Mo-La_2O_3烧结坯的韧化机制研究

通过扫描电镜、定点探针分析、X射线衍射分析及俄歇电子能谱分析研究了Mo La2 O3 烧结坯的韧化机制。结果表明 :La2 O3 的加入提高了烧结钼坯的横向断裂强度和韧性 ;Mo La2 O3 烧结坯的韧化机制源于间隙杂质在La2 O3

Mo-La_2O_3烧结坯间隙杂质的研究

通过扫描电镜 (SEM)、电子探针 (EPMA)、X射线衍射 (XRD)及俄歇电子能谱 (AES)研究了 Mo- La2 O3烧结坯中的间隙杂质。结果表明 :L a2 O3的加入提高了烧结钼坯的抗弯强度和韧性。间隙杂质不仅存在于 Mo中 ,而且在 La2 O3粒子表面吸附 ,使晶界杂质浓度降低。

Mo-La_2O_3阴极La_2O_3表面富集研究

采用俄歇电子能谱法研究了 Mo- L a2 O3阴极材料中 L a2 O3向表面的富集过程。结果表明 ,在高温下 ,L a2 O3以 L a3+ ,O2 - 离子的形式分别向表面扩散 ,然后在表面上重新结合成分子。在 112 3 K～ 142 3 K范围内 ,L a3+ ,O2 -离子的扩散系数分别为 :DL a=3.6 70 3× 10 - 1 6 exp (- 1.0 16 39× 10 5 / RT) m2 / s;DO=1.5 12 2× 10 - 1 6 exp (- 8.130 6 6× 10 4/ RT) m2 /

碳化La_2O_3-Mo阴极材料的高温XPS研究

采用高温 X射线光电子能谱 (XPS)对碳化 La2 O3- Mo阴极材料表面 La的价态进行了研究。结果表明 ,材料中的 La2 O3可以被 Mo2 C还原成单质 La。单质 La的结合能高于 La2 O3的结合能。从实验上证实单质 La3d5/2的结合能为 835.96e V,并首次给出单质 La3d3/2结合能实验数值为 852 .2 3e V。

Mo-La_2O_3阴极碳化机理

研究了碳化温度、碳化时间、碳化时苯的压强对Mo La2 O3 阴极碳化度大小和碳化层组织的影响。结果表明 :在 172 3K ,苯的压强为 1.5× 10 -2 Pa,碳化 6min后Mo La2 O3 阴极碳化度达到 19.7%,碳化层为疏松多孔的Mo2 C组织 ,有利于阴极热电子发射。应用扫描电镜 (SEM)、X射线衍射仪 (XRD)等手段对Mo La2 O3 阴极碳化层的显微组织和微观结构、物相等进行了观察与分析。并从热力学与动力学两方面对Mo La2 O3 阴极碳化机理进行了探讨。

Chemical States of Lanthanum in Carbonized La_2O_3-Mo Thermionic Cathode Materials

The chemical reaction between lanthanum oxide and molybdenum carbide was studied by thermodynamic calculation, thermal analysis and in situ X ray Photoelectron Spectroscopy. The theoretical results show that at the environment allowing for the evaporation of lanthanum, such as in high vacuum, La 2O 3 in the La 2O 3 Mo materials can be reduced to metallic lanthanum by molybdenum carbide (Mo 2C). To confirm the conclusion, many analysis methods such as XRD, SPS, and TG DTA were taken. The experimental results show that the chemical state of lanthanum changes during heating. It was proved, for the first time, that reacted metallic lanthanum appears at the surface of this kind of material at high temperature.

Al2O3/La2O3/(W,Mo)C硬质合金刀具表面微织构参数优化

通过水热法制备粒度均匀的Al2O3/La2O3/(W,Mo)C纳米复合粉体,采用放电等离子烧结技术制备Al2O3/La2O3/(W,Mo)C无黏结相硬质合金刀具,利用激光加工技术在刀具表面制备不同沟槽参数的表面微织构,采用正交试验法研究不同沟槽参数的刀具对钛合金干切削性能的影响。结果表明:沟槽间距对切削力和粗糙度影响最大,沟槽深度次之,沟槽宽度影响最小;Al2O3/La2O3/(W,Mo)C无黏结相刀具在沟槽深度为10μm、沟槽间距为100μm、沟槽宽度为30μm时,对TC4钛合金切削性能最好,且刀具前刀面无磨损,后刀面为边界磨损,沟槽织构有效抑制了月牙洼磨损,提高了刀具寿命。

Chemical stability of La_2O_3 in La_2O_3-Mo cathode materials

Chemical stability of La 2O 3 in carbonized and uncarbonized La 2O 3 Mo cathodes was studied by in situ XPS analysis. Experimental results show that chemical stability of La 2O 3 is not good enough. In vacuum and at high temperature, oxygen can be dissociated from the lattice of La 2O 3 in the uncarbonized La 2O 3 Mo cathode. Binding energy shifts of La?3d5/2 and La?3d3/2 core peaks, and obvious decrease of satellite peak intensity in La?3d doublet with increasing temperature show that metallic La appears at carbonized La 2O 3 Mo cathode surface at high temperature.

La_2O_3-Gd_2O_3-Mo secondary emission material

A new kind of materials La 2O 3-Gd 2O 3-Mo has been produced by powder metallurgy method. The composition and microstructure of the material were studied by XRD and SEM. It shows that no chemical reaction takes place among La 2O 3, Gd 2O 3, Mo and the rare earth oxides exist along molybdenum grain boundaries and in the pores. The emission property measurement results of this material show that adding rare earth oxide into molybdenum can improve the secondary emission coefficient of the emitter, and the emission property depends on the activating temperature. After La 2O 3-Gd 2O 3-Mo was activated at 1 360 ℃, the maximum secondary emission coefficient can be high to 2.62, which has exceeded that for practical uses(2.0).

Surface segregation of La_2O_3 molecules in Mo La_2O_3 cathode materials

The surface segregation of La 2O 3 in Mo La 2O 3 cathode was carried out by Auger electron spectroscopy. Lanthanum and oxygen ions (La 3+ and O 2- ) diffuse from the grain boundaries to the surface respectively, and these ions recombine into La 2O 3 molecules on the surface. The results were analyzed by kinetics of grain boundary diffusion. In the temperature range of 1 123～1 423 K, the diffusion coefficients of La 3+ and O 2- ions were found to fit with the following equations: D La =3.670 3×10 -16 exp(-1.016 39×10 5/ RT ) D O=1.512 2×10 -16 exp(-8.130 66×10 4/ RT ). [

Surface Carbonization of Mo La_2O_3 Cathode

The carbonized structures of Mo La 2O 3 cathode specimens have been investigated by means of FESEM and XRD, respectively. The substructure of carbonized layer in the Mo La 2O 3 cathode has been found for the first time. The results showed that the carbonized layer with uniform Mo 2C was helpful to emission, while the demixing carbonized layer with a compact MoC outside layer was harmful to emission. The uniform Mo 2C layer consists of coarse particles with lots of grain boundary crevices as well as holes arranging perpendicular to the wire axle and up to surface, which was beneficial to the migration of activated rare earth in activation and operating.

CF_4 decomposition over solid ternary mixture NaF-Si-MO(MO=La_2O_3,CeO_2,Pr_6O-(11),Nd_2O_3,Y_2O_3)

A solid ternary mixture consisting of NaF,silicon and one metal oxide such as La2O3,CeO2,Pr6O11,Nd2O3,and Y2O3 was prepared and usedas de-fluorinated reagent for CF4 decomposition.The results show that 90% conversion of CF4 can be reached initially over NaF-Si-La2O3,NaF-Si-CeO2,NaF-Si-Nd2O3,and NaF-Si-Y2O3 at 850 C.The fresh and used reagents were characterized using XRD and XPS techniques.It was found that the active components of NaF and metal oxides in NaF-Si-CeO2,NaF-Si-Pr6O11,NaF-Si-Nd2O3,and NaF-Si-Y2O3 weretransformed into inert phases of mixed metal fluorides and silicates,respectively,resulting in an ineffective utilization of these de-fluorinatedreagents,whereas no inert phases from NaF and La2O3 can be observed in the used NaF-Si-La2O3,indicating the NaF-Si-La2O3 reagent couldbe utilized more efficiently than the other reagents in CF4 decomposition.

La_2Mo_3O_(12)薄膜的制备和光学性能研究

采用射频磁控溅射法制备La2Mo3O12薄膜并退火处理,用X射线衍射仪、扫描电镜、紫外-可见分光光度计、椭偏谱仪研究了薄膜的结晶特性、表面形貌和光学性能.结果表明,射频磁控溅射制备的La2Mo3O12薄膜为非晶态,退火后La2Mo3O12薄膜结晶主要为四面体结构和少量单斜结构,且薄膜表面平整,晶粒均匀.其光学带隙为3.63 eV,对近紫外光(200～280 nm)有良好的吸收性能,折射率在1.8到2.15之间,消光系数符合正常色散关系.

载荷和速率对(W,Mo)C/Al2O3/La2O3材料高温摩擦磨损性能的影响

采用热分解法和还原法制备了(W,Mo)C/Al2O3/La2O3粉末,利用等离子烧结技术在1600℃烧结制备了(W,Mo)C/Al2O3/La2O3复合陶瓷材料,并测试其力学性能。以Si3N4为对磨件在HT-1000试验机上进行高温摩擦磨损实验,研究材料在600℃时摩擦速率和载荷对摩擦系数以及磨损率的影响,并利用扫描电镜(SEM)和能谱仪(EDS)分析微观形貌,探究其磨损机制。实验结果表明,在600℃,7.5 N条件下,随着摩擦速率的增加摩擦系数和磨损率都在减小。当摩擦速率为33.6 m·min-1时具有最低的摩擦系数和磨损率,分别为0.4和4.21×10-6mm3·Nm-1。在600℃,16.8 m·min-1条件下,随着载荷的增大,摩擦系数和磨损率逐渐增加。在600℃,5.0 N,16.8 m·min-1时摩擦系数和磨损率最低分别为0.36和4.95×10-6mm3·Nm-1。通过分析得出:在600℃,7.5 N时,较高的摩擦速率能够有效排出(W,Mo)C/Al2O3/La2O3材料和对磨件产生的多余热量和磨屑,使摩擦系数和磨损率降低。在600℃,16.8 m·min-1时,在高载荷条件下产生大的交变应力以及反复的磨粒磨损,使摩擦系数和磨损率升高。(W,Mo)C/Al2O3/La2O3材料磨损机制主要为磨粒磨损、扩散磨损、粘结磨损和氧化磨损。

Improvement of conversion efficiency of silicon solar cells using up-conversion molybdate La_2Mo_2O_9:Yb,R (R=Er, Ho) phosphors

The goal of this work was aimed to improve the power conversion efficiency of single crystalline silicon-based photovoltaic cells by using the solar spectral conversion principle, which employs an up-conversion phosphor to convert a low energy infrared photon to the more energetic visible photons to improve the spectral response. In this study, the surface of multicrystalline silicon solar cells was coated with an up-conversion molybdate phosphor to improve the spectral response of the solar cell in the near-infrared spectral range. The short circuit current （Isc）, open circuit voltage （Voc）, and conversion efficiency （η） of spectral conversion cells were measured. Preliminary experimental results revealed that the light conversion efficiency of a 1.5%–2.7% increase in Si-based cell was achieved.

稀土钼热阴极材料研究与应用

综述了近年来稀土钼热阴极材料的研究和应用情况 ,着重对La2 O3 Mo阴极材料近年来的研究进展进行了介绍。稀土钼作为一种资源丰富、发射性能优良、易加工、无放射性污染的新型热阴极材料 ,己逐步取代具有放射性污染的ThO2 W阴极材料 ,在中大功率电子管器件中获得应用。

镧钼合金在电火花切割加工中的应用研究

进行了镧钼丝与纯钼丝作电火花切割电极丝的对比试验。试验结果显示 :在合理控制镧钼丝加工工艺的条件下 ,镧钼丝具有较高的抗拉强度和高温强度 ,其线切割使用寿命明显高于纯钼丝 ,试验数据显示提高 5 0 %左右。实践表明 ,在电火花线切割加工行业 ,用镧钼丝代替纯钼丝作电极丝 ,可有效降低切割成本 。