真空等离子喷涂氧化铝——氧化钛涂层

真空等离子喷涂,可对许多材料在很宽范围的基体上,作为一种高质量的涂层的来源正在获得大家的认同。在真空下喷涂形成的涂层邮极好的耐磨损、抗腐蚀和高温特性。在本研究中,为了使喷涂的陶瓷涂层的气孔率得到最大程度的减少,使用了控制真空度的喷涂方法将氧化铝－－氧化钛喷涂于石墨上。实验是在使用统计学的分数因子设计参数研究而进行的。操作参数是围绕Taguchi设计的实验典型参数变化的,Taguchi设计的实验表明,等离子 涂参数的范围和它们对测量涂层性能的影响,Taguchi设计研究了三个影响等离子喷涂的变量对测量灵敏度的影响：电流、主气流量和辅气流量来评价。涂层的质量用涂层厚度、气孔率、粗糙度和显微硬度来评价。本文讨论了喷涂参数对涂层质量的影响。用高功率和高辅气流比率的总弧气流量形成了最好的涂层。文中还讨论了在惰性气氛（如He）中,热循环对陶瓷试样的影响。结果表明,涂层没有衷变。为了证明使用涂层保护石墨免遭氧化是可行的,用真空等离子喷涂陶瓷涂层于石墨上。     

高压汽轮机等离子喷涂MCrAlY涂层的热机械性能

文章研究了两种不同的涂层：真空等离子喷涂的ＮｉＣｏＣｒＡｌＹＴａ和电镀的ＮｉＣｏＣｒＡｌＹＴａ,这些涂层都是沉积在ＡＭ３单晶合金上的,试验研究了喷涂后的单晶试样的拉伸和蠕变性能,从拉伸试验中测定了ＤＢＴＴ,蠕变试验是在圆柱型试样上和在薄的平板试 进行的,所有涂层的均在试验前后进行了检测分析。     

等离子喷涂PWA53—5涂层组织缺陷的分析

采用光学显微镜对ＰＷＡ５３－５涂层进行组织缺陷分析。     

宏观粗化基体上等离子喷涂TiC涂层的热冲击抗力

对宏观粗化基体上等离子体喷涂的ＴｉＣ涂层的热冲击力与喷砂基本上等离子体喷涂的ＴｉＣ涂层的热冲击抗力进行了对比研究，宏观粗化限制收缩应力，增加结合面积并产生了涂层内薄层间的褶皱强化，已进行机械振动和热冲击试验及其数学模化，在宏观粗化的基本上体喷涂的涂层抗力之所以提高可能是由于薄层的皱或波纹以及热应力的特殊分布所致。     

等离子喷涂耐蚀涂层在罗茨风机修复上的应用

大型化工企业的关键设备罗茨风机，在长期工作后因腐蚀而降低生产效率，本文就用等离子喷涂技术对其修复进行试验探讨，重点介绍了涂层材料选择，工艺试验，工装准备及喷涂过程，得出了修复后使用效果良好的结论。     

等离子喷涂铝硅-聚苯酯涂层工艺及性能研究

采用大气等离子喷涂(APS)的方法制备铝硅聚苯酯封严涂层。通过正交试验,以结合强度为判据,优化了铝硅聚苯酯涂层等离子喷涂工艺参数,研究了涂层的结合强度、硬度、孔隙率等性能。结果确定优化的工艺参数为:电弧电流500A、主气流量75 L/min、辅气流量7 L/min、喷涂距离120mm。在优化的喷涂工艺参数下获得的涂层结合强度达到6.5MPa,孔隙率为8.3%,硬度在52-55 HR15Y,具有良好的抗老化性能,为实际生产提供了依据。     

等离子涂涂层结合情况的评价

等离子喷涂涂层的结合情况用断裂力学方法并结合机理以深入研究，这样，变形能对于附着破坏或粘结破坏形式的释放可能与涂层的显微结构特性有关，涂层薄层的塑性变形和液滴与基体间，或与先前固化的材料之间的接触效果是决定涂层性能的重要因素。     

等离子喷涂γ—Al2O3和α—Al2O3涂层的性能和结构

用优选的喷焰参数制备了含有９９．５％以上的γ－Ａｌ２Ｏ３的喷涂态涂层，该涂层具有０．１－１μｍ直径的颗粒，其薄层厚度为１－４μｍ。用同样的喷焰条件，但缓慢地在基体上移动，产生了含有α－Ａｌ２Ｏ３涂层。在每个喷焰的喷道中观察到三种类型的显微结构：类型Ｉ，在较下面的区域，认为已形成了γ－Ａｌ２Ｏ３晶核，并且由于喷焰和涂层的热量而转变成α－Ａｌ２Ｏ３相；类型Ⅲ；在类型Ｉ上连，形成了α－Ａｌ２Ｏ３晶核，在     

基于机器视觉的热障涂层内部裂纹在线检测方法及传热特性研究

燃气轮机服役过程中,热障涂层(以下简称涂层)内部裂纹萌生和扩展是导致涂层失效的主要原因。通过数值重构方法获得了含不同长度裂纹的热障涂层（TBCs）微结构,基于耦合双分布格子波尔兹曼方法（DDF-LBM）建立了热障涂层与冷却气膜流动传热模型,研究了热障涂层内部和表面温度分布特性。结果表明：出现裂纹会极大地改变涂层的温度分布情况,增加涂层温度不均匀性,造成局部烧结,进一步产生应力集中,极易导致涂层分层断裂,从而影响其耐久性。同时,基于耦合检测算法（GEMSS）通过大量机器学习训练,提出了热障涂层内裂纹定位和长度估算的在线检测评估方法。该方法能有效确定裂纹位置,高精度估算裂纹长度,为高温叶片在线健康度评估和寿命预测提供理论基础和技术支撑。     

燃气轮机应用的热障涂层

简要叙述了燃气轮机热燃气通流部件上热障涂层镀数工艺的进展情况,最新开发的EB－PVD方法是TBC技术的重大突破,简介了EB－PVD方法及其设备。     

Thermal Stress in Fabrication of Thermal Barrier Coatings

Thermal stress in the fabrication process of thermal barrier coating system (TBCs) has a significant effect on the quality of TBCs and the durability of gas turbine. In this work, a new analytical model was developed to calculate the thermal stress during the fabrication process of TBCs. Variations of the material properties with temperature of TBCs were well considered in the present model. Several spraying factors: such as pre-heating temperature, cold gas dynamic spraying (CGDS) method, thickness of top coating and thickness of substrate, which has significant effects on thermal stress generation, are also discussed in this work.     

Overall Thermal Performances of Double-Wall Effusion Cooling Covered by Simulated Thermal Barrier Coatings

A coupling configuration of double-wall cooling and exterior surface thermal barrier coating(TBC)is one of the most promising thermal protection methods of hot components of modem gas turbine.The combined influences of coating thickness,impingement layout,and cooling air flowrate on the overall thermal performances of such configuration were discussed deeply,to provide the valuable guidance of design.Overall effectiveness measurements were implemented under engine-matched Biot numbers and mainstream-to-coolant temperature ratio.Conjugate heat transfer simulations provided the additional information difficult to be acquired by the measurements.The results indicated that the contribution of TBC is much larger than that of increasing the cooling air amount.The thicker TBC can produce the stronger insulation,while the higher risk of thermal damage of itself.The larger coolant flowrate enlarges the benefit of TBC,while the trend is suppressed by the thick TBC.The constant coating thickness cannot bring to the uniform metal temperature,which can be solved through properly adjusting the backside impingement.The trends in overall effectiveness with TBC’s thickness are independent on the change of internal impingement.     

Subamorphous Thermal Conductivity of Crystalline Half-Heusler Superlattices

The quest to improve the thermoelectric figure of merit has mainly followed the roadmap of lowering the thermal conductivity while keeping unaltered the power factor of the material. Ideally an electron-crystal phonon-glass system is desired. In this work, we report an extraordinary reduction of the cross-plane thermal conductivity in crystalline (TiNiSn):(HfNiSn) half-Heusler superlattices (SLs). We create SLs with thermal conductivities below the effective amorphous limit, which is kept in a large temperature range (120–300 K). We measured thermal conductivity at room temperature values as low as 0.75 W m^?1 K^?1, the lowest thermal conductivity value reported so far for half-Heusler compounds. By changing the deposition conditions, we also demonstrate that the thermal conductivity is highly impacted by the way the single segments of the SL grow. These findings show a huge potential for thermoelectric generators where an extraordinary reduction of the thermal conductivity is required but without losing the crystal quality of the system     

保温用天然生物质材料的热湿特性

实验分析一些廉价天然材料(椰壳和花生壳)的导热特性。利用同心球稳态测量方法测量确定椰壳和花生壳的导热系数,以及导热系数随温度的变化规律,同时以硅酸铝纤维材料为标准试样,与天然材料的导热性能进行对比分析。还对这些材料的低温吸湿作了初步测试,分析此类材料作为低温绝热材料的吸湿特性。研究结果表明,所有材料的导热系数均随温度的升高而增大,且增大速率都近似相等。影响天然生物质材料导热性质的因素主要有：纤维或多孔固体材料中的导热、孔隙中空气的对流换热,如果温度足够高的话,还有辐射换热。     

TBCs粘结层抗高温氧化行为研究

该文采用超音速火焰喷涂方法,在镍基高温合金基体上制备NiCoCrAlTaY粘结层,通过XRD、SEMi析方法,研究了相同温度不同氧化时间粘结层的抗高温氧化行为及氧化机理,分析计算得到粘结层的氧化动力学规律,最后总结了控制TGO生长的方法。分析表明：TGO的生长使粘结层Al元素贫化,Ni、Cr元素氧化产生复杂的尖晶石类金属氧化物,是粘结层抗氧化性能降低的根本原因,为热障涂层的结构设计及优化提供了依据。     

非良导体热导率的测定

结合湿度控制仪设计了测定非良导体热导率的方法,即通过作冷却曲线的方法求出冷却速率,从而算出热导率。     

基于热障涂层的柴油机活塞热分析研究

以某非道路高压共轨柴油机作为研究对象,结合标定工况下活塞温度场试验测试结果,建立了不同厚度的热障涂层活塞有限元仿真分析模型,分析了热障涂层对活塞基体温度场、热应力及热变形分布特点和变化规律的影响.结果表明,热障涂层活塞的最高温度较铝合金活塞最大降幅14.83％;热障涂层活塞的热应力随瓷层厚度的增加而降低,较铝合金活塞有...     

The Interfacial Layer and the Thermal Conductivity of Nanofluid

Nanofluids are a class of colloidal dispersion of nanosized particles which are found to exhibit anomalous heat conducting properties compared to other conventional heat transfer fluids. Among various factors responsible for this anomaly, the role of nanolayer thickness is found to be quite important. This article includes its effect by suggesting a new exponential form for the profile of thermal conductivity in the interfacial layer. The effect of nanoparticle size, the volume fraction, and the ratio of thermal conductivity of the nanoparticle to the base fluid form part of the discussion. The presented scheme predicts well the enhancement of thermal conductivity of two nanofluids, alumina/EG and CuO/water, used as an example. © 2013 Wiley Periodicals, Inc. Heat Trans Asian Res, 43(3): 288–296, 2014; Published online 3 October 2013 in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.21084