Effect of Applied Stresses on the Microstructure and Dissolution Behavior of Plasma Sprayed Wollastonite Coatings

Wollastonite coatings were deposited on the U-shape titanium alloy coupons by atmospheric plasma spraying.The effect of applied stresses on the microstructure and dissolution behavior of wollastonite coatings was investigated.The microstructure and composition of coatings were examined by scanning electron microscope(SEM)and electron diffraction spectroscopy(EDS).In addition,the dissolution behavior of coatings was evaluated by immersion in simulated body fluid(SBF).More apatite is observed on the surface of coatings under a tensile stress and a stress-free condition after immersion in the SBF solution,whereas almost no apatite can be found for the coatings under a compressive stress.The dissolution rate of coatings characterized by the pH changes and the ion concentration of Ca,Si and P in the SBF solution is lower under the compressive stress than those under a tensile stress or a stress-free condition.It can be concluded from the experimental results that the compressive stress inhibits the dissolution of wollastonite coatings and the formation of apatite,whereas a tensile stress enhances the two processes.     

激光重熔工艺对热喷涂陶瓷层微观结构的影响

研究了在１Ｃｒ１８ＮｉｏＴｉ基体上热喷涂Ａｌ２Ｏ３－１３％ＴｉＯ２陶瓷层，进行激光重熔对陶瓷微观结构的影响。激光重熔陶瓷层中，主要组成相为ａ－ＡＩ２Ｏ３及ＡＩ２ＴｉＯ５，在条件合适时，在ａ－ＡＩ２Ｏ３中还有一种超结构，即有序相析出；有序相的存在可阻碍表面裂纹的产生；激光重熔陶瓷层中，扫描速度增加，表面裂纹的宽度增加；激光输出功率增加，表面裂纹的宽度亦增加。     

发光复合冷喷涂层的组织结构及发光性能研究

目的 在45#钢表面制备可高效快捷监测涂层摩擦磨损状况的耐磨自敏涂层（Cu-14A1-X/ SrAl2O4:Eu2+,Dy3+）。方法 用冷喷涂方法,在45#钢基体表面制备含不同体积分数的铝酸锶与高铝青铜粉末的复合发光涂层。采用X射线衍射仪（XRD）、扫描电子显微镜（SEM）和荧光分光光度计,分析了荧光粉比例对自敏复合发光涂层的相组成、发光性能、表面及截面形貌的影响。结果 复合涂层的物相与原始粉末基本相同。随着涂层粉体中铝酸锶磷光粉体积分数的增加,相同工艺下制备的涂层厚度逐渐增大。三种涂层与基体的结合强度随着铝酸锶粉末颗粒所占的比重增大,呈现出先增大后略微降低的趋势。同时,随着磷光粉体积分数的改变,铝酸锶颗粒在复合涂层表面的沉积率最大为13.6%,且沉积率变化的趋势逐渐减小,相应地,涂层的发光强度也降低。结论 高铝青铜与铝酸锶粉末配比为7∶3时,涂层发射光谱符合4f65d1→4d7的宽带发射,在受到激发后,均发出耀眼的黄绿色光,具有很好的指示效果,且铝酸锶粒子对涂层起钉扎作用,沉积好,结合强度高。     

Effect of Oxidation Behavior on the Mechanical and Thermal Properties of Plasma Sprayed Tungsten Coatings

Tungsten (W) coatings have been prepared via air (APS) and vacuum plasma spraying (VPS) technologies, respectively. The microstructures and chemical compositions of the coatings were comparatively studied; meanwhile, the mechanical and thermal properties were evaluated. The results obtained showed that oxide content in the VPS-W coating was apparently lower than that of the APS-W coating because of the different surrounding atmosphere, which influenced the mechanical and thermal properties of the coatings directly. Similar microstructures were observed for the VPS-W and the APS-W coating, but the VPS-W coating was much denser. The bonding strength of the VPS-W coating was much higher than that of the APS-W coating. Thermal conductivity of the VPS-W coating was 59.3 W/m · K at room temperature while the APS-W coating was 32.2 W/m  K. Thermal loading experiments of electron beam showed that the VPS-W coating could withstand the heat load of 10.75 MW/m², while the APS-W coating formed serious cracks on its surface at the load of 7.5 MW/m².     

CoNiCrAlY黏结层结构设计及其对热障涂层结合强度和抗热震性能的影响

目的 设计热障涂层黏结层结构,改善涂层结合强度和抗热震性能。方法 制备了5种结构的CoNiCrAlY黏结层,即超音速火焰喷涂(HVOF)底层+等离子喷涂(APS)上层的双层结构黏结层试样,对其进行1 050℃真空热处理3 h后的试样,APS黏结层试样,HVOF黏结层试样及其真空热处理试样。再在以上5种试样表面制备Y₂O₃部分稳定ZrO₂(YSZ)陶瓷层,研究黏结层的表面粗糙度、相组成、微观组织结构及其对涂层试样结合强度、热震性能的影响。结果 制备态的黏结层由γ/γ’和β-NiAl两相组成,真空热处理后β相含量增多,表面粗糙度下降。在所有涂层试样中,双黏结层的涂层试样的结合强度最低,为28.43 MPa;对其真空热处理后得到的涂层试样的结合强度最高,达到39.42 MPa,主要原因在于热处理促进了两黏结层之间的扩散,提高了界面强度。双黏结层的涂层试样的抗热震性能最好,200次热震后涂层无明显剥落,而APS黏结层的涂层试样的抗热震性能最差,涂层抗热震性能的差异在于黏结层微观结构的不同。结论 双黏结层的结构设计综合了APS、H...     

铜基体上等离子体喷涂钨涂层性能研究

介绍了铜基体上等离子喷涂1 mm钨涂层核聚变试验装置壁材料的制备,并对真空和大气等离子体喷涂钨涂层性能进行了比较研究,内容主要包括微观形貌、气孔率、杂质含量、结合强度和热负荷性能.结果表明,气孔率和氧杂质含量差异是大气和真空等离子体喷涂钨涂层热负荷性能差异的主要原因.     

稀土对电沉积Ni-W合金组织和性能的影响

通过电沉积技术在45~#钢基体表面上制备了Ni-W-Er_2O_3复合镀层,利用SEM、EDS及XRD等分析了镀层的组织结构和表面形貌,采用磁性厚度仪、显微硬度计、电化学工作站等测试手段对合金镀层的厚度、显微硬度以及耐蚀性能进行了精确测定。结果表明:所制备的合金镀层组织致密,晶粒细小,未见有明显缺陷存在,镀层与基体结合良好;稀土氧化物Er_2O_3的加入可以保证基体材料获得高硬度、高W含量且具有良好耐蚀性能的Ni-W-Er_2O_3复合镀层,且当添加量为16 g/L时,其综合性能最优。     

热处理温度对Cr/Al涂层组织结构及性能的影响

目的提高物理气相沉积Cr/Al涂层与基材锆合金的结合强度,减少涂层表面微观缺陷及内应力。方法采用多弧离子镀及磁控溅射技术在锆合金表面溅射Cr/Al涂层,并将涂层试样分别置于600、800℃保护气氛炉中热处理30 min。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、X射线光电子能谱仪(EDS)及光学显微镜(OM),分析了Cr/Al涂层热处理前后相组成、表面形貌、截面形貌、元素成分变化及涂层剪切后的剥落形貌。利用弹簧拉压试验机,测试了未处理涂层、600℃和800℃热处理涂层试样与基材锆合金的结合强度。结果 600、800℃热处理涂层相比未处理涂层,表面更加平滑,表面孔隙及微观缺陷较少,但与基材锆合金的结合强度并没有明显变化,未热处理涂层、600℃热处理涂层、800℃热处理涂层与基材锆合金的结合强度分别为44.07、44.12、44.08 MPa。结论热处理后,涂层出现Al Cr2、Al8Cr5、Al9Cr17、Al9Cr4、Al86Cr14等多种Cr-Al合金相,有利于涂层表面孔隙及大颗粒等缺陷的减少。但热处理前后,涂层与基材的结合强度未发生明显变化。     

不锈钢表面冷喷涂铜涂层制备及性能研究

目的 通过工艺的匹配优化,采用冷喷涂技术在不锈钢表面制备高结合强度铜涂层,并研究热处理工艺对不锈钢表面冷喷涂铜涂层组织及性能的影响规律。方法 分别以高纯氮气和氦气作为加速气体,通过冷喷涂技术,在1 mm厚的304不锈钢基体表面制备铜涂层。采用光学显微镜(OM)对涂层的孔隙率及微观组织结构进行表征。采用场发射扫描电子显微镜(FESEM)对涂层拉伸断面结构进行分析。借助维氏显微硬度仪、万能拉伸试验机和涡流导电仪测试分析退火热处理工艺对不锈钢基体表面冷喷涂铜涂层硬度、结合强度和电导率的影响规律。结果 利用氮气作为加速气体,在薄304不锈钢基体上获得铜涂层困难,涂层形成后,易发生整体剥落。使用氦气作为加速气体,可在薄304不锈钢板表面成功制备结合强度高于81.7 MPa、硬度为99.6HV0.1、孔隙率小于0.1%的高致密铜涂层。退火热处理引起涂层组织再结晶,可显著消除冷喷涂过程中的加工硬化影响。随着热处理温度从300℃上升到500℃,涂层硬度由99.6HV0.1下降至63.7HV0.1。退火温度为400℃时,涂层导电率最优(93.94%IACS)。当热处理温度升高到500℃,涂层导电率异常下...     

Mg元素对热浸镀锌基合金镀层组织结构的影响

采用热浸镀方法在Q235钢板表面制备了Mg的质量分数分别为0.0%,0.1%,0.3%,0.5%的锌基合金镀层。利用扫描电子显微镜(SEM)、能谱仪(EDS)、辉光光谱仪(GDOES)等手段分析了Mg含量变化对镀层组织结构的影响。结果表明:随着镀层中Mg含量的增加,合金镀层的表面晶粒逐渐变小;Mg元素富集于晶界之中,起到细化晶粒的作用;Mg推迟了ζ相向δ相的转变,使镀层结构中的δ相层减薄。     

Q345R板材表面冷喷涂Al-Zn涂层的组织及性能研究

目的 研究添加元素Zn含量的变化对涂层的显微组织、孔隙率、硬度及涂层-基体间界面结合强度等的影响规律.方法 采用冷喷涂技术在Q345R板材表面制备性能优良的纯Al和Al-Zn复合涂层,通过扫描电子显微镜对涂层的形貌进行分析,通过维氏显微硬度计对涂层的力学性能进行表征,并揭示涂层与基体间的界面结合机理.结果 冷喷涂纯Al...     

热处理对冷喷涂Fe涂层组织与性能影响研究

冷喷涂作为一种新型的涂层技术,在制备大部分金属涂层、金属陶瓷复合涂层方面有着巨大的潜力。本文采用冷喷涂在Al基体上制备了Fe涂层,并结合喷涂后热处理研究了涂层组织与性能特点。结果表明,所得Fe涂层的内部组织比较致密;受到喷涂过程中空气的影响,喷涂射流呈现亮流,所制备涂层表面有较大、较深气孔。在较低温度下热处理后Fe涂层的显微组织变化不明显,显微硬度明显降低;Fe涂层与Al基体之间形成约10μm厚度的金属间化合物层。     

稀土CeO2对激光熔覆WC-Co镍基复合涂层组织形貌和性能的影响

采用激光熔覆技术,以自熔合金粉末Ni60B为金属基,微米和纳米12％Co-WC颗粒为陶瓷增强相以及少量的稀土CeO2作为第二添加相,在45钢表面制备复合陶瓷涂层.观察了涂层的截面和表面组织,研究了稀土对涂层硬度和磨损性能的影响.结果表明:CeO2作为第二相明显细化了熔覆层的组织,将涂层中的板块状组织细化到4μm左右,并...     

H13钢表面电火花沉积WC-Ni基金属陶瓷涂层微观组织及摩擦磨损性能

为了提高H13钢表面性能,延长其使用寿命,采用电火花沉积工艺在H13钢基体上制备了WC-Ni基金属陶瓷涂层,并分别以Ni和Mo作为过渡层制备了复合涂层.利用XRD、SEM、EDS、显微硬度计和摩擦磨损试验机分析了涂层的物相、微观组织、显微硬度和摩擦磨损性能.结果表明,WC-Ni涂层表面由溅射状沉积斑点堆积而成,横截面分为涂层区、过渡层和基体3个区域,WC硬质相弥散分布于涂层内.Ni/WC-Ni复合涂层的表面较为光滑平整,Ni过渡层的引入并未改变涂层的物相,界面处WC硬质相异常长大.Mo/WC-Ni复合涂层表面存在微细裂纹,且生成了新相Fe9.7Mo0.3.复合涂层的硬度均高于WC-Ni涂层,复合涂层的摩擦系数和磨损失重均低于基体与WC-Ni涂层,Mo/WC-Ni复合涂层具有更好的耐磨性.     

Thermal Performance and Microstructure of Vacuum Plasma Sprayed Tungsten Coatings under Cyclic Heat Load

采用真空等离子喷涂技术在铜基体表面制备了钨涂层,分别通过NiCrAl和W75Cu25涂层作为中间层。5 MW/m2, 2 s的高热负荷电子束实验表明NiCrAl中间层提高了涂层的热导率并降低了热应力和残余应力值。W75Cu25涂层作为中间层则表现出较差的热疲劳性能。高热负荷电子束真空等离子喷涂钨涂层表现出侵蚀和微裂纹。因热应力导致涂层发生塑性变形,在高温情况下裂纹起源于熔融的钨颗粒,但是,裂纹被钨涂层塑性变形和孔洞所抑制     

Effect of Al Content on Microstructure and Cyclic Oxidation Performance of Pt-Aluminide Coatings

The effect of Al content, i.e., the amount of Al picked up during aluminizing, on the microstructure and cyclic oxidation properties of Pt-aluminide coatings has been investigated. The cast Ni-base superalloy CM-247 was used as the substrate material and a single-step, high-activity pack aluminizing process was used to produce the Pt-aluminide coatings. The Al content of these coatings was varied by using packs with different compositions of the Al source. Pt-aluminide coatings having three different Al contents, namely 6.5, 16, and 21 mg cm^-2, were evaluated for their cyclic oxidation resistance at 1200°C in air. It was found that the Pt-aluminide coatings, irrespective of their Al contents, evolve in the same manner during aluminizing and result in a three-layer structure with an outer PtAl₂+NiAl two-phase layer, an intermediate NiAl layer, and the inner interdiffusion layer. The stability of this three-layer coating structure over long periods of aluminizing, however, is dependent on the availability of Al from the pack during this period. Below a certain threshold Al availability, the two-phase outer layer transforms to a single-phase NiAl structure causing the coating to change from its three-layer structure to a two-layer one. Cyclic oxidation results indicate that, while a minimum Al content in Pt-aluminide coatings is essential for deriving the best oxidation performance, increasing the Al content beyond a certain level does not significantly enhance oxidation behavior. The effect of Al content on aspects, such as coating degradation and nature of coating–surface damage during cyclic oxidation, is also discussed.     

基板温度对EB-PVD ZrO2涂层微观组织及残余应力的影响

采用电子束物理气相沉积(EB-PVD)技术在不锈钢基板上沉积ZrO2涂层.研究基板温度对涂层微观组织和残余应力的影响.结果表明:沉积的涂层均为t-ZrO2结构,涂层表面平整致密;随着基板温度的升高,涂层表面颗粒逐渐长大,表面粗糙度增大;涂层残余应力也随着基板温度的升高而增加,当基板温度为1000 ℃时,涂层残余应力的增量最大,ZrO2涂层的残余应力主要是由于涂层与基板热膨胀系数差别而产生的热应力引起.     

热处理对氮化铝化学镀铜组织性能的影响

目的优化化学镀铜氮化铝(AlN)基板的综合性能,掌握热处理对其镀层致密度、界面结合强度和热导率的作用机理,并对划痕膜层失效行为进行分析。方法采用化学镀铜法实现AlN陶瓷基板表面金属化,对其进行200~500℃热处理。利用X射线衍射仪、扫描电镜、激光导热仪,对Cu-AlN基板的物相结构、显微形貌、热学性能进行分析。采用划痕法对镀层结合力进行评价,并通过划痕形貌对膜层失效行为进行分析。结果未热处理的Cu-AlN基板表面存在鼓泡现象,结合强度为24.7 N,热导率为156.8 W/(m K)。热处理消除了Cu-AlN基板的鼓泡现象,300℃热处理的Cu-AlN基板综合性能优异,表面Cu颗粒分布均匀,结构较为致密,结合强度为32.6 N,热导率达163.8 W/(m K);当500℃热处理时,Cu-AlN基板表面存在氧化现象,形成CuO,结合强度急剧降低为18.5 N,热导率为161.2 W/(m K)。Cu-AlN基板的基膜失效方式为点剥离,随着载荷的增加,点剥离增多,膜层开裂,AlN逐渐裸露,Cu膜层磨损形貌宏观上表现为由塑性变形引起的犁沟磨损,芯部发生拉伸变形,边界呈现卷曲变形。结论对Cu-AlN进行合理热处理,可改善镀层表面组织与致密度,提高结合强度和导热性能。     

Microstructure and Wear Performance of Arc Sprayed Fe-FeB-WC Coatings

Two Fe-FeB-WC coatings were deposited on the Q235 steel substrate by arc spraying. The microstructure and the abrasive wear performance of the coatings were characterized by x-ray diffraction (XRD) and scanning electron microscope (SEM). The wear mechanisms of the coatings were examined. It was found that Fe-Cr alloy and Fe₂B are present in the coating as the main phases. The results showed that adding hard particle powders could obviously increase the hardness and wear resistance of the coatings. The average microhardness of the coatings was about 870 to 920 HV_0.1. The coatings exhibited excellent abrasive wear resistance, being 3.3 to 4.8 times higher than that of arc sprayed 3Cr13 coating.     

等离子喷涂氧化铝碳纤维复合涂层的结构及耐磨性能

采用机械球磨方法制备了短线碳纤维,并与氧化铝粉末充分混合,利用等离子喷涂工艺制备了碳纤维质量分数为4%的复合涂层。利用场发射扫描电镜、拉曼光谱、X射线衍射、拉伸试验、摩擦磨损试验等对复合涂层的结构和性能进行了表征和测试分析。结果表明,碳纤维在等离子喷涂过程中较好地保持了原有结构和形貌,主要存在于氧化铝扁平粒子界面,碳纤维的加入使氧化铝涂层与基体之间的结合强度增加了38%,复合涂层耐磨性能比纯氧化铝涂层提高了64%,摩擦因数降低了50%。涂层耐磨性能的改善主要归功于参与磨损的碳纤维本身优异的润滑性能及其对氧化铝扁平粒子界面的结合作用,该复合涂层在低载荷摩擦磨损环境中具有潜在的应用价值。