纳米SiC涂层的电泳沉积工艺及其抗氧化性能

过去,对电泳沉积siC涂层的研究大多局限于沉积机理方面,对涂层的制备技术方面鲜有报道.为此,采用电泳沉积法在石墨基体上涂敷纳米SiC,分析了沉积时间、电压、粘结剂、添加剂量、固含量和沉积参数对纳米SiC沉积状况的影响,得出了电泳沉积制备SiC涂层的优化参数:电压120 V,SiC纳米粉末固含量30 g/L,PVB 15 g/L,正丁醇1.0%(体积分数),时间3 min.所制备样品经烧结处理即为石墨的SiC涂层,涂层经氧化后能形成致密的SiO2保护膜,具有优良的抗氧化性能.     

电泳沉积-烧结制备石墨材料SiC涂层的研究

采用电泳沉积法在石墨基体上制备厚度可控的Si涂层,考察了电泳沉积参数(电压、沉积时间、固含量及添加剂量)对涂层沉积量的影响.所制备的Si涂层通过烧结与石墨基体发生在位反应形成SiC涂层.用SEM观察涂层烧结前后的形貌,发现烧结后Si渗入基体内部.孔径分布数据表明所形成的SiC涂层导致石墨孔径变小.实验提供了一种制备SiC涂层的新方法,电泳沉积一烧结可用于C/SiC复合材料的制备.     

水热电泳沉积功能陶瓷涂层技术的研究进展

水热电泳沉积技术结合了水热法和电泳沉积法的优点,是近几年发展起来的制备功能涂层的重要工艺技术,有着良好的应用前景.详细介绍了水热电泳沉积技术的原理、影响沉积工艺的因素,概述了水热电泳沉积动力学并总结了该技术在制备功能陶瓷涂层上的应用.指出水热电泳沉积技术是很有发展前景的涂层制备工艺;在进行水热电泳沉积应用研究的同时,应进一步开展其理论研究,探索水热电泳沉积技术的原理,建立合理的具有指导意义的理论及数学模型.     

沉积电压对水热电泳沉积硅酸钇涂层显微结构的影响

采用水热电泳沉积法在SiC-C/C复合材料SiC内涂层表面制备了硅酸钇抗氧化外涂层,并借助X射线衍射(XRD)、扫描电子显微镜(SEM)对涂层的相组成及显微结构进行了表征.讨论了沉积电压对硅酸钇涂层沉积量及显微结构的影响,并研究了不同沉积电压下涂层沉积量与时间的关系,同时测试了涂层试样的抗氧化性能.研究结果表明,随着沉积电压的升高,涂层的沉积量有所增加,涂层的致密性和均匀性也逐渐得到改善.当电压为210V时达到最佳,继续升高沉积电压,涂层的均匀性变差,当沉积电压为240V时,涂层出现明显开裂;不同沉积电压下涂层沉积量随时间呈抛物线变化;涂层在1500℃静态空气中经过10h氧化后,失重仍然小于2%.     

粉末粒度对等离子喷涂Al2O3-13%TiO2陶瓷涂层组织结构及性能的影响

等离子喷涂粉末的粒度影响涂层组织结构与性能。选用4种不同粒度的Al2O3-13%TiO2(AT13)粉末等离子喷涂陶瓷涂层,研究了喷涂粉末粒度对涂层组织结构、孔隙率、显微硬度和沉积效率的影响。结果表明:采用较细的喷涂粉末制备的AT13涂层致密、均匀,孔隙率低;随着喷涂粉末粒度增大,涂层的孔隙率增加,显微硬度降低,沉积效率先增后减;采用粒度为38～44μm的粉末喷涂涂层时沉积效率最高,达到51%,涂层组织也较致密,这是等离子喷涂AT13陶瓷层较理想的粒度。     

高频感应炉制备碳化钛粉的研究

以颜料级二氧化钛和木炭为原料,探索一种高频感应碳热还原制备超细碳化钛粉末的新方法,并借助XRD,SEM/EDS,原子吸收光谱仪,X射线荧光光谱仪以及激光粒度分析仪等设备对粉末进行表征。结果表明,原料二氧化钛和木炭在很短的时间内充分反应并制备出低杂质含量的超细碳化钛粉末,反应温度为1490～1510℃,粒度分布(D50)在1～10μm之间,粉末颗粒形状一致,分布均匀且无大块团聚现象。晶格常数计算表明,原料配比为1∶3时制备的碳化钛粉末中可能存在亚化学计量的TiCx(x1)。当原料配比为1∶4时制备出化学计量的碳化钛粉末(TiC1.0)。     

烧结NdFeB永磁体表面TiO2/聚氨酯基复合涂层的制备及耐蚀性研究

采用阴极电泳沉积在烧结NdFeB永磁体表面制备了TiO_2纳米颗粒增强的聚氨酯涂层,研究了电泳沉积过程中电流密度的变化趋势和电泳液中二氧化钛颗粒浓度对复合涂层的表面形貌、粗糙度、接触角、显微硬度和耐蚀性的影响。结果表明,电泳沉积过程中电流密度随着时间的延长而降低,大致可分为3个阶段;二氧化钛颗粒可均匀弥散地分布在聚氨酯基体中,随着电泳液中二氧化钛浓度的增加,复合涂层中镶嵌的颗粒越多,导致表面粗糙度和硬度增大,而接触角降低;复合涂层可大幅度降低NdFeB试样在H_2SO_4溶液中浸泡的质量损失,且二氧化钛浓度越大,质量损失越小,即纳米二氧化钛颗粒的掺入进一步提高了NdFeB永磁体的耐蚀性。     

电泳沉积制备BG／BG—FHA复合涂层

采用电泳沉积在Ti6A14V钛合金表面制备了以生物玻璃（BG）为中间层,BG与氟取代磷灰石（FHA）复合粉末为表层的BG／BG—FHA涂层。通过XRD、SEM、EDS和电子万能力学试验机对BG／BG—FHA复合涂层的物相结构、微观形貌和涂层结合力进行了分析,优化了涂层的热处理制度,并通过模拟体液浸泡实验研究了涂层的体外...     

氮碳化钛涂层制备技术的研究进展

氮碳化钛涂层具有优良的力学及摩擦学性能,作为硬质耐磨涂层,已广泛用于切削刀具、钻头和模具等,具有广阔的应用前景.综述了氮碳化钛涂层主要的制备技术,分析了温度、化学组分、涂层厚度等因素对涂层性能的影响,并指出了其发展趋势.     

紫外-可见光谱分析碳纳米管电泳液浓度对阴极场发射性能的影响

将酸化的碳纳米管(CNT)粉末、硝酸镁置于异丙醇溶剂中超声处理,制备成分散均匀的CNT电泳液.采用不同CNT浓度的电泳液在CrCuCr电极上电泳沉积CNT薄膜,并对阴极样品进行场发射性能测试;同时采用紫外-可见光谱仪对CNT电泳液进行光谱分析.结果表明,CNT浓度为0~0.13 g/L的电泳液在258 nm处存在光谱吸收,且其吸光度与相应CNT浓度呈良好的线性关系;当CNT浓度为0.12 g/L时电泳沉积制备的CNT阴极场发射性能较好,其开启电场为0.903 V/μm,当电场强度为1.395 V/μm时场发射电流密度为2.903 mA/cm2.利用紫外-可见光谱可以有效地分析电泳液中CNT浓度,为电泳沉积良好质量的CNT薄膜提供了保证.     

Electrophoretic deposition of YSZ powders for solid oxide fuel cells

The technological feasibility of applying Electrophoretic Deposition (EPD) to Solid Oxide Fuel Cells (SOFCs) has been studied. Here, EPD characteristic of SOFC composition material powders has been investigated from the viewpoint of DC and AC electrochemical experiments. An electrolyte of SOFCs required gas tight dense coating. Commercial YSZ (3–8 mol% yttria stabilized zirconias) powders, as for the electrolyte materials, and various organic solvents were used in this study. In the case of 8YSZ (Tosoh, TZ-8Y) dispersed n-propanol bath, the zeta potential of 8YSZ particle showed positive and grain size distribution showed less than 0.1 m. 8YSZ powder can be electrophoretically deposited onto the substrate because dispersed particle has charged and the charged particle acts as a migration onto the substrate by the potential gradient, and dense uniform coating was obtained less than 100 V/cm. On the other hand, as-deposited YSZ coating acts as a function of insulated layer. Potential gradient in the EPD bath has decreased because resistance of YSZ layer becomes higher than that of EPD bath with the progress of EPD under applied constant voltage. However, EPD bath characteristic itself does not change with the progress of EPD. It is suggested that the YSZ powder well dispersed EPD bath can be found by using 8YSZ and n-propanol.     

Microstructure and wear properties of Fe–TiC surface composite coating by laser cladding

AISI 1045 steel surface was alloyed with pre-placed ferrotitanium and graphite powders by using a 5-kW CO₂ laser. In situ TiC particles reinforced Fe-based surface composite coating was fabricated. The microstructure and wear properties were investigated by means of scanning electron microscopy, transmission electron microscopy, and X-ray diffraction, as well as dry sliding wear test. The results showed that TiC carbides with cubic or flower-like dendritic form were synthesized via in situ reaction between ferrotitanium and graphite in the molten pool during laser cladding process. The TiC carbides were distributed uniformly in the composite coating. The TiC/matrix interface was found to be free from cracks and deleterious phase. The coatings reinforced by TiC particles revealed higher wear resistance than that of the substrate.     

C/ Ti 原子比对反应火焰喷涂TiC/ Fe 复合涂层组织结构和硬度的影响

以TiFe 粉和碳的前驱体(石油沥青) 为原料, 用前驱体碳化复合技术制备了Ti-Fe-C 反应喷涂复合粉末, 并采用普通火焰喷涂技术成功制备了TiC/ Fe 陶瓷金属复合涂层。研究了不同C/ Ti 原子比对反应火焰喷涂TiC/ Fe 复合涂层相组成、显微结构和硬度的影响。结果表明, 前驱体碳化复合技术制备的Ti-Fe-C 系反应喷涂复合粉末中C/ Ti 原子比是影响涂层相组成、显微结构和硬度的关键因素。C/ Ti 原子比不同, 涂层的相组成和硬度不同; 随着C/ Ti 原子比增大, 涂层中TiC 团聚富集区增大, 涂层的孔隙率也随之增大。      

感应熔覆原位自生TiC/Ni基复合涂层的组织与耐磨性研究

为了提高16Mn钢的干滑动磨损耐磨性能,以Ni60、钛粉和石墨粉为原料对16Mn钢表面进行感应熔敷处理,制备出以TiC颗粒为增强相的原位自生复合涂层,利用金相、SEM、XRD等技术分析了涂层的显微组织,在室温干滑动磨损试验条件下测试了涂层的耐磨性.结果表明:涂层中TiC颗粒均匀分布于共晶基体上,整个涂层组织均匀、无气孔、无裂纹;涂层与基材形成了良好的冶金结合,涂层具有很高的硬度,在室温干滑动磨损试验条件下具有优异的耐磨性能.     

Electrophoretic deposition of HA/MWNTs composite coating for biomaterial applications

A composite coating of hydroxyapatite (HA)/multi-walled carbon nanotubes (MWNTs) has been fabricated by electrophoretic deposition (EPD). The nano powders of HA and MWNTs were dispersed in ethanol with total concentration of 0.005 g/mL and MWNTs 20% and 30% contents (wt). And the pH value of suspension was adjusted in a range from 4 to 5. After stabilization the mixture was ultrasonically treated for 3 h to form a stable suspension. Prior to the electrophoretic deposition, the titanium substrate was hydrothermally treated at 140 in NaOH (10 mol/L) solution for 6 h. A titanium sheet and circinal net of stainless steel were used as a cathode and an anode respectively, and a constant deposition voltage of 30 V was applied for 50-60 s in the EPD process. The thickness of the coatings was controlled from 10 mum to 20 mum. The samples of composite coating were then sintered in a resistance tube furnace in flowing argon at 700 for 2 h. The structure of the as prepared coating was characterized by SEM and XRD, and the bonding force of the coating/substrate was measured by an interfacial shear strength test. It is shown that the bonding strengths between the coating and the titanium substrate is as high as 35 MPa. The cell culture experiments indicate that the prepared composite coating of HA/MWNTs possesses good biocompatibility.     

等离子喷涂TiC-Graphite复合涂层摩擦磨损性能

等离子喷涂TiC涂层具有良好的综合性能, 在极端环境能起到较好的耐磨保护作用, 而石墨是一种优异的自润滑材料。通过喷雾干燥与真空烧结技术制备不同石墨添加量(1.25%、2.5%、5%和10%, 质量分数)的TiC-Graphite球形粉体, 并采用大气等离子喷涂技术制备TiC-Graphite复合涂层。对涂层的相组成、显微结构和力学性能进行了表征, 并对涂层的摩擦磨损性能进行了比较研究。结果发现, TiC-Graphite涂层主要由TiC和石墨相组成。随石墨添加量增大, TiC-Graphite涂层截面微裂纹增多, 表面粗糙度增大, 硬度下降。石墨对TiC涂层在高载荷的磨损性能影响更显著。在50 N高载荷条件, 随石墨添加量增大, TiC-Graphite涂层磨损率降低后急剧增大, 而摩擦系数持续减小。当石墨添加量为2.5%时, 涂层获得最低的磨损率为0.67×10^-5 mm³/(N·m), 同时具有较低的摩擦系数(0.35), 与不添加石墨的TiC涂层相比, 分别降低了72.4%和27.8%。     

Microstructural studies and wear assessments of Ti/TiC surface composite coatings on commercial pure Ti produced by titanium cored wires and TIG process

Tungsten Inert Gas (TIG) process and titanium cored wires filled with micro size TiC particles were employed to produce surface composite coatings on commercial pure Ti substrate for wear resistance improvement. Wire drawing process was utilized to produce several cored wires from titanium strips and titanium carbide powders. Subsequently, these cored wires were melted and coated on commercial pure Ti using TIG process. This procedure was repeated at different current intensities and welding travel speeds. Composite coating tracks were found to be affected by TIG heat input. The microstructural studies using optical and scanning electron microscopy supported by X-ray diffraction showed that the surface composite coatings consisted of α′-Ti, spherical and dendritic TiC particles. Also, greater volume fractions of TiC particles in the coatings were found at lower heat input. A maximum microhardness value of about 1100 HV was measured which is more than 7 times higher than the substrate material. Pin-on-disk wear tests exhibited a better performance of the surface composite coatings than the untreated material which was attributed to the presence of TiC particles in the microstructure.     

激光熔覆原位TiC/Fe复合涂层增强相形成机制研究

激光熔覆技术在制备原位自生颗粒增强金属基耐磨复合涂层领域具有良好的应用前景。以廉价钛铁和石墨为熔覆粉末,采用横流CO2激光器在低碳钢基体上制备了TiC增强Fe基复合涂层,并对涂层物相组织和TiC增强相的形成机制进行了研究。结果表明,增强相TiC通过原位冶金反应形成,在熔体的冷却过程中析出长大,具有树枝晶和鱼骨状两种形态。树枝晶形态的TiC为熔体先析出相,其生长形态受界面前沿成分过冷和晶体生长习性控制。鱼骨状TiC由δ-Fe和TiC的准共晶反应形成,溶质原子扩散特征和晶面能决定了共晶TiC的最终鱼骨状形貌。均匀弥散分布的TiC增强相有助于提高涂层的耐磨损性能。     

Ti811合金表面激光熔覆Ti2Ni+TiC+Al2O3+CrxSy复合涂层的组织和性能

以TC4+Ni45+Al₂O₃+MoS₂+Y₂O₃混合粉末为熔覆材料,采用同轴送粉技术在Ti811合金表面进行激光熔覆制备复合涂层,使用SEM、EDS和XRD等手段分析了涂层的微观组织,测试了涂层的显微硬度和摩擦磨损性能。结果表明,在激光熔覆过程中Ti811合金中的Ni和C分别与Ti发生反应,原位生成金属间化合物Ti₂Ni和硬质增强相TiC;MoS₂分解后S与Cr发生硫化反应生成了软质润滑相Cr_xS_y。网状形态的Ti₂Ni、近球状和枝晶形态的TiC以及点状的Al₂O₃,均匀分布在熔覆层中。硬质相强化和软质相润滑的共同作用,使激光熔覆层具有较高的显微硬度和较优良的耐磨性能。激光功率为900 W的熔覆层其平均显微硬度值达1303.5HV_0.5,其耐磨性能最佳。     

Incorporation of montmorillonite in epoxy to obtain a protective layer prepared by electrophoretic deposition

An electrophoretic deposition (EPD) process was successfully used to obtain a composite epoxy coating containing montmorillonite. To disperse and obtain the intercalation of montmorillonite particles, a suitable procedure was optimized. This procedure did not require the use of additional chemicals and it was performed at room temperature.The microstructural analysis (TEM and XRD) confirmed that the intercalation of montmorillonite layers with epoxy was achieved. Functional characterisations (EIS and TMA) demonstrated the improved properties of the reinforced epoxy coating with respect to the simple epoxy coating.Moreover, the EPD process resulted more efficient in obtaining a montmorillonite-reinforced epoxy coating than a simple epoxy coating.