等离子喷涂六钛酸钾涂层工艺研究

为了探索六钛酸钾热障涂层的制备工艺,通过正交试验分析方法,采用等离子喷涂工艺制备了钛酸钾热障涂层.研究了喷涂工艺对涂层物相结构的影响,采用定量金相分析了涂层组织.结果表明:喷涂工艺对涂层的物相结构有显著影响,随喷涂工艺的改变,涂层由类似于八钛酸钾的某种结构转变为以六钛酸钾结构为主的相结构;涂层孔隙分布均匀,孔隙率在10%左右.     

等离子喷涂制备热障涂层的研究进展

等离子喷涂是制备热障涂层最常用的技术。综述了大气等离子喷涂、超音速等离子喷涂、低压等离子喷涂制备热障涂层的研究进展,分析了这3种制备技术的优缺点,并对等离子喷涂制备热障涂层的发展趋势进行了展望。     

热喷涂及电子束物理气相沉积技术在热障涂层制备中的应用

对常用热障涂层制备技术,包括火焰喷涂、爆炸喷涂、大气等离子喷涂、高能等离子喷涂、超音速等离子喷涂、低压等离子喷涂、溶液注入等离子喷涂及电子束物理气相沉积技术进行了综述.介绍了上述几种制备技术的原理、工艺特点、存在不足及解决措施.认为发展爆炸喷涂工艺、溶液注入等离子喷涂工艺与EB-PVD工艺及其在新型热障涂层制备中的应用将是热障涂层制备技术研究的重点.     

纳米ZrO2热障涂层热震性能研究

为了研究纳米热障涂层的热震性能,采用等离子喷涂工艺制备了纳米Y2O3-ZrO2(YSZ)热障涂层,并测试了涂层的热震性能.借助扫描电镜和X射线衍射等手段分析了涂层的物相构成和组织结构.结果表明,涂层中保留未完全熔融的小尺寸颗粒,且存在大量的孔径＜1 μm的微孔,该结构对提高涂层的热震性能极为有利.纳米涂层抗热震性能显著优于常规热障涂层,从室温至1 000℃,经800次热循环,涂层无明显的脱落现象.     

等离子喷涂热障涂层多层结构的研究进展

基于热障涂层的发展现状，总结了SPS（悬浮液等离子喷涂）、SPPS（溶液前驱体等离子喷涂）及PS-PVD（等离子喷涂-物理气相沉积）技术及其制备的热障涂层结构性能特点；综述了等离子喷涂热障涂层单层、多层和梯度涂层的发展，着重总结了La₂Zr₂O₇、Gd₂Zr₂O₇、La₂Ce₂O₇ 3种陶瓷材料体系结构变化对涂层性能的影响；展望了热障涂层多层结构的发展前景。     

粘结层喷涂方法对铜基体与热障涂层结合强度的影响

为提高铜基体上热障涂层的工作温度和寿命,分别采用超音速火焰喷涂(HVOF)和等离子喷涂(APS)制备NiCrAlY粘结层,采用等离子喷涂制备ZrO2-8%Y2O3陶瓷面层.用拉伸试验测试了热障涂层的结合强度,利用SEM分析了拉伸断口的成分分布和微观形貌.研究表明,用HVOF制备粘结层的热障涂层的结合强度为47.9 MPa,用APS制备粘结层的热障涂层的结合强度为31.2 MPa.与等离子喷涂制备粘结层相比,采用超音速火焰喷涂制备粘结层可明显提高ZrO2陶瓷涂层的结合强度.     

纳米结构热障涂层研究进展

本文主要综述了目前制备纳米结构热障涂层的三种方法,即大气等离子喷涂、溶液前驱体等离子喷涂和悬浮液等离子喷涂,并对这三种方法的工艺过程、制备原理、涂层的微观结构特征和研究现状进行了归纳。最后,总结了纳米结构热障涂层研究目前存在的问题,并对其发展趋势进行了展望。     

反应等离子喷涂TiN/Ti3O复相陶瓷涂层

采用等离子反应合成技术,制备出了TiN/Ti3O复相陶瓷涂层,并分析了复相涂层的组织及其性能.研究结果表明:复相涂层主要由TiN相组成,并含有少量的钛的氧化物;复相涂层具有典型的层状组织结构,且层与层之间结合较好;制备的复相涂层的韧性得到明显提高,其韧性优于等离子喷涂Al2O3陶瓷涂层;特别是复相涂层具有优于M2钢的耐磨性.     

45钢表面大气等离子喷涂氧化钇部分稳定氧化锆热障涂层及其性能

为了制备高性能热障涂层,缩短国内外差距,在45钢表面大气等离子喷涂氧化钇部分稳定的氧化锆(YSZ)热障涂层。利用X射线衍射和扫描电镜分析YSZ涂层的相结构和微观形貌,分别测定了YSZ涂层的孔隙率、热导率、显微硬度、结合强度及隔热性能。结果表明:YSZ涂层的孔隙率、隔热温差随喷涂电压增大而减小,随喷涂距离的增加而增大;维氏硬度、结合强度和热导率随喷涂电压增大而增大,随喷涂距离增加而减小;当喷涂电压为80 V,喷涂距离为100 mm时,YSZ热障涂层的结合强度为36.78 MPa,热导率为0.705 W/(m·K),具有较好的隔热性能。     

等离子喷涂制备氧化锆陶瓷涂层的显微组织

采用等离子喷涂方法制备了纳米氧化锆热障涂层,并对涂层的显微组织进行了分析。结果表明：涂层由熔化区和部分熔化区组成,涂层中含有较多的孔隙,其形貌主要为长条形和近球形,未发现有贯穿性孔洞,但有细小且无明显方向性的微裂纹;涂层中的纳米氧化锆颗粒熔化长大程度不同,部分颗粒长大成为微米级。     

液相等离子喷涂制备纳米ZrO2/Y2O3涂层的研究

传统的喷涂技术制备的ZrO2/Y2O3涂层存在原料需团聚烧结致密,纳米晶粒不定和物理性能不佳等缺点.采用一种新型的液相等离子喷涂法制备了纳米氧化锆热障涂层,初步分析了液相前驱体液滴在等离子焰流中和基体表面的沉积变化过程,研究了雾化液滴尺寸对纳米氧化锆涂层的显微结构,特别是其相结构的影响;同时分析了纳米氧化锆涂层的抗热震循环性能.结果表明,纳米氧化锆涂层可以承受1 000多次的热循环试验,具有优良的抗热震性能.     

等离子喷涂氧化锆纳米涂层显微结构研究

利用大气等离子喷涂（APS）技术,在不锈钢基体上制备了氧化锆纳米结构涂层.运用XRD、SEM与TEM等分析手段对喷涂用粉末原料和涂层的显微结构、物相组成进行了观察和确定.实验结果表明,纳米氧化锆粉末经喷雾造粒后的颗粒粒径主要分布在15～40μm之间,流动性好,适合于等离子喷涂用.等离子喷涂氧化锆纳米涂层颗粒分布在60～120nm之间,晶粒发育良好.涂层物相由四方和立方相氧化锆所组成.氧化锆纳米涂层的气孔率约为7％,结合强度为45MPa。     

Coatings on graphite crucibles used in melting uranium

Standard coatings for graphite crucibles used for melting uranium have generally been zirconia based and have been applied as a paint or by flame spraying. These coatings do not provide adequate protection at the temperatures normally required for melting uranium alloys. Yttria provides superior protection above 1300°C but becomes less satisfactory above 1450°C when applied directly on graphite. The utilization of a protective niobium/zirconia bilayer coating between the yttria and the graphite results in improved performance at 1500°C. Yttria has been satisfactorily applied both by plasma spraying and by brush applying a stable suspension. When the protective niobium layer is used, coating adherence after melting is excellent and multiple use of coatings is practical. The coatings adhere to graphite with a high coefficient of thermal expansion (CTE) (≈7 μm m^-1 °C^-1) much better than to standard crucible grade graphite (≈4μm m^-1 °C^-1). A single Nb/Y₂O₃-coated high CTE graphite crucible has been used for seven melts at 1450°C without repair or increased carbon contamination.The yttria paint coating is cost effective when compared with flame- or plasma-sprayed zirconia.     

氧化锆纳米等离子涂层的结构与热震性能研究

利用大气等离子喷涂技术, 制备了氧化锆纳米结构和常规结构涂层, 并对涂层的显微结构进行了探查. 结果表明: 纳米结构涂层是由直径为100nm左右的柱状晶粒组成的层状结构; 涂层中存在大量的微裂纹和分布均匀的细小圆气孔. 纳米结构的涂层具有比常规涂层更好的抗热震性能, 其热震行为与常规涂层不同.     

Effect of powder structure on microstructure and electrical properties of plasma-sprayed 4.5 mol% YSZ coating

Electrolyte coatings by atmospheric plasma spraying were prepared by 4.5 mol% ytrria-stabilized zirconia (YSZ) powders manufactured by agglomerate-sintered (A-S) and fusing-crashed (F-C) processes. Microstructure of the powders and the coatings were characterized using scanning electron microscopy. The electrical conductivity of the coatings was investigated using both impedance spectroscopy and DC methods. The results showed that the electrical conductivity of coating prepared with A-S powder was lower than that with F-C powder. It was found from the impedance analysis that both the grain and grain boundary resistances were large in the coating formed by A-S powder. This fact resulted from deposition of partially melting of spray particles. A model was proposed to explain the effect of powder structure and melting state on the coating microstructure and properties.     

Detection of Melting Temperatures and Sources of Errors Using Two-Color Pyrometry During In-flight Measurements of Atmospheric Plasma-Sprayed Particles

Growing demands on the quality of plasma-sprayed coatings require reliable methods to monitor and optimize the spraying processes. As the coating microstructures are dependent on the characteristics of the powder feedstock, particle in-flight diagnostics is of great importance. In particular, the melting status of the particles is critical in this regard. Thus, the accurate determination of the particle temperature is necessary. In-flight particle temperature measurements during atmospheric plasma spraying (APS) of tungsten, molybdenum, and yttria-stabilized zirconia by two-color pyrometry were analyzed statistically. The diagnostic tool applied is the DPV-2000 (Tecnar). The particle temperature distributions allow for assessment of the melting status of the particles as well as the identification of the melting temperature and particle fractions in the molten and solidification state. Furthermore, the relevant systematic and material-dependent sources for measurement errors using two-color pyrometry were investigated. Their influence was carefully estimated and corrected. As long as there are reliable data available on the emissivity of the powder material, good agreement between the corrected measured melting temperatures and the reference data can be expected.     

等离子喷涂参数对钽涂层组织及性能的影响

采用等离子喷涂法制备了钽金属涂层，用电子显微镜分析了不同工艺条件下钽涂层的化学成分、表面形貌，测试了涂层与基材的结合强度。结果表明，采用优化的等离子喷涂工艺参数，可以制取组织致密、厚度均匀的钽涂层；钽粉的颗粒尺寸对材料的熔化状态影响较大；在试验的喷距范围内，喷距对粉末的熔化状态和涂层结合强度均无明显影响。     

用镍基薄带钎料真空熔结Cr3C2-NiCr涂层的组织和性能

提出了一种采用薄带钎料进行真空熔结的新方法，用BNi-2薄带钎料粘贴在Cr3C2-NiCr预置层表面进行了真空熔结处理，对涂层的组织和微动磨损性能进行了研究。结果表明，真空熔结涂层组织致密，涂层与基体、涂层内部硬质相与粘结相之间可形成良好的冶金结合。涂层主要由Cr3C2，Cr7C3，Cr23C6，Ni的硼化物、Cr的硼化物等硬质相和镍基固溶体韧性相组成。基于致密的组织、良好的结合和硬质相强化，真空熔结Cr3C2-NiCr涂层的抗微动磨损性能明显优于等离子喷涂Cr3C2-NiCr涂层和1Crl8Ni9Ti不锈钢。     

超音速等离子喷涂氧化铈稳定氧化锆涂层的摩擦磨损性能

目前对氧化铈稳定氧化锆涂层的研究较少,且对涂层摩擦学性能的研究不够深入。利用超音速等离子喷涂技术,在45钢基体上制备了氧化铈稳定氧化锆涂层。采用XRD、SEM及EDS等对粉料及涂层的显微结构和物相组成进行了分析;利用划痕仪对涂层的结合力进行了测试;在干摩擦条件下对涂层的摩擦磨损性能进行了测试。结果表明:涂层在基体表面铺展良好,与基体结合紧密,结合力为30 N。载荷为200 N时涂层的质量磨损率极低,且摩擦系数随载荷的增大而减小。     

Plasma spraying of zirconia-titania-silica bio-ceramic composite coating for implant application

Zirconia-titania-silica (ZTS) bio-ceramic composite coating was deposited on titanium surface via plasma spray process. The original feedstock was prepared by mixing equal amounts (wt.%) of each powder in ceramic pot followed by stirring with ceramic ball. The resulting composite powder was sprayed at two different stand-off distances (SOD: 45 and 50 mm). Silica particles are distributed uniformly in the coating matrix. Amorphous silica was detected by energy-dispersive X-ray spectroscopy (EDXS) and FT-IR analysis which showed the spectra of Si-O and Ti-O stretching bonds. Anatase phase, the main phase of titania in feedstock, was transformed into rutile phase in the coating structure. The spraying efficiency was increased as the stand-off distance decreased. High intensity of tetrahedral zirconia phase was detected in the composite coating sprayed at 50 mm SOD.