共查询到19条相似文献,搜索用时 281 毫秒
1.
2.
3.
4.
热障涂层用Nd2O3-CeO2-ZrO2陶瓷粉末制备及其性能研究 总被引:3,自引:0,他引:3
采用化学沉淀法制备了热障涂层用Nd2Zr2O7(NZ)以及CeO2-Nd2O3-ZrO2(NCZ)陶瓷粉末.通过电感耦合等离子体原子发射光谱(ICP-AES),X射线衍射、DSC及霍尔流速计对粉末化学组成、相组成,高温相稳定性和流动性能进行了研究.通过高温膨胀仪、DSC和激光热导仪分别测定其热膨胀系数和导热系数.结果表明,掺杂的NCZ粉末保持了NZ的烧绿石相结构, 120℃时粉末为无定形的混合氧化物,900℃时转化为复合氧化物,1200℃时转变为单一的锆酸钕烧绿石相;高温下NCZ无明显相变;在高于1400℃的温度下煅烧后,NCZ的流动性得到显著改善;添加CeO2可提高锆酸钕的热膨胀系数,而对其导热系数和比热系数的影响不大. 相似文献
5.
6.
利用熔体提拉法生长了大尺寸,高质量的新型激光自倍频晶体Nd:GdxY1-x(Ca4O(BO3)3(简称Nd:GdYCOB),对Nd:GdYCOB晶体的XRD衍射图进行指标化,得到它的晶胞参数为a=8.080A;b=16.016A;c=3.538A,β=101.18,μ=491.1A3,对取自不同部位的晶体粉末进行ICP原子发射光 分析表明晶体整体组份均匀一致,根据熔体和晶体粉末的ICP数据计算,Nd:GdYCOB晶体中Nd3 的分凝系数为0.63,首次报道了Nd:GdYCOB晶体200-3000nm室温透过光谱和室温荧光光谱及荧光寿命,室温透过光谱表明Nd:GdYCOB晶体的紫外吸收边在-220nm,具有很宽的透光波段(-220-2700nm);Nd:GdYCOB晶体在800nm附近存在很强的吸收,适合于LD泵汪,为光光谱表明Nd:GdYCOB晶体是一种很有潜力的RGB(red,green,blue)激光自倍频晶体,掺杂4%,5% Nd:GdYCOB晶体的荧光寿命分别为105us和100us。 相似文献
7.
8.
9.
自变频激光晶体Nd3+:GdAl3(BO3)4的研究 总被引:1,自引:0,他引:1
采用熔盐法生长出尺寸为30mm的Nd3+:GdAl3(BO3)4优质晶体,进行了吸收光谱和荧光光谱的测定研究,计算得到晶体发射截面为σe1061.9=2.9×10-19cm2和σe1338mm=5.5×10-20cm2.采用染料激光器作为泵浦源,对晶体进行了自变频激光实验研究,在紫外可调谐(378-382nm)、绿光531nm、蓝光(436-443nm)、红光(669nm)和红外可调谐(1305-1365nm)波段实现了激光输出,输出的最大功率分别为:105μJ/脉冲、119.5μJ/脉冲、445μJ/脉冲、19μJ/脉冲和31μJ/脉冲. 相似文献
10.
11.
12.
13.
S. Rudtsch H. P. Ebert F. Hemberger G. Barth R. Brandt U. Groß W. Hohenauer K. Jaenicke-Roessler E. Kaschnitz E. Pfaff W. Pößnecker G. Pottlacher M. Rhode B. Wilthan 《International Journal of Thermophysics》2005,26(3):855-867
The results of an inter laboratory comparison of thermal conductivity, thermal diffusivity, specific heat capacity, and thermal
expansion measurements on austenitic stainless steel in the temperature range between 20 and 1000°C are presented here. Mean
values are presented for the physical properties studied. Reliable relative expanded uncertainties can be stated for the properties
determined, which were achieved by applying good measurement practice, i.e., 3% for thermal expansion, 5% for specific heat
capacity and thermal diffusivity, and 6% for thermal conductivity. The mean values derived from this intercomparison agree
well with the results of a previous intercomparison in 1990.
An erratum to this article is availabale at . 相似文献
14.
The thermal conductivity of nanoscale nickel particles due to phonon heat transfer is extrapolated from thin film results calculated using nonequilibrium molecular dynamics (NEMD). The electronic contribution to the thermal conductivity is deduced from the electrical conductivity using the Wiedemann–Franz law. Based on the relaxation time approximation, the electrical conductivity is calculated with the Kubo linear-response formalism. At the average temperature of T=300 K, which is lower than the Debye temperature ΘD=450 K, the results show that in a particle size range of 1.408–10.56 nm, the calculated thermal conductivity decreases almost linearly with decreasing particle size, exhibiting a remarkable reduction compared with the bulk value. The phonon mean free path is estimated, and the size effect on the thermal conductivity is attributed to the reduction of the phonon mean free path according to the kinetic theory. 相似文献
15.
Measurements of thermal conductivity and thermal diffusivity of twin pellets of Se90−x
Te5Sn5In
x
(x = 0, 3, 6, and 9) chalcogenide glasses were carried out at room temperature using transient plane source technique. The measured
values of thermal conductivity and thermal diffusivity were used to determine the specific heat per unit volume of these glasses
in the composition range of investigation. Results indicated that both values of thermal conductivity and thermal diffusivity
were increased with addition of indium concentration at the cost of selenium, whereas the specific heat per unit volume was
slightly decreases with increase of indium content. This compositional dependence behavior of the thermal conductivity and
diffusivity can be explained in terms of the iono-covalent type of bonds, which In (indium) makes with Se as it is incorporated
in the Se–Te–Sn glass. 相似文献
16.
采用热键合技术制备了Yb:Y3Al5O12/Y3Al5O12(Yb:YAG/YAG)复合晶体,对复合晶体进行了结构表征和键合质量检测.利用光学显微镜和扫描电镜观察了复合晶体横截面的形貌;在偏光显微镜下观察键合区域的应力,利用干涉条纹来表征复合晶体的光学均匀性;通过红外透过光谱的测量来检测复合晶体的键合质量.实验结果表明:热键合技术制备的Yb:YAG/YAG复合晶体键合界面处无界面缺陷,不存在复合界面空间过渡层,光学均匀性良好. 相似文献
17.
18.
M. Marinelli F. Mercuri U. Zammit F. Scudieri 《International Journal of Thermophysics》1998,19(2):595-601
The photopyroelectric technique has been used to measure simultaneously the specific heat, the thermal conductivity, and the thermal diffusivity of 9CB liquid crystal in the temperature range 35 to 60°C, where the sample undergoes a weakly first-order phase transition and a second-order one. Measurements of the anisotropy of the thermal conductivity have also been performed, and the data have been used to establish the order of the above-mentioned phase transitions. Pretransitional effects in the isotropic phase in the thermal diffusivity have been found, and they have been associated with similar effects reported for the specific heat. 相似文献
19.
“声子液体”热电材料β-Cu2-xSe具有优异的热电转换效率,采用分子动力学模拟的方法研究其热传导性能,分析了类“液态”离子的扩散能力和材料导热性能的相关性,并探究了材料加工处理手段(掺杂和空位)对材料热传导性能的影响。结果表明:类“液态”离子扩散能力和导热系数存在极强的相关性,β-Cu2-xSe中Cu^+移动能力的增强会增加晶格的非简谐振动,从而强化了声子散射,导致材料导热系数的降低。掺杂和空位对“声子液体”热传导性能有不同的影响:材料内部存在空位时,Cu^+倾向于在晶格缺陷中移动,降低了与Se构成的固定亚晶格碰撞概率,造成声学支声子频率的下降,有效地降低了导热系数,提高了材料的热电转换效率;相比空位,掺杂对导热系数的影响不明显。 相似文献