电刷镀制备镍/钴多层膜的工艺优化

采用单液法电刷镀制备200μm厚的Ni/Co多层膜镀层。镀液配方和工艺为:NiSO_4·7H_2O 250 g/L,CoSO_4·7H_2O 17~50 g/L,H_3BO_3 35 g/L,NaCl 20 g/L,十二烷基硫酸钠0.1~0.5 g/L,pH 2.0~5.0,温度40~60℃。通过单因素试验确定镀液的CoSO_4·7H_2O与NiSO_4·7H_2O的质量浓度比为1∶10,镍、钴单层的沉积电压分别为9.0 V和3.5 V。通过对比不同厚度单层膜的Ni/Co多层膜镀层的表面形貌、元素组成、表面粗糙度、显微硬度和耐磨性能,分析单层膜厚度变化对Ni/Co多层膜镀层性能的影响,最终确定较优单层膜厚度为4μm。所得Ni/Co多层膜镀层的显微硬度为496.8 HV,摩擦因数为0.42,耐磨性最好。     

镍铁–立方氮化硼复合电刷镀工艺研究

通过复合电刷镀在20钢基体表面制备镍铁–立方氮化硼(CBN)复合镀层。研究了施镀电压、镀液温度及镀笔速率对复合镀层中CBN含量的影响,分析了镀层中CBN含量与耐磨性之间的关系。复合电刷镀NiFe–CBN的镀液组成和最佳工艺条件为:NiSO4·6H2O 270~300 g/L,FeCl2·2H2O 23~27 g/L,H3BO326~30 g/L,Na3C6H5O7·2H2O 20~30 g/L,糖精2~3 g/L,十六烷基三甲基溴化铵0.2~0.3 g/L,pH 3.2~4.0,电压14 V,温度50°C,镀笔速率15 m/min,时间100~120 min。在最佳工艺下所得镀层的CBN质量分数为9.8%,显微硬度为770 HV,耐磨性和结合力良好。     

脉冲喷射电沉积制备钴–碳化铬复合镀层

采用包覆有50%(质量分数)Ni的C_(r3)C_2微米颗粒(粒径3~5μm)为第二相,以脉冲喷射电沉积制备Co–C_(r3)C_2复合镀层。镀液组成和工艺参数为:CoSO_4·7H_2O 430 g/L,C_(r3)C_2 200 g/L,H_3BO_3 30 g/L,NaCl 5 g/L,十六烷基三甲基溴化铵适量,pH=4,温度40°C,电压18 V,镀液流量2.4 L/min,喷头移动速率1.2 mm/s。研究了脉冲参数对复合镀层颗粒复合量、表面粗糙度、显微硬度以及耐磨性的影响,并探讨了颗粒复合量对镀层性能的影响。C_(r3)C_2颗粒的复合量越高,复合镀层的显微硬度就越高,耐磨性也越好,但表面粗糙度增大。最优脉冲参数为:占空比30%,脉冲周期200 ms。所得Co–C_(r3)C_2复合镀层的颗粒含量达11.98%,显微硬度为542.6 HV,摩擦因数为0.443。C_(r3)C_2颗粒在镀层中分布均匀,与基质金属结合牢固。     

脉冲电沉积铜-锡-镍-聚四氟乙烯复合镀层的组织结构和摩擦学性能

采用脉冲电沉积法在碳素工具钢表面制备Cu-Sn-Ni-PTFE复合镀层。镀液配方和工艺为:K_4P_2O_7·3H_2O 266.5 g/L,Cu_2P_2O_7·4H2O 20 g/L,NiSO_4·4H_2O 0.06~0.14 mol/L,KNaC_4H_4O_6·4H_2O 31.6 g/L,Na_2SnO_3·3H_2O 40 g/L,KNO_3 40 g/L,Na_3C_6H_5O_7·2H_2O 20 g/L,PTFE 10 g/L,pH 9.5~10.0,温度35~40℃,电流密度2.5 A/dm~2,脉冲频率3 000 Hz,占空比60%,转速100 r/min,时间1 h。研究了镀液中Ni~(2+)浓度对复合镀层表面形貌、组成、显微硬度及摩擦磨损性能的影响。结果表明,镀液中Ni~(2+)浓度为0.1 mol/L时,Cu-Sn-Ni-PTFE镀层表面均匀、致密,显微硬度高达391 HV,耐磨性最好。     

电流密度对喷射电沉积钴–磷合金镀层的影响

采用喷射电沉积法在45钢棒表面制备Co-P合金镀层。镀液组成和工艺参数为:CoSO_4·7H_2O 200 g/L,H_3PO_4 50g/L,H_3BO_3 30 g/L,NaCl 25 g/L,pH=1.0,温度50℃,喷头移动速率1.2 mm/s,电流密度10~70A/dm~2。研究了电流密度对Co-P合金镀层的表面形貌、相结构、显微硬度和耐磨性的影响。结果表明:在10~70A/dm~2电流密度范围内,随电流密度从10A/dm~2增大到70 A/dm~2,Co-P合金镀层的厚度变化不大,晶粒细化,显微硬度升高,耐磨性改善,但电流密度高于40A/dm~2时所得镀层的表面平整度下降。     

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。     

镀液中石墨烯添加量对镍-石墨烯复合电镀层微观结构和耐磨性的影响

为提高巴氏合金的耐磨性,将石墨烯作为增强相添加到由240g/L NiSO_4·6H_2O、45 g/L NiCl_2·6H_2O、30 g/L H_3BO_3、20 g/L Na_2SO_4和0.1 g/L十二烷基苯磺酸钠组成的镀镍液中,在ZSnSb8Cu4合金上电沉积得到镍-石墨烯复合镀层。采用扫描电镜、X射线衍射仪和摩擦磨损试验仪考察了镍-石墨烯复合镀层的表面形貌、组织结构和耐磨性。结果表明,复合电沉积镍-石墨烯能够有效提高巴氏合金基体的耐磨性,而镀液中石墨烯添加量的增大能使镀层晶粒细化,显微硬度升高,摩擦因数和磨损率减小。当镀液中石墨烯的质量浓度为400 mg/L时,镍-石墨烯复合镀层的显微硬度较高,耐磨性最优。     

镀液中二硫化钼添加量对镍-二硫化钼复合电镀层耐磨性的影响

以MoS_2作为增强相添加到由240 g/L NiSO_4·6H_2O、45 g/L NiCl_2·6H_2O、30 g/L H_3BO_3、20 g/L Na_2SO_4和0.2 g/L十六烷基三甲基溴化铵组成的镀液中,在45钢表面电沉积得到Ni–MoS_2复合镀层。采用扫描电镜、X射线衍射仪和摩擦磨损试验仪考察了MoS_2添加量对Ni–MoS_2复合镀层的表面形貌、相结构和耐磨性的影响。随着MoS_2添加量的增大,Ni–MoS_2复合镀层表面凸起的胞状结构增多,显微硬度先增大后减小,摩擦因数降低。当MoS_2的添加量为2 g/L时,所得Ni–MoS_2复合镀层的显微硬度为860.5 HV,耐磨性较佳。     

脉冲频率对电镀镍–铬合金性能的影响

以Q235钢为基体,采用脉冲电镀方法在三价铬体系镀液中制备了Ni–Cr合金镀层。镀液组成和工艺条件为:CrCl364.6 g/L,NiSO4·6H2O 31.4 g/L,V(二甲基甲酰胺)∶V(水)=1∶1,C6H5Na3O7·2H2O 117.64 g/L,pH 3.0,NaBr 103 g/L,搅拌速率200 r/min,温度55°C,时间40 min。借助带有能谱仪的扫描电镜、电化学工作站、摩擦磨损试验机、维氏硬度计等设备,研究了脉冲频率对镀层微观形貌、耐蚀性能、耐磨性能及显微硬度的影响。结果表明,随脉冲频率增大,Ni–Cr合金镀层的耐蚀性、耐磨性及显微硬度均呈先升高后降低的趋势,较适宜的脉冲频率为1 000 Hz。     

电流密度对喷射电沉积钴–镍合金镀层组织及性能的影响

采用NiSO_4·6H_2O与CoSO_4·7H_2O的质量浓度比不同的镀液在黄铜上喷射电沉积Co–Ni合金,研究了电流密度对Co–Ni合金镀层表面形貌、元素组成、晶体结构、显微硬度和耐磨性的影响。结果表明:随着电流密度的增大,Co–Ni合金镀层的晶粒先细化后粗化,Co含量减小。镀层在Co含量高于85%时基本为密排六方(hcp)相,低于85%时为hcp和面心立方(fcc)两相共存。镀层的晶粒越细,则显微硬度越高,耐磨性越好。在CoSO_4·7H_2O和NiSO_4·7H_2O的质量浓度分别为200 g/L和100 g/L的条件下,镀层受电流密度的影响较小,Co含量稳定在96%左右,表面均匀致密,显微硬度高达425 HV,耐磨性较好。     

超音速火焰喷涂碳化钨-钴铬涂层替代电镀硬铬的研究

采用超音速火焰喷涂(HVOF)工艺在300M钢基体上制备了WC-CoCr涂层,研究了其显微结构、显微硬度、相组成、耐磨性和耐蚀性,并与300M钢电镀硬铬试样进行了性能对比。研究结果表明,HVOF工艺制备的WC-CoCr涂层性能优良,耐磨性和耐蚀性优于电镀硬铬镀层,可以替代电镀硬铬作为耐磨涂层使用。     

AI2O3溶胶的体积分数对Zn-Ni-AI2O3复合镀层性能的影响

向Zn-Ni合金镀液中加入AI2O3溶胶,获得了Zn-Ni-AI2O3复合镀层。研究了A12O3溶胶的体积分数对镀层的相结构、表面形貌、横截面形貌、显微硬度、耐磨性及耐蚀性的影响。结果表明:当A12O3溶胶的体积分数低于6 mL/L时,不会对镀层的相结构产生影响。但当A12O3溶胶的体积分数较高时,会改变镀层的相结构,并影响镀层的致密性。当AI2O3溶胶的体积分数为6 mL/L时,镀层的耐磨性和耐蚀性均最佳。     

Cr–C/h-BN 自润滑复合镀层的制备与摩擦学性能

在三价铬Cr–C镀液中添加1~5 g/L的h-BN自润滑微粒,运用直流电沉积技术在Q235碳素结构钢基体上制备了Cr–C/h-BN复合镀层。利用扫描电镜(SEM)、X射线衍射仪(XRD)、显微硬度计、摩擦磨损试验机等设备分析了h-BN微粒添加量、电流密度等工艺参数对镀层组织和性能的影响。结果表明:在电流密度20 A/dm2,h-BN添加量3 g/L的条件下,可获得h-BN微粒体积分数为6.15%的复合镀层。h-BN微粒的添加改善了Cr–C合金镀层的耐磨性,Cr–C/h-BN复合镀层在室温干摩擦条件下的磨损率减少了22%,平均摩擦因数由原先的0.49降低至0.31。     

锡-铁合金电沉积工艺的优化

通过正交试验对电镀Sn-Fe合金的镀液配方进行优化,研究了电流密度和镀液p H对Sn-Fe合金镀层微观结构、显微硬度、光泽和耐蚀性的影响,得到最优镀液配方和工艺条件为:葡萄糖酸钠120 g/L,硫酸亚锡40 g/L,硫酸亚铁20 g/L,H3BO320 g/L,聚氧乙烯-聚氧丙烯-聚氧乙烯嵌段聚醚(EPE4600)30 mL/L,pH 4,温度25℃,电流密度2.0 A/dm2。在该条件下可电镀得到表面光亮、结晶细致、耐蚀性良好的Sn-Fe合金镀层。     

Properties of silver–antimony alloys electrodeposited from ferrocyanide–thiocyanate electrolytes

The influence of electrolysis conditions on the internal stress, microhardness, electrical contact resistance, wear resistance, roughness, and friction properties of silver–antimony alloys deposited from ferrocyanide–thiocyanate electrolytes is studied. The internal stress of the coatings depends strongly on their antimony content. Stress changes and transition from compressive to tensile stress at increased antimony content in the alloy are observed. By internal stress measurements, conclusions can be drawn concerning the homogeneity or heterogeneity of the coating, that is, whether the coating consists of one or two phases. The changes in microhardness are related to variations of the internal stress and to the phase transition. The codeposition of antimony leads to a reduction of the coating roughness. Increased Sb content of the alloy leads to an increase in the electrical contact resistance and to reduction of the contact forces and wear resistance of the coatings. At large deviations from equilibrium, an oscillating electrochemical reaction is observed leading to space-time structures on the electrode surface.     

Ni-Al_2O_3复合镀层制备及其在棘轮轴轴颈的应用

采用电沉积方法在棘轮轴轴颈镀覆Ni-Al_2O_3复合镀层,以期提高其耐磨性能。选用平板形阴极先进行理论性研究,分析了镀液中纳米Al_2O_3颗粒浓度对Ni-Al_2O_3复合镀层形貌及耐磨性能的影响。结果表明,随着镀液中纳米Al_2O_3颗粒浓度由5 g/L增加至20 g/L,Ni-Al_2O_3复合镀层的磨损量逐渐降低;当镀液中纳米Al_2O_3颗粒浓度为20 g/L时,Ni-Al_2O_3复合镀层中Al_2O_3的质量分数最高,达到4.56%,磨损量最低,约为3.93 mg。Ni-Al_2O_3复合镀层改善了棘轮轴轴颈的表面形貌,降低了棘轮轴轴颈的摩擦系数,可作为减摩耐磨层,有效提高棘轮轴轴颈的耐磨性能。     

电流密度对电镀铜-镍合金微观结构和耐蚀性的影响

采用直流电沉积法在高锰铝青铜基体上制得Cu-Ni合金镀层,镀液组成和工艺条件为:CuSO4·5H2O 20 g/L,NiSO4·6H2O 84 g/L,C6H5O7Na3·2H2O 75 g/L,十二烷基硫酸钠0.5 g/L,H3BO320 g/L,电流密度15~30 mA/cm^2,pH 7,温度55℃,搅拌速率300 r/min,时间60 min。研究了电流密度对Cu-Ni合金镀层元素成分、微观形貌和耐蚀性的影响。结果表明,在电流密度30 mA/cm^2下所得到的Cu-Ni合金镀层最厚,为25μm,耐蚀性最好,经乙酸盐雾试验168 h后表面仅有几个微小的腐蚀坑。     

影响ABS塑料三价铬镀层耐蚀性的因素

指出了三价铬镀层"发霉"(抗蚀性差)的主要原因,分析了ABS塑料的选择、成型及三价铬镀层的结构、镀后清洗、包装防护等对三价铬镀层耐蚀性的影响。强调ABS塑料表面粗糙度及后处理的重要性,给出了改善三价铬镀层耐蚀性的措施。     

Effect of electrolyte concentration on the tribological performance of MAO coatings on aluminum alloys

Micro-arc oxidation (MAO) is an efficient approach to improve the hardness, wear resistance, and other properties of aluminum alloys. In order to investigate the effect of the electrolyte concentration on the properties of MAO coatings for LY12 alloy, the voltage variation during the MAO process was recorded. The surface morphologies and phase compositions of the coatings produced with different electrolytes were investigated using scanning electron microscopy and X-ray diffraction, respectively. The roughness and thickness of the coatings were measured using a pocket roughness meter and an eddy-current thickness meter, respectively. The tribological performances of the coatings were investigated against GCr15 bearing steel on a ball-on-disc wear tester in open air. The results showed that with an increase in the Na₂SiO₃ content, the working voltage of the MAO process decreased, the roughness and thickness of the coatings increased significantly, and the relative content of the α-Al₂O₃ phase decreased. With an increase in the KOH content, the working voltage decreased slightly, the roughness and thickness of the coatings increased slightly, and the α- and γ-Al₂O₃ phase contents remained unchanged. The friction coefficient and wear rate of the coatings increased with an increase in the Na₂SiO₃ and KOH concentrations. A decrease in the porosity and roughness and an increase in the α-Al₂O₃ content of the coatings reduced their wear mass loss.     

Surface modification of ceramic coating for enhanced hydrophobicity and wear properties

In this paper, a micro–nano structural ceramic coating with good hydrophobicity and wear resistance was successfully prepared by sol–gel method, which is assisted by pore-forming agent and nanoparticles 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane modified. The surface morphology, hardness, roughness, wettability, and tribological properties of three different surface coatings were characterized. With the complication of the surface structure, the roughness of the coating increases from 1.30 to 2.05 μm. Under the combined effect of roughness and long hydrophobic chains, the contact angles of the coatings before and after modification under saline conditions increased from 56.31 to 140.59° (pH4); from 55.58 to 134.40° (pH7); from 53.80 to 132.26° (pH10). Through the comparison of wear rate and wear morphology, it is found that the micro–nano structure coating has the lowest wear rate (0.705 × 10^–6 mm³·N^–1·s^–1) and the smallest plastic deformation. This means that in addition to the good hydrophobicity and chemical stability, the micro–nano structure on the surface also improves the wear resistance of the coating.