三元化学镀镍合金层的性能研究

本文对三元化学镀镍合金层进行综述，内容包括镀层的性能、应用和发展前景。     

化学镀Ni-W-P三元合金工艺与性能研究

化学镀Ni-P合金由于磷的共沉积呈非晶态，因而具有耐蚀性好、硬度高及耐磨等一系列优点，但随着科学技术的发展，已经不能满足更高的要求，人们开始致力于引入第三种甚至第四种元素，以期获得具有特殊性能的化学镀镍基三元或四元合金，即通过合金化的方法，来改善Ni—P合金镀层的物理化学特性。     

化学镀的国内外研究现状及展望

本文总结了化学镀技术国内外发展及应用现状,指出了该项技术亟待解决的问题,展望了其应用前景.     

石墨化学镀铜工艺及摩擦性能研究

对石墨表面处理工艺、石墨表面化学镀铜工艺进行了研究,采用正交实验设计方法对镀铜工艺进行优化,对所制备的镀铜石墨表面进行XRD、SEM微观表征;将所制备的镀铜石墨加入聚四氟乙烯中,采用冷压烧结工艺制备固体润滑剂,并测定其摩擦性能.试验结果表明:选用敏化及活化工艺来进行石墨镀前预处理为佳;化学镀时石墨表面能直接生成大量均匀分布的铜微晶,生长至彼此侧面相连时就得到完整镀层,并且石墨颗粒越小,化学镀铜活性越高,因而非常适合用于制备高性能的金属石墨复合材料;当镀铜温度为75 ℃,CuSO4浓度为25 g/L,EDTA浓度为30 g/L时,所制备的固体润滑剂摩擦因数较低,曲线平稳且磨损量较小.     

化学镀Ni—P合金与氮碳共渗复合强化的组织与结构研究

讨论了复合渗层的组织、相结构以及耐磨性。结果表明,Ｎｉ－Ｐ合金经氮碳共渗后基体中的铁和Ｎｉ－Ｐ合金层中的镍相互扩散,形成“钉扎效应”,显著提高镀层与基体间的结合力;此外,弯曲和折断试验表明,经氮碳共渗后的Ｎｉ－Ｐ合金层与基体金属的结合强度远大于经热处理后的Ｎｉ－Ｐ合金层;共渗后的镀层,其耐磨性优于经热处理后的镀层。     

刀具化学镀结合力研究

通过对刀具化学镀中影响镀层与基体问结合力的因素研究和讨论，提出了相应的改进方法，并总结出了一些具体的试验工艺。     

镁合金低污染化学镀技术研究

镁及其合金表面综合防护性差,表面强化处理成为镁制品加工业中不可或缺的重要环节,化学镀因其众多技术优势在轻合金的表面改性中具有重要地位,但经典的化学镀工艺存在工序繁杂、毒性大、成本高等诸多弊端,针对镁合金化学镀工艺技术中存在的主要问题,对镁合金化学镀展开以低污染、低成本为主要目标的研究。结果表明,改变现有化学镀的镀前处理方式,同样可以实现化学镀镀层的顺利生长,从而以更加环保的方式,在镁合金表面获得致密、光滑、均匀的合金镀层。     

钕铁硼磁体表面化学镀Ni-Cu-P合金工艺及性能研究

研究了Nd-Fe-B磁体表面化学镀Ni-Cu-P合金的工艺过程。扫描电镜照片显示Ni-Cu-P合金镀层呈胞状结构,颗粒较均匀;X射线衍射图谱分析,该镀层为微晶状态。通过该工艺得到的Ni-Cu-P合金镀层有良好的耐腐蚀性和耐磨性能,符合工业应用要求。     

Two-body abrasive wear of electroless nickel composite coatings

The two-body abrasive wear of electroless nickel (EN), EN-silicon carbide, and EN-alumina composite coatings have been investigated using a scratch test with a diamond indenter. The coatings were heat treated at temperatures of 100–500° C. The hardness of the coatings increased with heat treatment temperature from 500 HV100 for the as-deposited condition to 1008 HV100 when fully hardened. Scratch testing showed that the as-deposited coating had scratch tracks with a high degree of plasticity, signs of microploughing and tensile cracking and was characterised as a ductile failure. On the other hand, the heat-treated coatings showed chipping and cracking on the edge of the scratch tracks, failing in a brittle manner. The heat-treated EN-silicon carbide coatings, however, exhibited no cracking nor chipping, believed to be due to its higher fracture toughness than the other heat-treated coatings, attributable to its lower phosphorus content. The volume of material removed from the silicon carbide scratch track was 1/3 of the volume removed from the steel substrate at a 20 N load, and showed the best wear/ scratch resistance of any of the coatings tested.     

Improvement in tribological properties of plasma-sprayed Cr3C2–NiCr coating followed by electroless Ni-based alloy plating

Electroless-plated Ni-based alloy coatings, Ni, Ni–Co and Ni–Mo coatings with thickness less than 5 μm were deposited on surfaces of plasma-sprayed Cr₃C₂–NiCr coating. The tribological properties of these electroless-plated coatings against the as-sprayed Cr₃C₂–NiCr coating as sliding pairs were investigated with a block-on-ring arrangement in air at room temperature. It was found that all the Ni-based alloy coatings effectively improved the tribological properties of the Cr₃C₂–NiCr coating. Especially when the Cr₃C₂–NiCr coatings plated with Ni–Co and Ni–Mo coatings were against the as-sprayed Cr₃C₂–NiCr coating as sliding pairs, friction coefficients of 0.10 to 0.13 and coefficients wear coefficients less than 10⁻⁶ mm³·N⁻¹·m⁻¹ were achieved. Through examination and analysis of the worn surfaces employing scanning electron microscopy and X-ray photoelectron spectrometer, the improvement in tribological properties of the Cr₃C₂–NiCr coating may be attributed to the transformation of wear mechanism and the formation of CrO₃ on the worn surfaces.     

合金化渗氮的组织性能与应用

针对合金化涌氮的组织性能进行了研究,研究结果表明,合金化渗氮可形成高硬度,低脆性和致密的渗层;４０Ｃｒ钢合金化参氮后的接触疲劳强度与常规气体氮碳共渗相比提高８３．３３％。     

Early stages of wear of copper steel, and electroless nickel against

The early stages of wear of copper, mild steel, an alloy steel, and electroless nickel in the as-deposited and heat-treated conditions, with a load of 50 g against a dry nitrided steel wheel with a surface speed of 0.28 m s⁻¹, were measured using a Talysurf and a precision relocation technique, and the worn surface was examined using scanning electron microscopy. Wear occurred mainly by abrasion. Extensive ploughing with cooper resulted in metal removal and redeposition on the surface. Rapid and severe removal of patches of material occurred witb mild steel, and fragments of the metal were redeposited on the surface. As-plated electroless nickel formed many small cracks in the wear tracks. These were absent in the heat-treated coating when surface damage occurred by brittle fracture of the Ni₃P. Profilometry results taken during the wear tests were analysed and related to the microscopical results and the wear processes.     

激光冲击强化对TiAl合金组织和性能的影响

为研究激光冲击强化对TiAl合金组织和性能的影响,利用波长为1 064nm、脉宽为20ns、单脉冲能量为0～22J的Nd:YAG激光器对TiAl合金试件进行了实验研究。采用显微硬度计、表面粗糙度仪和扫描电镜分别测量了激光冲击强化前后的表面显微硬度、粗糙度和表面微观形貌,利用X射线应力分析仪测量了激光冲击强化表面残余应力和晶面极性,并分析了其高温稳定性。实验结果表明:当单脉冲能量增加到9J时,表面显微硬度增加了33.4%,粗糙度由0.042μm增大到了0.285μm,表面残余压应力由20MPa增加到了297MPa,表面微观形貌出现了凸凹不平,局部纹理和层状微结构。将9J激光冲击强化后的试件在650℃下保温4h后,残余压应力值从297MPa降到230MPa,显微硬度值从377HV0.2降到345HV0.2,(002)晶面取向有向中心移回的趋势。得到的数据显示,激光冲击强化能够极大地改善TiAl合金的组织和性能,且具有一定的高温稳定性。     

铝合金轮毂的结构优化及试验分析

针对铝合金轮毂有限元分析模型中的应力集中和强度富余情况,利用ANSYS软件对其进行结构优化,使其应力分布更加合理,达到了提高材料的利用率和减轻自重的目的.优化后的轮毂通过了弯曲疲劳试验、径向疲劳试验和冲击试验,且试验结果与有限元分析结果基本吻合,从而论证了该轮毂研发途径的可行性.     

A parametric investigation of the friction performance of electroless Ni‐B coatings

Friction performance of electroless Ni‐B coatings sliding against steel is experimentally investigated in this paper. Friction performance is measured in terms of coefficient of friction (COF) for varying tribological testing parameters such as load, speed and time. Taguchi‐based optimisation of the testing parameters is attempted to find the optimal combination of testing parameters for minimum COF. An analysis of variance reveals that all the testing parameters have significant influence on the friction performance of the coating. Also, the interaction between load and speed is found to affect the friction more compared with the rest of the interactions. The coating characterisation is done with the help of scanning electron microscopy (SEM), energy dispersive X‐ray and X‐ray diffraction analysis. It is found that the Ni‐B coating is amorphous in the as‐deposited condition but gradually turns crystalline with heat treatment. The sliding tracks observed with SEM showed that abrasive failure is the predominant wear mechanism. Copyright © 2010 John Wiley & Sons, Ltd.     

化学镀Ni-P光纤布拉格光栅的均匀轴向拉力响应

研究了化学镀Ni-P涂敷后光纤布拉格光栅(ENFBG)的均匀轴向拉力响应特性.利用其轴对称特性,分析了光栅的应力及应变状态;采用有限元方法数值分析了光栅应变,并实验验证了数值分析结果.数值分析表明:处于纤芯处的光栅被均匀拉伸,剪应变远小于正应变,可忽略;正应变与轴向拉力成正比,ENFBG中心波长的变化正比于均匀轴向拉力变化;但由于化学镀层与光纤力学特性的差异,镀层对FBG轴向均匀拉力响应起去敏作用.当化学镀层厚度为7.25μm时,ENFBG的均匀轴向拉力实测灵敏度为12.45 pm/MPa,相关系数为0.999 6,理论计算值为12,744 pm/MPa,但随着镀层厚度的增加,灵敏度呈下降趋势.镀层在为FBG提供良好保护的同时,ENFBG中心波长对于轴向拉力保持线性响应.实验显示ENFBG是性能良好的轴向拉力传感器.     

磁盘润滑膜的结构和铺展特性研究

采用基于粗粒珠簧模型的分子动力学模拟方法,研究磁盘润滑膜极性全氟聚醚(Perfluoropolyether,简称PFPE)在无定形碳表面的结构和铺展特性。结构特性的模拟结果表明,极性PFPE膜具有复杂的层状结构,在近壁面层以一个单体直径的层厚层状堆叠,在体相层以(4~5)Rg(Rg为综合回转半径)的层厚呈现二聚体结构。铺展特性的模拟结果表明,极性PFPE呈现具有先驱膜、肩状结构和垂直台阶的复杂台阶状铺展形貌,与结构特性的结果具有良好的对应。此外,比较具有不同极性端基的PFPE的铺展形貌,表明端基与壁面的作用和端基间的作用,尤其后者,对铺展行为具有重要的影响。     

汽车雨刮片的结构与耐久性能研究

雨刮片可以清洁汽车玻璃上的雨水、灰尘、雪等,保持驾驶员的视野清晰。介绍了汽车雨刮片的结构分类:有骨雨刮片、无骨雨刮片、复合雨刮片,研究了它们各自的优点和缺点;对雨刮片的3种卡接口形式U Hook、Top Look、复合接口的结构进行了对比;对雨刮片的耐久性能进行了阐述,以达到优化雨刮片结构和延长雨刮片使用寿命的目的。