Ni-P/nano-Al_2O_3复合镀层的制备及性能

以汽车模具配件—导柱常用的20Cr钢为基材,在其表面制备Ni-P/nano-Al_2O_3复合镀层及普通Ni-P镀层。对Ni-P/nano-Al_2O_3复合镀层的微观形貌、晶相结构、显微硬度和摩擦磨损性能进行了测试与分析,并与Ni-P镀层和基材进行了对比。结果表明,Ni-P/nano-Al_2O_3复合镀层的晶粒细小,结构更加致密,显微硬度平均值可达到436.4 HV,高于Ni-P镀层的357.3 HV和基材的190HV;与Ni-P镀层相比,Ni-P/nano-Al_2O_3复合镀层能更有效地改善基材的摩擦磨损性能。NanoAl_2O_3颗粒复合量对Ni-P/nano-Al_2O_3复合镀层的显微硬度和摩擦磨损质量损失率有一定影响,增加颗粒复合量可以提高复合镀层的显微硬度,改善其摩擦磨损性能。     

电刷镀镍–钨–二硫化钼复合镀层的组织和耐摩擦磨损性能

采用复合电刷镀工艺在2Cr13不锈钢基材上制备了Ni–W–纳米MoS_2复合镀层。采用扫描电镜、显微硬度计和摩擦磨损试验机对镀层微观形貌、显微硬度和耐摩擦磨损性能进行分析。结果表明:与Ni–W合金镀层相比,Ni–W–纳米MoS_2复合镀层的表面更加平整、致密,显微硬度较低,耐摩擦磨损性能较优。随镀液中Mo S2纳米颗粒质量浓度的增大,复合镀层的摩擦因数小幅下降,磨损量先降后升。当镀液含20 g/L MoS_2时,所得Ni–W–纳米MoS_2复合镀层的综合性能最优。     

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.     

40Cr钢汽车传动轴表面电沉积Ni-SiC纳米复合镀层的研究

在以40Cr钢为基材的汽车传动轴表面制备出Ni-SiC纳米复合镀层,检测并分析了复合镀层的显微结构、硬度、抗磨损性能和耐腐蚀性能,并与40Cr钢基材进行了对比。结果表明,Ni-SiC纳米复合镀层主要由Ni、SiC相组成,其平均硬度约为558.4 HV,是40Cr钢硬度的1.5倍。镀层稳定时的摩擦因数维持在0.39左右,相比40Cr钢明显降低,镀层的腐蚀速率也明显低于40Cr钢。Ni-SiC纳米复合镀层能提高汽车传动轴的抗磨损性能和耐腐蚀性能。     

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。     

汽车活塞销镀Ni-Co合金镀层表面改性及性能研究

利用电镀技术,在汽车活塞销表面制备Ni-Co合金镀层实现表面改性。概述了活塞销表面改性的工艺过程,观察了表面改性后活塞销的形貌,检测了Ni-Co合金镀层与活塞销基体的结合强度以及表面改性后活塞销的硬度、抗拉强度及耐摩擦磨损性能。结果表明,Ni-Co合金镀层与活塞销基体结合牢固,表面改性后活塞销的表面平整均匀,硬度和抗拉强度均提高,表现出较好的耐摩擦磨损性能。Ni-Co合金镀层有效改善了活塞销的表面状况,使活塞销的硬度提高约17%,抗拉强度提高约7.2%,磨损量和磨损速率分别下降17.5%和17.9%。     

Ni-P-纳米Al2O3复合镀层耐磨性能研究

本文通过在Ni-P合金化学镀液中加入纳米α-Al2O3颗粒,获得Ni–P–纳米Al2O3复合镀层。采用SEM对Ni–P–Al2O3复合镀层的表面形貌进行分析;采用EDX对复合镀层中的元素进行分析;用显微硬度计测量了不同Al2O3质量分数下镀层的硬度值;通过MM-W1立式万能摩擦磨损试验机对复合镀层的磨损性能进行了评价,并分析了复合镀层的磨损机理。结果表明:纳米Al2O3的加入可以增加镀层的硬度,并能有效地降低摩擦副之间的犁沟效应及摩擦表面发生粘着的面积,从而减少镀层的磨损。     

工程车活塞杆用45~#钢电沉积Ni-WC纳米复合镀层的研究

在工程车活塞杆常用材料45#钢表面电沉积Ni-WC纳米复合镀层。分析了纳米复合镀层的表面形貌和物相结构,测试了纳米复合镀层的耐磨性和耐蚀性,并与45#钢的性能做比较。结果表明:纳米复合镀层表面较平整、均匀,结构较致密,主要由Ni相、WC相组成,Ni相的质量分数为81.25%,WC相的质量分数为6.53%,孔隙率低于0.5%,平均摩擦因数约为0.28;相同条件下,纳米复合镀层的腐蚀速率低于45~#钢的;纳米复合镀层能够提供有效的磨损防护和腐蚀防护,提高45~#钢的耐磨性和耐蚀性。     

电沉积铜基纳米碳化硅复合镀层实验研究

采用电沉积方法,制备铜基纳米碳化硅复合镀层。研究溶液搅拌方式或溶液中引入添加剂,对Cu-SiC纳米微粒复合镀层表面形貌和性能的影响。利用超声搅拌制备的Cu-SiC纳米微粒复合镀层的表面形貌平整而且致密,与磁力搅拌所得镀层相比显微硬度提高约32%,接近143 HV,磨损质量损失降低约33%,每平方毫米为0.056 mg。溶液中引入添加剂,制备的Cu-SiC纳米微粒复合镀层的表面形貌和性能无明显改观,但采用超声波搅拌制备的Cu-SiC纳米微粒复合镀层的表面形貌和性能改观较为明显。添加剂发挥的作用与超声搅拌引发的综合作用叠加,促使复合镀层的表面形貌和性能进一步改善。     

憎水性Ni-PTFE复合镀层的制备及其摩擦磨损性能的研究

采用复合电镀法制备Ni-PTFE复合镀层,考察了表面活性剂、电流密度、pH值和镀液中PTFE添加量对复合镀层中PTFE含量的影响.并进一步研究了镀层中PTFE含量对复合镀层硬度、摩擦磨损性能和憎水性能的影响.结果表明,最佳工艺条件下制备的复合镀层具有良好的憎水性和优异的摩擦磨损性能.     

汽车活塞销表面纳米复合镀层的制备及耐磨性预测

在汽车发动机活塞销表面制备Ni-ZrO_2纳米复合镀层,以期提高活塞销表面的耐磨性。通过正交试验,得到影响纳米复合镀层磨损量的因素主次顺序,并在正交试验基础上建立BP神经网络模型,对纳米复合镀层的磨损量进行预测,进而评价其耐磨性。研究表明:BP神经网络模型能用于预测纳米复合镀层的磨损量,磨损量的预测值与实验值具有较高的拟合度。通过正交试验与运用BP神经网络模型优化的最佳参数组合相同,采用最佳参数组合制备的纳米复合镀层的磨损量较低(仅为4.26mg),其耐磨性良好。     

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。     

活塞式压缩机曲轴连杆轴颈表面改性实验研究

采用纳米复合镀方法,对活塞式压缩机曲轴连杆轴颈进行表面改性。表征了表面改性前后曲轴连杆轴颈的形貌,测试了表面改性前后曲轴连杆轴颈的硬度和疲劳性能。结果表明:表面改性后曲轴连杆轴颈的形貌显得平整、致密,硬度更高,疲劳性能有所改善。镀纳米复合镀层以实现表面改性,能够提高曲轴连杆轴颈的性能。     

合金钢导套微损伤外表面的修复研究

利用电镀技术并辅助适度的低温热处理,镀覆Ni-Si C纳米复合镀层作为修复层,修复合金钢导套微损伤外表面。采用扫描电镜表征修复后导套外表面的显微结构,用划痕法检测修复层的附着强度,并通过干摩擦试验和盐雾试验检测修复后导套外表面的耐磨性能和耐蚀性能。结果表明,修复后导套外表面平滑、均匀,组织结构致密,修复层附着牢固;修复后导套外表面的磨损量和腐蚀率均低于全新导套,磨痕形貌和腐蚀形貌也不同。Ni-Si C纳米复合镀层能够起到减摩和防护的双重作用,修复后导套外表面的耐磨性能和耐蚀性能均符合预期。     

Investigation of tribological properties of micro-arc oxidation ceramic coating on Mg alloy under dry sliding condition

To enhance wear resistance of Mg alloy, micro-arc oxidation (MAO) ceramic coatings on Mg substrate were prepared in silicate electrolyte under various currents. It was found that the surface roughness and thickness of MAO coating were increased with the increase of current. The dry tribological tests showed that the friction coefficient and wear resistance of thicker coatings (obtained under currents of 3?A and 4?A) were much higher than that of Mg alloy and the thin coating (obtained under current of 2?A), meanwhile the lifetime of the coating obtained under 4?A was longer than the other coatings under higher load. The wear type of thin MAO coating was slight abrasive wear under low load, whereas translated to severe adhesive wear under high load. While the main wear mechanism of thick MAO coating was slight abrasive wear or scratch under the given test condition, which was attributed to the thick intermediate layer improved load support for the soft substrate. The tribological study indicated that the MAO coating obtained under 4?A current had better wear resistance and life time due to its compact microstructure and thickness.     

Effect of MoS2/PTFE coatings on performance of Si3N4/TiC ceramics in dry sliding against WC/Co

To enhance the tribological performance of Si₃N₄/TiC ceramics, MoS₂/PTFE composite coatings were deposited on the ceramic substrate through spraying method. The micrographs and basic properties of the MoS₂/PTFE coated samples were investigated. Dry sliding friction experiments against WC/Co ball were performed with the coated ceramics and traditional ones. These results showed that the composite coatings could significantly reduce the friction coefficient of ceramics, and protect the substrate from adhesion wear. The primary tribological mechanisms of the coated ceramics were abrasive wear, coating spalling and delamination, and the tribological property was transited from slight wear to serious wear with the increase of load because of the lower surface hardness and shear strength. The possible mechanisms for the effects of MoS₂/PTFE composite coatings on the friction performance of ceramics were discussed.     

Study on the tribological performance of ceramic coatings on titanium alloy surfaces obtained through microarc oxidation

Through microarc oxidation, a ceramic coating is directly formed on the surface of Ti6Al4V alloy, by which its surface property is greatly improved. Microstructure, phase composition and tribological performance of the coatings were characterized. The results showed that the coating with 10-μm thickness is compact in the inner layer and porous in the surface layer. The coating is mainly composed of rutile and anatase TiO₂. The tribological behavior of the microarc oxidation ceramic coating under dry sliding against SAE52100 steel was evaluated on a ball-on-disc test rig. The Ti6Al4V alloy was characterized by adhesion wear and scuffing under dry sliding against the steel, while the polished ceramic coating experienced much abated adhesion wear and scuffing under the same testing condition. The polished ceramic coating showed good friction-reducing and fair antiwear ability in dry sliding against the steel. This is attributed to the smooth surface and rutile TiO₂.     

Tribomechanical and microstructural properties of cathodic arc-deposited ternary nitride coatings

Sintered carbides are promising materials for surfaces that are exposed to extreme wear. Owing to their high service load, ceramic-based thin films are coated on carbides using different techniques. In this study, non-toxic and cobalt-free powder metallurgy-sintered carbide samples were coated with TiN, TiAlN, CrAlN, and TiSiN ceramic-based thin film coatings by cathodic arc physical vapor deposition. The microstructure (phase formation, coating thickness, surface roughness, and topography), mechanical properties (hardness, modulus of elasticity, and plasticity indices), and tribological properties (nanoscratch and wear behavior) of the thin film coatings were investigated. No cracks or defects were detected in these layers. The ceramic-based ternary nitride thin film coatings exhibited better mechanical performance than the TiN coating. The TiN thin film coating had the highest average surface roughness, which deteriorated its tribological performance. The ternary nitride thin film coatings exhibited high toughness, while the TiN thin film coating exhibited brittle behavior under applied loads when subjected to nanoscratch tests. The wear resistance of the ternary nitride coatings increased by nearly 9–17 times as compared to that of the TiN coating and substrate. Among all the samples investigated, the substrate showed the highest coefficient of friction (COF), while the TiSiN coating exhibited the lowest COF. The TiSiN thin film coating showed improved mechanical and tribological properties as compared to other binary and ternary nitride thin film coatings.