可溶性阳极电刷镀纳晶Ni-P-SiC复合镀层的耐磨损性能

采用可溶性镍阳极电刷镀方法,在铜片上制备了Ni-P纳晶镀层和Ni-P-SiC复合镀层,镀层表面平整、致密、无裂纹.纳米颗粒的加入没有改变镀层的纳米晶结构,对镀层磷含量影响不大.硬度测试和摩擦磨损试验表明:纳米SiC的加入起到细晶强化和弥散强化作用,可以提高镀层的硬度和耐磨性能:添加纳米颗粒后镀层磨损方式由黏着磨损转变为磨粒磨损.     

镍基纳米SiC-Al2O3复合电刷镀层的组织及性能

在45#钢基体上制备了n-Al2O3/Ni和n-SiC–Al2O3/Ni复合刷镀层,采用能谱仪(EDS)、X射线衍射仪(XRD)、扫描电镜(SEM)和T-11球盘式磨损试验机等设备对比研究了2种复合刷镀层的组织及性能。EDS分析结果表明,n–Al2O3/Ni复合刷镀层中纳米颗粒特征元素Al的质量分数为5.65%,n-SiC–Al2O3/Ni复合刷镀层中纳米颗粒特征元素Al的质量分数为5.63%,Si元素的质量分数为4.86%。SEM分析结果表明,与n-Al2O3/Ni复合刷镀层相比,n-SiC–Al2O3/Ni复合刷镀层的表面更加平整,组织更加细化。n-SiC–Al2O3/Ni和n-Al2O3/Ni复合刷镀层的显微硬度分别为587HV和555HV,n-SiC–Al2O3/Ni复合刷镀层的耐磨性是n-Al2O3/Ni复合刷镀层的1.7倍。     

电刷镀镍／镍包纳米Al2O3颗粒复合镀层微动磨损性能研究

应用电刷镀技术制备了含有镍包钠米Al2O3颗粒的镍基复合镀层，与快速镍镀层对比考察了该复合镀层高温硬度的变化，同时还从微动磨损角度考察了该复合镀层耐磨性和摩擦因数的变化。结果表明：与快速镍镀层相比，镍／镍包纳米Al2O3复合镀层具有更高的高温硬度和更好的抗微动磨损性能；复合镀层在400℃左右表现出较明显的强化趋势，具有较好的综合性能；纳米Al2O3颗粒使复合镀层的结构致密和细化，在磨损过程中起到了一定的减轻粘着和降低摩擦的作用；复合镀层的微动磨损机理主为要粘着磨损。     

复合电刷镀镍–钨–钴–纳米碳化硅及其性能

采用电刷镀工艺在45钢表面制备了Ni-W-Co-n-Sic(纳米碳化硅)复合镀层,镀液组成和工艺条件为:NiSO_4·7H_2O 393 g/L,Na_2WO_4·2H_2O 23 g/L,H_3BO_3 31 g/L,柠檬酸42 g/L,Na_2SO_4 6.5 g/L,CoSO_4·7H_2O 3 g/L,NaF 5g/L,n-SiC 0~30 g/L,温度25~45℃,pH 1.4~2.4,电压5~7 V,镀笔速率0.8 m/s,时间25 min。以Ni-W-Co合金镀层的外观为指标,筛选得到较适合的复合电刷镀电压为6 V。研究了镀液n-SiC含量对镀层的组织结构、显微硬度和摩擦磨损性能的影响。结果表明,镀液中n-SiC含量为15~25 g/L时,可以获得颗粒均匀分布、无微裂纹的Ni-W-Co-n-SiC复合镀层。随镀液中n-SiC含量增大,复合镀层的晶化程度、Ni固溶度和显微硬度均提高,耐磨性改善,但摩擦因数的变化不大。     

复合电刷镀技术修复气缸套的应用研究

本文通过分析汽车气缸套磨损的规律、原因以及气缸套磨损后的可修复的工艺方法，采用含WC纳米微粒的镍基复合电刷镀层作为修复层或强化层，结果表明其耐磨损性能和耐腐蚀性能都高于未经电刷镀处理或单一镍基电刷镀层的气缸套。     

含纳米粉镀液的电刷镀复合镀层试验研究

应用电刷镀技术制备了含有纳米SiC粉的镍基复合镀层，对该复合镀层的显微硬度和摩擦学性能进行了测试，并讨论了主要工艺参数对这些性能的影响规律。测试结果表明：纳米SiC粉的加入可以一定程度的提高复合镀层的硬度。快镍复合纳米SiC镀层的摩擦因数低于快镍镀层的摩擦因数。镀液中纳米SiC粉和添加剂浓度增加时，复合镀层的摩擦因数有降低趋势。与快镍镀层相比，快镍复合纳米SiC镀层的耐磨性有较大幅度的提高。还采用光学显微分析(OM)和电子探针(EPMA)研究了对该复合镀层的表面形貌、组织和元素分布特点，并提出了纳米SiC粉与镍共沉积的机理。     

复合电刷镀技术修复气缸套的应用研究

本文通过分析汽车气缸套磨损的规律、原因以及气缸套磨损后的可行修复工艺方法，采用含WC纳米微粒的镍基复合电刷镀层作为修复层或强化层，结果表明其耐磨损性能和耐腐蚀性能都高于未经电刷镀处理及单一镍基电刷镀层的气缸套。     

船用柴油机活塞杆表面微粒增强镍基复合镀层的制备及其性能分析

采用电沉积方法,在船用柴油机活塞杆表面分别制备纳米微粒增强镍基复合镀层、亚微米微粒增强镍基复合镀层和微米微粒增强镍基复合镀层。分析了三者的显微形貌、晶相结构及磨痕形貌,并测定了硬度。结果表明:与亚微米微粒增强镍基复合镀层和微米微粒增强镍基复合镀层相比,纳米微粒增强镍基复合镀层的外观显得更加光亮,硬度接近5 800 MPa。     

Ni-SiO2纳米微粒复合镀层的电沉积及其耐蚀性研究

采用控电流电沉积技术以铜为基体制备了Ni-SiO2纳米微粒复合镀层.通过改变镀液中SiO2纳米微粒的质量浓度,考察了其对镀层中SiO2微粒的质量分数、电沉积速率及镀层耐蚀性能的影响,对纯镍镀层与Ni-SiO2纳米微粒复合镀层的耐蚀性进行了比较.研究了阴极电流密度对复合镀层耐蚀性能的影响,并采用扫描电子显微镜对镀层形貌进...     

镍基纳米复合镀层的研究现状

镍基纳米复合镀层中由于复合纳米颗粒的特性而被广泛应用。就国内外镍基纳米复合镀层的研究现状进行了分析,对镍基纳米复合镀层的沉积机理、镀层结构特点、影响纳米颗粒与镍金属电沉积的主要工艺因素、镀层性能及应用进行了阐述。当前具有更优良硬度、耐磨性、耐腐蚀性、减摩性、催化功能和抗高温氧化性的镍基纳米复合镀层是行业的研究热点。对镍基纳米复合镀层的研究还属于初步阶段,理论研究还需进一步深入。     

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。     

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.     

Cracking induced tribological behavior changes for the HVOF WC-12Co cermet coatings

HVOF sprayed WC based cermet coatings have been widely used in industries as barriers against wear and hydrodynamic cavitation due to their high hardness and relatively high toughness. However, cracking of the coatings can occur during coating production or in service, which can reduce operational performances. It can be difficult to assess the performance impact due to cracks within the coating and as to whether the cracked coatings should be resprayed or removed from service. In this work, artificial cracks of different widths were introduced to liquid fuel HVOF sprayed WC-12Co coating through uniaxial tension of the coated steel substrate to assess the implications of such cracking. Tribological performances of the cracked coatings were examined using rubber wheel dry abrasion, ‘ball on disc’ sliding wear, and ultrasonic cavitation erosion. The results show that the crack deteriorates the abrasive wear resistance of the coating at the initial stage due to preferable mass loss at the cracks. However, after 30?min of abrasion, all the cracked coatings showed the same wear rate as compared to the non-cracked coating, with the abrasive wear resistance acting independent to the crack characteristics. Because the cracks could store wear debris and thus minimize the debris induced abrasion to the coating surface during sliding wear test, both improvement in wear resistance and reduction in coefficient of friction (COF) were detected in the cracked coatings. During the cavitation test, it was found that the mass loss of the specimen increased significantly (up to 75%)with crack width and density suggesting that the crack presence greatly deteriorated the cavitation resistance of the cermet coatings.     

环氧树脂基复合涂层摩擦磨损性能研究

研究了不同质量分数石墨、碳纤维、纳米ZrO2对环氧树脂(EP)涂层摩擦磨损性能的影响,并用扫描电子显微镜观察了涂层磨损表面形貌并探讨了磨损机理。结果表明:石墨质量分数为20%时复合涂层的磨损率仅为纯EP的7.75%;纳米ZrO2质量分数为4%时复合涂层的磨损率为纯EP的30%;纳米ZrO2与碳纤维以及石墨的协同作用提高了EP的摩擦磨损性能。EP复合涂层的磨损机理以粘着磨损、磨粒磨损以及疲劳磨损为主。     

SiAlON–epoxy nanocomposite coatings: Corrosion and wear behavior

In this study, epoxy powder as a matrix was combined with different contents of silicon–aluminum–oxygen–nitrogen (SiAlON) nanoparticles using a planetary ball mill. Pure epoxy and nanocomposite powders were applied on the surface of plain carbon steel components by the electrostatic spraying method. Curing of the coatings was done in an oven or microwave for the appropriate time. The coating structure and morphology of the SiAlON nanoparticles were studied by scanning electron microscopy and transmission electron microscopy, respectively. The corrosion properties of the coatings were assessed by immersion, Tafel polarization, and electrochemical impedance spectroscopy tests in 3.5% NaCl solution. The results show that addition of 10 wt % SiAlON nanoparticles markedly increases the corrosion resistance of epoxy coatings. Thus, it can be inferred that the corrosion rate of these coatings is 15 to 18 times lower than that of pure epoxy samples and 8 to 11 times lower than coatings with 20 wt % SiAlON. The higher corrosion resistance of nanocomposite coatings can be attributed to the barrier properties of SiAlON nanoparticles. The tribological performance of the coatings was studied with the pin‐on‐disk test. The results of wear testing show that the samples containing 10 wt % SiAlON provide about five times more wear resistance than pure ones and about two times more than coatings with 20 wt % SiAlON. However, the coefficient of friction for nanocomposite coatings is reduced about 50% compared to the pure sample. Also, the curing process in either regime (oven or microwave) has the same effect on the corrosion and wear properties, and the coatings are completely crosslinked. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43855.     

Nylon 11/silica nanocomposite coatings applied by the HVOF process. II. Mechanical and barrier properties

Nylon 11 coatings filled with nominal 0–15 vol % of nanosized silica or carbon black were produced using the high velocity oxy‐fuel combustion spray process. The scratch and sliding wear resistance, mechanical, and barrier properties of nanocomposite coatings were measured. The effect of powder initial size, filler content, filler chemistry, coating microstructure, and morphology were evaluated. Improvements of up to 35% in scratch and 67% in wear resistance were obtained for coatings with nominal 15 vol % contents of hydrophobic silica or carbon black, respectively, relative to unfilled coatings. This increase appeared to be primarily attributable to filler addition and increased matrix crystallinity. Particle surface chemistry, distribution, and dispersion also contributed to the differences in coating scratch and wear performance. Reinforcement of the polymer matrix resulted in increases of up to 205% in the glass storage modulus of nanocomposite coatings. This increase was shown to be a function of both the surface chemistry and amount of reinforcement. The storage modulus of nanocomposite coatings at temperatures above the glass transition temperature was higher than that of unfilled coatings by up to 195%, depending primarily on the particle size of the starting polymer powder. Results also showed that the water vapor transmission rate through nanoreinforced coatings decreased by up to 50% compared with pure polymer coatings. The aqueous permeability of coatings produced from smaller particle size polymers (D‐30) was lower than the permeability of coatings produced from larger particles because of the lower porosities and higher densities achieved in D‐30 coatings. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2272–2289, 2000     

Al2O3-CoCrAlY 复合陶瓷激光熔覆层的组织与性能

研究了Ａｌ２Ｏ３－ＣｏＣｒＡｌＹ复合陶瓷涂层的组织结构、成分分布及其耐磨性能。结果表明：等离子喷涂层的组织呈层片状,面层由α－Ａｌ２Ｏ３和少量的γ－Ａｌ２Ｏ３组成,层间为机械结合界面,涂层平均硬度为８９７ＨＶ０．２。经激光重熔后的组织为单一的α－Ａｌ２Ｏ３柱状晶,在ＣｏＣｒＡｌＹ与基体间有界面相形成,其界面为冶金结合,层间存在着平缓的成分过渡;Ａｌ２Ｏ３与ＣｏＣｒＡｌＹ间的界面结合状况得到了明显的     

纳米Nb粉对等离子弧喷焊铁基合金组织与耐磨性的影响

采用等离子弧喷焊技术在Q235表面制备未添加与分别添加1wt%, 3wt%和5wt%纳米Nb粉的铁基合金喷焊层。通过X射线衍射仪(XRD)、金相显微镜(OM)、扫描电镜(SEM)和能谱仪(EDS)对喷焊层的相组成、显微组织、微区成分及磨损形貌进行分析;利用维氏硬度仪和销盘磨损仪检测喷焊层截面硬度和表面耐磨性。结果表明,铁基喷焊层主要由α-Fe, γ-Fe和Cr7C3组成,添加纳米Nb粉后原位生成NbC相,且随Nb含量增至5wt%,出现了Cr23C6相。纳米Nb粉的加入使喷焊层组织中未转变的奥氏体增多,组织形貌由近等轴晶转变为树枝晶,并且添加5wt%纳米Nb粉的喷焊层组织发生明显细化。添加纳米Nb粉使喷焊层的硬度明显提高,其中添加1wt%和3wt%纳米Nb粉的喷焊层硬度均可达约766 HV0.3。纳米Nb粉的加入同时提高了喷焊层的耐磨性,磨损机制由黏着磨损变为磨粒磨损。     

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.     

Preparation and properties of Ni-W-P-TiO2 nanocomposite coatings developed by a sol-enhanced electroplating method

Several Ni-W-P-TiO₂ nanocomposite coatings were developed by the sol-enhanced electroplating method. The phase and elemental compositions of coatings were determined, and the surface and cross-section morphology were characterized. The mechanical and corrosion performance were systematically tested. The results revealed the addition of 5 ml·L^-1 TiO₂ sol caused a compact coating surface, while higher concentrations of TiO₂ reduced the coating thickness and led to the inferior surface microstructure. The comparison in physiochemical properties of prepared coatings confirmed the superior performance of the Ni-W-P-TiO₂ nanocomposite coating at 5 ml·L^-1 TiO₂ sol addition. Under this condition, the best mechanical properties were achieved when abrasive wear was the dominating wear-resistance mechanism, and the best corrosion resistance was obtained due to its smooth and compact surface microstructure.