Al_2O_3含量对ZrO_2/Al_2O_3复相陶瓷流变性能和抗弯强度的影响

采用有机泡沫浸渍法制备ZrO_2/Al_2O_3复相陶瓷,分析Al_2O_3添加量对泡沫陶瓷显微形貌、相结构、抗弯强度和浆料流变性能的影响,确定制备复相陶瓷的最佳工艺参数。实验结果表明,ZrO_2/Al_2O_3复相陶瓷由m-ZrO_2相、t-ZrO_2相和Al_2O_3相组成;当Al_2O_3的含量为20 wt%时,烧结的陶瓷颗粒致密均匀,陶瓷的抗弯强度最佳,浆料表观粘度增加;增加Al_2O_3的含量到40 wt%,陶瓷出现较多气孔,浆料的表观粘度增加幅度不大;Al_2O_3的添加影响了复相陶瓷的致密性、晶粒尺寸、相结构等因素;制备ZrO_2/Al_2O_3复相陶瓷时,最佳工艺参数为20 wt%Al_2O_3和80 wt%ZrO_2。     

Al2O3-ZrO2-Y2O3非晶陶瓷的常温力学性能研究

对Al_2O_3-ZrO_2-Y_2O_3非晶陶瓷块体进行维氏硬度和单轴压缩测试,研究其常温力学性能,并与同组成完全析晶的陶瓷进行了对比。结果表明,Al_2O_3-ZrO_2-Y_2O_3非晶陶瓷的维氏硬度为4. 2GPa±0. 1GPa,而多晶陶瓷的硬度为14. 3GPa±0. 2GPa;非晶陶瓷的硬度明显低于相同组成的多晶陶瓷。在单轴压缩中,非晶陶瓷和多晶陶瓷都发生了脆性断裂,非晶陶瓷压缩强度为210MPa,最大压缩应变为3. 4%,而多晶陶瓷分别为590MPa和1. 8%;相比于完全析晶的Al_2O_3-ZrO_2-Y_2O_3多晶陶瓷,非晶陶瓷表现出低强度、低弹性模量和高应变量的特征。     

Al2O3—TiB2陶瓷刀具材料的研制及其耐磨性能研究

本文研制成功了一种新型陶瓷刀具材料即Al_2O_3-Ti B_2陶瓷刀具材料。文中讨论了该材料的研制方法,力学性能和微观结构特点,并对该材料的磨损行为和磨损机理进行了研究。结果表明:Ti B_2粒子的弥散可以明显提高该材料的耐磨性。加工淬火钢时该材料的抗磨损能力明显优于Al_2O_3-TiC陶瓷刀具材料。Al_2O_3-Ti B_2陶瓷刀具材料的磨损过程主要受粘着、耕犁和微破损机制的控制。     

ZrO2增韧Al2O3陶瓷耐磨性的研究

本文对五种不同含量ZrO_2增韧Al_2O_3陶瓷在磨粒磨损条件下的耐磨性进行了试验研究。试验结果表明,ZrO_2增韧Al_2O_3陶瓷的磨损机理不同于金属,它并不是简单的显微切削机理或犁沟机理,其耐磨性与陶瓷的硬度和弹性模量没有单调的依赖关系,而与材料的断裂韧性和抗弯强度呈现比较一致的趋向关系。扫描电镜对摩擦表面和抗弯断口的对比观测表明,ZrO_2增韧Al_2O_3陶瓷磨损破坏机理属于一次性脆性断裂机理。因此,欲提高该陶瓷的耐磨性应当着重于提高陶瓷的韧性和强度。利用ZrO_2的马氏体相变,可望提高陶瓷的韧性和强度,故可望提高Al_2O_3基陶瓷的耐磨性。     

ZrO2—Al2O3系陶瓷复合材料力学性质

本文研究了ZrO_2-Al_2O_3系统陶瓷复合材料的力学性质,发现有两个最佳区域存在:在Al_2O_3基的陶瓷中,添加第二相ZrO_2颗粒可以使Al_2O_3瓷得到增韧和强化;在ZrO_2基的陶瓷中,添加少量Al_2O_3则可以通过Al_2O_3晶粒的裂纹弯曲和分叉增韧,强化ZrO_2的相变增韧,使ZrO_2瓷的强度和断裂韧性得到进一步的提高。适宜地控制YMSZ(Y_2O_3亚稳定ZrO_2)中Y_2O_3和TZP(四方相氧化锆多晶瓷)中的Al_2O_3量,可以获得高韧性和高强度的ZrO_2-Al_2O_3系陶瓷复合材料。     

Al_2O_3掺杂ZnO基高选择性丙酮气体传感器

采用溶胶-凝胶法,制得Al_2O_3掺杂质量分数分别为0、2.96%、4.96%、6.96%的纳米Al_2O_3-ZnO粉体,样品经700℃退火后对其物相及表面形貌进行表征,测试了不同Al_2O_3掺杂量Al_2O_3-ZnO样品的气敏特性,研究了结晶粒径、掺杂浓度、工作温度等对元件气敏特性的影响;通过对元件进行控温控湿老化实验,研究了老化温度、相对湿度对元件稳定性的影响;并根据气体吸附、脱附模型与半导体能带理论,对气敏机理进行了进一步的讨论。结果表明:Al_2O_3-ZnO对丙酮表现出良好的选择性和稳定性,掺杂为4.96%Al_2O_3的Al_2O_3-ZnO,经700℃退火后,在64℃下,对含量为100×10~(-6)(体积分数)的丙酮的灵敏度为29.24,响应时间和恢复时间均为2 s;丙酮含量低至10×10~(-6)时,灵敏度为3.23,响应时间和恢复时间分别为4 s和7 s。     

Al_2O_3掺杂对Zn-Bi系压敏陶瓷性能的影响

采用Al_2O_3掺杂,通过固相法制备Zn-Bi系压敏陶瓷,研究了不同比例Al_2O_3对ZnO陶瓷的晶粒大小、显微结构以及电性能的影响。研究表明ZBSCCMY配方中掺杂少量Al_2O_3制备得到ZnO压敏陶瓷样品的晶粒大小愈加均匀,显微结构更加致密;陶瓷物相主要由Zn O相、少量的Bi_2O_3相和微量的Zn_7Sb_2O_7尖晶石物相构成;少量Al_2O_3的掺杂改进了晶粒和晶界结构和成分,活化了晶界,降低烧制压敏陶瓷的烧结温度,优化了压敏陶瓷的非线性特性。当掺杂浓度为0.05 wt%、烧结温度为1100℃、保温2 h得到性能良好的压敏陶瓷,其压敏电位梯度可达810 V/mm,非线性系数为68,漏电流为2.4μΑ。     

低温烧结20wt% ZrB_2(ZrO_2)/Al_2O_3复相陶瓷及微观结构表征

在高纯亚微米Al_2O_3粉中添入质量分数为20 wt%的亚微米ZrB_2(ZrO_2)粉体,采用高压干压的成型方法和恒速升温多阶段小保温的烧结方法制备出ZrB_2(ZrO_2)/Al_2O_3复相陶瓷。采用XRD、EDS和SEM对ZrB_2(ZrO_2)粉体和复相陶瓷进行相组成、元素分布和微观结构表征。结果表明:1500℃/8 h烧结制备的20 wt%ZrB_2(ZrO_2)/Al_2O_3复相陶瓷微观结构优良;杂质元素诱导晶粒生长,导致复相陶瓷表面出现Al_2O_3和ZrB_2(ZrO_2)聚集相;引入的ZrB_2(ZrO_2)颗粒使复相陶瓷发生剧烈的穿晶断裂,ZrB_2(ZrO_2)晶粒带动周围的Al_2O_3晶粒发生明显的撕裂,断裂模式为穿晶-沿晶混合断裂。     

静电纺丝制备Al_2O_3陶瓷纳米纤维

本文采用静电纺丝方法,制备出Al_2O_3陶瓷纳米纤维。做为结构陶瓷,Al_2O_3陶瓷纳米纤维具有潜在的应用价值。     

掺杂对Al_2O_3陶瓷微波介电损耗影响的研究进展

综述了掺杂对Al_2O_3陶瓷微波介电损耗影响的研究进展,概括介绍了Al_2O_3陶瓷微波介电损耗的影响因素,重点介绍了不同价态的掺杂助剂对Al_2O_3陶瓷微波介电损耗的影响,最后对这一研究方向的未来发展做了一些展望,希望对于研究改善Al_2O_3陶瓷微波介电损耗提供有益的参考。     

Synthesis of TiB2 by High-Dose Implantation of Boron Ions in Titanium Films

Boron ions were implanted at room temperature in Ti films at a high dose (7.1 × 10^I7 and 2.3 × 10¹⁸ ions/cm²), The formation of TiB₂ films was confirmed by X-ray diffraction. Boron concentration profiles in implanted films were studied by secondary-ion mass spectrometry.     

Chemical States of Implanted Aluminum Ions in Silica and Silicon Ions in Alumina

Aluminum and silicon ions have been implanted in silica glass and α-alumina single crystal, respectively, to doses ranging from 1 × 10¹⁵ to 1 × 10¹⁷ ions·cm^-2. The chemical states of these implanted ions have been studied by X-ray fluorescence spectroscopy. It is found that the implanted aluminum atoms are coordinated only by oxygen atoms, irrespective of implantation dose. On the other hand, the implanted silicon atoms are coordinated only by oxygen atoms at low doses and by both oxygen and silicon atoms at high doses. Although the chemical state of the aluminum atoms is unchanged by heat treatment, that of the silicon atoms is changed toward a less positively charged state. It is inferred that the chemical states of the implanted atoms are controlled by the transport process, although these tend to obey the thermodynamic stability.     

Chemistry and Structure of Beta Silicon Carbide Implanted with High-Dose Aluminum

Single-crystal β-SiC was implanted with aluminum to 3.90 × 10¹⁷ ions/cm² at 168 keV at 773 K. The resultant compositional and structural characteristics were studied by Rutherford backscattering spectrometry, Auger electron spectroscopy, X-ray photoelectron spectroscopy, and cross-sectional transmission electron microscopy. No aluminum redistribution was observed during implantation. The Si-to-C ratio exhibited a negative deviation from unity in the implanted region. The shift in the photoelectron binding energies indicated the formation of aluminum carbide. The studies by electron microscopy showed that the implanted region consists of slightly misoriented β-SiC crystals and textured crystalline aluminum carbide precipitates     

水溶液中纳米二氧化钛光催化降解甲基橙的影响因素

用沸腾回流直接水解法制备了粒径为25～35 nm纯锐钛矿型纳米二氧化钛(TiO2).用X射线衍射和透射电镜表征材料的结构与形貌.用该催化剂催化降解甲基橙,研究了催化剂用量、甲基橙的起始浓度、溶液pH值、光强度、溶液中添加金属离子的影响.结果表明:在较强紫外光照射下,当甲基橙的起始浓度为0.02 g/L,TiO2用量为1.0g/L,光催化效率最高.酸性条件有利于光催化降解甲基橙.掺加Fe3 或Zn2 的光催化效率显著增加.掺加Mn2 或Ca2对光催化活性没有影响.在紫外光区域(366 nm),样品对催化降解水溶液中甲基橙的活性较高.     

Complexation Equilibrium Constants of Poly(vinyl alcohol)-Borax Dilute Aqueous Solutions – Consideration of Electrostatic Charge Repulsion and Free Ions Charge Shielding Effect

Equilibrium dialysis experiments of dilute poly(vinyl alcohol) (PVA) in borax aqueous solution (PVA concentration was 2 g/L and borax concentration ranged from 0.0 M to 0.05 M) were carried out to determine the concentration of free borate ions in equilibrium with the PVA-borate complex at 25°C, and hence the amount of borate bound to PVA. The binding isotherm of borate ion on PVA molecules was investigated. The concentration of borate ion bound on PVA was found to increase with increasing borax concentration and reached an asymptote at high borax concentrations. The complexation equilibrium constant between borate and PVA diol was found to decrease initially then increases and finally decreases with increasing borax concentration while PVA concentration was fixed in a constant value. The equlibrium constant of free borate ion with borate-PVA diol complex was a balance result of excluded volume of PVA molecular chains, electrostatic charge repulsion between free borate ions and borate-PVA diol complexes, and electro-shielding of free Na⁺ ions on negatively charged PVA-borate complexes. In this study, the electrostatic charge repulsion between free borate ions and borate-PVA diol complex ions and free Na⁺ ions shielding effect are considered in the estimation of equilibrium constants of PVA diol-borate complexation. A fixed value of equilibrium constant is obtained with increasing borax concentration while borax concentraion is below a critical concentration [borax]_crt. As borax cocentration is higher than [borax]_crt, a lots of PVA diols form complexes with borate ions and a high shielding of free Na⁺ ions on negatively charged borate-PVA diol complexes causes the PVA-borate complexes to behave like neutral polymers. Few free PVA diol binding sites are available for reaction with free borate ions while borax concentration is higher than [borax]_crt resulting in a decrease in equilibrium constant with increasing borax concentration.     

高硅氧发光玻璃的制备及其荧光性能

石英玻璃具有低膨胀、耐热冲击、高机械强度和高化学隐定性等优点,是稀土和过渡金属发光离子掺杂的优选的基质材料。但发光离子在石英玻璃中容易自发形成团簇,产生浓度淬灭效应,介绍一种用二氧化硅质量分数超过95%的纳米微孔玻璃来抑制发光离子团簇的自发形成的新方法,以制备高发光强度的石英破璃和激光玻璃。该方法是将发光离子浸入微孔玻璃中并在适当气氛中烧结,目前已经制得多种颜色、量子效率接近于1的强发光玻璃,真空紫外光激发发光玻璃,高铒离子掺杂的高硅氧玻璃,还获得了新颖的低膨胀、耐高温的掺钕高硅氧激光玻璃和掺铋红外宽带发光玻璃用这种方法还容易进行多种发光活性离子掺杂,实现不同离子间的能量转换,提高发光强度和改变激发光的波长范围。这种新方法有望扩大石英发光玻璃的应用范围。     

X-RAY STUDY OF POTASH-SILICA GLASS*

X-ray diffraction studies have been made of two samples of potash-silica glass whose composition is 20.9% and 29.1% of K₂O by weight. A Fourier analysis of the intensity curves indicates a structure similar to that found in soda-silica glass. Each silicon is tetrahedrally bonded to 4 oxygen ions, with each oxygen bonded either to 1 or 2 silicons. The K⁺ potassium ions are situated in holes in the silicon-oxygen network with an average of about 10 oxygen neighbors.     

载铜蒙脱石对水产病原菌的抗菌活性及其机理

通过阳离子交换反应,合成载铜蒙脱石,并研究它对水产病原菌的抗菌效果。X射线衍射分析显示：载铜反应前后,蒙脱石的（001）面网间距从原先的1．544nm增加到了1．588nm,表明铜是以水合阳离子或复合阳离子形式进入蒙脱石晶格层间位置。体外抗菌试验表明：蒙脱石未显抗菌活性,而载铜蒙脱石对所试水产病原菌均有很强的抑制和杀灭作用,它对嗜水气单胞菌、荧光假单胞菌、副溶血弧菌的最小抑菌浓度分别为150,150,75mg／L,最小杀菌浓度分别为600,600,300mg／L。载铜蒙脱石的抗菌能力是两方面因素的协同作用：一方面是其表面剩余正电荷能从水介质中大量吸附表面带负电荷的细菌;另一方面是矿物释放的铜离子对细菌的抑制和杀灭作用。     

High dose N ion implantation effects on surface treated UNCD films

Ion implantation is commonly used to modify the surface or near-surface properties of materials. In this work, plasma treated ultrananocrystalline diamond (UNCD) films were implanted using 100 and 200 keV high dose (10¹⁶ ions/cm²) nitrogen ions and annealed. Detailed studies have been carried out to reveal the structural and chemical states of the surface treated UNCD films before implantation, as-implanted, and after annealing by using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and electron field emission (EFE) measurements. The high dose N ion implantation induced the formation of amorphous phase, which are converted into graphitic phase after annealing, and improved the field emission properties of UNCD films. The improved field emission is attributed to the surface charge transfer doping mechanism.     

Synthesis and spectroscopic analysis of Sm3+ doped CeO2 ceramic powders for the application of white LEDs

Orange-red light-emitting Sm³⁺-doped cerium oxide (CeO₂) ceramic powder with various concentrations of Sm³⁺ ions was prepared through a sol-gel process. X-ray diffraction and Rietveld analysis confirmed the formation of a purely cubic structure with a space group of $\mathit{Fm}\stackrel{?}{3}m$. The lattice parameters and unit cell volumes of the CeO₂:Sm³⁺ powder increased with the concentration of Sm³⁺ ions. The energy-dispersive X-ray spectra and corresponding mapping images confirmed the elemental composition and adequate dispersion of all elements in the CeO₂:Sm³⁺ powder. A broad excitation band at approximately 365?nm was observed in the excitation spectra of CeO₂:Sm³⁺ phosphors owing to the charge transfer transition from O 2p to Ce 4f orbitals. The Sm³⁺ doped CeO₂ phosphors emitted sharp luminescence with a main peak at 615?nm under excitation at 360?nm. The spectral analysis revealed that the CeO₂:Sm³⁺ phosphors exhibited strong orange-red emission. Concentration quenching was observed in the CeO₂:Sm³⁺ phosphors with 0.5?mol% of critical concentration of Sm³⁺ ions due to dipole dipole interaction of two nearest Sm³⁺ ions. The quantum efficiency was observed as high as 58%. The thermal stability of the present materials was estimated with the evaluation of activation energy as 0.31?eV. The broad excitation band and sharp orange–red emission indicated the potential use of CeO₂:Sm³⁺ phosphors for white light-emitting diodes.