热处理V膜制备VO_2薄膜的结构和光电性能

先用磁控溅射法在石英玻璃基片上制备了金属V膜,然后经过真空退火处理被转变为VO_2薄膜。研究了退火温度对VO_2薄膜表面形貌、晶体结构、光学性能和电学性能的影响。结果表明:随着退火温度由300℃增加到450℃,VO_2薄膜的结晶度明显增加。退火温度在400℃和450℃制备的样品是高纯M相单斜结构,晶粒发育较好,晶界清晰。不同温度退火的样品的表面V元素包含由4+和5+态,5+态的出现是由于表面V元素受环境中氧化导致。虽然退火温度的改变对VO_2薄膜的可见光透过率无明显影响,但是可以改善对太阳光的调节效率。VO_2薄膜半导体-金属相变温度和半导体相的电阻随热处理温度增加而增加,在400℃和450℃退火样品电阻相变前后的变化幅度可达2个数量级,450℃退火制备样品的滞后宽度和半导体金属相变临界温度分别为14.6℃和61.0℃。     

热处理V膜制备VO_(2)薄膜的结构和光电性能EI北大核心CSCD

先用磁控溅射法在石英玻璃基片上制备了金属V膜,然后经过真空退火处理被转变为VO_(2)薄膜。研究了退火温度对VO_(2)薄膜表面形貌、晶体结构、光学性能和电学性能的影响。结果表明:随着退火温度由300℃增加到450℃,VO_(2)薄膜的结晶度明显增加。退火温度在400℃和450℃制备的样品是高纯M相单斜结构,晶粒发育较好,晶界清晰。不同温度退火的样品的表面V元素包含由4+和5+态,5+态的出现是由于表面V元素受环境中氧化导致。虽然退火温度的改变对VO_(2)薄膜的可见光透过率无明显影响,但是可以改善对太阳光的调节效率。VO_(2)薄膜半导体-金属相变温度和半导体相的电阻随热处理温度增加而增加,在400℃和450℃退火样品电阻相变前后的变化幅度可达2个数量级,450℃退火制备样品的滞后宽度和半导体金属相变临界温度分别为14.6℃和61.0℃。     

TiO_2纳米晶制备条件对降解亚甲基蓝的影响研究

为研究不同的二氧化钛前驱体预处理条件对退火后二氧化钛性能的影响,以乙二醇和三氯化钛稀盐酸溶液为原料,在不同预处理条件下,采用溶剂热法制备了白色Ti O_2花状纳米球,并于320℃下退火,得到灰白色催化剂样品。对样品进行了结构、形貌及光催化性能测试。结果表明,在一定范围内,随着预处理搅拌时间的增加和预处理温度的升高,发现样品的晶相结构在退火之前无明显差异,但在320℃退火之后,样品会由单斜相二氧化钛逐渐趋于锐钛矿相。在预处理搅拌时间为11 h、预处理温度达到160℃的优化条件下,制备的催化剂样品为纳米薄片组成的花状纳米球二氧化钛,比表面积达到210 m~2/g,光催化降解亚甲基蓝效率可达99.6%。     

退火温度对纳米Co0.8Mg0.2Fe2O4/SiO2复合薄膜结构和磁性的影响

采用溶胶-凝胶旋涂法制备纳米Co0.8Mg0.2Fe2O4/SiO2复合薄膜.用X射线衍射仪、原子力显微镜及振动样品磁强计分析复合薄膜的结构、表面形貌和磁性,研究退火温度对复合薄膜结构和磁性的影响.结果表明:经800℃退火处理的样品中已形成Co0.8Mg0.2Fe2O4晶相;随着退火温度的提高,Co0.8Mg0.2Fe...     

TiO2薄膜的相变与光学性能

采用射频磁控溅射法在单晶硅片和石英玻璃片上沉积TiO2薄膜.通过X射线衍射、原子力显微镜、X射线光电子能谱、紫外可见光谱和荧光发射光谱对薄膜的结构、相组成和表面形貌进行了表征.研究了退火温度对薄膜相结构、表面化学组成、形貌及光学性能的影响.结果表明:沉积的TiO2薄膜为无定形结构,经400℃以上退火后的薄膜出现锐钛矿相,600℃以上退火后的薄膜开始出现金红石相,1000℃以上退火的薄膜完全转变为金红石相.随着退火温度的升高,晶粒尺寸逐渐增大,仅在950～l000℃时出现减小,1 000℃退火的薄膜组成为TiOx.随着退火温度的升高,薄膜的透射率下降,折射率和消光系数有所增加.     

HVO2薄膜相变的特性及热稳定性

采用射频溅射磁控溅射技术在Ar+H_2气氛下,以V_2O_5为溅射靶材在玻璃基片上制备了H掺杂VO_2(HVO_2)薄膜,研究了H_2流量和退火处理对HVO_2薄膜的结构、光电性能和热稳定性的影响。结果表明:H_2流量可以控制薄膜中H的含量,微量H的掺杂使HVO2薄膜相变温度降低到室温附近,过量的H掺杂会使薄膜处于金属态。当500℃下退火3 h后,薄膜物相、相变等特征明显变化,此时薄膜中的H不能稳定存在于VO_2晶格而溢出薄膜。当退火温度≤450℃、退火时间≤6 h时,薄膜保持较高的稳定性,这为室温附近使用HVO_2薄膜提供了基础。另外,随H_2流量增加,薄膜的平均透射率小幅度增加,最终稳定在37%左右。随着退火温度的增加,未引入H_2制备的VO_2薄膜的平均透射率在400℃退火后为30.9%,在450和500℃退火后为35.8%左右。H_2流量为0.1～0.5 m L/min时制备的样品在3种退火温度下的透射率均保持在38%左右。     

反应条件对氧化铁结晶行为的影响

借助扫描电镜、X射线衍射、红外光谱等分析手段,系统探讨了水热反应条件下,反应温度和时间对氧化铁结晶行为的影响.随着反应温度的升高,样品中的FeOOH相转变为Fe2O3,在表面吸附的SO2-4呈减少的趋势.晶体形状均为球形.随着反应时间的延长,样品中均含有Fe2O3和FeOOH相,在表面吸附SO2-4呈减少趋势,晶体尺寸增大,晶体形态由球形向纺锤形转变.     

掺Al的Ge-SiO_2薄膜的结构和光致发光性质

采用射频磁控溅射复合靶技术制备了掺Al的Ge SiO2 薄膜。薄膜在N2 保护下进行了不同温度的退火处理。采用FTIR ,XRD ,XPS分析了样品的结构。样品的PL谱结果表明退火温度、沉积温度以及样品中的Al含量对Al Ge SiO2 薄膜的光致发光的峰位和峰强有一定的影响。     

煅烧温度对纳米TiO2光催化降解甲基橙性能的影响

以钛酸四正丁酯为原料,采用溶胶-凝胶法制备了不同煅烧温度(500℃、600℃、700℃和800℃)的TiO2纳米粒子,对样品进行了TG-DTA、XRD、UV-Vis及IR分析,并以甲基橙为目标降解物,考察了煅烧温度对TiO2光催化性能的影响.结果表明:随着煅烧温度的升高,TiO2晶粒尺寸迅速长大,800℃时,出现金红石相;TiO2的吸收带边随煅烧温度的升高发生了不同程度的红移;600℃煅烧得到的TiO2粒子表面易羟基化,其光催化性能最好.     

退火温度对MoS2纳米薄膜微特性及光学性能的影响

本论文使用射频磁控溅射法在硅衬底上制备不同退火温度下的MoS2薄膜,利用SEM、XRD、光谱仪等手段对薄膜的表面形貌、结构、反射率等进行表征,分析退火温度对MoS2薄膜性能的影响。研究结果表明:退火温度对MoS2薄膜表面形貌影响明显,不同退火温度会改变MoS2薄膜XRD衍射峰的位置。退火温度越高,MoS2薄膜生长质量越好,MoS2薄膜反射率越高。     

含Y2O3的ZnO-Bi2O3-B2O3系统玻璃热学与电学性能研究

用红外光谱仪、拉曼光谱仪和差热分析仪研究了用“熔化-急冷”制得的用于SOFC封装的含Y2O3的ZnO-Bi2O3-B2O3系统玻璃的结构和转变温度(Tg);用X射线衍射仪、热膨胀系数仪和高阻计研究了由“模压成型-热处理”制得的该玻璃制品的微晶化、热膨胀系数(α)和体积电阻率(p)情况.结果表明:Y2O3≤0.5～1.0wt.％时,Y2O3能促进[BO3]向[BO4]转变,使α降低;Y2O3≥0.5～1.0wt.％时,玻璃中Bi-O键增多,又使α降低趋势趋缓;随Y2O3增加,其作用可能由破坏网络结构逐渐向增强网络结构转变,致T8先降后升;添加Y2O3延缓了玻璃的析晶;微晶化能提高α和ρ;添加Y2O3虽致α和ρ下降,但其值仍在SOFC封接玻璃的要求范围内.     

Oxygen barrier resistance of HfB2-MoSi2-TaB2 coatings in a wide temperature region

HfB₂-MoSi₂-based ultra-high temperature ceramic (UHTC) coatings have shown remarkable antioxidant effects owing to the formation of silicate glass layers with low oxygen permeability in high-temperature environments, which shows great potential in the antioxidation of carbon structural materials. To further enhance the oxidation resistance of the HfB₂-MoSi₂-based coating in a wide temperature region, the influence of volume ratio between HfB₂ and TaB₂ on the antioxidant capacity of the HfB₂-MoSi₂-TaB₂ coatings was investigated. The addition of 15 vol% TaB₂ in the 60HfB₂-40MoSi₂ coating delays the initial oxidation temperature of the 60HfB₂-40MoSi₂ sample from 300 °C to 500 °C, which decreased the oxidation loss by 75.85% during dynamic oxidation. In oxidation process at 900 °C and 1700 °C, the weight gains of the 45HfB₂-40MoSi₂–15TaB₂ coating reduced by 78.56% and 63.14%, respectively. Due to the coexistence of 45 vol%HfB₂ and 15 vol%TaB₂, the suitable Ta⁵⁺ promoted the homogenization and dispersion of Hf/Ta-oxides, which forms the coral-like Hf/Ta oxides skeleton in the glass layer, thus preventing the oxygen penetration and decreasing the inert factor of the HfB₂-MoSi₂ coating at 1700 °C by 51.19%. However, excessive TaB₂ weakened the self-healing ability of the Ta-Hf-Si-O glass layer and inhibited the oxygen barrier effect of the HfB₂-MoSi₂-TaB₂ coating.     

压埋法制备MgB_2超导材料的工艺

介绍了一种用压埋法合成块状MgB2超导体的新方法。采用该方法得到的样品的临界温度可高达38 4K,与常规方法得到的样品的临界温度相近。对这种方法的合成工艺进行了探讨,发现烧结温度(Ts)和保温时间(t)对样品的临界温度影响很大。在相同的0 5h保温时间条件下,烧结温度在1073～1123K温区获得的样品临界温度最高。固定烧结温度(1123K),不同保温时间下获得的样品的临界温度随着保温时间的增加而降低。进一步对样品的剩余电阻率比(RRR)进行研究,实验结果表明随着RRR数值的增加临界转变温度下降。这可能与样品内过量的杂质有关。     

JNX70-2型焦炉烘炉实践

焦炉投产前必须进行烘炉,而烘炉质量的好坏对焦炉的寿命至关重要。如何保证烘炉质量,是广大焦化工作者一直不断探讨的问题。在7 m焦炉从冷态转为正常加热的过程中,按照制定的升温计划,加强对火道的温度管理,使升温速率控制在允许的波动范围之内,同时通过定期测量炉体膨胀,加强对护炉铁件的调节,并及时对炉体裂缝进行修补,从而保证了焦炉的严密性,使新建焦炉从冷态平稳过渡到生产状态,为安全稳定生产奠定了基础。     

Effects of SiC or MoSi2 second phase on the oxide layers structure of HfB2-based composites

Monolithic HfB₂, HfB₂-30 vol% SiC and HfB₂-10 vol% MoSi₂ composites were prepared by SPS and oxidized in stagnant air at 1500 °C for 70 min. The microstructure of the oxide layer cross-sections showed that the oxidation extents were as follow: monolithic HfB₂ > HfB₂-30 vol%SiC > HfB₂-10 vol% MoSi₂.According to the EDS Line-scan, only one porous oxide layer containing a minor amount of B₂O₃was found on the HfB₂ oxidized surface whereas a thick silicate glass layer and a porous oxide layer below that existed on the surface of HfB₂-30 vol% SiC. After oxidation, the surface of HfB₂-10 vol% MoSi₂ had a narrow silicate-oxide compact layer covered by a very thin glass layer. X-ray diffraction patterns of the oxidized surfaces showed the monolithic HfB₂,the HfB₂-30 vol% SiC and HfB₂-10 vol% MoSi₂composites contain, upon oxidation, only m-HfO₂ phase, mainly m-HfO₂ with a minor amount of HfSiO₄ and mainly HfSiO₄ with a minor amount of m-HfO₂ phases, respectively. Based on the observations in this study, it is suggested that the elimination of the porous layer and subsequent increase of the HfSiO₄ phase are the main reasons for the better oxidation resistance of HfB₂-10 vol% MoSi₂.     

碳粉在O2-CO2气氛下的燃烧行为

采用综合热分析技术研究了碳粉在不同O2-CO2气氛下的燃烧行为. 结果表明,碳粉在升温燃烧过程中,随CO2浓度增加,TG和DTG曲线向高温区偏移,着火点温度和燃尽温度均呈上升趋势,较高温度才能满足碳粉与CO2反应的条件. 1100℃恒温条件下,TG, DTG和DTA曲线均随CO2浓度的增加向高温区偏移,CO2浓度高于20%时,TG曲线出现平台,相对应的DTG曲线出现波谷,DTA曲线出现波峰,且CO2浓度越高,平台出现得越早. 随CO2浓度的增加明显降低反应产生的热量. CO2含量小于80%时,CO2基本不参与反应,实际的热效应仅与O2含量有关,且符合平方根关系.     

2D/2D SnO2 nanosheets/Ti3C2Tx MXene nanocomposites for detection of triethylamine at low temperature

Highly active two-dimensional (2D) nanocomposites have been widely concerned in the field of gas sensors because of their unique advantages and synergistic effects. 2D/2D SnO₂ nanosheets/Ti₃C₂T_x MXene nanocomposites were synthesized by using layered Ti₃C₂T_x MXene and uniform SnO₂ nanosheets by hydrothermal method. Characterization results show that the SnO₂ nanosheets are well dispersed and vertically anchored on the layered Ti₃C₂T_x MXene surface, forming heterogeneous interfaces. Based on the gas-adsorption capabilities and synergistic effects of electronic properties, SnO₂ nanosheets/Ti₃C₂T_x MXene nanocomposites show high triethylamine (TEA) gas-sensing performance at low temperature (140 °C). The sensor responses of the nanocomposites and pure SnO₂ nanosheets to 50 ppm of TEA are 33.9 and 3.4, respectively. An enhancement mechanism for SnO₂ nanosheets/Ti₃C₂T_x MXene nanocomposites is proposed for highly sensitive and selective detection of TEA at low temperature. The combination strategy of two-dimensional metal oxide semiconductor and multilayer MXene provides a new way for the development of cryogenic gas sensors in the future.     

A novel NTC ceramic based on La2Zr2O7 for high-temperature thermistor

A novel negative temperature coefficient material based on lanthanum zirconate ceramics was proposed for high-temperature applications. This material was synthesized through a solid-state reaction by sintering at 1923 K for 10 h in air. The X-ray diffraction and scanning electron microscopy results confirmed that La₂Zr₂O₇ ceramics exhibited a pyrochlore phase with a relative density of 98.2 %. The resistance–temperature characteristics of the material revealed that La₂Zr₂O₇ ceramics exhibited an NTC feature within the broad temperature range of 973–1773 K in addition to maintaining high thermal constant B, and resistivity to ensure good sensitivity at high temperatures. These properties, along with high ceiling temperature, unique oxygen insensitivity, and excellent ageing coefficient of <0.7 % at 1773 K, render La₂Zr₂O₇ ceramics a promising candidate as thermistor materials with high-temperature NTC.     

SO_2催化氧化反应的平衡温度与最佳温度探讨

阐述硫酸生产过程中SO2 催化氧化反应的平衡温度与最佳温度的确定 ,应考虑催化剂的内表面利用率和综合校正系数对反应过程的影响 ,针对其反应过程推导出不同催化剂的平衡温度与最佳温度的计算式     

降低精洗甲醇温度 提高脱碳装置能力

针对低温甲醇洗装置高负荷运行时温度升高、系统失衡的问题,经过实测和计算提出改造方案,较好地消除了生产装置的瓶颈。