基体条件对Sm2Zr2O7/YSZ双陶瓷层热障涂层界面残余热应力的影响

采用有限元分析软件ANSYS对等离子喷涂Sm2Zr2O7/YSZ双陶瓷层热障涂层界面残余热应力分布进行了数值仿真。结果表明:基体厚度不同时,涂层界面Sm2Zr2O7/YSZ及界面YSZ/NiCoCrAlY对应应力及应力梯度基本不变,表明应力及应力梯度与基体厚度无关;但基体材质热膨胀系数对涂层系统界面的径向、轴向及剪切应力梯度有决定性的影响,且各应力梯度随金属基体的热膨胀系数差异增加而增大,表明基体材质是影响涂层界面径向残余热应力及应力梯度的根本原因。采用多层陶瓷结构并合理选择各层材质的热膨胀系数将更加有利于降低涂层应力梯度,进而改善涂层性能,延长涂层寿命。     

不同基体条件下Sm_2Zr_2O_7/YSZ热障涂层的残余应力

采用有限元法研究了基体条件对等离子喷涂Sm2Zr2O7/YSZ双陶瓷层热障涂层涂层的残余热应力,并与单一Sm2Zr2O7涂层进行了比较。计算结果表明,涂层的残余热应力随金属基体的热膨胀系数增加而增大,当基体厚度超过25mm后,径向应力不再变化,基体半径对涂层残余应力的影响可以忽略。Sm2Zr2O7/YSZ涂层的热应力明显小于单一的Sm2Zr2O7涂层,增加涂层的层数可缓解残余热应力。     

等离子喷涂Sm_2Zr_2O_7热障涂层残余热应力

采用有限元分析软件ANSYS对等离子喷涂Sm2Zr2O7热障涂层在金属基体材质类型、厚度、半径变化时涂层的残余热应力进行了分析。结果表明,金属基体的热膨胀系数对Sm2Zr2O7热障涂层的残余热应力有着显著影响,金属粘结层与表面陶瓷层界面处的残余应力及其应力梯度随着金属基体热膨胀系数增加而增大。金属基体厚度和半径不是影响Sm2Zr2O7热障涂层残余应力的主要因素。     

Sm_2Ce_2O_7/8YSZ热障涂层残余热应力及隔热性能计算机模拟

采用ANSYS软件分析了YSZ层厚度对Sm2Ce2O7/8YSZ热障涂层残余热应力的影响以及不同服役环境温度下涂层的隔热性能。结果表明,在涂层内部存在较大的热应力;径向应力及轴向应力在距离模型中心2~17 mm的范围内保持较为稳定的压应力,而在模型边沿处突然增加;当YSZ层厚度为0.9 mm时,涂层中的剪应力沿径向距离逐渐增大,而其他厚度下剪应力在模型边沿处急剧下降。当YSZ层厚度为0.3 mm时,涂层具有最小的热应力,从涂层表面至YSZ/粘结层界面处热应力逐渐降低。整个涂层表现出良好的隔热性能,其隔热性能随服役环境温度增加而增强。     

基体条件对等离子喷涂Sm_2Zr_2O_7热障涂层热冲击性能的影响

采用有限元分析软件ANSYS对等离子喷涂Sm2Zr2O7热障涂层在金属基体材质类型、厚度、半径变化时涂层的冲击热应力进行了分析。结果表明,涂层表面及表面层/金属粘结层界面处热应力及其应力梯度随着金属基体热膨胀系数增加而增大。当基体厚度超过20mm后,其对冲击热应力的影响基本可以忽略。当基体半径达到28mm后,涂层最大径向冲击热应力趋于稳定,最大轴向热应力随基体半径增加逐渐减小,最大剪切应力不受基体半径的影响。     

基于不同基体条件的Sm2Zr2O7/YSZ双层热障涂层界面残余热应力的数值仿真

采用有限元分析软件ANSYS对2Cr13基体等离子喷涂Sm2Zr2O7/YSZ双层热障涂层界面残余热应力分布进行了仿真。结果表明:在涂层Sm2Zr2O7/YSZ及YSZ/NiCoCrAlY界面存在较大的残余热应力,且应力梯度基本不变,表明应力梯度与基体厚度、半径无关。     

大气等离子喷涂ZrO_2与Sm_2Zr_2O_7热障涂层的热冲击性能

采用ANSYS软件计算了等离子喷涂Sm2Zr2O7和ZrO2热障涂层的冲击热应力,并与试验结果进行了对比。结果表明,涂层表面存在较大的径向冲击热应力,该应力在冷却5秒后达到最大值后趋于平稳,并在距离试样中心12mm处急剧下降。在表面陶瓷层/金属粘结层界面处亦存在较大的冲击热应力梯度。由于Sm2Zr2O7涂层中较大的热冲击应力使得其抗热冲击性能低于ZrO2涂层,试验结果与有限元计算结果吻合良好。     

Sm_2Ce_2O_7-YSZ功能梯度热障涂层热冲击性能计算机模拟

采用有限元技术分析了Sm_2Ce_2O_7-YSZ功能梯度热障涂层的水淬热冲击性能,研究了金属基体材质及尺寸对其热冲击性能的影响。结果表明,在Sm_2Ce_2O_7/YSZ功能梯度热障涂层中存在较大的冲击热应力。涂层径向热应力从中心处到试样边缘逐渐递减。基体的热膨胀系数对涂层冲击应力影响最明显,涂层中热应力随基体厚度增加而增大,但基体厚度超过20 mm后热应力趋于稳定。基体半径超过14 mm后径向应力不再增大,基体半径超过10 mm后轴向应力和剪切应力不再降低。与Sm_2Ce_2O_7涂层相比,Sm_2Ce_2O_7-YSZ功能梯度涂层具有最大热应力,其结构仍需要进一步优化。     

不同基体材质的Sm_2Ce_2O_7涂层热冲应力的数值模拟

采用ANSYS软件对Ni、45钢、SiC_f/SiC、2Cr13、1Cr13Ni9Ti五种不同基体Sm_2Ce_2O_7涂层的热冲击应力进行了计算,系统研究了基体材质对热应力的影响规律。结果表明,不同基体材质涂层均存在较大的热应力,最大热应力绝对值出现在热冲击瞬间,35 s后趋于稳定,径向应力的影响远大于轴向与剪切方向;径向应力在横向距离小于12mm时保持稳定,横向距离在12～18 mm范围内,应力梯度逐渐增大;SiC_f/SiC基体在表面及表面层/粘结层界面的应力状态为压应力,且表面径向、表面及表面层/粘结层界面的轴向应力梯度均低于其他基体涂层,有利于界面的结合及防止横向裂纹的扩展;热膨胀系数的差异造成SiC_f/SiC基体涂层与其他金属基体涂层的体积形变方向不一致,同时粘结层/基体界面应力绝对值及应力梯度略大于2Cr13基体涂层,基体的热膨胀系数是影响热冲击性能的关键因素之一。     

ZrO2涂层在小高炉单套风口上的试验研究

分别采用等离子喷涂两层和三层梯度隔热涂层的方法研究了梯度隔热涂层对高炉风口寿命的影响,并分别进行了工业试验。试验采用的两层结构即金属型粘结底层(Ni-Cr-Al-Y)和ZrO2陶瓷工作层;三层结构即在工作层的ZrO2涂层中配入3%～6%的CaO作为稳定剂来抑制ZrO2相变膨胀,在金属型粘结底层(Ni-Cr-Al-Y)上涂附25%Ni-Cr-Al-Y和75%ZrO2的复合粉作为中间过渡层以消除膨胀应力。两种涂层的厚度均为0.1mm。结果表明:这两种涂层结构设计都能够有效延长金属风口的寿命,使风口的寿命分别提高了1倍和3倍;但理想的涂层厚度应为0.3～0.5mm。     

Dy2Ce2O7和Y2Ce2O7稀土铈酸盐的制备及热导率

采用固相反应法在1600℃下保温10小时制备了Dy2Ce2O7和Y2Ce2O7陶瓷材料。分析了其相组成、微观组织和热导率。XRD结果表明,成功合成了具有萤石晶体结构的单一相Dy2Ce2O7和Y2Ce2O7。其组织结构致密,晶界清晰,无未反应物或杂质相存在。由于氧空位以及取代原子与基质原子之间的质量差异所导致的声子散射,使得Dy2Ce2O7和Y2Ce2O7具有比YSZ更低的热导率,这些结果表明,Dy2Ce2O7和Y2Ce2O7均可用作将来热障涂层用候选材料。     

H2/Ar等离子体射流反应器的模拟

建立了直流电弧等离子体射流反应器的计算流体动力学模型 ,在模型中同时考虑流动、对流换热和共轭热传导等过程 ,消除了以往对反应器内壁温度估计造成的误差 .对湍流的模拟采用了常见的标准k -ε双方程湍流模型 .用SIMPLEST算法模拟与计算了反应器内等离子体的温度场和速度场     

热等离子体裂解天然气和煤制乙炔乙烯

乙炔和乙烯均属化学工业基础原料,现在主要由石油和电石制得．随着石油资源的枯竭和人们环保意识的提高,人类正在寻求其他资源途径和技术途径来获得需要的诸如乙炔和乙烯等化工基本产品．利用相对丰富的天然气(NG)和煤炭资源,采用热等离子体技术制备乙烯和乙炔是很有前途的方法之一．     

Crystallization of zeolite L from Na2O-K2O-Al2O3-SiO2-H2O system

Zeolite L powder was prepared from the substrate mixture of Na₂O-K₂O-Al₂O₃-SiO₂-H₂O system at temperatures of 373-443 K. In order to investigate the factors which influence the synthesis outcome, a reference system which yields zeolite L in a reproducible manner was chosen and subjected to controlled changes in synthesis parameters. The crystalline zeolite L samples obtained were characterized by elemental chemical analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM). It was established that phase purity, morphology, and the size of crystals of crystalline product were affected by molar ratios of the substrate, such as SiO₂/Al₂O₃, (K₂O+Na₂O)/SiO₂, Na₂O/(K₂O+Na₂O), and H₂O/(K₂O+Na₂O). Amorphous silica powder (Zeosil) was the preferred silica source, and the crystallization rate was promoted by introducing gel aging, seeding, and rapid heating rate.     

Photocatalytic activity of Cu2O/TiO2, Bi2O3/TiO2 and ZnMn2O4/TiO2 heterojunctions

Cu₂O/TiO₂, Bi₂O₃/TiO₂ and ZnMn₂O₄/TiO₂ heterojunctions were studied for potential applications in water decontamination technology and their capacity to induce an oxidation process under VIS light. UV–vis spectroscopy analysis showed that the junctions-based Cu₂O, Bi₂O₃ and ZnMn₂O₄ are able to absorb a large part of visible light (respectively, up to 650, 460 and 1000 nm). This fact was confirmed in the case of Cu₂O/TiO₂ and Bi₂O₃/TiO₂ by photocatalytic experiments performed under visible light. A part of the charge recombination that can take place when both semiconductors are excited was observed when a photocatalytic experiment was performed under UV–vis illumination. Orange II, 4-hydroxybenzoic and benzamide were used as pollutants in the experiment. Photoactivity of the junctions was found to be strongly dependent on the substrate. The different phenomena that were observed in each case are discussed.     

碳酸钠—过氧化氢—水体系相图的绘制

进行了Na2CO3-H2O2-H2O体系溶解度的测定并绘制成相图,最后对其应用进行了讨论。     

Stable Ti/RuO2-Sb2O5-SnO2 electrodes for O2 evolution

RuO₂-based electrodes are generally known to be unstable for O₂ evolution. In this paper, a stable type of RuO₂-based electrode, Ti/RuO₂-Sb₂O₅-SnO₂, is demonstrated for O₂ evolution. In the ternary oxide coating, RuO₂ serves as the catalyst, SnO₂ as the dispersing agent, and Sb₂O₅ as the dopant. The accelerated life test showed that the Ti/RuO₂-Sb₂O₅-SnO₂ electrode containing 12.2 molar percent of RuO₂ nominally in the coating had a service life of 307 h in 3 M H₂SO₄ solution under a current density of 0.5 A cm⁻² at 25 °C, which is more than 15 times longer than other types of RuO₂-based electrodes. Instrumental analysis indicated that RuO₂-Sb₂O₅-SnO₂ was a solid solution with a compact structure, which contributed to the stable nature of the electrode.