热喷涂纳米陶瓷涂层的研究现状及进展

热喷涂技术是制备纳米结构陶瓷涂层最具前途的方法之一.本文简要介绍了热喷涂陶瓷涂层的性能、研究现状,并对热喷涂纳米陶瓷涂层面临的问题进行了讨论.     

纳米复合陶瓷涂层研究现状

介绍了国内外纳米复合陶瓷涂层的性能以及各种喷涂技术制备纳米陶瓷涂层的研究现状.与传统涂层相比,纳米涂层在韧性,强度和耐磨性能等方面有了很大的提高.分析了面临的主要问题,并提出相应的解决办法.     

热喷涂纳米陶瓷涂层的应用

采用热喷涂技术制备纳米结构涂层是构筑纳米结构材料最具前途的方法之一,本文综述了热喷涂陶瓷涂层材料的性能、制备方法及应用方面的研究现状,并对热喷涂纳米陶瓷涂层面临的问题及研究的发展趋势进行了讨论。     

热化学反应法制备纳米复合陶瓷涂层及性能研究

采用热化学反应法在Q235钢上制备纳米复合陶瓷涂层,对涂层进行结构分析及性能测试。试验结果表明:涂层在600℃固化产生了新陶瓷相;涂层较致密,涂层与基体结合良好;涂层大大提高了基体的耐蚀性和耐磨性。     

风挡玻璃表面涂层的制备与研究

在众多的涂层材料中,有机无机复合涂层材料在改善有机玻璃表面性能方面表现出独特的优点。本文中选择以透明甲基硅树脂为有机涂层,而后在有机涂层中添加纳米级陶瓷颗粒。固化成膜后,陶瓷纳米颗粒均匀分散在甲基硅树脂分子链中,无机相的存在将明显改善有机基体表面性能,将有机玻璃的耐磨性提高到了无机玻璃的水平。     

陶瓷涂层结构优化及失效机理的研究现状

陶瓷涂层以其优异的耐磨损、耐高温、耐腐蚀等性能表现出巨大的工程应用前景。但是,在服役过程中因温度变化和受力诱发的裂纹产生、扩展,甚至导致涂层开裂、剥落及失效,这些因素限制了涂层的应用,因此通过结构优化改善陶瓷涂层的抗开裂、剥落性能较为重要。本文首先论述了纳米结构涂层、耐磨多层涂层、复合涂层的失效机理及其结构优化。提出了利用单次喷涂制备粘结层和陶瓷层的方法,通过该方法可以消除陶瓷层与粘结层间的界面形态,提高涂层的断裂韧性、粘结强度。最后展望了陶瓷涂层在材料组分设计和工艺优化研究中应重点关注的方面。     

纳米陶瓷热喷涂若干问题的试验研究

就制备Al2O3-3TiO2纳米陶瓷涂层的热喷涂系统热源，焰流速度和纳米陶瓷棒进行了试验研究，提出了采用低温、高速、强力、纳米陶瓷棒制备纳米陶瓷涂层的热喷涂工艺。     

物理悬浮破碎与化学插层溶胶-凝胶相结合制备纳米ZrO_2结构陶瓷涂层研究

采用物理悬浮破碎与化学插层溶胶-凝胶相结合的方法,通过低温成膜制备出纳米ZrO2结构陶瓷涂层。利用扫描电镜(SEM)和X射线衍射试验(XRD)方法表征了陶瓷涂层的微观结构和晶形。通过热震、耐磨蚀测试、附着力和硬度检测手段,检测其成膜的宏观性能。结果表明,低温成膜的结构陶瓷热震性能够承受800℃的温度,而纳米ZrO2大部分为四方相,陶瓷涂层有较好的致密度,涂层与基材结合良好,抛光后断面涂层厚度20μm左右,耐磨蚀能力超过普通陶瓷涂层,附着力达到0级,硬度为9H,具有很好的实用性。     

镁合金表面纳米Al2O3陶瓷涂层的制备及耐磨性研究

采用热化学反应法在MB2镁合金表面制备了含有纳米Al2O3粒子的陶瓷涂层。采用XRD分析了微米Al2O3陶瓷涂层和纳米Al2O3陶瓷涂层的相结构,并测试了这两种涂层的耐磨性及耐热冲击性。结果表明,微米级Al2O3陶瓷涂层磨粒磨损及黏着磨损耐磨性相对于镁合金基体分别提高了14%及47%,且涂层中有新相MgMnSiO4生成;纳米Al2O3陶瓷涂层耐磨性及耐热冲击性优于以微米粒子制备的陶瓷涂层,磨粒磨损及黏着磨损耐磨性相对于基体分别提高了55%及100%,涂层中产生新相Mg2SiO4和Al2SiO5。     

纳米陶瓷及其纳米复相陶瓷的研究现状

综述了纳米陶瓷和纳米复相陶瓷的的研究现状．探讨了纳米陶瓷的力学性能及其热喷涂纳米陶瓷涂层存在的问题．分析了纳米复相陶瓷的增韧机理，为纳米陶瓷的研究和应用提供了理论依据。     

Microstructure analyses and thermophysical properties of nanostructured thermal barrier coatings

Nanostructured 8 wt% yttria partially stabilized zirconia coatings were deposited by air plasma spraying. Transmission electron microscopy, scanning electron microscopy, and X-ray diffraction were carried out to analyze the as-sprayed coatings and powders. Mercury intrusion porosimetry was applied to analyze the pore size distribution. Laser flash technique and differential scanning calorimetry were used to examine the thermophysical properties of the nanostructured coatings. The results demonstrate that the as-sprayed nanostructured zirconia coatings consist of the nonequilibrium tetragonal phase. The microstructure of the nanostructured coatings includes the initial nanostructure of powder and columnar grains. Moreover, micron-sized equiaxed grains were also exhibited in the nanostructured coatings. Their evolution mechanisms are discussed. The as-sprayed nanostructured zirconia coating shows a bimodal pore size distribution, and has a lower value of thermal conductivity than the conventional coating.     

Plasma-sprayed nanostructured YSZ thermal barrier coatings: Thermal insulation capability and adhesion strength

Adhesion strength and thermal insulation of nanostructured Yttria Stabilized Zirconia (YSZ) thermal barrier coatings (TBC) were investigated and compared with those of conventional YSZ TBCs. A Nickel based superalloy (IN-738LC) was used as the substrate with NiCrAlY bond coat, and nanostructured and conventional YSZ top coats were applied by using air plasma spray (APS). The adhesion strength of coatings was evaluated according to ASTM C633-01, and their thermal insulation capability was evaluated using a specially designed test setup at an electrical furnace. The results revealed the nanostructured YSZ coating to have a bimodal microstructure consisting of nanosized particles and microcolumnar grains. The bimodal microstructure of nanostructured coatings prevented crack propagation by splat boundaries and unmelted particles, thereby improving the bonding strength. Also, due to the presence of nano-zones in the microstructure of nano TBCs, coatings exhibited superior thermal insulation capability.     

Characterization of multi-scale synergistic toughened nanostructured YSZ thermal barrier coatings: From feedstocks to coatings

The nanostructured 8YSZ thermal barrier coatings were deposited by atmospheric plasma spraying onto K417 G nickel-based superalloy with high velocity oxygen fuel sprayed NiCoCrAlYCe bond-coat using as-prepared nanostructured t´-Zr_0.9Y_0.1O_1.95 feedstocks for the first time. The microstructure and mechanical properties of nanostructured and conventional 8YSZ coatings were comparatively investigated systematically. The results revealed that both coatings were composed of t´-Zr_0.9Y_0.1O_1.95 phase and the formation mechanism of t´ phase was elucidated. The nanostructured 8YSZ coatings demonstrated typical bi-modal microstructure, whereas the conventional 8YSZ coatings exhibited mono-modal microstructure. Furthermore, the bi-modal microstructure of nanostructured 8YSZ coatings was analysed by elastic modulus and nanohardness Weibull distribution plots. The high and low slopes in Weibull distribution plots corresponded to unmelted and melted regions of nanostructured 8YSZ coatings, respectively. The fracture toughness and bonding strength of nanostructured coatings were higher than that of conventional 8YSZ coatings. Finally the reasons were explained in detail.     

Microstructural,mechanical and tribological properties of nanostructured YSZ coatings produced with different APS process parameters

Plasma sprayed ceramic coatings can be used in turbine engines as thermal barrier or abradable coatings, in order to improve the durability of the components as well as the efficiency. The presence of nanostructures, deriving from partial melting of agglomerated nanostructured particles, represents an interesting technological solution in order to improve their functional characteristics. In this work nanostructured yttria stabilized zirconia (YSZ) coatings were deposited by air plasma spraying (APS). The influence of the main process parameters on their microstructural, mechanical and tribological properties was investigated by scanning electron microscopy (SEM), indentation techniques at micro- and nano-scale and wear tests, respectively. Their porous microstructure was composed of well melted overlapped splats and partially melted nanostructured areas. This bimodal microstructure led to a bimodal distribution of the mechanical properties. An increase of plasma power and spraying distance was able to produce denser coatings, with lower content of embedded nanostructures, which exhibited higher elastic modulus and hardness as well as lower wear rate.     

Microstructure, mechanical properties and thermal shock resistance of plasma sprayed nanostructured zirconia coatings

Nanostructured yttria stabilized zirconia (YSZ) coatings were deposited by Atmospheric Plasma Spraying (APS). X-ray diffraction (XRD) was used to investigate their phase composition, while scanning electron microscopy (SEM) was employed to examine their microstructure. The coatings showed a unique and complex microstructure composed of well-melted splats with columnar crystal structure, partially melted areas, which resembled the morphology of the powder feedstock, and equiaxed grains. Vickers microhardness of nanostructured zirconia coatings was similar to that of the conventional ones and strongly depended on the indentation load. Otherwise, a higher thermal shock resistance was found. This effect was addressed to the retention of nanostructured areas in coating microstructure and to the corresponding high porosity.     

Comparative study on effect of oxide thickness on stress distribution of traditional and nanostructured zirconia coating systems

Numerical based assessment of traditional and nanostructured yttria stabilized zirconia (YSZ) thermal barrier coating systems (TBCs) has been carried out with varying thickness of thermally grown oxide (TGO). Radial, axial and shear stresses are determined for both coatings and are presented in comparison with few novel and interesting results. Elastic strain energy for TGO failure assessment is determined from calculated stress within TGO for varying thickness. Radial stresses at TGO/bond coat interface and maximum axial stresses in nanostructured zirconia coatings are found to be lower than in traditional YSZ up to a critical TGO thickness of 6 –7 μm, after which stresses in nanostructured zirconia coatings increase considerably. However, radial compressive stresses in nanostructured TBCs are lower in all TGO thickness cases and shear stresses are slightly higher with relatively more prominent difference at high oxide thickness.     

等离子喷涂纳米结构AT13基涂层硬度的双态分布

利用等离子喷涂技术制备纳米结构AT13基陶瓷涂层,通过SEM观察涂层组织结构并利用HXD-1000显微硬度计测量涂层的Vickers硬度,所得结果与对应成分的常规AT13涂层进行对比,结果表明常规涂层只含有单相层片结构,而纳米结构涂层含有双态分布(完全熔化层片结构和部分熔化颗粒结构),常规涂层的硬度平均值要低于纳米结构涂层,纳米结构涂层中存在依赖于微观结构双态分布的硬度Weibull双态分布,而且完全熔化区的硬度由于组织致密明显高于部分熔化区。采用三因素三水平对等离子喷涂纳米结构涂层工艺进行设计,得到影响涂层硬度的最主要的因素是电压,其次是电流。     

The Mechanism of High Thermal Shock Resistance of Nanostructured Ceramic Coatings

The nanostructured and the conventional ZrO₂ coating samples were thermal shocked at a series of temperatures. The elastic modulus and the hardness of two kinds of coatings were investigated by the nanoindentation tests. The results show that the corresponding mechanical properties of the conventional coatings increase monotonically with increasing temperature difference of the thermal shock. While the modulus and the hardness of the nanostructured coatings fluctuate slightly with increasing thermal shock temperature difference. Furthermore, the interface energy release model of the thermal shock strain energy was proposed for the nanostructured coatings. The theoretical prediction agrees with the experimental result.     

Microstructure and nanomechanical properties of plasma-sprayed nanostructured Yb2SiO5 environmental barrier coatings

In this study, nanostructured and conventional Yb₂SiO₅ coatings were prepared by atmospheric plasma. The microstructure and nanomechanical properties of these coatings were compared before and after heat treatment. The results show that the nanostructured Yb₂SiO₅ coatings have a mono-modal distribution, and the conventional Yb₂SiO₅ coatings have a bimodal distribution. Both types of coatings had improved nanomechanical properties after heat treatment. However, the increased elastic modulus and nanohardness of the nanostructured Yb₂SiO₅ coating were more apparent than those of the conventional Yb₂SiO₅ coatings. The nanostructured Yb₂SiO₅ coating had a higher elastic modulus than the conventional Yb₂SiO₅ coating, reflecting its high density. Subsequently, the microscopic morphology and micromechanical properties of the coatings were analyzed after heat treatment. Defects in the coatings, including pores, and microcracks, were significantly reduced with grain growth after thermal treatment, and the nanostructured Yb₂SiO₅ coatings had improved healing ability and micro-mechanical properties.