等离子喷涂Sc2O3、Gd2O3和Y2O3复合稳定ZrO2热障涂层相稳定性及导热性研究

采用化学共沉淀-煅烧法制备了Sc2O3、Gd2O3和Y2O3复合稳定ZrO2陶瓷原粉,陶瓷原粉经球磨、团聚造粒和烧结处理后得到适于等离子喷涂工艺的热喷涂粉末。测试分析了Sc2O3、Gd2O3和Y2O3复合稳定ZrO2热喷涂粉末微观形貌、流动性及其等离子喷涂涂层的相稳定性及导热性。结果表明Sc2O3、Gd2O3和Y2O3复合稳定ZrO2材料及其等离子喷涂涂层具有优异的高温相稳定性,即使在1400℃热处理500小时依然呈四方相结构、无单斜相出现,涂层热导率比单一Y2O3稳定ZrO2涂层明显降低,Sc2O3、Gd2O3和Y2O3复合稳定ZrO2可以用作新型超高温热障涂层材料。     

Y2O3和La2O3对金属陶瓷内衬显微硬度和耐蚀性的影响

研究了钇、镧等添加物对金属陶瓷内衬显微硬度和耐蚀性的影响。结果表明:加入Y2O3、L a2O3和S iO2可使陶瓷层的孔隙度降低,一定程度上使耐蚀性增加。L a2O3对提高陶瓷层性能的效果比Y2O3要好。     

La2O3对ZrO2-Y2O3-Ta2O5陶瓷材料结构及性能的影响

采用固相合成法在氧化钇部分稳定氧化锆(YSZ)陶瓷材料的基础上引入氧化物Ta2O5以及稀土氧化物La2O3取代部分Y2O3,获得一种新型的La2O3-ZrO2-Y2O3-Ta2O5陶瓷材料。分别利用X射线衍射仪、扫描电子显微镜和STA-449C热膨胀仪对材料的物相组成、微观结构及热膨胀性能进行表征。结果表明,陶瓷材料的主晶相仍为四方相,晶粒尺寸减小,在RT～1200℃温度范围内热膨胀系数有所减小。     

La2O3-Mo阴极材料中La2O3稳定性研究

本文采用高温光电子能谱方法对La2O3-Mo阴极及碳化La2O3-Mo阴极材料表面La2O3的化学稳定性进行了研究。实验结果表明,La2O6并不具备文献报道的极好的化学稳定性。材料中的La2O3在高温、真空条件下,其部分晶格氧发生分离。La2O3可以被Mo2C还原成单质La。单质La的结合能高于La2O3的结合能。实验证实单质La3d5／2的结合能为835．96eV,并首次给出La3d3／2的结合能实验数值为852．23eV。     

掺杂Y2O3的ZnO导电陶瓷正电子寿命谱研究

用正电子湮没技术,结合X射线衍射结构分析,对掺杂Y2O3的ZnO导电陶瓷烧结过程进行了研究,给出了掺杂含量、烧结温度和烧结时间对材料结构的影响特征,研究发现Y2O3掺杂量增加,ZnO导电陶瓷材料完整性变差;烧结温度升高,ZnO陶瓷产生微空洞为主的缺陷;烧结时间增加,微空洞缺陷数目明显增加.同时对正电子湮没机制与ZnO陶瓷导电特性的关联进行了研究.     

Sm2O3掺杂PbTiO3陶瓷的制备与电性能研究

采用溶胶-凝胶法制备了Sm2O3掺杂的PbTiO3陶瓷,并对其制备条件和电性能进行了研究.结果表明Sm2O3掺杂能够缩短凝胶形成时间,降低PbTiO3陶瓷烧结温度,改善烧结性能;Sm2O3掺杂PbTiO3陶瓷的电阻率均低于纯PbTiO3陶瓷,当掺杂量为0.003(n(Sm2O3)∶n(PbTiO3))时,电阻率最低,为5.8×108Ω*m;通过XPS分析,得到了Sm2O3掺杂PbTiO3陶瓷中各元素的结合能位置,表明Sm3+、Ti4+等都存在着不同程度的变价,导致了PbTiO3陶瓷导电性的提高.     

镧改性固体催化剂SnO2-WO3/La2O3的制备及其催化性能

500℃焙烧3 h条件下制备了摩尔比nSn∶nW=2∶1,含3.0%(质量分数,下同)La2O3的镧改性固体催化剂SnO2-WO3/La2O3,采用IR分析对其进行了表征。通过改变催化剂用量、30%H2O2用量、反应时间及催化剂重复使用性等因素,系统考察了该稀土改性双金属氧化物催化氧化环己酮合成己二酸的催化性能。实验结果表明,己二酸的适宜合成条件为:100 mmol环己酮,1.25 g催化剂SnO2-WO3/La2O3,50 mL 30%H2O2,回流反应7 h,目的产物己二酸收率达77.7%。SnO2-WO3/La2O3连续使用6次己二酸收率仍可接近40%。     

热喷涂玻璃-Cr2O3陶瓷涂层的性能

以SiO2-Al2O3系玻璃与Cr2O3陶瓷粉末为原料,采用高温烧结、球磨破碎工艺制备玻璃态物质包覆Cr2O3陶瓷颗粒的玻璃-Cr2O3陶瓷复合粉末,利用氧-乙炔火焰热喷涂技术在45号钢表面喷涂SiO2-Al2O3-Cr2O3玻璃陶瓷保护涂层。利用扫描电镜(SEM)对SiO2-Al2O3-Cr2O3玻璃陶瓷粉末与涂层的微观形貌进行表征。采用粘接拉伸法检测涂层与基体的界面结合强度,在介质溶液中进行腐蚀实验,研究玻璃与陶瓷粉末的配比对涂层微观结构与性能的影响。研究表明:当SiO2-Al2O3系玻璃的含量(质量分数)为40%时,涂层具有较好的综合性能,与基体的结合强度达30.4MPa,在10%CH3COOH溶液(体积分数)、8%NaOH溶液(质量分数)和3.5%NaCl溶液(质量分数)中腐蚀120 h的腐蚀速率分别为112.6、87.1和83.1 mg/(h.m2)。     

CeO2对不锈钢基SiO2-BaO-Al2O3-Cr2O3陶瓷涂层性能的影响

采用高温熔烧法于1Cr18Ni9Ti不锈钢基材表面制备掺CeO2的SiO2-BaO-Al2O3-Cr2O3陶瓷涂层,研究了不同含量CeO2对涂层的抗氧化性、抗热震性和硬度的影响。研究结果表明,含CeO2的不锈钢基SiO2-BaO-Al2O3-Cr2O3陶瓷涂层能有效阻止不锈钢基体的氧化增重,提高涂层的抗热震性能及硬度。本实验条件下,CeO2含量2.8%时,涂层具有最好的抗氧化性能和抗热震性能。     

非晶La2O3薄膜的阻变存储性能研究

采用脉冲激光技术在Pt/Ti/SiO2/Si衬底上沉积了非晶La2O3薄膜,制作并分析了Pt/La2O3/Pt堆栈层的直流电压与脉冲电压诱导的电阻转变特性。Pt/La2O3/Pt器件单元表现出了稳定的双极性电阻转变,其高低阻态比大于两个数量级。经过大于1.8×106s的读电压,高低阻态的电阻值没有明显的变化,表现出了良好的数据保持能力。通过研究高低阻态的电流电压关系、电阻值与器件面积的关系,揭示了导电细丝的形成和破灭机制是导致Pt/La2O3/Pt器件发生电阻转变现象的主要原因。     

Solubility of carbon in CaO-B2O3 and BaO-B2O3 slags

The solubility of carbon in molten CaO-B₂O₃ and BaO-B₂O₃ slags at high temperatures was measured to understand the dissolution mechanism of carbon into the slags. The B₂O₃-bearing slags, which have a wide range of liquids, at the temperature of interest have been applied to investigate the effect of basicity on the solubility of carbon from the saturation of acidic or basic components. The solubility of carbon, as a function of the composition of slags, shows a minimum value, and it is suggested that carbon dissolves by different mechanisms in the acidic and basic slags, respectively. From the infrared spectra measurements, the wave number indicating the B-C bond was found to be about 1150 cm⁻¹ in the acidic region of slags; hence, the incorporation of carbon into the borate network was confirmed qualitatively. The carbide capacity was compared to the nitride capacity, showing that the dissolutions of carbon and nitrogen into the slags are similar.     

CaO-La2O3-B2O3-Eu2O3转光玻璃的合成及荧光性质

X射线衍射研究表明CaO-La2O3-B2O3-Eu2O3体系的玻璃化温度在1025℃附近.荧光光谱和ESR谱研究表明,在CaO-La2O3-B2O3-Eu2O3玻璃体系中存在着Eu2+和Eu3+两种价态离子. 316, 360, 379, 394, 413, 462和532nm锐线激发峰和592,616和650红区发射峰分别对应Eu3+的f-f激发跃迁和5D0-7FJ (J=1,2,3)跃迁发射;351nm和427nm宽带激发峰和蓝区发射分别对应Eu2+的5d-4f激发跃迁和发射.     

Al2O3La2O3Y2O3/Cu复合材料的电弧侵蚀特性研究

采用喷射沉积和内氧化法制备出Al₂O₃La₂O₃Y₂O₃/Cu复合材料,研究该材料在直流20 V/20 A的工作条件下触点的电弧侵蚀特性,并与Al₂O₃/Cu材料进行了对比分析.利用电子天平、扫描电镜等方法分析电弧侵蚀后触点的质量变化和表面微观结构.结果表明,通过添加Y₂O₃、La₂O₃稀土氧化物颗粒,可有效降低触头材料的材料转移量.Al₂O₃La₂O₃Y₂O₃/Cu材料的抗熔焊性和抗烧损性优于Al₂O₃/Cu材料的性能.在直流阻性负载条件下Al₂O₃La₂O₃Y₂O₃/Cu阳极触头表面形成凹坑,阴极触头表面形成凸起,触点表面显示出浆糊状凝固物和喷发坑等电弧侵蚀形貌特征.      

CaO--TiO2--Fe2O3三元系中Ca3TiFe2O8的生成机理

钒钛磁铁矿是烧结矿重要的原料之一,Ca₃TiFe₂O₈作为钒钛烧结矿中矿物被发现之后,其生成机理尚不明确.本文采用X射线衍射分析、元素能谱分析和TG-DSC分析相结合的方法,研究了Ca₃TiFe₂O₈的生成机理以及不同温度、CaO与TiO₂含量下Ca₃TiFe₂O₈的生成规律.实验结果表明,Ca₃TiFe₂O₈由Ca₂ Fe₂O₅和CaTiO₃反应生成,即CaO和Fe₂O₃反应生成Ca₂ Fe₂O₅;其后,与CaTiO₃反应生成Ca₃TiFe₂O₈.反应时间越长,Ca₃TiFe₂O₈的生成量越大,但反应温度对Ca₃TiFe₂O₈生成的影响并不明显.另外,还发现CaO含量越高,Ca₃TiFe₂O₈越易于生成,而且等摩尔Fe₂O₃和CaO下只要存在TiO₂,就会有Ca₃TiFe₂O₈生成.      

CaO含量对CaF2-Al2O3-CaO-Ce2O3渣系中Ce2O3行为的影响

在Fe-Cr-Al合金中添加微量的稀土元素可显著改善合金的使用性能, 文中以电渣重熔生产Fe-Cr-Al合金所用稀土渣为研究对象, 根据离子-分子共存理论(IMCT)建立了1 823 K时CaF₂-Al₂O₃-CaO-Ce₂O₃四元渣系热力学质量作用浓度模型.结果表明:当渣系中CaO和Al₂O₃的质量百分数之比维持在1:1, 即w_CaO /w_Al2O3=1时, 随着Ce₂O₃含量增加, 渣中铈铝酸盐Ce₂O₃·Al₂O₃质量作用浓度(活度)显著增加, 但炉渣物相种类没有变化.渣系中Ce₂O₃含量分别在10 %, 20 %, 30 %, 40 %时, w_CaO /w_Al2O3值对组元活度的影响各不相同但有共同特征, 表现在处于约1.0~1.8时, CaO活度增加最迅速, Ce₂O₃活度增加, Ce₂O₃·Al₂O₃活度下降, 说明渣中CaO含量增加促进了Ce₂O₃·Al₂O₃分解而导致Ce₂O₃活度增加, 选取渣系进行熔融和X射线衍射实验, 用jade 5.0软件分析物相, 实验结果与计算一致.      

Effect of Fe2O3 Loading Amount on Catalytic Properties of Monolithic Fe2O3/Ce0.67Zr0.33O2 -Al2O3 Catalyst for Methane Combustion

Ce0.67Zr0.33O2-Al2O3 solid solution was prepared by the co-precipitation method. Fe2O3-based catalysts supported on the solid solution were obtained by the impregnation method. The article revealed that the optimal loading amount of Fe2O3 on Ce0.67Zr0.33 O2-Al2O3 in our experimental condition for catalytic combustion of methane was 8% （ mass fraction）. The prepared catalysts were characterized by BET, TPR, XRD analyses, and their catalytic activity was investigated after being calcined at 873 K and after being aged in water gas at 1273 K. When the loading amount of Fe203 was 8% （ mass fraction）, the catalyst held the highest activity, and the best temperature speciality and thermal stability. The complete-conversion temperature of methane for fresh and aged sample was 788 and 838 K, respectively. The range between the light-off temperature and the complete-conversion temperature was only 15 K. The characterization results of XRD indicated that Fe2O3 was well dispersed on the Ce0.67Zr0.33O2-Al2O3 matrix. The results of BET and TPR were in good harmony with the catalytic activity results.     

Research on Y2O3：Eu Phosphor Coated with In2O3

Y2O3：Eu red phosphor for FED application was prepared by high temperature solid-state reaction. The In2O3 coating by precipitation method to the phosphor was applied and the analyses of XRD, Zeta potential, SEM, EDS and low voltage cathodoluminescence （CL） were conducted for investigating the coating effect. The results showed that In2O3 coating promoted the low voltage CL of the phosphor efficiently. The promotion was possibly due to the enhancement of the surface conductivity of the phosphor grains.     

Study on thermal expansion behavior of Dy2O3 - Al2O3 - SiO2 glass

Employing Dy2O3, Al2O3, and SiO2 as starting materials, several series of Dy2O3-Al2O3-SiO2 sealing glass were prepared. The relationship between their coefficients of thermal expansion and the contents of Dy2O3, Al2O3, and SiO2 were studied respectively. Experimental results showed that Dy2O3 and Al2O3 had a positive effect on the coefficient of thermal expansion of glass, whereas, SiO2 had a negative effect. The coefficient of thermal expansion of glass showed an apparent linear relation to the contents of these three raw materials, from which an estimation model was built, to calculate the coefficient of thermal expansion of sealing glass. Relative errors of the calculating results to testing results were no more than 2%, which suggested that the estimation model was reasonable. This study provides a good theory reference for the practical utilizing of this sealing material, through which a proper glass composition for good sealing could be easily found.     

Synthesis of Al2O3/TiCN-0.2%Y2O3 Composite by Hot Pressing

Al2O3/TiCN composites were synthesized by hot pressing.The influences of components and HP temperature on mechanical properties,such as bending strength,breaking tenacity and Vickers hardness were investigated.The results showed that the mechanical properties of Al2O3/TiCN composite increased with temperature when hot pressing temperature is below 1650 ℃.The mechanical properties reached their maximums when the composites were sintered at 1650 ℃ for 30 min under hot pressing pressure of 35 MPa,the value of bending strength,breaking tenacity and Vickers hardness was 1015 MPa,6.89 MPa·m1/2,and 20.82 MPa,respectively.When hot pressing temperature was above 1650 ℃,density decreased because of decomposition with increased temperature,and mechanical properties dropped because of rapid growth of grains in size at high temperature.Microstructure analysis showed that the addition of Y2O3 led to the formation of YAG phase so as to inhibit the growth of crystals.This helped to improve breaking tenacity of the composites.TiCN particles with diameters of 1 μm dispersed at Al2O3 grain boundaries,inhibited grain growth and enhanced mechanical properties of the composites.SEM study of the propagation of indentation cracks showed that the bridge linking behavior between matrix and strengthening phase might lead to the formation of the coexisted field of crack deflection,branching and bridge linking.The mechanism of this phenomenon was that the addition of Y2O3 improved the dispersion of TiCN particles so as to enhance the tenacity of the composites.The breaking tenacity was changed from 5.94 to 6.89 MPa·m1/2.