基于电接触强化的铝合金表面电刷镀镍层改性研究

[目的]对铝合金进行表面处理可提高其硬度和耐磨性,拓宽铝合金材料在机械零件方面的应用。[方法]采用电刷镀技术在1060铝合金表面制备Ni镀层,再通过电接触强化技术对Ni镀层进行改性。采用扫描电子显微镜和维氏硬度计考察了Ni镀层电接触强化前后的微观组织和显微硬度。通过摩擦磨损试验对比了1016铝合金及Ni镀层电接触强化前后的耐磨性。[结果]经电接触强化后,Ni镀层内部的裂纹及孔洞类缺陷减少,晶粒间隙减小,致密性提高,显微硬度增大到524.4～560.3 HV0.1范围内。1016铝合金在摩擦磨损试验后存在较深的犁沟和剥落,耐磨性较差。Ni镀层的耐磨性优于1016铝合金,但在摩擦过程中会发生剥落。经电接触强化的Ni镀层在摩擦过程中摩擦因数平稳,表面只是轻微擦伤,耐磨性最佳。[结论]结合电刷镀镍和电接触强化技术可显著提高铝合金的表面性能。     

激光强化电刷镀Ni镀层残余应力研究

利用Nd3+:YAG激光器和电刷镀设备制备了激光强化电刷镀Ni层,采用X-射线衍射法测定了镀层的轴向残余应力,分析了残余应力随镀层厚度变化的情况.结果表明,当镀层δ从10μm增加到200μm时,激光电刷镀Ni层轴向残余应力由压应力逐渐过渡为拉应力,最大值为197 MPa(激光功率300W、镀层δ为200μm),比普通电...     

激光强化电刷镀技术及试验研究

综述了激光强化电沉积技术的发展和研究现状，概括了激光强化电沉积机理、激光对镀层性能的影响，进行了激光强化电刷镀工艺试验，利用扫描电镜和显微硬度计对镀层性能进行了检测。结果表明，激光强化电刷镀可以细化镀层晶粒，提高硬度，并可实现一定的结晶取向性。     

激光强化电刷镀n-Al2O3/Ni复合镀层残余应力研究

利用Nd3+:YAG激光器对电刷镀过程进行强化,在45钢上制备了n-Al2O3/Ni复合镀层。采用X射线衍射法测定了镀层的轴向残余应力及其随镀层厚度变化情况。结果表明,镀层厚度从10μm增加到200μm,激光强化电刷复合镀层的轴向残余应力由压应力逐渐转变为拉应力。当激光功率为600W时,厚度为200μm的镀层的残余应力为103MPa,比普通电刷镀层降低约255MPa。分析了激光对n-Al2O3/Ni电刷复合镀层轴向残余应力的影响机理。     

SiC强化镍基纳米复合电刷镀层的干摩擦磨损特性

采用电刷镀技术制备了快速镍和,n-SiC/Ni、n-SiC/Ni-W复合镀层,研究了镀层的干摩擦磨损特性,测定了镀层的显微硬度,采用扫描电子显微镜(SEM)观察分析了镀层磨痕形貌.结果表明:纳米粒子的加入可以显著地提高镀层的耐磨性.纳米复合镀层的磨损机制以磨粒磨损为主,而纯镍镀层以粘着磨损和磨粒磨损为主.     

电刷镀Monel合金

蒙乃尔(Monel)合金是一种机械性能和加工性能好、耐腐蚀性强的Ni—Cu合金。Ni—Cu晶态合金镀层有良好的耐腐蚀性、耐磨性和较高的硬度，并具有良好的导电性和可焊性，其综合性能较Ni—P合金优越得多。采用电刷镀技术，利用X光衍射仪等测试手段，对Ni—Cu合金刷镀溶液的配方组成、施镀工艺、镀层组织结构及成份进行了分析研究，从而确定了Ni—Cu镀液的组成及刷镀工艺。     

脉冲宽度对电刷镀制备Ni/CNT纳米晶复合镀层显微结构及性能的影响

在不同工艺参数下利用电刷镀技术制备镍-碳纳米管纳米镀层。将碳纳米管添加到刷镀镍的基础镀液中,并以球磨的方式加以分散。镀液中碳纳米管质量浓度为3 g/L。利用扫描电子显微镜和X-射线衍射对镀层晶粒尺寸、显微结构以及形貌进行分析,利用显微硬度仪和球磨磨损试验机对镀层硬度及磨损量进行测试。结果表明,在直流电流下所制备的Ni/CNT镀层的晶粒尺寸约为20 nm;在脉冲电流下,Ni/CNT镀层晶粒尺寸有所降低,并且当脉冲宽度变短时,镀层表面更为平整。随着热处理温度的升高,Ni/CNT镀层的晶粒尺寸有所增加,当加热温度达到500℃时,镀层晶粒尺寸超过50 nm。脉冲电流下所制备的镀层的显微硬度明显高于直流电流下,并且随着脉冲的变短镀层硬度增大。在300℃以下时,Ni/CNT镀层硬度有轻微变化,当温度升高到400℃以上时,镀层硬度明显降低。脉冲电流下所制备复合镀层的耐磨性较直流电流下更好,并且随着脉冲的变短,镀层耐磨性增强。     

摩擦电刷镀Ni-W-D合金镀液改良及镀层性能研究

给出了改良的Ni—W—D合金镀液配方,并介绍了镀液性能参数。采用自制的摩擦电刷镀装置进行了工艺实验。测定了镀层性能并采用X-射线衍射仪测试了镀层的相组成。分别用扫描电镜和能谱仪对镀层形貌及组成进行了观察与分析。结果表明：改良后的镀液得到的镀层有良好的结合力、较高的硬度和耐磨性,硬度平均值在620HV以上;且该镀层为单相镍面心立方固溶体,表面和横截面无明显裂纹,其中Ni,W．Co,Fe含量分别为84．05％,4．39％,7．66％,3．89％。     

电刷镀Ni／n-SiO2复合镀层的组织和性能研究

采用直流和脉冲电刷镀技术制备了Ni／SiO2纳米复合镀层。应用OM和SEM对镀层的表面形貌和显微组织进行了观察，分析结果表明脉冲电流对镀层的生长有明显的影响。脉冲电流的占空比和频率等参数将会改变镀层致密程度和粗糙度。与直流电流相比，脉冲电流电刷镀复合镀层具有高的硬度和低的摩擦因数。脉冲电流电刷镀复合镀层的耐磨损性能明显改善。     

化学复合镀Ni-P-Cr_2O_3工艺及镀层性能的研究

研究了Ni P Cr2 O3 化学复合镀工艺 ,以及热处理对镀层硬度、耐磨性的影响 ,并与Ni P镀层作了对比。结果表明 ,通过制定合理的镀制工艺和控制镀液中Cr2 O3 固体颗粒的添加量 ,可提高镀速 ,获得Cr2 O3 颗粒含量适宜的复合镀层。另外 ,采用正确的热处理工艺 ,可使镀层的硬度、耐磨性显著改善     

Effect of particle size on the co-deposition of diamond with nickel in presence of a redox-active surfactant and mechanical property of the coatings

Particle reinforced Ni/diamond composite coatings containing various amount of the reinforcement (up to 57.6 vol.%) were prepared by the electroplating technique using a Watt's nickel bath in which the diamond particles were dispersed with the aid of a redox-active surfactant containing an azobenzene moiety. Five different sizes of diamond particles with the mean diameter ranging from 0.21 to 2.91 μm were used to investigate the effect of the particle size in their co-deposition with nickel under the influence of the above redox-active surfactant and the mechanical property especially the micro-hardness and the abrasion wear of the composite coatings reinforced with various amount of the diamond particles was studied. Among all, the smallest diamond particles exhibited the highest particle co-deposition of 57.6 vol.%. The micro-hardness and the wear resistance of this composite with the 57.6 vol.% diamond were about 4.5 and 14 times, respectively, than that of a nickel coating without any reinforcement.     

Ni-Al2O3复合镀层的腐蚀摩擦学性能研究

用电镀方法制得Ni-Al2O3复合镀层,研究电镀Ni-Al2O3复合镀层的结构以及其硬度、耐磨性、抗腐蚀性与电镀电流密度的关系。结果表明:复合镀层的显微硬度比纯镍镀层硬度成倍提高,复合镀层耐磨性比镍镀层提高20%以上;抗腐蚀性提高70%以上。X射线衍射结果显示,复合镀层由Ni及非晶Al2O3组成,Ni相为面心立方晶体结构,晶格常数为0.353nm,小于纯镍镀层,晶粒尺寸为23.8nm,大于纯镍镀层。     

Ni-ZrO2复合镀层的腐蚀摩擦学性能研究

用电镀方法制得Ni-ZrO2复合镀层,研究电镀Ni-ZrO2复合镀层的结构以及其硬度、耐磨性、抗腐蚀性与电镀电流密度的关系。结果表明：复合镀层的显微硬度比纯镍镀层硬度成倍提高,复合镀层耐磨性比镍镀层提高20％以上;抗腐蚀性提高70％以上。X射线衍射结果显示,复合镀层由Ni及非晶ZrO2组成。Ni相为面心立方晶体结构,晶格常数为0．353nm,小于纯镍镀层,晶粒尺寸为23．8nm,大于纯镍镀层。     

Wet abrasive wear behavior of WC-based cermet coatings prepared by HVOF spraying

In this study, three kinds of WC-based cermet coatings including WC–CoCr coating, WC–Ni coating and WC–Cr₃C₂–Ni coating were prepared by the high-velocity oxygen-fuel (HVOF) spraying process. Scanning electron microscopy (SEM), energy disperse spectroscopy (EDS) and Vickers hardness tester were used to analyze the microstructure and mechanical properties of these coatings. The WC–CoCr coating presented the highest average microhardness of 1205 HV_0.3, and then followed by the WC–Cr₃C₂–Ni coating (1188 HV_0.3) and the WC–Ni coating (1105 HV_0.3). The abrasive wear behavior of the WC-based coatings under the conditions of different applied loads and sediment concentrations were studied by a wet sand-rubber wheel tester. The results indicated that the abrasive wear loss rates of all the coatings increased with the increment of applied load or sediment concentration. In addition, the coatings with higher microhardness appeared to have higher abrasive wear resistance. The abrasive wear resistance of the WC-based coatings was 4–90 times higher than that of AISI 304 stainless steel under the same testing condition. The abrasive wear mechanism of the WC-based coatings was deduced to be the extrusion and removal of binder phases, as well as the fragmentation and peel-off of hard phases.     

超声波功率对Cu-SiO_2复合镀层形貌与性能的影响

采用超声波辅助电沉积工艺制备Cu-SiO_2复合镀层,借助扫描电镜、粗糙度仪、显微硬度计和摩擦磨损试验机,研究超声波功率对复合镀层形貌、显微硬度和摩擦磨损性能的影响。结果表明,较低功率(0~160 W)超声波起不到改善和提高复合镀层形貌与性能的效果,较高功率(240~400 W)超声波能够明显改善复合镀层的形貌平整性和致密性,并且提高性能;超声波功率过高,反而使复合镀层形貌变差,性能下降。超声波功率为400 W时,复合镀层呈颗粒状形貌,表面粗糙度仅为0.42μm,显微硬度达到166.8 HV,磨损质量损失率为1.07 mg/min,表现出良好的摩擦磨损性能。     

粘结剂对超音速火焰喷涂碳化钨涂层磨粒磨损性能的影响

采用超音速火焰喷涂(HVOF)工艺在35钢基体上制备了WC-10Ni涂层和WC-12Co涂层,研究了镍、钴这两种粘结剂对WC涂层的显微硬度、摩擦系数和抗磨粒磨损性能的影响,采用扫描电子显微镜观察涂层磨损前后的表面形貌,探讨了WC涂层的磨粒磨损机理。结果表明,以HVOF方法制备的2种WC涂层均有较高的显微硬度,WC-10Ni涂层和WC-12Co涂层与SiC砂纸摩擦副之间的干摩擦系数相差不大。2种涂层在低载荷下均有较好的抗磨粒磨损性能,但在较高载荷下WC-12Co涂层的抗磨性明显优于WC-10Ni涂层。2种涂层的磨粒磨损形式主要为均匀磨耗磨损,磨损机理以微切削和微剥落为主。WC-12Co涂层的磨损表面损伤较轻微,综合性能优于WC-10Ni涂层。     

Effect of microstructure and mechanical properties on wear behavior of plasma-sprayed Cr2O3-YSZ-SiC coatings

In this study, the microstructure and mechanical properties of the atmospheric plasma-sprayed Cr₂O₃ (C), Cr₂O₃-20YSZ (CZ), and Cr₂O₃-20YSZ-10SiC (CZS) coatings were evaluated and also compared with each other, so as to explain the coatings wear behavior. Microstructural evaluations included X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) equipped with energy dispersive X-ray spectroscopy (EDX) and porosity measurements. Mechanical tests including bonding strength, fracture toughness, and micro-hardness tests were used to advance our understanding of the correlation between the coatings properties and their wear behavior. The sliding wear test was conducted using a ball-on-disk configuration against an alumina counterpart at room temperature. Addition of multimodal YSZ and subsequent SiC reinforcements to the Cr₂O₃ matrix resulted in an increase in the fracture toughness and Vickers micro-hardness, respectively. It was found that the composite coatings had comparable coefficients of friction with pure Cr₂O₃ coatings. When compared with the C coating, the CZ and CZS composite coatings with higher fracture toughness exhibited superior wear resistance. Observation of the wear tracks of the coatings indicated that the lower wear rates of the CZ and CZS coatings were due to the higher plastic deformation of the detached materials. In fact, improvement in the wear resistance of the composite coatings was attributed to a phase transformation toughening mechanism associated with tetragonal zirconia which created more ductile tribofilms during the wear test participated in filling the pores of coatings.     

Tribological properties of YSZ and YSZ/Ni-YSZ nanocomposite coatings prepared by electron beam physical vapour deposition

Metal-ceramic nanocomposite coatings have been applied to many industrial applications owing to their remarkable properties such as wear, corrosion and high temperature oxidation resistance than that of metals and alloys in high temperature environments. In this study, YSZ and Ni-YSZ nanocomposite coatings deposited by electron beam physical vapour deposition (EBPVD) for high temperature environments have been investigated. Initially friction and wear behaviour of YSZ coatings deposited at various substrate temperature were studied. Then the effect on wear response of Ni-YSZ nanocomposites with different Ni content were investigated using a ball-on-disc micro tribometer. The structural and tribochemical changes that occurred in the wear tracks of YSZ and Ni-YSZ coatings were investigated using field emission scanning electron microscopy and Raman spectroscopy. The results obtained on sliding wear and friction behaviour of these nanocomposite coatings suggest that 50 wt.% of Ni in YSZ nanocomposite provides good wear resistance behaviour than that of other coatings. Such an improvement in tribomechanical and wear performance of the nanocomposite coating could be attributed to the optimum amount of Ni which promotes the formation of NiO from Ni due to the frictional heat between nanocomposite coating and the sliding counter body in wear track as confirmed by Raman analysis.     

Design and development of TiC-reinforced 410 martensitic stainless steel coatings fabricated by laser cladding

AISI 410 martensitic stainless steel (MSS) coatings, reinforced with TiC ceramic particles of varying contents (0, 5%, 10% and 15%), have been fabricated by laser cladding technology for the first time in this study. The microstructure evolution and properties of the laser-cladded specimens are carefully investigated by advanced techniques, including XRD, SEM, TEM, EDS, a micro-hardness tester and a ball-on-disc tribological tester. The obtained results show that the as-cladded 410 MSS coating is mainly composed of coarse lath martensite (M), a few austenite (A) and M₂₃C₆. After addition of TiC ceramic particles, the lath-shaped M is significantly refined, meanwhile the nano-sized Ti-enriched ceramic precipitates (TiC and Ti(C,N)) are formed in the composite coatings. However, microcracks and pores occur in the laser-cladded coating with addition of TiC up to 15%. It is found that both the microhardness and wear resistance of the coatings are enhanced with an increasing TiC content, and the 10% TiC-reinforced coating exhibits the optimal comprehensive performance, with much higher microhardness and wear resistance in comparison to the TiC-free MSS coating. The remarkable properties of the TiC-reinforced 410 MSS coatings can be mainly ascribed to the synergistic effects of microstructural refinement, nano-precipitation hardening and second-phase strengthening.