共查询到17条相似文献,搜索用时 187 毫秒
1.
2.
3.
通过Ni,W、P与CeO2、SiO2纳米颗粒的脉冲共沉积,在普通碳钢表面制备了Ni-W-P-CeO2-SiO2纳米复合镀层.在一定的脉冲频率和平均电流密度下,研究了正向脉冲占空比对纳米复合镀层的化学组成、沉积速率、显微硬度和显微组织的影响.结果表明:增大正向脉冲占空比时,纳米复合镀层的晶粒尺寸增大,沉积速率和显微硬度降低.当正向脉冲占空比控制在10%时,沉积速率最快(为48.6 μm/h),显微硬度最高(为696 HV).纳米复合镀层中的P含量随着正向脉冲占空比的增大而增加,但CeO2、SiO2纳米颗粒及W的含量不断降低,正向脉冲占空比对W的沉积量影响最明显. 相似文献
4.
通过Ni、W、P与CeO2、SiO2纳米颗粒的脉冲共沉积,在普通碳钢表面制备了Ni–W–P–CeO2–SiO2纳米复合镀层。在一定的脉冲频率和平均电流密度下,研究了正向脉冲占空比对纳米复合镀层的化学组成、沉积速率、显微硬度和显微组织的影响。结果表明:增大正向脉冲占空比时,纳米复合镀层的晶粒尺寸增大,沉积速率和显微硬度降低。当正向脉冲占空比控制在10%时,沉积速率最快(为48.6μm/h),显微硬度最高(为696HV)。纳米复合镀层中的P含量随着正向脉冲占空比的增大而增加,但CeO2、SiO2纳米颗粒及W的含量不断降低,正向脉冲占空比对W的沉积量影响最明显。 相似文献
5.
6.
研究了峰值电流密度对脉冲镍钴合金纳米镀层的成分、晶粒尺寸、显微硬度、抗拉强度的影响.结果发现:在一定范围内,峰值电流密度的增大,可以降低镀层钴含量、表面粗糙度和晶粒尺寸,使菜花胞状结构更明显,提高镀层显微硬度(最高可达600 kg/mm2)和抗拉强度(最高可达1 200 MPa).然而,峰值电流密度太大又会使显微硬度和强度下降.与采用类似方法制得的纯镍纳米镀层相比,镍钴镀层的显微硬度并未明显升高.这说明在该纳米材料中,固溶强化效果并不很明显,而以细晶强化为主. 相似文献
7.
在氨基磺酸盐镀液体系中,采用电沉积法制备了纳米晶镍镀层和四种纳米晶Ni-Co合金镀层,采用FESEM、EDS和XRD表征了镀层的表面形貌、成分和晶体结构。结果表明,镍镀层和四种Ni-Co镀层的晶体结构都是简单面心立方结构;与镍镀层相比,Ni-Co合金镀层的平均晶粒尺寸减小,且当镀层钴含量为41.3%时,Ni-Co合金的平均晶粒尺寸最小为14.6 nm。在一定范围内,钴含量的增加有利于改善Ni-Co合金镀层的表面质量以及实现晶粒细化。 相似文献
8.
在45钢表面以超声波辅助脉冲电沉积制备Ni-TiN复合镀层。研究了平均阴极电流密度、脉冲占空比、超声功率和TiN粒子(平均直径20~30 nm)添加量对复合镀层的TiN粒子含量和显微硬度的影响。得到较优的工艺参数为:NiSO4ꞏ6H2O 300 g/L,NiCl2ꞏ6H2O 30 g/L,H3BO330 g/L,十二烷基硫酸钠0.3 g/L,TiN 25 g/L,pH 4.1~4.3,温度40°C,平均阴极电流密度4 A/dm2,脉冲占空比40%,脉冲频率1000 Hz,超声功率300 W,机械搅拌速率200 r/min,时间60 min。该条件下所得Ni-TiN复合镀层的TiN质量分数为8.35%,显微硬度为819 HV,表面平整、致密,晶粒尺寸均匀。 相似文献
9.
10.
11.
采用脉冲电沉积技术在304不锈钢表面制备Ni-Cu合金镀层,镀液组成和工艺条件为:NiSO4ꞏ6H2O 200g/L,CuSO4ꞏ5H2O 10 g/L,十二烷基硫酸钠0.2 g/L,柠檬酸钠80 g/L,糖精0.2 g/L,pH 4.0,温度25°C,搅拌速率30 r/min,平均电流密度40~120 mA/cm2,脉冲频率0~100 Hz,占空比20%~90%,时间30 min。研究了平均电流密度、脉冲频率和占空比对Ni-Cu合金镀层的元素组成、表面形貌和显微硬度的影响,得到较优的工艺参数为:平均电流密度40 mA/cm2,脉冲频率50 Hz,占空比60%。该条件下所得Ni-Cu合金镀层由质量分数分别为56.53%和43.47%的Ni和Cu组成,呈“菜花”状形貌,结晶细致、均匀,显微硬度为614.4 HV。 相似文献
12.
在0.05 cm~2的玻碳材料上利用双脉冲法电沉积纳米晶体镍。在主要成分为300 g/L NiSO_4·6H_2O,45 g/L NiCl_2·6H_2O,40 g/L H_3BO_3,5 g/L C_7H_5NO_3S,0.05 g/L C_(12)H_(25)NaO_4S的镀液中,把晶粒粒径当成研究标准,通过调整脉冲工艺参数,得到最佳工艺条件,即脉冲平均电流密度9 A/dm~2、脉冲占空比r_正=30%、r_反=10%、T_正=100 ms、T_反=10 ms、脉冲频率1 kHz、镀液θ为55℃、pH为1.5。X-射线衍射结果表明,在最佳工艺条件下,利用双脉冲法在玻碳材料上获得了平均粒径在18 nm的纳米晶体镍。 相似文献
13.
14.
Hardening effect induced by incorporation of SiC particles in nickel electrodeposits 总被引:7,自引:0,他引:7
E.A. Pavlatou M. Stroumbouli P. Gyftou N. Spyrellis 《Journal of Applied Electrochemistry》2006,36(4):385-394
Pure Ni and nickel matrix composite electrocoatings containing micron- and nano-SiC particles (1 μm and 20 nm respectively)
were produced under direct and pulse current conditions from an additive-free Watts type bath. The effect of the particle
size, codeposition percentage of SiC and type of imposed current on the microhardness as well as on the microstructure of
the electrodeposits were investigated. Ni/SiC composite deposits prepared under either direct or pulse current conditions
exhibited a considerable strengthening effect with respect to pure Ni coatings. The improved hardness of composite coatings
was associated to specific structural modifications of Ni crystallites provoked by the adsorption of H+ on the surface of SiC particles, thus leading to a (211) texture mode of Ni crystal growth. Pulse electrodeposition significantly
improved the hardness of the Ni/SiC composite coatings, especially at low duty cycles, in which grain refinement and higher
SiC incorporation (vol. %) was achieved. The enhanced hardness of Ni/nano-SiC deposits, as compared to Ni/micron-SiC composites,
was attributed to the increasing values of the number density of embedded SiC particles in the nickel matrix with decreasing
particle size. In addition, the observed hardening effects of the SiC particles might be associated to the different embedding
mechanisms of the particles, which could be characterized as inter-crystalline for micron-SiC and partially intra-crystalline
for nano-SiC particles. 相似文献
15.
采用脉冲电沉积法,通过调节电流密度控制涂层的晶粒尺寸,在铜基体上制备了平均晶粒尺寸为6~32 nm的Zn涂层,采用XRD, SEM和显微硬度、摩擦实验等手段,表征了涂层的微观结构,并研究了其力学性能与摩擦学性能. 结果表明,纳米晶Zn涂层的表面平整致密,平均晶粒尺寸随电流密度增大而减小,随着晶粒尺寸减小,涂层的显微硬度增大,摩擦系数降低. 当电流密度从0.3 A/cm2增大至2.4 A/cm2时,平均晶粒尺寸从32 nm下降为6 nm,显微硬度从低于0.5 GPa增大至2.0 GPa以上,在大气环境中与Si3N4球之间的滑动摩擦系数从0.18降低至0.05. 硬度随晶粒尺寸的变化规律符合经典的Hall-Petch关系. 相似文献
16.
《Ceramics International》2016,42(16):18380-18392
Nanosized silicon nitride (Si3N4) particles reinforced Nickel-tungsten composite coatings were deposited on the surface of C45 steel sheet by pulse electrodeposition. The effect of duty cycle, frequency, current pattern and presence of Si3N4 nanoparticles on microstructure, phases and corrosion resistance and mechanical properties of the coatings were investigated. The Si3N4 phase was incorporated into Ni-W alloy matrix uniformly and the inclusion content of in the coating was analyzed by energy dispersive x-ray spectrometer (EDS). The structure, microhardness and surface roughness of the coatings was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), Vickers micro-indenter and atomic force microscopy (AFM). The corrosion protection of steel by the coatings was evaluated by weight loss and electrochemical impedance spectroscopy (EIS). Corrosion rates of the coatings were determined using the Tafel polarization test. The results indicated that the duty cycle of 60%, pulse frequency of 1000 Hz, average current density of 5 A/dm−2, and Si3N4 nanoparticles concentration of 30 g/L were the optimal plating conditions. The amount of Si3N4 particles incorporated into the coating that were produced under the optimum plating conditions was 2.1 wt%, and the microhardness was 1031 Hv as well as the crystallite size of this coating was 27 nm. 相似文献