TBC控制器在高性能时间测量系统中的应用

在高性能时间测量系统中,高性能时间数字转换芯片只能通过JTAG进行初始化和控制,为此选择了TBC控制器来实现的方法.介绍了TBC控制器对该转换芯片配置的方案,并详述了该方案的软件编程.     

Wetting,infiltration, and interaction behavior of calcium-magnesium-alumino-silicate towards Gd/Yb-modified SrZrO3 coatings deposited by solution precursor plasma spray

Wetting of thermal barrier coatings (TBCs) with calcium-magnesium- alumino-silicate (CMAS) leads to sintering and phase transition, which are major issues in the aerospace industry. We prepared Sr(Zr_1−2xYb_xGd_x)O_3−x (x = 0, 0.05, 0.1, and 0.15) coatings using solution precursor plasma spraying with inter-pass boundaries (IPBs) and vertical cracks, and analyzed the CMAS wettability at 1350 °C using the sessile-drop method. The wetting and diffusion dynamics of the CMAS melt on the surface of the coating were studied using a CCD camera, revealing that the Sr(Zr_0.7Yb_0.15Gd_0.15)O_2.85 coating had the lowest spreading speed (2.60 × 10⁻⁴ mm/s, spreading balance process). Furthermore, a greater extent of crack bending and smaller crack diameter can prevent the coatings from penetration of the CMAS melt.     

Effects of different nano-agglomerated powders on the microstructures of PS-PVD YSZ coatings

Plasma spray physical vapor deposition (PS-PVD) is a technology that combines the advantages of traditional atmospheric plasma spraying (APS) and electron beam physical vapor deposition (EB-PVD). As the feedstock of the PS-PVD, nano-agglomerated powder is critical on determining the microstructure of the obtained coating. In this study, a method to characterize the cohesion of nano-agglomerated powders was investigated. The nano-agglomerated powders fractured into smaller particles under ultrasonic waves. Their particle size distributions were measured to quantitatively compare their cohesiveness. The change rate in the percentage of powders with particle size less than 5 μm was selected as the value for the cohesion comparison. A high change rate corresponded to a faster fracture and lower powder cohesion. Furthermore, the fracture behavior and heat and mass transfer process of nano-agglomerated powders in the plasma torch were studied by combining 3-D simulation and observation of the microstructures of PS-PVD coatings sprayed with different powders. To obtain a quasi-columnar coating, the nano-agglomerated powder required high cohesion. Finally, a suitable powder was selected and quasi-columnar structure coatings were obtained by optimizing the PS-PVD parameters.     

Through thickness changes to stiffness and thermal conductivity in thermal barrier coatings subjected to gradient exposure

Sintering-induced increases in the elastic modulus and thermal conductivity of thermally sprayed Thermal Barrier Coatings (TBCs) under constraint by a bond-coated substrate due to thermal gradient exposure have been measured. The results suggest the degree of sintering due to this constrained thermal exposure to be significantly lower when compared to free standing exposed specimens. Overall, a ∼30% increase in elastic modulus and ∼12% increase in thermal conductivity have been measured in a ∼ 450 µm thick TBC after 12 h of gradient exposure. Here, the top surface of the TBC was kept at 1250 °C, and the gradient was determined based on a constant backside cooling air flow rate. The elastic modulus, measured across the thickness of coating, reveals that in the region near the top surface, the elastic modulus increased by ∼ 50%. Contrastingly, no significant increase in elastic modulus was observed near the metal/coating interface. The dynamic evolution of thermal conductivity and sintering under gradient exposure and constraint was calculated using an analytical model which was then used to rationalize the experimental observations.     

氧化铝封孔对大气等离子喷涂热障涂层抗高温氧化性能的影响

为了减少氧气在大气等离子喷涂热障涂层（TBC）中的渗透通道，进而提高涂层抗高温氧化性能。采用溶胶凝-胶法制备Al2O3封孔剂，通过1100 ℃高温氧化试验，研究封孔作用对陶瓷层中氧气传输、TBC微观形貌以及热生长氧化物（TGO）生长行为的影响规律，阐明封孔对提高TBC抗高温氧化性能的作用机理。结果表明:Al2O3封孔有效阻碍了陶瓷层氧气的渗透，降低了TBC的氧化速率。直至氧化100 h，通过封孔的TBC始终具有更小的TGO厚度与氧化增重，而且抛物线氧化速率（Kp）相比传统TBC下降了14.99 %。     

基于TMS320C6000和MPC860视频信号处理平台

基于TMS320C6000DSP和MPC860的视频信号处理平台的硬件设计方案。该处理平台通过加载不同的程序，可以工作在不同的情况之下。     

一种热障涂层的形貌和相结构特征研究

研究了一种热障涂层的形貌和相结构组成。溅射NiCrAlY粘结层由γ-Ni相和β-NiAl相组成，是柱状结构，其晶粒度小，属于微晶，有利于形成α-Al2O3膜。溅射NiCrAlY粘结层经真空处理后，发生γ和γ’的转变，以及β-NiAl和脱溶。EB-PVD TBC 具有开放性的柱状结构，并且存在大量的t'-ZrO2相，使涂层性能大大优化。