Spray drying of sol-gel precursors for the manufacturing of PZT powders

The preparation of fine PZT-powders via spray drying is described. The precursor solution was composed of Zr- and Ti-n-propoxide and lead acetate trihydrate or basic lead acetate. The hydrolysis and condensation reactions were controlled by the addition of acetylacetone as chelating agent.Depending on water content and solvent in the initial sols, spray dried micronsized gel powders with different morphologies and hydrolytic reactivities were obtained.     

Cr4＋：Nd3＋：YAG自调Q陶瓷激光器输出特性的计算分析

利用Siegman速率方程组，采用自适应变步长龙格一库塔数值方法，对Cr4＋：Nd3＋：YAG自调Q陶瓷激光器的输出特性进行了数值模拟，详细讨论了Nd3＋：YAG陶瓷厚度以及Cr^4＋离子浓度对陶瓷激光器的重复频率、峰值功率、单脉冲能量、脉冲宽度、以及平均输出功率等输出特性的影响。研究结果表明，随着参与作用的Nd^3＋离子数的增加，输出激光脉冲重复频率和平均输出功率均会明显提高；随着Cr^4＋离子浓度的升高，输出激光脉冲重复频率和平均输出功率则会明显下降。     

Er3+/Yb3+共掺的氧化镧钇透明陶瓷的光谱性能研究

采用传统无压烧结工艺制备了Yb³⁺/Er³⁺共掺的氧化镧钇透明陶瓷并对其光谱性能进行了研究.样品具有较大的吸收和发射截面.La₂O₃的添加使样品的荧光寿命(τ_s)与玻璃接近，当Yb³⁺和Er³⁺的掺杂量分别为5at%和0.5at%时，测得τ_s=9.65　ms.这种荧光寿命长、发射截面大和线宽窄的特性有利于微型、可集成化和大功率激光输出的实现. 关键词： 透明陶瓷 吸收光谱 发射光谱 荧光寿命     

Simultaneous Electrodeposition of Reduced Graphene Quantum Dots/Copper Oxide Nanocomposite on the Surface of Carbon Ceramic Electrode for the Electroanalysis of Adenine and Guanine

In this study, simultaneous deposition of copper oxide and electro-reduced graphene quantum dots (ErGQDs) on the surface of carbon ceramic electrode (CCE) was reported. The prepared ErGQDs-CuO/CCE was carefully characterized with Fourier transform infrared spectroscopy, X-ray diffraction, fluorescence spectroscopy, scanning electron microscopy and electrochemical techniques in details. According to scan rate studies in hexacyanoferrate, a remarkable increase in the surface coverage in the presence of ErGQDs was achieved. According to square wave voltammetry results, limit of detection, linear range and sensitivity of the developed biosensor for the simultaneous measurement of Adenine (A) and Guanine (G) were obtained to be 0.041 and 0.111 μM, 0.1–13 μM and 0.25–23 μM, and 4.261 and 1.311 μA μM cm⁻² respectively.     

Processes occurring during the sintering of porous ceramic materials by TG/DSC

Ceramic blocks with high porosity and low heat conductivity are effective tools to improve the indoor comfort level and also to reduce energy consumption. The main objective of this study was focused on the development of the porous ceramic blocks processing with different pore forming agents by adapting a German technology to the Brazilian environmental conditions. In this process, the clay mixtures are homogenized before sampling as the sintering of porous ceramic materials was about 900–1100°C. TG/DTG, DSC and coupled MS experiments were carried. The formed products have low apparent density, high porosity and reasonable mechanical strength with a good heat and acoustic insulation properties.     

高速车削300M超高强度钢时的Al2O3 基陶瓷刀具磨损机理研究

使用Al2O3基陶瓷刀具对300M超高强度钢进行了干切削试验,采用电子扫描显微镜（SEM）观察刀具的磨损形貌,并通过能谱分析仪（EDS）测量了陶瓷刀具磨损微区的各元素含量,分析了陶瓷刀具的主要磨损机理.结果表明：陶瓷刀具磨损的主要机理为粘结磨损、磨粒磨损和氧化磨损.粘结磨损主要发生在前刀面上,且受刀具材料和工件材料接触点应力状态的影响.刀具前、后刀面的磨损边缘区易发生氧化磨损.     

Release of charges under external fields of PbLa（Zr,Sn,Ti）O3 ceramic

This paper investigates the pyroelectric of poled antiferroelectric (AFE) ceramic Pb 0.97 La 0.02 (Zr 0.69 Sn 0.196 Ti 0.114)O 3 and its remnant polarization dependence of hydrostatic pressure.The results show that the bound charges of poled sample can be released in short time by temperature field or pressure field.The released charge abruptly forms a large pulse current.The phenomena of released charge under external fields result in the ferroelectric-AFE phase transition induced by temperature or hydrostatic pressure.     

Preparation of Activated Carbon Functional Ceramics From Coal Pitch

The influences of different impregnation temperatures,pre-oxidation,carbonization temperatures and activation conditions on the iodine value and carbon deviations was discussed.SEM,EDS,and BET techniques were used to investigate the microstructures and properties of materials.Results showed that activated carbon functional ceramic exhibited excellent comprehensive properties when porous ceramics adsorbed the coal pitch at 150 ℃ for 0.5 h,oxidized at 420 ℃ for 1.0 h,and carbonizated at 700 ℃ for 1.0 h and then activated by using KOH(20wt%) as agent at 800 ℃ for 1.0 h,as confirmed by the high iodine value(162.6 mg/g) and high specific surface area(83.5 m2/g).     

Synthesis and characterization of NixMg1−xAl2O4 nano ceramic pigments via a combustion route

MgAl₂O₄ was successfully used as a crystalline host network for the synthesis of nickel-based nano cyan refractory ceramic pigments. Different compositions of Ni_xMg_1−xAl₂O₄ (0.1 ? x ? 0.8) powders have been prepared by using a low temperature combustion reaction (LTCR) of the corresponding metal nitrates with urea (U) as a fuel at 300 °C in an open air furnace. The as-synthesized samples were characterized by thermal analysis (TG-DTG/DTA), X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). UV-Vis and diffuse reflectance spectroscopy (DRS) using CIE- L^∗a^∗b^∗ parameters methods have been used for color measurements. The results show that the Ni_xMg_1−xAl₂O₄ samples are the crystalline phase with a particle size of 8.85-43.66 nm in the temperature range 500-1200 °C. The density, particle size, shape and color are determined for all the prepared samples with different calcination times and temperatures.     

AgO修饰硅藻土基多孔陶瓷复合材料的制备及热分解非等温动力学

采用化学氧化法,以过硫酸钾为氧化剂制备了AgO修饰硅藻土基多孔陶瓷复合材料,用XRD、XPS、压汞仪对制备的复合材料进行表征,借助热重法和线性升温理论对复合材料的热分解过程和热分解动力学进行研究。结果表明,AgO修饰硅藻土基多孔陶瓷复合材料具有晶体结构,主要由正方晶系方石英和单斜晶系AgO组成;复合材料平均孔直径为3.862 μm,中值孔直径为0.354 μm,表观密度为1.794 g·mL^-1,孔隙率为57.985%;复合材料中AgO的分解分两步,在158 ℃开始分解成Ag₂O,更高温度时进一步分解成Ag;AgO分解服从核生成和核成长机理,其表观活化能为136.94 kJ·mol^-1,反应频率因子为2.48×10¹⁴ s^-1。同参比AgO粉末相比,复合材料中AgO的热稳定性提高。