碳酸盐热分解制备纳米YSZ粉末及其涂层研究

以纯氧氯化锆、氧化钇和硝酸为原料,以碳酸铵沉淀剂,采用共沉淀法制备碳酸锆与碳酸钇的混合物,经喷雾干燥制粒、热处理后得到纳米YPSZ团聚粉末.由等离子喷涂方法制备了YPSZ涂层,用XRD、SEM等分析手段观察和确定涂层的物相组成和显微结构.     

等离子喷涂CeO2改性La2Zr2O7纳米热障涂层高温性能研究

研究了不同Ce掺杂量对La2Zr2O7相结构稳定性的影响,确定了Ce原子掺杂量为5.45％的CeO2改性La2Zr2O7涂层（CLZ）.研究了采用大气等离子喷涂制备的涂层与原始粉末化学成分计量比偏离情况.经共沉淀制粉、喷雾干燥团聚造粒、大气等离子喷涂制备了Ce原子掺杂量为5.45％的新型纳米CLZ热障涂层,研究了涂层的长期组织结构稳定性、抗热震性以及失效机制.结果表明,CLZ涂层具有良好的长期组织结构稳定性,涂层在1150℃下热震循环寿命达到26次.涂层失效主要以层状撕裂为主.陶瓷层和粘结层热膨胀不匹配、粘结层发生氧化可能是导致CLZ涂层热震失效的主要原因.     

溶剂类型对液相等离子喷涂涂层性能影响

溶液前驱体等离子喷涂(SPPS)和悬浮液等离子喷涂(SPS)采用溶液前驱体或悬浮液替代传统大气等离子喷涂中的喷涂粉末,可制备出由大量细小粒子组成的具有纳米结构及独特性能的涂层。本文以溶液前驱体和悬浮液的溶剂类型为线索,介绍了采用SPPS和SPS技术制备YSZ、Al2O3、Ti O2涂层的研究进展。     

低压等离子喷涂纳米YSZ-Al_2O_3涂层组织性能的研究

低压等离子喷涂纳米氧化锆热障涂层,具有独特的组织结构。纳米团聚颗粒在高温等离子射流中部分熔化后沉积到基体上,团聚颗粒能够保留部分纳米结构,形成一种以纳米晶为主的纳米-微米二元结构涂层,为热障涂层的制备提供了一种新的技术方案。YSZ涂层高温服役中,纳米晶粒容易烧结长大。本文通过向YSZ粉体中加入少量的纳米α-Al_2O_3,探讨其抑制YSZ热生长的机制。首先制备了YSZ-Al_2O_3纳米混合物团聚粉末,并借助低压等离子喷涂技术制备涂层。结果表明纳米晶区占主导地位,纳米晶区嵌有少量的微米晶粒。涂层经1400℃,10h热处理,微观组织结构分析表明,α-Al_2O_3的加入对YSZ晶粒热生长具有部分抑制作用。     

铈锆酸镧涂层高温时效行为和热震性能研究

采用等离子喷涂制备了铈锆酸镧涂层,采用扫描电子显微镜(SEM)、X射线衍射分析(XRD)、图像分析法等研究了喷涂功率对沉积态涂层表面和截面微观结构、孔隙率等的影响规律,研究了涂层在1200℃、1300℃高温100h时效下相稳定性、微观结构、孔隙率的变化,比较了不同喷涂功率涂层的抗热震性能。研究结果表明:随着等离子喷涂功率的增加,喷涂过程中半熔融颗粒比例减小,涂层的孔隙率减小。涂层经1200℃、1300℃高温保温100 h后仍然具有单一的烧绿石结构,随着热处理温度升高,涂层孔隙率减小。研究了不同功率喷涂的涂层从1250℃到冷水中的热震行为,失效机制分析表明:陶瓷层与粘结层热应力不匹配造成陶瓷层底部产生裂纹是导致涂层失效的主要方式。     

等离子喷涂氧化钇稳定氧化锆涂层的分形特征与断裂韧性

采用超音速等离子喷涂和普通大气等离子喷涂制备了微米级氧化钇稳定氧化锆（yttria-stabilized zirconia,YSZ）基热障涂层,使用SprayWatch-2i系统测试喷涂过程中粒子飞行速度及表面温度,通过扫描电镜和图像分析技术表征涂层微观结构,利用压痕法测试了断裂韧性和弹性模量,采用基于分形思想的面积-周长幂率定量表征两种工艺条件下孔隙不规则形态,并研究了分形维数对涂层断裂韧性的影响。结果表明:超音速等离子喷涂和普通大气等离子喷涂YSZ涂层孔隙都具有分形特性;超音速等离子喷涂YSZ涂层分形维数是普通等离子喷涂涂层的1.12倍,孔隙结构更复杂,涂层断裂韧性更高。     

等离子喷涂纳米Al_2O_3-13%TiO_2涂层的研究现状和展望

本文综述了国内外制备纳米Al2O3-13%TiO2团聚粉末和等离子喷涂纳米Al2O3-13%TiO2涂层的组织结构及其性能的研究现状。分析了影响纳米Al2O3-13%TiO2团聚粉末性能的因素;讨论了纳米Al2O3-13%TiO2涂层双重结构的形成机理,及其组织形貌和性能;指出制备纳米Al2O3-13%TiO2涂层存在的问题并展望了未来的应用前景。     

团聚钼粉和烧结钼粉等离子喷涂涂层的性能研究

本文通过喷雾干燥法制备了团聚钼粉,通过"喷雾干燥+烧结"的方法制备了烧结钼粉,然后对两种粉末进行了等离子喷涂实验,并对制备的涂层的形貌、粗糙度、硬度和孔隙率等进行了检测分析。结果表明,利用烧结钼粉制备的涂层的性能均优于团聚钼粉制备的涂层,其中烧结钼粉涂层的粗糙度为7μm,硬度为449.69HV和孔隙率为1.27%。     

液相等离子喷涂涂层研究进展

悬浮液等离子喷涂(SPS)和溶液前驱体等离子喷涂(SPPS)采用悬浮液或溶液前驱体替代传统等离子喷涂中的粉末材料,可制备出由大量细小粒子组成的具有纳米结构及独特性能的涂层,近年来,引起了广泛关注。本文以SPS和SPPS涂层应用方向为线索,介绍了SPS和SPPS涂层研究进展,并与传统等离子喷涂制备的涂层性能进行对比,展示了SPS和SPPS涂层的优点和应用价值。     

致密化工艺对氧化钛粉末及等离子喷涂涂层性能影响研究

采用喷雾干燥法制备了一种球形氧化钛团聚粉末, 并通过高温烧结及感应等离子球化工艺对团聚粉末进行 致密化处理。 利用扫描电子显微镜 (SEM)、 霍尔流速计和粉末颗粒强度仪对粉末性能进行了表征, 研究了不同致 密化处理工艺对粉末颗粒强度、 松装密度及流动性的影响。 采用大气等离子喷涂 (APS) 工艺制备了氧化钛涂层, 并对涂层的微观组织进行研究。 研究结果表明, 高温烧结工艺及等离子球化工艺均可有效提升氧化钛团聚粉末 的致密度, 经过高温烧结工艺后氧化钛粉末内部的细小颗粒呈现烧结熔融的趋势, 而采用等离子球化处理后的 团聚粉末直接形成了致密球体结构。 相比于高温烧结工艺, 等离子球化工艺对氧化钛粉末的致密化效应更为明 显, 粉末的颗粒强度可达 187.86 MPa, 松装密度可由 0.79 g/cm3 提升至 1.69 g/cm3, 流动性由 163.22 s/50g 加快 至 100.27 s/50g。 该粉末经过大气等离子喷涂沉积形成的氧化钛涂层孔隙率为 2.8 %, 与未经致密化工艺处理的氧 化钛团聚粉末相比, 制备的涂层致密化水平有了较大程度的提升, 涂层的平均显微硬度值由 434.18 HV0.3 提升至 744.37 HV0.3, 涂层的结合强度均值由 11.07 MPa 提升至 29.93 MPa。     

大气等离子喷涂工艺对纳米结构和传统Yb2SiO5 涂层微观结构的影响

纳米材料由于具有一些独特的效果而表现出了独特的性能,纳米结构稀土硅酸盐被认为是很有前景的环境 障碍涂层 ( EBC ) 材料之一。稀土硅酸盐材料中Yb2SiO5 因其卓越的高温相稳定性、对水蒸气环境的耐久性、低 热导率以及优秀的化学稳定性受到了研究者们的广泛关注。本文研究了大气等离子喷涂工艺 ( APS ) 参数对纳米 结构和传统Yb2SiO5 涂层微观结构的影响,并研究了相同大气等离子喷涂工艺下,纳米结构Yb2SiO5 喂料和传统 Yb2SiO5 喂料对涂层微观结构的影响,分析了APS 制备过程中不同结构喂料对涂层结构影响机制。结果表明：相 同喷涂参数制备的纳米结构Yb2SiO5 涂层孔隙率低于传统Yb2SiO5 涂层,以及纳米结构Yb2SiO5 涂层的铺展性和 融化度均优于传统Yb2SiO5 涂层,表明纳米结构Yb2SiO5 涂层为很有前途的环境障碍涂层之一。     

Correlation of microstructure and wear resistance of Al2O3-TiO2 coatings plasma sprayed with nanopowders

Correlation of microstructure and wear resistance of Al₂O₃-TiO₂ coatings plasma sprayed with nanopowders was investigated in this study. Four kinds of nanostructured Al₂O₃-13 wt pct TiO₂ coatings were fabricated by varying plasma-spraying parameters and were compared with an Al₂O₃-13 wt pct TiO₂ coating fabricated with conventional powders. The nanostructured coatings showed a bimodal microstructure composed of fully melted regions of γ-Al₂O₃ and partially melted regions, while the conventional coating mostly consisted of fully melted γ-Al₂O₃, together with some TiO₂-rich regions and unmelted Al₂O₃ powders. The wear test results revealed that the wear resistance of the nanostructured coatings was 3 or 4 times better than that of the conventional coating, because the preferential delamination seriously occurred along TiO₂-rich regions in the conventional coating. In the nanostructured coatings, TiO₂ was homogeneously dispersed inside splats and around, thereby leading to higher splat bonding strength and to better wear resistance over the conventional coating.     

再造纳米小颗粒 给力传统大工业

随着纳米科学技术的快速发展,纳米材料被成功地应用到热喷涂领域。研究表明,热喷涂纳米陶瓷涂层比传统陶瓷涂层具有更高的结合强度、韧性、热震性能、耐磨抗蚀性能和可加工性。这种热喷涂纳米陶瓷涂层是利用纳米粉末为原料经过特殊的再造粒过程得到可喷涂喂料,然后方可制备出纳米结构陶瓷涂层。与传统微米结构陶瓷涂层相比,该纳米陶瓷涂层的韧性、结合强度、抗热震性能高1～2倍,耐磨性能高4～8倍,抗疲劳性能提高10倍。发展这样的国际领先的先进表面工程新材料技术,对推动我省的科技和产业发展无疑有重大的战略和经济意义。可以促进我省传统产业的结构调整和产品的升级换代,可以提高我省产品的市场竞争力和我省企业的活力和经济效益。     

Wear of Plasma Sprayed Conventional and Nanostructured Al<Subscript>2</Subscript>O<Subscript>3</Subscript> and Cr<Subscript>2</Subscript>O<Subscript>3</Subscript>, Based Coatings

An ever increasing demand for high-performance ceramic coatings has made it inevitable for developing techniques with precise control over the process parameters to enable the fabrication of coatings with the desired microstructure and improved structural properties. The literature on plasma sprayed nanostructured ceramic coatings such as of Al₂O₃, Cr₂O₃, and their composites obtained using reconstituted nano sized ceramic powders has been reviewed in this study. Ceramic coatings due to their enhanced properties are on the verge of replacing conventional ceramic coatings used for various applications like automotive systems, boiler components, power generation equipment, chemical process equipment, aircraft engines, pulp and paper processing equipment, land-based and marine engine components, turbine blades etc. In such cases, the advantage is greater longevity and reliability for realizing the improved performance of ceramic coatings. It has been observed that the plasma sprayed nanostructured ceramic coatings show improvement in resistance to wear, erosion, corrosion, and mechanical properties as compared to their conventional counterparts. This article reviews various aspects concerning the plasma sprayed ceramic coatings such as (i) the present understanding of formation of plasma-spray coatings and factors affecting them, (ii) wear performance of nanostructured Al₂O₃, Cr₂O₃ and their composite ceramic coatings in comparison to their conventional counterparts, and (iii) mechanisms of wear observed for these coatings under various conditions of testing.     

氧化铈稳定纳米氧化锆高温性能的研究

等离子喷涂热障涂层技术广泛应用于航空发动机热端部件的高温防护。应用大气等离子喷涂法成功制备了纳米氧化铈氧化钇稳定的氧化锆(CYSZ)涂层,并与常规氧化钇稳定氧化锆(YSZ)涂层在1300℃下热处理10小时,研究高温对两种涂层性能的影响,与常规的YSZ涂层相比,CeO2的掺杂使涂层具有更高的稳定性。经过高温处理,CYSZ涂层的相结构没有发生明显变化。显微形貌结果表明,CYSZ涂层没有产生裂纹缺陷,涂层中纳米区域晶粒度随着温度的升高略有增大,这表明了纳米结构的CYSZ涂层具有更优异的高温稳定性。热循环氧化实验结果证明,CYSZ涂层具有更长的热循环寿命以及优异的高温抗氧化性能。     

Investigation of three steps of hot corrosion process in Y_2O_3 stabilized ZrO_2 coatings including nano zones

Phase transformation of tetragonal ZrO2 to monoclinic phase and also increment of bond coat oxidation kinetic（TGO thickening） can substantially restrict the life time of thermal barrier coating systems（TBCs）. So, nanostructured and conventional Y2O3 stabilized ZrO2 coatings were evaluated in fused V2O5-Na2SO4 salts during thermal exposure in air. Microstructural characterization showed lower hot corrosion products（monoclinic zirconia, YVO4 crystals） formation and reduction of TGO thickness in thermal barrier coating system consisting of nanostructured Y2O3 stabilized ZrO2（YSZ） top coat. It was found that inhomogeneities, pores and micro-cracks played a principal role in the molten salts infiltration into the YSZ coating during three steps of hot corrosion process. In the nanostructured YSZ coating with tri-model structure, nano zones which surrounded by fully molten parts could fill the aforementioned defects and could act as barrier for the oxygen and corrosive molten salts penetration into the TBC.     

Synthesis and Characterization of Nanostructured NiCrFeSiB HVOF Coating

The nickel based as-atomized thermal spray feedstock powder (NiCrFeSiB) was ball milled to produce the nanostructured powder. The feedstock powder was mechanically milled using two station planetary ball-mill. The milled and unmilled feedstock powders were coated using High-velocity oxygen fuel system to produce nanostructured and conventional coatings respectively on the carbon steel substrate (SA210 Grade C). The metallurgical characterization of feedstock powders and coatings were performed using scanning electron microscope, High resolution- transmission electron microscope coupled with energy dispersive spectroscopy and X-ray diffraction techniques. The developed coatings were mechanically characterized by microhardness test and bond strength measurement techniques. The porosity of the coating was measured by analyzing the optical microscope image using the image-J software. In this study, nanostructured coatings exhibited higher hardness, less porous and better bond strength compared to conventional coating.     

超音速等离子喷涂纳米防污陶瓷涂层研究

以NiCr合金为底层,含防污成分的纳米Al_2O_3-13%TiO_2为面层,采用超音速等离子喷涂方法制备纳米防污陶瓷涂层。研究了不同工艺对涂层截面形貌、孔隙率、显微硬度及结合强度的影响,探讨了涂层的防污性能,获得了较优的喷涂工艺参数:Ar流量3.6～3.8 m~3/h,H_2流量0.4 m~3/h,电流400～420A,电压150V,喷距100mm,送粉量30g/min。采用较优超音速等离子喷涂工艺制备的纳米防污陶瓷涂层孔隙率可达0.8%,HV_(0.3)≥987,结合强度≥35.15 MPa,并且抗海生物附着性能优良。     

Synthesis of nanostructured Cr3C2-25(Ni20Cr) coatings

On the basis of the nanocrystalline Cr₃C₂-25 (Ni20Cr) feedstock powders produced by mechanical milling, a nanostructured coating has been synthesized using high velocity oxygen fuel (HVOF) thermal spraying. The properties of the nanostructured coating were compared to those of the conventional coating of the same composition using scanning electron microscope (SEM), transmission electron microscope (TEM), and microhardness tests. The nanostructured Cr₃C₂-25 (Ni20Cr) coating synthesized in this study had an average carbide particle size of 24 nm. Discontinuous elongated amorphous phases were observed in the nanostructured coating. The conventional Cr₃C₂-25 (Ni20Cr) coatings produced using blended elemental powders exhibited an inhomogeneous microstructure. The observed homogeneity of the nanostructured coating is attributed, in part, to the microstructural improvement of the starting powder. The nanostructured Cr₃C₂-25 (Ni20Cr) coating yielded an average microhardness value of 1020 DPH₃₀₀, which corresponds to a 20 pct increase in microhardness over that of the conventional coating. The nanostructured Cr₃C₂-25 (Ni20Cr) coating also exhibited a higher apparent fracture toughness relative to that of the conventional coating. The apparent mechanical property improvements in the nanostructured coating were thought to result from the uniformity of the microstructure and the high performance associated with a nanostructured structure. In addition, the mechanism that is present during the milling of a system containing nondeformable particles is discussed in light of the TEM observations.     

Microstructure and thermal cycling behavior of nanostructured yttria partially stabilized zirconia (YSZ) thermal barrier coatings

Nanostructured yttria partially stabilized zirconia(YSZ) coatings were prepared by atmospheric plasma spraying(APS) using the conglomeration made by zirconia nanoparticle as the raw materials.The measurement methods,which consisted of scanning electron microscopy(SEM),transmission electron microscopy(TEM) and thermal cycling behavior,were used to character the morphology,composition and thermal oxidation behavior of the powder and the coatings.From the results,it was shown that the YSZ coating was the laminar structure,and the elements distribution in the bond and top coat were well-proportioned.The YSZ coatings were composed of fine grains with size ranging from 30 to 110 nm.The laminar layers with columnar grains were surrounded with unmelted parts of the nanostructured powder and some equiaxed grains.In the as-sprayed nanostructured zirconia coatings,there existed pores that were less than 1 μm.The cracks were observed on some of the crystal border.The cyclic oxidation experiment showed that the nanostructured coating had longer thermal cycling lifetime to exhibit the promising thermal cyclic oxidation resistance.The failure of the nanostructured TBC was similar to the failure of conventional APS TBC.