等离子喷涂-物理气相沉积YSZ热障涂层的制备及微观结构研究

热障涂层与冷却技术结合可以极大地提高航空涡轮发动机叶片的服役温度,而羽毛柱状结构的等离子喷涂-物理气相沉积(PS-PVD)热障涂层因其热导率低、应变容限良好、热循环寿命长等优势备受关注.通过进行物相分析,使用扫描电子显微镜(SEM)观察热障涂层表面及截面的形貌结构;在SEM二维图像的基础上,使用图像法计算孔隙率.结果表明:通过PS-PVD设备制备出的热障涂层结晶度良好,空间点矩阵属于P/nmc(137),为四方结构,涂层平均平面孔隙率较大,为20.03%,具有良好的隔热性能.     

钢表面ZrO2陶瓷纳米等离子喷涂

采用等离子喷涂技术在20Cr钢表面等离子喷涂纳米ZrO2涂层,并用1Cr18Ni9作中间梯度涂层,用以制造特殊管状绝热体.利用SEM方法研究了梯度涂层的结构和显微组织,通过摩擦磨损试验对涂层的耐磨性能进行了分析,用热震法研究了涂层和基体的结合力,并用有无热障涂层的箱体进行实际模拟对比试验,测试了涂层的隔热性能.研究结果表明,ZrO2纳米陶瓷层和1Cr18Ni9梯度层可以形成良好的机械结合;喷涂后的试样表面显微硬度显著提高,耐磨性比GCr15轴承钢提高2.84倍;纳米陶瓷梯度涂层使20Cr钢的隔热性能和抗高温氧化性能显著提高.     

真空热处理对热障涂层组织形貌及元素扩散的影响

为了研究真空热处理对CoNiCrAlY涂层组织形貌及元素扩散的影响,采用超音速火焰喷涂(HVOF)设备在镍基高温合金基体上制备了CoNiCrAlY涂层.对部分样品进行真空热处理,利用大气等离子喷涂8YSZ陶瓷层.采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、能谱分散谱仪(EDS)等分析了热障涂层的相组成、微观组织、元素扩散与热震性能,研究了真空热处理对热障涂层的影响.结果表明,真空热处理后,CoNiCrAlY涂层颗粒间界面消失且涂层发生均质化;涂层与基体界面处元素发生扩散;热障涂层的抗热震性能提高.     

等离子喷涂复合热障涂层的静态氧化行为

采用等离子喷涂方法，在GH536高温合金基材上制备了传统的双层热障涂层（TBCs）和两种含有Al2O3与ZzO2陶瓷复合层的三层热障涂层，传统TBCs结构为Ni22Cr10AlY合金连接层和8％Y2O3部分稳定的ZrO2陶瓷顶层；三层TBCs分别用了置于陶瓷层内侧及外侧的Al2O3复合层，三种类型试样的100h,1050℃静态氧化试验结果表明：三层涂层较双层涂层的氧化阻力提高，双层涂层的氧化阻力最差，不同复合层形式试样氧化动力学曲线不同，内置复合层的氧化增重最小，氧化阻力最佳。1050℃是氧化增重的临界点，外置复合层试样的氧化增重出现明显增加趋势。     

基于等离子喷涂法的火箭弹尾翼热障涂层试验研究

针对火箭弹飞行中尾翼遭受气动加热损伤而造成飞行失效的问题,通过分析其尾翼结构特征,设计了适应尾翼工况的热障涂层结构和等离子喷涂制备方法,分析了预处理对热障涂层与基体结合力的影响,以及等离子喷涂工艺参数对热障涂层沉积率的影响,并进行了热障涂层静态和动态测试试验.试验结果表明,该热障涂层与基体的结合强度由10MPa提高至20MPa,风洞试验中,热障涂层可以在1 800℃高温和20s时间内,克服气动热而不产生剥落.     

镁合金表面APS法制备ZrB_2-ZrC基复合涂层

针对镁合金抗烧蚀性差的问题,采用高能等离子喷涂在AZ91镁合金表面引入NiCoCrAlTaY过渡层后制备复合结构陶瓷涂层.复合陶瓷抗烧蚀层结构设计为小颗粒的SiC和ZrO_2填充于大粒径的ZrB_2和ZrC颗粒周围的四组元复合结构.采用球磨机械混合的方法将平均粒径为10μm的ZrB_2和ZrC粉末及平均粒径为1μm的SiC和ZrO_2粉末混合均匀,形成1μm小颗粒的SiC和ZrO_2均匀填充于10μm粒径的ZrB_2和ZrC颗粒的混合结构粉末作为喷涂粉末,通过大气等离子喷涂方法在46.5kW功率条件下制备复合结构陶瓷涂层.研究结果表明:复合陶瓷层内部组织为小尺寸的SiC和ZrO_2填充于大粒径的ZrB2和ZrC颗粒的四组元复合结构,达到四元复合结构的设计,涂层内部颗粒发生明显的扁平化,涂层显微硬度达到1 311kgf·mm~(-2).通过X射线衍射分析发现在涂层制备过程中粉末没有发生明显的相结构改变,透射电子显微镜微区分析表明在ZrB_2和ZrC大颗粒交界处出现B_2O_5Si非晶环带玻璃相的亚稳结构,有利于抗烧蚀性的提高.     

等离子喷涂ZrO2纳米热障涂层及热导率

采用大气等离子喷涂技术制备了纳米ZrO2热障涂层,采用XRD和SEM方法分析了涂层的相结构和微观组织,并采用激光脉冲法测量了纳米涂层的热导率．结果表明,喷涂前后涂层与粉末的相成分没有发生变化,涂层具有典型的等离子涂层微观组织结构,孔隙率约为12．33％．纳米涂层热导率的平均值约为传统微米ZrO2涂层的86％,涂层中大量的纳米晶是纳米涂层隔热性能改善的主要原因．     

激光制备陶瓷热障涂层的研究和发展

论述了激光制备陶瓷热障涂层的研究和发展状况 .激光制备陶瓷热障涂层包括激光重熔和激光熔覆两种方法 .激光重熔等离子喷涂热障涂层可获得等离子喷涂涂层所不具备的外延生长致密的柱状晶组织 ,提高涂层应变容限及热震性能 .激光熔覆可获得自动分层的梯度热障涂层成分及柱状晶组织 ,改善涂层的高温氧化及热震性能 .通过激光工艺参数的优化及涂层体系成分及性能的合理设计 ,可获得优于等离子喷涂 ,接近电子束物理气相沉积的热障涂层性能     

界面形貌对残余应力的影响

以等离子喷涂热障涂层为研究对象,采用有限元分析软件ANSYS中热应力分析功能,对于不同的界面形貌模型,分析计算了其热障涂层中的残余应力的分布和极值,从而得出了不同的界面形貌对涂层中残余应力的一些影响规律。     

等离子喷涂改性YSZ涂层耐熔融玻璃腐蚀机制

采用Al2O3、TiO2掺杂改性8％Y2O3-ZrO2(质量分数,YSZ)陶瓷粉末,通过等离子喷涂制备Al2 O3-TiO2-Y2O3-ZrO2(AT+YSZ)热障涂层,1 200℃,保温2 h,对两种涂层进行熔融玻璃腐蚀试验.采用扫描电子显微镜(SEM)、X射线衍射仪(XRD)、维氏显微硬度分析仪对AT+YSZ涂层及...     

Properties of plasma sprayed NiCrAlY (ZrO_2 Y_2O_3) coating on refractory steel surface

1INTRODUCTION1Cr18Ni9Ti,i.e.188austeniticstainless steel,isakindofausteniticrefractorysteelwidely appliedinmanyfields,containingahighcontentofCrthatcanimproveheatandoxidationresistances,andalsoNicapableofformingastableaustenitic structure.However,suchstee…     

NiCoCrAlY/Al_2O_3-13%TiO_2复合涂层的耐锌铝腐蚀性

为了解决热镀锌铝工艺中沉没辊受到熔融锌铝液腐蚀的问题,采用超音速火焰喷涂技术在316L基体上制备了NiCoCrAlY粘结层,并利用等离子喷涂技术制备了NiCoCrAlY/Al_2O_3-13%TiO_2复合涂层.结果表明,复合涂层界面处的热膨胀系数突变减缓,使得界面处的应力集中减少,从而对裂纹扩展起到延缓和抑制作用,因而复合涂层的抗裂性能增强.复合涂层在锌铝液中的使用寿命可以达到9 d,高于传统Al_2O_3-13%TiO_2涂层.复合涂层的结合强度也高于传统Al_2O_3-13%TiO_2涂层,但复合涂层的最终失效形式依然是由两种材料的热胀系数不匹配所导致的涂层开裂.     

Properties of plasma sprayed NiCrAlY+(ZrO2+Y2O3) coating on refractory steel surface

NiCrAlY+(ZrO₂+Y₂O₃) thermal barrier coating was prepared on the surface of refractory steel 1Cr18Ni9Ti with plasma spraying technique. The phases and microstructure of the thermal barrier coating were determined by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that the bonding between thermal barrier coating and substrate is sound. The surface hardness of 1Cr18Ni9Ti reaches up to 1 000 HV, but that of substrate is only 300 HV. The patterns sprayed with CoNiCrAlY+(ZrO₂+Y₂O₃) ceramic coating have a good heat insulation effect at 800 °C for heat insulation temperature difference reaches 54 °C, which increases the operating temperature and service life of refractory steel. Foundation item: Project (5040202140) supported by Scientific Research Common Program of Beijing Municipal Commission of Education     

Surface adhesive properties of continuous PBO fiber after air-plasma-grafting-epoxy treatment

It was found that air dielectric barrier discharge(DBD) plasma contributed to the grafting of epoxy resin onto continuous PBO fiber surface. This air-plasma-grafting-epoxy method yielded a noticeable enhancement in the interfacial adhesion between PBO fiber and thermoplastic matrix resin, with the interlaminar shear strength of the resulting composites increased by 66.7%. DSC and FTIR analyses were then used to study the curing behavior of epoxy coating on PBO fiber surface, deduce the possible grafting reactions and investigate the grafting mechanism. More importantly, TGA measurement showed that the grafting of epoxy onto PBO fiber had almost no effect on the composite heat resistance, and there was more thermoplastic matrix resin adhering to the fiber surface; the latter could also be clearly found in the SEM photos. Thereby, the air-plasma-grafting-epoxy treatment was proved to be an effective method for the improvement of continuous PBO fiber surface adhesive properties.     

Composite thermal protection coating on woven silica fiber fabrics

A composite coating with inner and outer layers was prepared for the thermal protection of woven silica fiber fabrics.Using a sol mixture of a silica sol and AlF3/SiO2 particles mixed in the stoichiometric molar ratio for mullite,hollow silica spheres and short mullite fibers were added to the inner layer and outer layer,respectively.The phase composition and thermal evolution of the coating,along with the interfacial microstructure between the coating and the matrix,were characterized by means of X-ray diffraction,differential scanning calorimetry/thermogravimetry,scanning electron microscopy,and tensile strength testing.Mullite whiskers grew between 950°C and 1200°C and helped prevent thermal cracking during the drying and densification processes.The hollow silica spheres might play dual roles,weakening the adhesion between the coating and the fibers by reducing their direct contact,but strengthening the joining between the coating and substrate by embedding themselves among the fabrics.     

Al(OH)_3/聚丙烯酸酯复合乳液的制备及其对涂层玻璃纤维网格布机械性能的影响

通过种子乳液聚合的方法,采用纳米氢氧化铝(ATH)无机改性剂,制备ATH/聚丙烯酸酯复合乳液(PA)作为玻璃纤维纤网格布的涂层。通过粒径分析、透射电镜(TEM)、热重分析(TG)和极限氧指数值(LOI)对复合乳液的结构和性能进行了表征。通过扫描电镜和电子织物强力仪对复合乳液涂层后玻纤布的表面形态和力学性能进行观察和测试。结果表明:纳米ATH粉体可以有效参与乳液聚合反应;当ATH含量为3‰时,复合乳液的固含量高,粒径分布均匀且较窄,成膜性、热稳定性均较高;该复合乳液可以在玻纤网格布上形成均匀致密的薄膜,涂层后玻纤网格布的断裂强力和LOI值均有所增大。     

Micro-dynamic behavior and self-adjusting water transmit mechanism of water-transferring composite

Constructional and micro-dynamic process of the water-transferring composite was analyzed. This composite can transmit water to soil with a self-adjustable speed to ensure the survival of seedlings in arid and semi-arid regions when it is embedded in soil around the roots of the seedlings. It is obtained from natural plant fiber coated with a colloid made by mixing a certain proportion of polyacrylamide and montmorillonite. The rules of water being transmitted to soil by the coating under different condition were tested by M-30 quick moisture measure instrument. The process of water-desorption of the coating material was investigated by a Perkin Elmer Diamond S II thermal multi-analyzer. Moreover, the micro-dynamic behavior was detected by a FEIQuanta 2000 environment scanning electron microscope. The results demonstrate that montmorillonite has lower water-desorption energy barrier than polyacrylamide and can lose water more easily. montmorillonite particles bridge up to be the main water-transmit material at low water potential (when the soil relatively dry or when the temperature is high), and they break bridge at high water potential while the polyacrylamide acts as the main water-transmit material.     

Preparation and characteristic of self-regulation water-transmitting coating fiber

Common clay, Kaolin and Bentonite were used as additives to prepare water-transmitting coating fiber, respectively, and the water-transmitting characteristic of coating fiber was studied. Different water-transmitting coating fibers were prepared by coating fiber using coating material with different mass proportions of additives to adhesive. And the coating materials were made from three kinds of inorganic clays as additives respectively and polyvinyl alcohol (PVA) as adhesive. Furthermore, the surface morphology and water-transmitting capacity of coating fiber were studied by SEM, Perkin Elmer Diamond S II thermal multi-analyzer and instrument for quick measurement moisture M30. The experimental results indicate that water-transmitting coating fibers made from three kinds of clays all have water-transmitting capacity. The surface of water-transmitting coating fiber prepared by common clay T is continuous and compact, and the water-transmitting effect is better than coating fibers made from other clays. Funded by the National High Technology Research and Development Program of China (2001AA322100), the Ministry of Education of Republic of China (106086), and the Cooperation and Merger Found of Beijing (ZH114140537)     

304N不锈钢表面电弧喷涂复合涂层高温氧化防护机制

为了延长奥氏体不锈钢部件在高温环境下的工作寿命,采用电弧喷涂方法在304N不锈钢表面制备45CT/Al复合涂层,对复合涂层试件进行1 100℃×350 h的连续氧化实验,考察其高温氧化行为,通过研究复合涂层的微观组织变化,探索其高温防护机制.实验结果表明,复合涂层以两种方式为304N不锈钢基体提供有效的高温氧化保护.一方面保证在涂层体系中具有足够的Al、Cr元素,在涂层外表面形成以Al2O3为主的氧化物防护层,阻止氧化介质的向内侵入;此外,在复合涂层下的基体金属中形成层状分布的AlN扩散阻挡层,延缓复合涂层体系中Al、Cr抗氧化元素的质量分数减少,使复合涂层保持持久的高温氧化防护能力.