, Ni/SiC and Ni/graphite. The results show that the Ni/CNT coating has a microhardness value of 865 Hv, greater than for SiC reinforced composite deposits. The Ni/CNTs composite coating possesses not only a higher wear resistance but also a lower friction coefficient, resulting from their improved mechanical characteristics and the unique topological structure of the hollow nanotubes.     

碳纳米管镍基复合刷镀层的组织和性能

研究了碳纳米管镍基复合刷镀层的组织、显微硬度和耐磨性等。结果表明：与常规镀层相比，含有碳纳米管的复合镀层组织明显细化，显微硬度有较大的提高，硬度热稳定性和耐磨性得到了明显的提高。     

Friction and Wear Behavior of Nanocrystalline Nickel in Air and Vacuum

A bulk and dense nanocrystalline (NC) Ni with a mean grain size of 26 nm and a microhardness of 370–382 HV were fabricated by an electro-deposition technique. The microstructure and microhardness of the NC Ni samples were examined. The friction and wear behavior of the NC Ni samples under dry condition both in air and in vacuum were investigated in comparison with a conventional coarse-grained (CG) Ni with a mean grain size of 2.2 μm and a microhardness of 80–90 HV using a pin-on-disk type tribometer. The results show that the NC Ni sample possesses lower friction and higher wear resistance both in air and in vacuum, compared with the CG Ni sample. An important and interesting result is that for the both samples tested, the friction coefficients in vacuum are higher than those in air, while the wear loss occurs reverse case. In the air atmosphere, the NC Ni exhibits a mild wear, and avoids the severe wear that happens on the CG Ni, which is mainly attributed to which is mainly attributed to formation of a mechanical mixed layer on the worn surface of the harder NC Ni. In the vacuum atmosphere, compared with CG Ni, NC Ni shows a significant decrease in the plastic deformation and adhesive wear.     

Fabrication of graphene/nickel composite microcomponents using electroforming

This paper introduces combined processes to fabricate graphene platelet (GPL)/nickel (Ni) composite microcomponents. The process involves co-deposition of Ni and GPL into SU-8 micromolds to form the components, where SU-8 molds of 400 μm in thickness were fabricated using UV lithography and an electrolyte with a GPL concentration of 0.2 g/L was used for the electroforming process. Pure Ni microcomponents were also fabricated under the same condition for comparison. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to examine the surface morphologies and microstructures of the microcomponents. Grain sizes were estimated based on the XRD results. A Raman microscope was used to characterize the GPLs in the GPL/Ni composite microcomponents. Hardness property was characterized using a Vickers hardness tester. Ni and GPL/Ni microcomponents of 200 μm in thickness are successfully electroformed and show good shape retention and high precision. Microscopy examinations show that GPLs are evenly deposited in the Ni matrix and agglomeration of GPLs occurs during the electroforming process. The addition of GPLs leads to significant grain refinement of Ni matrix, and the microhardness value of the composite microcomponents is twofold higher than that of pure Ni microcomponents. The research results prove a novel method to fabricate high-precision microcomponents with excellent mechanical performance by introducing GPLs into Ni matrix.     

Microstructures and abrasive wear performance of PTAW deposited Ni–WC overlays using different Ni-alloy chemistries

The microstructures and performance of Ni–WC (nickel–tungsten carbide) composite overlays deposited by plasma transferred arc welding are studied using a combination of microscopy, hardness, and wear testing. The Ni–WC overlays had microstructures consisting of γ-Ni dendrites, with interdendritic Ni-based eutectics, borides and carbides. Overlays which were produced with a low hardness Ni-alloy matrix contained a smaller fraction of interdendritic phases relative to the high hardness Ni-alloys.The dissolution of WC particles was observed following deposition of the MMCs, and this promoted the formation of secondary carbide phases. Ni-alloys with low carbon and low Cr content exhibited the least dissolution of WC. The Ni–WC overlays produced using these dilute alloys generally performed better in ASTM G65 wear tests. This was due to the increased fraction of retained WC phase, and the reduced fraction of brittle secondary carbide phases when the Ni-alloy contained no Cr.     

巴基管粒度对其复合镀层摩擦学性能影响的研究

用无电解复合镀方法,在４５号钢基体上镀了一层镍－磷－巴基管复合镀层。本文详细实验研究了粒度对镍－磷－巴基管复合镀层摩擦学性能的影响。结果表明：巴基管复合镀层具有极优的摩擦学性能,而且巴基管的粒径愈小,复合镀层的摩擦学性能则愈优。     

巴基管的润滑性能研究

本文实验研究了镍－磷－巴基管复合镀层的润滑性能，结果表明：巴基管复合镀层具有优良的减摩，耐磨特性，说明巴基管是一种性能优异的固体润滑材料。     

Microstructure and wear resistance of nickel–carbon nanotube composite coating from brush plating technique

This paper investigates the microstructure and wear resistance of nickel–carbon nanotube (CNT) composite coating deposited by brush plating technique. The Ni/CNT coating deposited with a pulse current source has less porosity, higher hardness and higher wear resistance than that with a DC source. CNTs greatly improve the coating performance. The wear mechanism is mainly the smearing of the Ni/CNTs coatings, instead of the fracture for the Ni coatings.     

Y2O3改性石墨/CaF2/TiC/镍基合金复合涂层微观组织与摩擦学性能研究

为提高石墨/CaF₂/TiC/镍基合金（GCTN）复合涂层的力学性能和摩擦学性能,运用等离子喷涂技术在45钢表面制备了Y₂O₃改性GCTN复合涂层,研究了Y₂O₃对复合涂层的微观组织、显微硬度、断裂韧性和摩擦磨损性能的影响。结果表明：Y₂O₃改性GCTN复合涂层主要由γ-Ni、CrB、Cr7C₃、TiC、CaF₂和石墨等物相组成。Y₂O₃在等离子火焰加热作用下与C元素反应生成活性元素Y,Y净化了复合涂层的微观组织,并细化了CrB、Cr₃C7等硬质相晶粒,提高了其致密性。当Y₂O₃质量分数为0.5%时,复合涂层的显微硬度和断裂韧性分别为593.3MPa和6.82MPa·m^1/2,比不含Y₂O₃的复合涂层分别增大了8%和22%,其机理主要是Y₂O₃细化了CrB、Cr₃C₇等硬质相晶粒,起到了细化强化作用。由于GCTN-0.5Y₂O₃复合涂层的显微硬度和断裂韧性显著提高,减少了其黏着磨损和微观断裂磨损,因而GCTN-0.5Y₂O₃复合涂层的摩擦因数和磨损率最小,分别为0.085和0.39×10-3mm3/m。     

Effect of carbon nanotube addition on the tribological behavior of carbon/carbon composites

Carbon nanotube composite coatings were applied onto carbon/carbon composites to improve wear properties. Carbon nanotubes have been prepared by catalytic pyrolysis of hydrocarbons. The nanotube slurry was prepared by addition of phenolic resin and solvent to infiltrate into C/C composites. The nanotube added composites were then carbonized in a nitrogen atmosphere. Ball-on-disc type wear tests were performed to evaluate the tribological properties of the carbon nanotube added carbon composites. The result showed that addition of nanotube has the potential to increase the wear resistance of carbon composites. Changes in Raman spectra, morphology and surface damage were studied to explain observed wear behavior.