等离子喷涂氧化锆涂层及激光重熔涂层的摩擦磨损性能

采用等离子喷涂制备了常规氧化锆涂层和纳米氧化锆涂层,并对制备的纳米氧化锆涂层进行了激光重熔处理,系统地研究了3种氧化锆涂层(常规、纳米和激光重熔涂层)在常温和高温下的摩擦磨损性能.结果表明,纳米氧化锆涂层耐磨性能明显优于常规氧化锆涂层,而激光重熔处理后的纳米氧化锆涂层在常温和高温下,都表现出最低的摩擦系数和最好的耐磨性能.这3种涂层的表面粗糙程度、涂层孔隙率和裂纹状况明显不同,从而表现出不同的摩擦磨损特性;说明纳米粉末等离子喷涂结合激光重熔技术是提高氧化锆涂层性能的有效方法.     

超音速火焰喷涂NiCrC涂层的滑动摩擦磨损行为

采用空气助燃超音速火焰(HVAF)喷涂技术,分别以相同成分的气雾化合金粉体和低温球磨纳米晶合金粉体作为喂料,制备出高质量的耐磨耐蚀粗晶和纳米晶NiCrC合金涂层。利用SRV摩擦磨损试验机、表面形貌仪和扫描电镜等设备对两种涂层和45钢试样的滑动摩擦磨损行为进行了对比研究。结果表明:在载荷为10～30 N的无润滑剂常温滑动摩擦条件下,两种涂层具有较为接近的滑动摩擦系数,但纳米晶NiCrC涂层的抗磨损性能远优于常规粗晶涂层。三种测试材料都呈现出磨粒磨损和粘着磨损的特征,随着载荷的增加,磨损程度逐渐加剧,同时粘着磨损的特征更加突出。此外,两种涂层材料在磨损过程中都出现了颗粒部分或整体剥落的现象,加剧了涂层的磨损程度。     

等离子喷涂纳米Al2O3/TiO2涂层耐磨性的研究

采用液相喷雾造粒的方法将纳米粒子团聚成微米级颗粒,并利用等离子喷涂技术制备出了含有纳米结构的陶瓷涂层。在MM200型环块磨损试验机上进行了常温干摩擦试验,比较了纳米结构涂层和传统陶瓷涂层的耐磨损性能,利用扫描电镜观察了磨损后的磨痕形貌。结果表明,纳米涂层的耐磨损性能明显好于传统陶瓷涂层,且随着磨损载荷的增大,纳米涂层和传统涂层的磨损机制的变化是不同的。传统涂层的磨损机理主要是微裂纹和颗粒的剥落,而相同条件下纳米涂层则由于涂层韧性的提高,几乎不存在微裂纹,主要表现为涂层的局部剥落和粘着。     

纳米氧化锆涂层的制备、显微结构及抗热震性能研究

利用大气等离子喷涂技术在不锈钢基体上制备了纳米氧化锆涂层.运用XRD、SEM、TEM、拉曼光谱和金相技术等分析手段对涂层的显微结构、物相组成进行了观察与分析;利用热冲击试验测试涂层的抗热震寿命.结果表明,纳米氧化锆经喷雾造粒后的颗粒粒径主要分布在15～70 μm之间,流动性好,适合等离子喷涂,粉末和涂层的物相均由四方氧化锆组成;在喷涂过程中,喷涂工艺参数(氩气流量)有规律的地影响着涂层的显微结构,进而影响涂层的抗热震性能.     

等离子喷涂层与微弧氧化膜层的摩擦磨损性能比较

采用等离子喷涂法在钛合金基体上制备了纳米氧化锆陶瓷涂层,采用微弧氧化法在锆合金基体上制备了氧化锆陶瓷膜层。通过摩擦磨损试验研究了纳米陶瓷涂层和微弧氧化膜层的摩擦磨损性能。结果表明:在往复滑动磨损条件下和两种载荷水平下,两种涂层均呈现相同的耐磨性规律;在较大载荷下,微弧氧化膜层的磨痕深度较大,即纳米ZrO2陶瓷涂层的耐磨性优于微弧氧化陶瓷膜层。     

等离子喷涂纳米硫化亚铁自润滑涂层的分析与摩擦学性能

摩擦磨损是造成零部件失效的重要原因,而摩擦磨损过程主要发生在固体的表面,等离子喷涂纳米硫化亚铁自润滑涂层能够有效地减少摩擦面的磨擦和磨损.本研究利用自制的纳米尺寸的硫化亚铁颗粒作为等离子喷涂的喂料,在钢基体表面制成了纳米硫化亚铁自润滑涂层.等离子喷涂制得的涂层成分以硫化亚铁为主,经过XRD分析结果的计算,涂层是纳米结构的硫化亚铁颗粒构成的.用等离子喷涂纳米硫化亚铁自润滑涂层进行摩擦磨损试验,结果表明该涂层具有明显优于热处理后GCr15钢的摩擦磨损性能,相同试验条件下摩擦系数降低了1/3～1/2,磨损体积减小50%～70%,而且在真空条件下的摩擦磨损性能比在大气压下还要好,摩擦系数降低1/3,磨损量降低了70%.     

火焰喷涂和等离子喷涂FeCrBSi涂层及其防滑和耐磨性能研究

目的采用大气等离子喷涂(APS)和火焰喷涂(FS)在304不锈钢基体上制备FeCrBSi涂层,并对比研究两种工艺制备涂层的防滑和耐磨性能。方法通过光学显微镜、场发射扫描电镜和X射线衍射仪对涂层的显微形貌和结构进行分析,通过维氏硬度计测试涂层的显微硬度。采用摩擦磨损试验机和三维光学显微镜,测量涂层在干摩擦条件下的摩擦系数和磨损量。结果两种喷涂方法制备的涂层多孔,在喷涂过程中极少发生氧化。与火焰喷涂涂层(749HV0.1)相比,大气等离子喷涂涂层(837HV0.1)具有更高的维氏硬度值。在摩擦试验中,火焰喷涂涂层的磨损率为(38.63±2.37)×10~(-6)m~3/(N·m),而大气等离子喷涂涂层的磨损率为(9.5±0.49)×10~(-6)m~3/(N·m),但两种涂层的摩擦系数区别较小,在频率2 Hz、载荷10 N的条件下的摩擦系数为0.6~0.7。结论两种涂层的磨损机制均为疲劳磨损,喷涂态FeCrBSi涂层具有较好的防滑耐磨性能,且大气等离子喷涂涂层性能优于火焰喷涂涂层。     

纳米掺杂Al2O3＋13wt% TiO2等离子喷涂涂层的抗磨损性能

采用纳米掺杂(5%～30%)方法制备出纳米包覆微米级粒子的AT13等离子喷涂粉末,并利用大气等离子喷涂技术制备出了含有纳米复相结构的陶瓷涂层.在MM-200型磨损试验机上进行了常温干摩擦试验,比较了纳米复相结构涂层和传统陶瓷涂层的耐磨性能,利用扫描电镜观察了磨损后的磨痕形貌.结果表明,纳米复相涂层的耐磨性能明显好于传统陶瓷涂层,且随着磨损载荷的增大,纳米复相涂层和传统涂层的磨损机制的变化是不同的,传统涂层的磨损机理主要是微裂纹和颗粒的剥落,而相同条件下纳米复相涂层则由于涂层韧性的提高,主要表现为涂层的粘着磨损与局部剥落,并对纳米掺杂等离子喷涂涂层对AT13涂层磨损机制的影响进行了探讨.     

爆炸喷涂石墨烯改性涂层的工艺及自润滑耐磨机制研究

为了降低WC-12Co耐磨涂层的摩擦系数,采用四种制粉工艺（湿法球磨、湿法搅拌、烧结破碎、喷雾造粒）将石墨烯复合于WC-12Co粉末中,基于爆炸喷涂技术制备了石墨烯自润滑耐磨涂层。借助SEM、EDS、Raman等手段分析了不同制粉工艺对获得粉末及涂层中石墨烯的组织形貌、物相组成。采用显微硬度计、万能拉伸机研究了涂层的力学性能。采用UMT-2摩擦磨损试验机研究了涂层的摩擦磨损性能。结果表明,喷雾造粒工艺可实现更多的石墨烯在WC-12Co颗粒表面的均匀、紧密粘附,涂层内部石墨烯含量较高,且仍以透明状、薄层状态嵌合在组织内部,结合强度约68MPa,硬度约940HV0.3,石墨烯涂层摩擦系数降低约25%,石墨烯在摩擦过程中不断裸露于磨痕表面,在微区内形成润滑膜,起到较好的自润滑、减磨效果。     

等离子喷涂Al2O3涂层与高硬配副的摩擦学性能研究

目的 研究大气等离子喷涂Al2O3涂层在高硬配副下的摩擦磨损行为.方法 通过大气等离子喷涂(APS)制备了厚度约为380μm的Al2O3涂层,利用纳米压痕仪测量了Al2O3涂层和两种摩擦副的硬度和弹性模量.采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)对喷涂粉末、涂层以及磨痕的相结构和形貌进行了表征分析,通过X射线能量色散谱仪(EDS)分析了涂层磨痕中对偶元素的转移.另外,还通过CSM摩擦机系统地研究了该涂层的摩擦磨损行为.借助X射线光电子能谱仪(XPS)分析了磨痕中的化学组成.结果 制备的Al2O3涂层主要以γ-Al2O3相为主,且存在一定孔隙,并出现层状结构.在摩擦实验中发现,在同一摩擦副下,Al2O3涂层的摩擦系数随着载荷的增加而逐渐降低,磨损率随之增大.由于摩擦配副力学性能的差异,使Al2O3涂层表现出不同的摩擦磨损行为.以Si3N4为摩擦副时,Al2O3涂层的摩擦系数较小,但磨损率大,磨损机制主要是磨粒磨损和粘着磨损.在摩擦过程中,Si3N4对偶副会与空气中的水反应,生成少量具有润滑效果的Si(OH)4胶体.以WC为摩擦副时,Al2O3涂层的摩擦系数大,但磨损率低,磨损机制主要是粘着磨损和磨粒磨损,并伴有疲劳磨损.在摩擦过程中,由于产生了摩擦热,Al2O3涂层磨痕表面的γ-Al2O3相转变为 α-Al2O3相,摩擦配副的硬度和弹性模量越大,摩擦系数越高,γ-Al2O3相的转变也越多.结论 因高硬度的Si3N4和WC对偶球拥有不同的力学性能,对大气等离子喷涂制备的Al2O3涂层的摩擦磨损机理有显著的影响,并且在摩擦过程中,涂层磨痕内的γ-Al2O3相会向α-Al2O3相转变.     

Nanostructured yttria stabilized zirconia coatings deposited by air plasma spraying

Nanostructured yttria partially stabilized zirconia coatings were deposited by air plasma spraying with reconstituted nanosized powder. The microstructures and phase compositions of the powder and the as-sprayed nanostructured coatings were characterized by transmission electron microscopy（TEM）, scanning electron microscopy（SEM） and X-ray diffxaction（XRD）. The results demonstrate that the microstructure of as-sprayed nanostructured zirconia coating exhibits a unique tri-modal distribution including the initial nanostructure of the powder, equiaxed grains and columnar grains. Air plasma sprayed nanostructured zirconia coatings consist of only the nontransformable tetragonal phase, though the reconstituted nanostructured powder shows the presence of the monoclinic, the tetragonal and the cubic phases. The mean grain size of the coating is about 42 nm.     

爆炸压涂制备纳米氧化锆涂层及其组织与性能研究

运用爆炸压涂技术在钢基体上制备了较大面积的纳米氧化锆涂层。利用扫描电镜、X射线衍射等手段研究了纳米氧化锆涂层的微观组织、孔隙率和晶粒度。结果表明,制备的纳米氧化锆涂层结构致密,涂层的孔隙率为5%;与基体结合紧密;爆炸压涂前后氧化锆成分未发生变化;涂层中的氧化锆仍然以稳定的单斜相存在,不存在立方相;涂层中的氧化锆晶粒与粉末晶粒尺寸基本一致。爆炸压涂制备的陶瓷涂层能够保持纳米粉末材料的尺寸和特性。     

Influence of Al on the microstructure and mechanical properties of Cr–Zr–(Al–)N coatings with low and high Zr content

Low Zr (S1) and high Zr (S2) quaternary Cr–Zr–(Al–)N coatings with increasing Al content were deposited by d.c. reactive magnetron sputtering. The structure, fracture cross-section morphology and mechanical properties of the coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), nanoindentation, scratch testing and Vickers micro-indentation testing. All the coatings present an fcc NaCl-type B1 structure; in the low Zr content coatings, the diffraction peaks shift towards higher angles as the Al content increases. The grain size is approximately constant in a range from 6 to 8 nm, except for high Zr content films where a significant decrease in crystalline order is observed (grain size ~ 2.5 nm). In both series, the microstructure changed from equiaxed to columnar with increasing Al content. The highest hardness and strongest adhesion values were achieved in coatings with lower Zr and Al content. Conversely, the coatings with high Zr and the highest Al content exhibited an abrupt decrease in hardness, adhesion strength and toughness.     

K417G高温合金纳米氧化锆热障涂层的制备与性能

通过探讨喷涂工艺参数对纳米氧化锆涂层结构和性能影响的规律，使纳米氧化锆未熔颗粒基本上保持原始氧化锆粉末的纳米级晶粒大小，熔化的颗粒则起粘结剂的作用，使涂层内氧化锆颗粒问结合牢固，涂层结构致密。纳米氧化锆热障涂层与常规氧化锆涂层相比导热系数降低，隔热效果得到明显提高。力学试验结果则表明，纳米结构热障涂层在硬度、抗热冲击性能、耐冲击性以及结合强度等方面都明显高于常规粉末制备的涂层。     

Microstructure and Thermal Characterization of Plasma-Sprayed Nanostructured La2Ce2O7-Doped YSZ Coatings

Nanostructured La₂Ce₂O₇-doped YSZ coatings were developed using atmospheric plasma-spraying technique by optimizing various process parameters. To ensure the retention of nanostructure, the molten state of nanoagglomerates was monitored using plasma and particle diagnostic tools. It was observed that the morphology of the coating exhibits a bimodal microstructure consisting of nanozones reinforced in a matrix of fully-molten particles. The thermal diffusivity of nano-LaCeYSZ coatings is lower than that of nano and bulk YSZ. The reason for this change in thermal diffusivity may be attributed to scattering of phonons at grain boundaries, point defect scattering and higher inter-splat porosity. Also, the thermal conductivity of the nanocomposite coatings was lower than those of nanostructured and bulk YSZ coatings. XRD results show cubic zirconia with a small amount of tetragonal zirconia. The average grain size of the as-sprayed La₂Ce₂O₇-YSZ nanocomposite coatings is ~150-200 nm. The improved thermal behavior is mainly due to a dense, packed, and more compact structure of the coatings.     

Transmission electron microscopy observation of microstructure of plasma-sprayed nanostructured zirconia coating

Nanostructured zirconia coatings deposited by plasma spraying technique were observed using transmission electron microscopy (TEM). It was found that the as-sprayed nanostructured zirconia coating had bimodal microstructures in terms of grain size distribution in the direction parallel to substrate surface. One was in the range 30–120 nm, which was the dominative structure of the coating, and the other was about 150–400 nm. The cross-section micrograph of the plasma sprayed nanostructured zirconia coating revealed that the coating still exhibited lamellar structure with columnar grains extending through its thickness. In conjunction with partially molten zirconia grains, amorphous regions were found. Domain structure and superlattice structure were observed in the plasma-sprayed nanostructured zirconia coating. The formations of the domain and superlattice structures are discussed in this paper.     

纳米氧化锆热障涂层组织结构和高温稳定性能分析

采用大气等离子喷涂技术制备了纳米氧化锆热障涂层.利用FESEM和XRD对纳米氧化锆热障涂层的微观组织和物相组成进行研究.微观组织分析结果表明,纳米氧化锆热障涂层展现出独特的微观复合结构,包括未熔纳米颗粒和柱状晶组织.物相分析结果表明,纳米氧化锆热障涂层主要由非平衡四方相组成.纳米氧化锆热障涂层高温稳定性能试验结果表明,涂层晶粒度随着服役温度和服役时间的增加而增加,但仍保持纳米结构;涂层物相组成不随服役环境的变化而变化.     

硫脲对 304 不锈钢镀镍层抗腐蚀性能的影响

目的研究硫脲对电镀镍层形貌、晶型、晶粒尺寸以及抗腐蚀性能的影响。方法在添加和不添加硫脲两种条件下,对304不锈钢进行电镀镍。通过XRD和SEM对比镀层的晶相结构、晶粒尺寸和微观形貌,通过Tafel曲线和EIS电化学阻抗谱对比分析样品的抗腐蚀性能。结果添加硫脲前后,镍镀层的择优生长方向从200晶面转变为111晶面,晶粒平均尺寸从60.2 nm减小为20.7 nm。由于硫脲吸附在金属表面,阻滞了溶液中金属离子放电,从而提高了阴极极化作用;同时,硫脲分子吸附在晶体生长的活性点上,有效抑制了晶体生长;因此,镍晶粒得到细化。关于腐蚀性能,镀镍304不锈钢的耐腐蚀性能最好,其次是304不锈钢基体,最差的是含硫镀镍304不锈钢。结论硫脲能够改变镍镀层晶体的择优取向,并且细化晶粒。硫脲影响电镀镍层抗腐蚀性能的机理是:阴极吸附的硫脲通过电化学还原产生H2S,进一步与Ni2+反应生成Ni S,Ni S再与富集的Ni反应生成Ni3S2。随着电镀的进行,Ni3S2被更多地沉积在镍镀层的表面,降低了镍层表面钝化膜的致密性;而且,Ni3S2与镍层存在电势差,故易发生原电池腐蚀。此外,晶粒细化导致晶界和晶面的缺陷增加,也使得腐蚀加速。故镀液中加入硫脲,镀层的耐腐蚀性能大大降低。     

Thermo-physical properties of plasma sprayed Yttria Stabilized Zirconia Coatings

This article investigates the thermo-physical properties of plasma sprayed zirconia coatings produced by agglomerates of submicron size particles as the feedstock. The microstructure of these deposits is consisted of splats and non-molten particles. This bimodal structure generally shows a better performance than conventional coatings. The agglomerated feedstock with internal submicron size porosity may significantly affect porosity related properties, such as the thermal diffusivity. In this study different process parameters were used to deposit yttria stabilized zirconia coatings with conventional and bimodal structures. Results showed a good correlation between the shape and distribution of pores and thermal diffusivity of the coatings.     

From nanocrystalline to amorphous structure in beryllium-based coatings

The material properties of vapor deposited coatings are sensitive to the growth morphology and microstructure. For certain applications it is desirable to deposit Be-rich coatings that are homogeneous, isotropic, dense, mechanically strong, and smooth. One way to develop this set of properties is to refine the grain size in these deposits to the nanoscale range. In this study, the compositional effects of Cu, Fe, and B additions on the microstructure of Be coatings have been characterized with transmission electron microscopy. Fe and B additions are found to have a dominant affect on grain refinement. Furthermore, an amorphous Be-B phase is found in deposits having compositions in excess of 11 at.% B. Nanoindentation was used to assess the mechanical properties of the coatings. The measured hardness values are correlated with the grain size and compositions of the coatings. The presence of amorphous Be-B phases is found to decrease the coating hardness.