氩弧熔覆原位自生(Ti,Nb)C增强镍基复合涂层的抗磨性能

以Ti、C、Nb粉和Ni60A合金粉末为原料,采用氩弧熔覆技术在16Mn钢基材表面分别制备(Ti,Nb)C颗粒增强Ni60A复合涂层(C-Ti-Nb-Ni60A涂层)和Ni60A涂层。应用金相显微镜(OM)、扫描电镜(SEM)、X射线衍射(XRD)对2种涂层的显微组织和物相进行观察与分析,测试涂层的显微硬度和不同载荷下的磨损性能,分析磨损机制。结果表明:C-Ti-Nb-Ni60A复合涂层与基体间呈冶金结合,界面间无气孔和裂纹;C-Ti-Nb-Ni60A复合涂层的显微硬度较基体16Mn钢提高近5倍,较Ni60A涂层提高0.45倍;常温干滑动200 N载荷条件下,CTi-Nb-Ni60A复合涂层的耐磨性能较基体16Mn钢提高6倍,较Ni60A涂层提高近2倍。16Mn钢表面发生严重的磨粒磨损和粘着磨损,Ni60A涂层表面以磨粒磨损为主,C-Ti-Nb-Ni60A复合涂层的磨损机理为显微檫伤磨损。     

烧结熔覆钢表面镍基合金涂层的组织和性能

采用Ni25、Ni45、Ni60合金粉末通过烧结熔覆法在45钢表面制备出不同成分的镍基合金涂层。通过金相显微镜观察和X射线衍射分析等手段对合金涂层的组织形貌、相组成和界面结构进行研究,并对涂层显微硬度进行了测试。结果表明：通过烧结熔覆可以在45钢表面获得较为致密的镍基合金涂层。Ni25合金涂层组织主要为比较粗大的γ-(Ni, Fe)奥氏体以及少量的Cr₂₃C₆碳化物相;Ni45和Ni60合金涂层中除了γ-(Ni, Fe)奥氏体和Cr₂₃C₆碳化物之外,还出现了CrB硼化物。不同成分镍基合金涂层与45钢基体在界面处均形成了良好的冶金结合。当烧结温度1100℃、保温时间15 min时,涂层微观组织致密,硬质相颗粒尺寸较小,分布均匀。Ni60合金涂层的硬度最高,约为HV 735;Ni45合金涂层次之,约为HV 534;Ni25合金涂层硬度最低,只有HV 236。     

镍磷合金碳化硅复合镀层的制备与磨损性能研究

采取化学沉积方法，获得镍磷合金碳化硅复合材料镀层，研究了复合镀层的构成与磨损性能。研究结果表明，镍磷合金中加入碳化硅，不会影响其组织结构，但会显著地提高硬度和耐磨性；复合镀层经过热处理，组织结构发生变化；６７３Ｋ／１ｈ处理后，硬度与耐磨性最高，较镍磷合金镀层具有更高的硬化性能。     

电接触强化对火焰喷涂Ni60-WC涂层及40Cr基材组织及性能的影响

在40Cr基材上利用氧-乙炔火焰喷涂镍基碳化钨(Ni60-WC)复合涂层后,对涂层进行电接触强化。通过金相显微镜观察电接触强化前后涂层截面的显微组织形貌,利用维氏显微硬度仪分析涂层截面的显微硬度分布,并通过SEM面扫描分析涂层与基材的钨元素分布。结果表明,电接触强化工艺能够显著提高涂层质量及硬度,并使涂层与基材间形成良好的冶金结合。     

电弧喷涂含陶瓷颗粒铝基复合涂层的微结构和性能

采用5052半硬铝带分别包覆Al_2O_3、SiC、B_4C、TiC陶瓷颗粒制备的粉芯丝材进行电弧喷涂试验,制备了含陶瓷颗粒的铝基复合涂层。利用光学显微镜、XRD分析了涂层的微观组织和相结构,测试了复合涂层的显微硬度、耐磨性及耐腐蚀性。研究结果表明,制备的铝基复合涂层中含有一定数量的未熔陶瓷颗粒,涂层较为致密,无明显缺陷。含陶瓷铝基涂层的物相主要由Al和所添加的陶瓷相构成,其中在含B_4C陶瓷涂层中还存在Al_3BC、Al_4C_3和AlB_2等新相。陶瓷颗粒的加入有利于提高铝基复合涂层的显微硬度,其中B_4C的加入使涂层中基体相显微硬度提高了1.5倍,这是由于B_4C陶瓷和Al反应生成Al_3BC、Al_4C_3和AlB_2硬质相。复合涂层的耐磨性均优于纯铝涂层,摩擦磨损的形式主要为粘着磨损。动电位极化腐蚀试验表明,含SiC和TiC陶瓷涂层具有较低的腐蚀电流,耐蚀性较好,含SiC陶瓷的复合涂层出现了明显的钝化现象。     

Q235钢表面氩弧熔覆MoNiSi/Ni_3Si金属硅化物复合涂层组织与性能研究

以Mo粉、Si粉、Ni粉为原料,采用氩弧熔覆技术在Q235钢基材表面原位合成了MoNiSi/Ni3Si金属硅化物复合涂层,分析和测试了涂层的显微组织、显微硬度和耐磨性.结果表明:在Q235钢表面成功制备了以MoNiSi/Ni3Si为基体,以金属硅化物MoNiSi为增强相的复合涂层.性能分析结果表明:涂层的显微硬度可达1 000HV,涂层耐磨性较基体提高12倍.     

Cr12MoV钢表面Ni60-WC复合涂层的烧结熔覆制备及组织性能研究

以Ni60-WC合金粉末为原料,通过烧结熔覆在Cr12MoV钢基体表面制备出Ni60-WC复合涂层。采用金相显微镜、X射线衍射仪、洛氏硬度计等分析了Ni60-WC复合涂层的相组成、组织形貌、界面结构和剖面硬度分布,研究了烧结温度、保温时间及热处理工艺对复合涂层组织和性能的影响。结果表明:Ni60-WC复合涂层主要由γ-Ni基固溶体和WC、W_2C、B_6Fe_(23)、BNi_3、FeNi等硬质相组成。当烧结温度为1 050℃、保温时间为30 min时,复合涂层微观形貌致密,孔隙数量较少,界面处形成良好的冶金结合。热处理促进了涂层与基体之间合金元素的扩散,有效提高了基体和涂层的硬度,涂层硬度值由59 HRC提高到65 HRC。     

离心式注水泵火焰超音速喷涂金属陶瓷涂层性能试验研究

通过研究离心式注水泵的使用工况及失效机理,设计了一种火焰超音速喷涂工艺制备的以镍、钴合金为主的复合金属陶瓷涂层提高离心式注水泵叶轮的泵效,对涂层进行金相观察、显微硬度分析、涂层结合强度试验及耐空蚀性能测试,结果表明,镍基金属陶瓷涂层与基体结合强度高,抗空蚀性能优良.     

Ni-SiO2复合镀层电沉积制备及组织性能研究

利用直流电沉积方法在Zr-4合金表面制备了Ni-SiO₂复合镀层,采用场发射扫描电镜、显微硬度计、电化学工作站、摩擦磨损试验机等研究复合镀层的表面形貌、显微硬度、耐腐蚀性及摩擦磨损性能。研究结果表明:与单一的Ni镀层相比较,Ni-SiO₂复合镀层的显微硬度值有所提升,表面更为均匀,Ni-SiO₂复合镀层的耐腐蚀性能和耐磨性能也得到明显提升。且当SiO₂颗粒添加量为10 g/L时,复合镀层的综合性能较优。      

铝合金表面激光熔覆稀土CeO_2+Ni60组织及摩擦磨损性能

为了提高铝合金材料的表面性能,使其具有较高的硬度和耐磨性,利用激光熔覆技术在6063铝合金表面制备了添加稀土氧化物CeO2的Ni60合金熔覆层。分析了激光熔覆CeO2+Ni60熔覆层的宏观形貌、显微组织及硬度,研究了其摩擦磨损性能,并与未添加稀土的Ni60合金熔覆层和铝合金基体进行了对比研究。结果表明,加入2%CeO2可降低Ni60熔覆层表面起伏,获得较好的熔覆层宏观形貌,同时有效地减少Ni60熔覆层中的裂纹、孔洞和夹杂物,促进晶粒细化,提高熔覆层的组织均匀性;添加2%CeO2的Ni60熔覆层比未加稀土的Ni60熔覆层组织更加均匀,晶粒较细小,气孔等组织缺陷更少,熔覆质量较好;在相同深度位置的显微硬度,2%CeO2+Ni60熔覆层明显高于Ni60熔覆层,2%CeO2+Ni60熔覆层最高硬度可达HV0.051180,是6063铝合金基体平均硬度的8.4倍;在相同磨粒磨损条件下,2%CeO2+Ni60熔覆层试样的耐磨性是铝合金基体的7.1倍,是Ni60熔覆层试样的1.6倍;激光熔覆Ni60可以显著降低铝合金表面摩擦系数,而添加稀土元素Ce能提高Ni60熔覆层的摩擦系数稳定性,从而改善耐磨性能。     

Development of CeO2 nanorods reinforced electrodeposited nickel nanocomposite coating and its tribological and corrosion resistance properties

A simple electrodeposition technique was used to prepare Ni-CeO_2 nanorods composite coating(Ni-CeO_2 NRs) using Watt's nickel plating bath containing CeO_2 nanorods(NRs) as the reinforcement phase under optimized process conditions. The X-ray diffraction analysis(XRD) was used for the structural analysis of Ni-CeO_2 NRs composite coatings and their average crystalline size is ～22 nm for pure Ni and ～18 nm,respectively. The crystalline structure is fcc for the Ni-CeO_2 nanocomposite coatings. The surface morphology of the electrodeposited Ni-CeO_2 NRs composite coatings was analyzed by scanning electron microscopy(SEM). Microhardness of pure Ni and Ni-CeO_2 NRs composite coatings are found to be 253 HV and 824 HV, respectively. The inclusion of CeO_2 NRs increases the microhardness of Ni-CeO_2 NRs composite coatings. The corrosion resistance behavior of Ni-CeO_2 NRs composite coating was evaluated by Tafel polarization and AC impedance methods. It is revealed that CeO_2 NRs reinforced Ni matrix shows higher microhardness and corrosion resistance than existing reported electrodeposited pure Ni and CeO_2 nanoparticles reinforced Ni coatings.     

三价铬超声-脉冲电沉积Fe-Ni-Cr/SiC纳米复合镀层

利用超声-脉冲复合电沉积法,在三价铬镀液体系中,添加羧酸盐-尿素配合剂和SiC纳米颗粒,制备了Fe-Ni-Cr/SiC纳米复合镀层.研究了超声-脉冲工艺参数与SiC纳米粒子复合量、Cr含量及镀层厚度的关系;利用稳态极化曲线和循环伏安法分析了超声波对阴极电化学行为的影响.结果表明,超声-脉冲作用均有利于基质金属Fe、Ni和Cr的电沉积,提高了镀层中SiC和Cr的含量以及镀层的厚度.利用扫描电镜、X射线衍射仪和能谱仪对Fe-Ni-Cr/SiC纳米复合镀层的表面形貌、微观结构和组成等进行表征,发现采用该技术可制备厚度为23.56μm,SiC和Cr质量分数分别为4.1%和25.1%的Fe-Ni-Cr/SiC纳米复合镀层.磨损量和腐蚀曲线测试结果表明,SiC含量高的复合镀层,其耐磨性和耐蚀性更好.      

Preparation and tribological performance of electrodeposited Ni-TiB2-Dy2O3 composite coatings

TiB2 and Dy2O3 were used as codeposited particles in the preparation of Ni-TiB2-Dy2O3 composite coatings to improve its per-formance. Ni-TiB2-Dy2O3 composite coatings were prepared by electrodeposition method with a nickel cetyltrimethylanunonium bromide and hexadecylpyridinium bromide solution containing TiB2 and Dy2O3 particles. The content of codeposited TiB2 and Dy2O3 in the compos-ite coatings was controlled by adding TiB2 and Dy2O3 particles of different concentrations into the solution, respectively. The effects of TiB2 and Dy2O3 content on microhardness, wear mass loss and friction coefficients of composite coatings were investigated. The composite coat-ings were characterized by X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectrometer (ICP-AES) and scanning electron microscopy (SEM) techniques. Ni-TiB2-Dy2O3 composite coatings showed higher microhardness, lower wear mass loss and friction coefficient compared with those of the pure Ni coating and Ni-TiB2 composite coatings. The wear mass loss of Ni-TiB2-Dy2O3 composite coatings was 9 and 1.57 times lower than that of the pure Ni coating and Ni-TiB2 composite coatings, respectively. The friction coefficient of pure Ni coating, Ni-TiB2 and Ni-TiB2-Dy2O3 composite coatings were 0.723, 0.815 and 0.619, respectively. Ni-TiB2-Dy2O3 composite coat-ings displayed the least friction coefficient among the three coatings. DY2O3 particles in composite coatings might serve as a solid lubricant between contact surfaces to decrease the friction coefficient and abate the wear of the composite coatings. The loading-bearing capacity and the wear-reducing effect of the Dy2O3 particles were closely related to the content of Dy2O3 particles in the composite coatings.     

Fabrication and Characterization of Ni-SiC Nanocomposite Coatings on Al Substrates by Ball Impact Deposition Method

Micron-size Ni and SiC powder mixtures were used to prepare Ni-SiC nanocomposite coatings on an Al substrate by employing a high-energy ball milling technique. Ni:SiC weight ratio was varied over a wide range to explore the effect of the charge composition on the microstructure, composition, microhardness, and wear properties of the depositions. It was observed that the composition of the produced coating was correlated to the charge composition in a complex manner, which suggests that deposition rates for Ni and SiC particles significantly vary depending on the charge composition; SiC deposition rate was higher than that of Ni when Ni:SiC weight ratio was greater than 3:1. Diffusion of Al from the substrate into the Ni matrix provided evidence for the metallurgical bonding at the interface. Both microstructural and mechanical properties of the produced coatings were found to be crucially dependent on the charge composition. By increasing the SiC content in the charge from about 5 to 33 wt pct, the mechanical properties enhanced due to the dispersion strengthening effect of the incorporated SiC particles in the coatings and the crystallite size of the Ni matrix decreasing to the nanometer range. However, a further increase resulted in the formation of a coating with a poor degree of compaction. It was found that the composite coating with about 15 vol pct SiC, produced from the charge with Ni:SiC weight ratio of 2:1, showed a microhardness as high as 830 HV_0.05 along with excellent wear resistance. Despite the current sample size limitations for applying high-energy ball milling, the present findings demonstrate that the adopted technique holds good prospect for the synthesis of nanostructured metal matrix composite coatings with enhanced and tunable properties.

     

Alkaline Electrodeposition of Ni–ZnO Nanocomposite Coatings: Effects of Pulse Electroplating Parameters

The effects of applied current density (1–10 A/dm²), pulse frequency (1–100 Hz) and duty cycle (10–75 %) on the morphology and microhardness of Ni and Ni–ZnO coatings, incorporation rate of ZnO nanoparticles, current efficiency and deposition rate were investigated. Ni–ZnO composites exhibited a nodular morphology. At low current densities, smooth and compact Ni–ZnO coatings were obtained. As the current density increased more gaps and defects appeared on the coatings surface. Maximum incorporation rate of 4.04 vol% was achieved at the current density of 10 A/dm². Presence of ZnO nanoparticles in the electrolyte improved the current efficiency of the process and deposition rate of the matrix. The microhardness values of the composites were considerably higher than those of the nickel coatings.     

Characteristics and properties of Cu/nano-SiC and Cu/nano-SiC/graphite hybrid composite coatings produced by pulse electrodeposition technique

In this study, Cu/SiC and Cu/SiC/graphite nano-composite coatings were prepared by using pulse current electrodeposition technique. The effects of pulse parameters and graphite particles concentration of the bath on co-deposition of these particles were investigated. Morphology, composition, structure, microhardness, tribological behaviour and corrosion properties of Cu/SiC/graphite coatings were studied and compared to those of the substrate and Cu/SiC films. The results revealed that the optimum current density, pulse frequency and duty cycle for obtaining the highest graphite content within the coatings were 12?A?dm^?2, 15?Hz and 5%, respectively. According to X-ray diffraction results, all the coatings had face-centred cubic structure, but with different preferred orientations. While Cu/SiC coatings had higher hardness and corrosion resistance than the Cu/SiC/graphite hybrid composites, the lowest wear rate was obtained at Cu/6.8vol.-% SiC/6.7vol.-% graphite hybrid composite film.     

Comparison in the Oxidation and Corrosion Behavior of Aluminum and Alumina-Reinforced Ni/Ni-Co Alloy Coatings

In this study, a comparison in the oxidation and corrosion behavior of Ni/Ni-Co aluminum and alumina-reinforced electrodeposited composites has been made. The developed coatings were characterized for the morphology, structure, microhardness, oxidation, and corrosion resistance. It was found that the incorporation of Al particles in NiCo matrix is higher (9 wt pct) compared to Ni matrix (1 wt pct). In the case of aluminum oxide particles, about 5 and 7 wt pct had been obtained in Ni and NiCo matrices respectively. The difference in the surface morphology was observed with respect to metallic (Al) and inert ceramic (Al₂O₃) particle incorporation. X-ray diffraction studies showed the presence of predominant Ni (200) reflection in the coatings. Also, peaks corresponding to Al and Al₂O₃ particles were present. The Ni/NiCo-Al coatings exhibited higher microhardness values at 1273 K (1000 °C) compared to alumina-reinforced coatings, indicating better thermal stability of the former coatings. The NiAl coating showed one and two orders of magnitude improved oxidation resistance compared to NiCoAl and Ni/NiCo-Al₂O₃ coatings, respectively. It was observed that the Ni-Al composite coating exhibited poor corrosion resistance in 3.5 pct NaCl solution compared to the other coatings studied.     

Ni–ZrO2 Composite Coating by Electro-Co-Deposition

In the present investigation Ni–ZrO₂ metal matrix composite coatings were prepared on steel substrate using watt’s type solution through electro-co-deposition process with different weight percentages of zirconia powder dispersed in the bath. In the coating, nickel is present with faceted appearance along with ZrO₂. The microhardness and wear resistance of the coatings increase with increasing weight percentage of particles content in the coating. The hardness of the resultant coatings was found to be 325 VHN for pure Ni coating whereas 401VHN for Ni–ZrO₂ (15 g/l ZrO₂) coating depending on the particle volume in the Ni matrix. The results also showed that the wear resistance of the composite coatings was improved as compared to unreinforced Ni deposited material. Strengthening of the coating was attributed to the ZrO₂ dispersion and partially favorable texture.     

Y2O3对NiCr-Cr3C2金属陶瓷涂层热腐蚀性能影响行为研究

本文利用超音速火焰喷涂技术(HVOF),在20G钢表面制备了掺杂1wt.%、3wt.%、5wt.%三种不同含量Y2O3的NiCr-Cr3C2金属陶瓷复合涂层,并探究了其在650℃,Na2SO4/K2SO4熔盐环境中的热腐蚀性能。利用扫描电镜(SEM)、显微硬度计、拉伸试验机等对涂层的微观结构和力学性能进行了表征,利用X射线衍射仪(XRD)、拉曼光谱、X射线能谱仪(EDS)对复合涂层热腐蚀产物形貌、物相进行分析。结果表明掺杂1wt.%Y2O3的NiCr-Cr3C2复合涂层结构致密、孔隙率低、结合强度高,显微硬度达到801HV。热腐蚀过程中掺杂Y2O3的NiCr-Cr3C2复合涂层表面均生成耐蚀性良好且致密的Cr2O3膜。随着Y2O3掺杂量的增加,涂层的耐热腐蚀性能先升高后下降,当Y2O3掺杂量为1wt.%时,复合涂层表现出最佳的耐热腐蚀性能。