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51.
52.
《Ceramics International》2020,46(17):26731-26753
Thermal barrier coating (TBCs) are ceramic coatings that are deposited on metallic substrates to provide high thermal resistance. Residual stress is among the critical factors that affect the performance of TBCs. It evolves during the process of coating deposition and in-service loading. High residual stresses result in significant cracking and premature delamination of the TBC layer. In the present study, a hybrid computational approach is used to predict the evolution of internal cracks and residual stress in TBC. Smooth particle hydrodynamics (SPH) is first used to model the deposition of yttria-stabilized zirconia (YSZ) layer that contains various interfaces and micropores on a steel substrate. Then, three-dimensional (3D) finite element analysis is utilized to predict the evolution of internal cracks and residual stress in the ceramic coating layer. It is found that multiple cracks emerge during the solidification of the coating layer due to the development of high tensile (quenching) stresses. The cracking density is higher at regions near the coating interface. It is also found that compressive (residual) stresses are developed when the deposited coating is cooled to room temperature. The residual stress state is equibiaxial and nonlinear across the thickness/width of the TBC layer. The residual stress profile predicted compares well with that of hole drilling experiments. 相似文献
53.
Peng Yi Xiaoye Zhu Yongliang Jiang Wenlong Feng Zhihao Feng Yanchao Jin Guixin Dong 《International Journal of Applied Ceramic Technology》2020,17(5):2171-2181
In this study, the thermal and mechanical behaviors were investigated by simulating laser remelting of atmospheric plasma-sprayed yttria-stabilized zirconia coatings, and the molten depth and regions of stress concentration were compared between simulation and experiment. The heat treatment process of the remelted coating was also simulated. The crack formation mechanism in the YSZ coating remelted by laser and the heat-treatment effect on residual stress were investigated. Results showed that the simulated results were consistent with the experimental measurements, and the residual thermal stress was the main cause of cracks formation. The coating remelted by a laser power of 1500 W and a scanning rate of 9 mm/s possessed less residual concentrated stress and segmented cracks. Heat treatment released concentrated stress, which was still accurate for the ceramic coating. If the coatings were slowly heated to demonstrate heat treatment after laser remelting, the cracks in the remelted layer decreased correspondingly. 相似文献
54.
机械球磨技术因工艺简单、成本低廉而受到广泛关注,特别在粉体材料的混合、细化及合金化等领域有着广阔的应用前景。综述了由机械球磨原理发展而成机械涂覆技术的应用现状,包括用于材料表面改性的功能涂层和光催化降解的薄膜材料制备。分析了工艺参数、涂覆材料及涂覆基底等因素对涂覆效果(厚度)的影响规律,并对该技术在薄膜制备中表现出的简便、廉价且可在球形等形状复杂基底上成膜的独特优势做了讨论。基于当前机械涂覆技术制备的薄膜形貌、厚度不可控且成膜基底材质受限等现状,指出今后应该向拓展成膜基底材料类型和加快推进光催化薄膜材料的实际应用方向发展。 相似文献
55.
Currently, there is a growing interest in the application of silicon-based technologies for the development of advanced hybrid organic–inorganic coatings with strong weatherability. In this study, the sol–gel process is used to prepare such coatings on glass and their resistance to weathering effects is assessed afterwards. Various sols were prepared by mixing a silica-based inorganic matrix (tetraethyl orthosilicate) with different quantities of silica alkoxides functionalised with various organic groups. Subsequently, the sols were dip-coated onto glass samples at low temperatures without any heat treatment. The coatings prepared were analysed before and after three model ageing tests simulating various weathering parameters. After ageing, the best performing coatings showed good overall homogeneity and transparency (optical microscopy, SEM), improved water repellency and adhesion to the glass substrate (static contact angle measurements, cross-cut tape tests) and no colour or chemical composition changes (UV–VIS, FTIR). Compared with commercial hybrid silica products, the alkyl- and methacryloxy-functionalised silica coatings particularly displayed improved homogeneity, elasticity and barrier properties. Thus, these low temperature coatings, easily applicable to thin films, appear to fulfil the main requirements for the protection of the glass exposed to weathering phenomena. 相似文献
56.
随着我国环境保护法规《大气污染防治法》的修订和《涂料征收消费税通知》的公布,探讨了其对船舶涂料企业的冲击及其应对措施。 相似文献
57.
In this work, a one-step film formation method is demonstrated to obtain the patterned surface of an acrylate photocuring coating using nano-silica particles treated with a perfluoroalkoxysilane ((heptadecafluoro-1,1,2,2-tetra hydrodecyl) triethoxysilane) as a nanoadditive. Nanosilica particles were treated with perfluoroalkoxysilane and used in a UV-curable matrix. The typical patterns on the surface of the UV-cured films are revealed in AFM images. The surface properties of the cured films were investigated by measuring water contact angle and surface energy. The degree of conversion of the samples was obtained by FTIR analysis and pendulum hardness was measured using a Konig hardness meter. Scratch resistance of cured films was measured by standard scratch measuring pens. The characteristics obtained from AFM analysis showed that rough surface patterns in this system are controlled linearly by changes in the treated nano-particle concentration. The subtraction of surface energy of the cured film was clear and the water contact angle showed a 60% increase with the addition of a fluorinated nano-particle concentration. Surface hardness decreased and scratch resistance increased as the concentration of treated nanoparticles increased, while the final degree of conversion of the film remained unchanged. 相似文献
58.
Cerium malate (CeMal) was tested as a corrosion inhibitor for AA2024-T3 in this work. Corrosion inhibition on bare AA2024-T3 indicated that the inhibiting effect was a result of the synergistic effect of cerium cations and maleic anions. The corrosion of AA2024-T3 was stagnated by greatly reducing the corrosion current when CeMal was present in NaCl solutions. CeMal was adsorbed on the surface of AA2024-T3 forming a protective film in the initial stage. Then, cerium cations transformed to cerium oxide/hydroxides, precipitating on the cathode sites to inhibit the further corrosion. The electrochemical impedance spectra results of the sol-gel coatings proved that CeMal was an effective corrosion inhibitor in the sol-gel coatings to provide corrosion protection for AA2024-T3. 相似文献
59.
针对南方客户在使用我司客车一段时间后,车身涂层不同程度出现了起泡的质量问题,进行了现场查看,发现起泡位置在车身左右侧蒙皮,且发生在涂层最底层。初步分析原因是热镀锌板+阴极电泳漆 +原子灰三者之间配套存在问题,通过热镀锌板 +阴极电泳漆 +原子灰三者之间的耐高温 80 ℃配套试验,以及室外曝晒试验,得出镀锌板表面是否钝化、电泳漆膜致密程度和原子灰苯乙烯含量是造成涂层底层起泡的主要原因。为了控制涂层起泡问题,重新修订了我司原子灰、镀锌板、电泳漆的技术标准以及部分工艺文件。 相似文献
60.