等离子喷涂纳米Al2O3-TiO2陶瓷涂层研究综述

本文从纳米结构喂料制备、纳米Al2O3-TiO2涂层结构特征及其形成机制、喷涂工艺及在线控制、纳米Al2O3-TiO2涂层性能4个方面论述了等离子喷涂纳米Al2O3-TiO2涂层的研究进展。在此基础上,对等离子喷涂纳米Al2O3-TiO2涂层的前景进行了展望。     

等离子喷涂Al2O3+TiO2复合陶瓷涂层的组织结构

利用ＳＥＭ,ＴＥＭ,ＥＤＡＸ及Ｘ射线等手段研究了Ａｌ２Ｏ３＋ＴｉＯ２／ＮｉＣｒＡｌＹ复合陶瓷等离子喷涂层的组织结构,涂层呈片层状,Ａｌ２Ｏ３＋ＴｉＯ２陶瓷涂层由γ－Ａｌ２Ｏ３,ＴｉＯ２及少量的α－Ａｌ２Ｏ３组成,由于喷涂层温度比较高,部分熔化的Ａｌ２Ｏ３和大部分熔化的ＴｉＯ２发生了一定程度的互熔,形成了Ａｌ２Ｏ３＋ＴｉＯ２共晶组织。片层内由Ｎｉ基固溶体及弥散分布其上的γ相（Ｎｉ３Ａｌ）组成,片间为     

轴向送粉等离子喷涂制备TiB2/Al2O3复合陶瓷涂层

将Al2O3-30%(质量分数,下同)TiB2的复合粉与10%粒度为80～200 nm的Al2O3粉混合,喷雾干燥造粒制备成热喷涂喂料,采用三阴极轴向送粉等离子喷涂系统(Axial-Ⅲ)喷涂沉积TiB2/Al2O2涂层.用X射线衍射、扫描电子显微镜及能谱仪分析涂层物相组成、微观形貌,测试涂层表面显微硬度和Rockwell硬度.结果表明:涂层由α-Al2O3,γ-Al2O3,TiB2和少量TiO2组成;TiB2在涂层中主要以颗粒状形态存在.显微硬度为16.68 GPa;涂层表面Rockwell硬度平均值达52.9.     

聚四氟乙烯/Al2O3-13％TiO2复合涂层的制备及耐蚀性研究

首先采用大气等离子喷涂(APS)工艺在N80钢基体上制备Al2O3-13％TiO2(AT13)涂层,采用扫描电子显微镜(SEM)分析了不同功率下所得涂层的表面和截面形貌.然后在AT13涂层上采用溶胶-凝胶法制备聚四氟乙烯(PTFE)涂层.采用接触角测量仪和电化学工作站分别对涂层的水接触角及耐蚀性进行表征.结果表明,等离...     

等离子喷涂Al2O3陶瓷涂层的研究

研究等离子喷涂Al2O3陶瓷涂层的抗热震性能,分析并计算等离子喷涂Al2O3陶瓷涂层和AlAl2O3涂层中的残余应力,得出了两种涂层的应力分布,测试了TiO2含量对Al2O3陶瓷涂层性能的影响,检验了影响涂层质量的工艺参数.     

等离子喷涂-水热处理制备二氧化钛-羟基磷灰石复合涂层

为克服等离子喷涂羟基磷灰石生物涂层在结合强度和成分上的缺点，通过在钛合金基体上等离子喷涂二水磷酸氢钙和二氧化钻(锐钛矿型)复合粉末，并后续水热处理，制备了二氧化钛—羟基磷灰石复合涂层。结果表明：二水磷酸氢钙和二氧化钛复合粉末的等离子喷涂涂层由CaHPO4,Ca2P2O7,Ca3(PO4)2，非晶磷酸钙和二氧化钛组成。水热处理涂层由羟基磷灰石和二氧化钛组成，升高水热处理温度可提高涂层中羟基磷灰石的结晶性。随着原始粉中二氧化钛加入量的增加，喷涂涂层中磷酸钙的含量和水热处理涂层中羟基磷灰石的含量减少，羟基磷灰石的晶体形貌从细针状变为小颗粒状，喷涂涂层和水热处理涂层的结合强度也随之升高。当二氧化钛的质量分数为60％，水热处理涂层的结合强度可达17MPa。     

等离子喷涂沉积Al2O3-SiO2涂层的光学性能

采用等离子喷涂技术制备Al_2O_3-SiO_2涂层,研究不同喷涂参数下颗粒熔融状态、微观结构、物相组成对涂层光学反射率的影响规律。结果表明:随着等离子喷涂功率的增加,颗粒熔融状态逐渐变得更加充分,Al_2O_3-SiO_2涂层中SiO_2部分由晶态向非晶态转变,部分Al_2O_3和SiO_2固相反应生成了Al_6Si_2O_(13),新相的产生将使得整个涂层材料体系的相组成更加复杂丰富,相界面增多,有利于涂层光学性能的提高。此外,在涂层的内部,层状结构的形成和孔隙率的增加均有益于涂层光学性能的提高。因此,粉末的熔融状态、涂层的微观结构和物相组成的优化对提高Al_2O_3-SiO_2涂层的光学性能提供了可能。     

高温球阀喷涂Al2O3-TiO2和WC-Co涂层的耐磨粒磨损性能

采用激光等离子喷涂技术在已失效的高温球阀基体材料上制备Al2O3-TiO2与WC-Co金属陶瓷涂层,在摩擦磨损试验机上对涂层的耐磨粒磨损性能进行研究,利用扫描电镜、光学显微镜对涂层的显微组织结构、磨损表面及其相组进行分析,并采用维氏显微硬度计、WE-50型液压拉伸验机和箱式电热炉对涂层的显微硬度、结合强度及抗热震性进行测试.结果表明,Al2O3-TiO2金属陶瓷涂层的综合性能最好,可以用于失效高温球阀的再制造.     

管道等离子喷涂Cr_2O_3复合涂层及其耐蚀性能

采用等离子喷涂技术在X70管线钢表面喷涂Cr_2O_3复合涂层,利用X射线衍射仪、扫描电镜、维氏硬度计、划痕仪、电化学工作站等方法表征了涂层相关特征与性能。结果表明,相成分主要是Cr_2O_3和TiO_2,硬度可达4.928GPa,结合力可达46.15N,粘结层+陶瓷层试样腐蚀速率显著降低,对基体有很好的耐蚀保护作用。     

NiCrAlY含量对NiCrAlY/Al2O3涂层机械性能及介电性能的影响

采用大气等离子喷涂技术,以镍基合金(NiCrAlY合金)粉为吸收剂、氧化铝(Al2O3)为基体,制备出NiCrAlY/Al2O3(NA)复合涂层.分析了复合涂层的相组成及显微结构,研究了 NiCrAlY含量变化对复合涂层的机械性能及介电性能的影响.结果表明:喷涂后的涂层中出现了刚玉、铬刚玉等非金属相及唯一的金属相Ni.随着NiCrAlY含量的增加,复合涂层的抗弯强度、断裂韧性逐渐增强;在8.2～12.4 GHz频率范围内,涂层的介电常数实部与虚部值都随着NiCrAlY含量的变化而明显变化,且在NiCrAlY含量为25％时达到最高值,这主要与喷涂过程中分离出金属Ni的含量、冷却后的形状及分布状态有关.     

Formation mechanism of Al2O3-YAG amorphous ceramic coating deposited via atmospheric plasma spraying

Al₂O₃-YAG (Al₅Y₃O₁₂) amorphous ceramic coatings exhibit excellent crack propagation resistance under harsh wear services due to the amorphous phase contributing to the plastic deformation performance of the coating. However, the formation mechanism of the amorphous phase is ambiguous. This study mainly investigated the formation mechanism of Al₂O₃-YAG amorphous coating prepared by atmospheric plasma spraying from the perspective of crystallization chemistry. Nano and microsized powders with low eutectic point ratio were selected as feedstock for comparison. X-ray diffraction, scanning electron microscope, and electron backscattered diffraction were used to analyze the phase composition, morphologies, phase distribution, and structure of the coating. It is concluded that the significant thermodynamically stable structure of polycompound with high coordination numbers of cations prioritized crystallizing in the Al₂O₃-YAG melt, but it needed more time to crystallize and hardly crystallized in the limited time during plasma spraying. Therefore, the selection of as-sprayable powder should also be considered the critical factor for preparing amorphous coatings. The nanoscale or submicro scale powder distributed uniformly with low eutectic point ratio was chosen as the feedstock to ensure the powder droplets diffuse sufficiently during deposition.     

In situ (Al,Cr)2O3-Cr composite coating fabricated by reactive plasma spraying

In situ (Al,Cr)₂O₃-Cr composite coating was fabricated by reactive plasma spraying Al-Cr₂O₃ composite powder. Phase composition and microstructure of the as-sprayed coating was characterized by X-ray diffractometer, scanning electron microscope and transmission electron microscope. Indentation fracture behavior of the coating was investigated. It is found that the microstructure of the coating consists of [(Al,Cr)₂O₃+Cr] eutectic and Cr+[(Al,Cr)₂O₃+Cr] hypoeutectic. The eutectic microstructure of the coating shows the characteristic of nano structure, in which Cr particles with size less than 40 nm distribute in (Al,Cr)₂O₃ solid solution matrix. The hypoeutectic microstructure of the coating consists of Cr particles with size larger than 1 µm and [(Al,Cr)₂O₃+Cr] divorced eutectic. The toughness of the (Al,Cr)₂O₃-Cr composite coating is significantly improved compared with that of the conventional Al₂O₃ coating.     

等离子喷涂TiO2涂层的海水环境失效机制

运用电化学阻抗测试技术对不同腐蚀时间的涂层进行测试,参照等离子喷涂制备的TiO₂涂层的形貌结构特点,分析TiO₂涂层在海水介质中的腐蚀失效过程.研究表明：涂层的极化电阻在浸泡初期降低较快,后因腐蚀产物和污损物阻塞腐蚀通道,极化电阻又有所上升,趋于稳定.建立合适的等效电路分析涂层腐蚀的阻抗谱,考察各元件参数的变化,进一步分析涂层腐蚀的规律.     

等离子喷涂纳米二氧化锆涂层性能的研究

采用大气等离子喷涂技术,在镍基高温合金基体上制备了纳米氧化锆涂层.运用扫描电镜对涂层显微结构进行观察和分析,同时测试了涂层的显微硬度、结合强度扣热震性能.结果表明:纳米氧化锆涂层由完全融化区和部分融化区组成,孔隙率约为7%,显微硬度为655.81 HV,结合强度为54.37 MPa,在1 000℃下,可承受40次热循环,涂层无明显脱落现象.     

喷涂法制备硅藻土/Al2O3超疏水涂层

以十六烷基三甲氧基硅烷(HDTMOS)的水解液对微米硅藻土和纳米Al2O3进行改性;然后,以环氧树脂E51(E51)为粘接剂制得了悬浮液;最后,采用喷涂法将上述悬浮液喷涂于基底表面,经加热固化后制得硅藻土/Al2O3基复合超疏水涂层.通过单因素实验筛选出最佳制备工艺〔V(HDTMOS):V(乙醇)=0.04:1;m(硅...     

Microstructures,thermophysical properties and thermal cyclic behaviors of Nd2O3 and Sc2O3 co-doped LaMgAl11O19 thermal barrier coating deposited by plasma spraying

In this study, La_1-xNd_xMgAl_11-xSc_xO₁₉ (x = 0.1, 0.2, 0.3; abbreviated as LNMAS-1, 2, 3) coatings which are supposed to possess better properties than LaMgAl₁₁O₁₉ (LMA) were plasma-sprayed and their high-temperature performance were comparatively investigated. Results show that addition of Nd³⁺ and Sc³⁺ as dopants to LMA endows corresponding coatings with reduced thermal conductivity and enhanced thermal expansion coefficient, while maintaining advantageous phase stability, although still being subjected to amorphization in plasma flame and following crystallization upon high-temperature service. Furthermore, the doping could cause adherence increasing between topcoat/bondcoat, benefiting from improved melting condition, especially in LNMAS-2 and LNMAS-3 coatings, which is related to the specific powder morphology and lowered melting point. During exposure to 1350°C, mechanical performance and structure integrity of doped free-standing LNMAS coatings can be well preserved even after 400 h aging. In thermal cyclic fatigue test, LNMAS-2 and LNMAS-3 coatings undertake thermal cycling lifetime of ～181 and 191 cycles at 1100°C, respectively, 40% durable than that of LMA coating. These preliminary results suggest that LNMAS-2, 3 might be promising candidates for advanced thermal barrier coating applications.     

喷涂法制备硅藻土/Al2O3超疏水涂层的研究

以微米级硅藻土和纳米级氧化铝粒子为原料，构筑具有一定粗糙结构的表面，以十六烷基三甲氧基硅烷（HDTMOS）为低表面能改性剂，以环氧树脂为粘接剂，制得硅藻土/Al2O3基复合超疏水涂层。首先，通过HDTMOS水解液对硅藻土和氧化铝粒子进行表面改性，再加入环氧树脂溶液获得悬浮液，采用喷涂法将上述悬浮液喷涂于基底表面，经加热固化后得到超疏水涂层。通过单因素实验筛选出最佳制备工艺（ V(HTDMOS)∶V(乙醇)=0.04∶1；m(硅藻土)∶m(Al2O3) =1.5∶0.8；m(E51)∶m(丙酮) =1∶5），其表面水静态接触角高达163.4°，扫描电镜观察其表面呈粗糙度均匀的微观分级结构。涂层适用于滤纸、木块、不锈钢板等多种基底，均可表现出优异的超疏水性能。同时，该涂层经过100次的循环磨损实验后，其表面水静态接触角仍高达146.3°。     

Oxidation behavior of Al2O3 reinforced MoSi2 composite coatings fabricated by vacuum plasma spraying

MoSi₂, MoSi₂–10 vol.% Al₂O₃, MoSi₂–30 vol.% Al₂O₃ (denoted as MA0, MA1, MA3, respectively) coatings were fabricated by vacuum plasma spraying (VPS), and their oxidation behavior was examined at low temperature (500 °C) and high temperature (1500 °C). The test at 500 °C showed that the addition of Al₂O₃ effectively restrained the pest oxidation of MoSi₂. The MA1 coating had satisfactory fluid surface and presented good oxidation resistance at 1500 °C. However, the MA3 coating showed worse oxidation resistant behavior compared with the MA0 coating because of mullite formation.     

Non‐isothermal crystallization kinetics of Al2O3‐YAG amorphous ceramic coating deposited via plasma spraying

Crystallization kinetics of the newly developed Al₂O₃‐Y₃Al₅O₁₂ (YAG) amorphous ceramic coating fabricated by atmospheric plasma spraying (APS) were investigated via differential scanning calorimetry (DSC) under non‐isothermal conditions. The phase compositions and microstructure of the as‐sprayed coating were characterized by X‐ray diffraction (XRD) and Scanning electron microscopy (SEM). The glass transition temperature T_g, the onset temperature of crystallization T_c and the peak temperature of crystallization T_p presented heating rate dependence. The related kinetic parameters of activation energies (E_g, E_c, E_p) and Avrami exponents (n) were quantified using various methods including Kissinger, Augis–Bennett, Ozawa and Matusita–Sakka, etc., to understand the phase transition mechanism and crystallization process in depth. A series of parameters including devitrification interval ΔT, thermal stability (T_c, E_c), nucleation resistance E_c/RT_g and fragility index F were quantified in order to evaluate the nucleation mechanism, crystallization behavior and thermal stability of Al₂O₃‐YAG amorphous ceramic coating. Excellent thermal stability was witnessed in the studied coating. Furthermore, the YAG crystalline phases can be reasonably controlled and independently precipitated from the amorphous matrix via proper annealing.     

Preparation and characterization of a composite ceramic coating containing absorber LaFe12O19 by plasma spraying

A ceramic coating with both heat-resistant and electromagnetic (EM) wave absorption performances is prepared by the atmospheric plasma spraying (APS) method. The spraying powder is a composite material mainly containing LaFeO₃ and La(Mg/Fe)Al₁₁O₁₉ without EM absorption ability. During APS procedure, a new phase of LaFe₁₂O₁₉ is fabricated by the chemical reaction between Fe₂O₃ and LaFeO₃ at extremely high temperatures. The ceramic coating exhibits larger saturation magnetization (M_s) and higher EM absorption performance than that of the unsprayed sample. The coating Ms is 31 emu/g, and the optimal reflection loss is −39.30 dB at 3.5–5.2 GHz with 4.5 mm thickness. The ceramic coating with both heat-resistant and EM absorption properties is a potential application prospect material in the military industry.