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 in 10% 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 of 241 and 206 MPa respectively, while the single Ni?Mo?P coating exhibited a residual tensile stress of 257 MPa. 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.     

ABS塑料化学镀镍激光无钯活化工艺

化学镀是ABS塑料表面金属化最常用的方法之一,但在施镀前需要使用钯等贵金属对基体进行活化,使其具有催化活性。以NiSO_4与NaH_2PO_2混合配制活化液,涂覆于塑料基体表面,常温放置8~10min后,基体表面形成一层活化层;用激光均匀扫描基体表面,活化层在激光作用下反应生成活性Ni微粒使基体活化,再进行化学镀镍。采用正交试验优化激光活化各参数,通过扫描电镜对各阶段基体表面形貌进行表征,利用能谱和X衍射对活化及施镀后的基体表面成分进行分析,采用高低温冲击法检测镀层结合性。结果表明,当NiSO_4与NaH_2PO_2浓度分别为10g/L和40 g/L,光斑直径为1mm,扫描速率为5 mm/s,涂覆次数为2次时,镀覆效果最好;基体活化后,表面附着一层均匀的平均直径为30nm的活性Ni微粒催化核心;施镀后,镀层均匀致密,结合性较好。     

Microstructure and properties of open-cell Ni–Sn–P alloy foams prepared by electroless plating

In this study, open-cell Ni–Sn–P alloy foams were prepared by electroless plating. The influence of tin content on the surface morphology and properties of Ni–Sn–P alloy foams were investigated. The surface structure of Ni–Sn–P alloy foams became more uniform and compact with the increase of Sn content. The X-ray diffraction result showed that Ni–Sn–P alloy foams gradually transformed from an amorphous structure into crystallization with the increase of heat-treatment temperature. The introduction of Sn significantly enhanced the corrosion resistance of Ni–P coatings in 3.5 wt% NaCl solution, the corrosion current density decreased from 5.022 to 0.805 μA/cm² and the corrosion potential shifted positively from −0.423 to −0.294 V after adding 5.96 wt% Sn to Ni–P coatings. However, the corrosion resistance of Ni–Sn–P foams was deteriorated after heat treatment. Adding Sn to the Ni–P system slightly weakened the compressive strength of Ni–P binary foams. Nevertheless, significant improvement in the antioxidant performance of Ni–Sn–P alloy foams was indicated by the reduction of the mass change rate in that the mass change rate of Ni–P foams obviously reduced from 5.15% to 0.25% after adding 5.96 wt% Sn.     

高速钢微径立铣刀的Ni-Mo-P化学镀工艺

基于化学镀Ni-Mo-P具有高硬度、表面光洁、可在复杂型面上获得均匀镀层等优点,将其应用于高速钢微径立铣刀上,并通过铣削试验对镀层性能进行分析。结果表明:Ni-Mo-P三元合金镀层对于提高高速钢微径立铣刀的表面硬度、增强局部刚性具有一定效果;镀层结合力是影响Ni-Mo-P化学镀在高速钢微径刀具上推广应用的关键制约因素。     

钨粉化学镀铜对压制性能的影响

通过钨粉表面化学镀铜,使其表面包覆一层均匀的诱导铜膜,以此制备W-15Cu电子封装材料。采用扫描电镜和双对数压制方程理论分析,研究钨粉表面化学镀铜含量对钨粉压制性能的影响,结果表明钨粉表面化学镀铜可改善其压制性能,且随化学镀铜含量的增加,压制同等生坯密度的制品压力增大。     

Room temperature synthesis of samarium oxide nanotubes using cost-effective electroless deposition method

Nanotubes consisting of samarium oxide (SmNT) were fabricated by electroless deposition using ion track-etched polycarbonate templates. To achieve nanotubes with thin walls and small surface roughness, the tubes were generated by a procedure containing several steps under aqueous conditions. The approach reported below will process open-ended nanotubes with well-defined outer diameter and wall thickness.     

粉末冶金法炭纤维/Mg复合材料的界面对其力学性能的影响

采用表面化学镀镍前后的短炭纤维(Cf)做为增强体,纯镁粉为基体金属,通过粉末冶金法和热挤压制备镁基复合材料.采用SEM-EDS、TEM、XRD和拉伸等测试手段表征短炭纤维增强镁基复合材料的微观形貌、元素组成、物相组成及其力学性能.结果表明:炭纤维在复合材料中分布均匀且沿挤压方向定向排列;采用经过表面化学镀镍处理的短炭纤维与金属镁复合后界面结合状态优良,Mg2Ni物相的存在表明润湿性的改善是通过金属镁与涂层发生反应而实现;对比屈服强度测试值和理论计算值的大小,表明涂层炭纤维增强镁基复合材料的增强机理主要是界面载荷传递效应.     

镁合金无铬前处理直接化学镀镍磷新工艺

镁合金化学镀镍磷传统的前处理溶液中含氟化氢和六价铬,对环境有较大的污染,其化学镀液对镁合金基体的腐蚀也影响镀层质量。为此,以H3PO4＋Na2MoO4溶液代替HNO3＋CrO3进行酸洗,并采用NH4HF2活化。在以硫酸镍为主盐的化学镀液中加入三元配位剂,以提高镀液的质量,降低镀液对镁合金基体的腐蚀。结果表明：开发的环保...