复合助剂CaF2-Y2O3对AlN-BN复合陶瓷显微结构和热导性能的影响

用热压法制备了AlN-BN复合陶瓷材料,添加CaF2和Y2Os为烧结助剂,研究了烧结助剂的种类、含量以及不同保温时间对复合材料的物相组成、显微结构和热导率的影响.添加复合助剂(1～3)wt%Y2O3-3wt?F2的试样在保温过程中晶界相挥发明显,净化了复合材料的晶界,减少了复合材料中AlN晶格缺陷,获得了纯净的AlN-BN复合陶瓷.与单独添加CaF2助剂的试样相比,添加复合助剂的试样的介电性能没有明显下降,随复合助剂(1～3)wt%Y2O3-3wt?F2中Y2O3含量的增加,AlN-BN复合陶瓷的热导率显著提高.添加复合助剂3wt%Y2Os-3wt?F2的试样在1850℃下保温3h获得的热导率为132.7W·m-1·K-1.     

SnO2气敏元件烧结工艺与电性能关系的复阻抗分析

采用平面丝网印刷工艺制备ＳｎＯ２厚膜气敏试样,分别在不同烧结温度和保温时间下于空气中烧成,测量试样的灵敏度和稳定性,并通过复阻抗分析方法,研究了ＳｎＯ２气敏元件烧结工艺和电性能的关系,探讨烧结工艺对敏感材料微结构的影响,结果表明,适当调整结工艺参数可以使元件既有较高的气体灵敏度又有良好的长期稳定性,复阻抗分析表明,随保温时间延长,试样的电阻－电工线半圆弧的弥散角逐渐减小至零,说明适当延长保温时间使     

SnO2-CuO纳米粉体的制备研究

以无机盐为原料,氨水为沉淀剂采用共沉淀法合成了SnO2-CuO纳米粉体.探讨了共沉淀法制备SnO2-CuO的最佳PH值范围,研究了煅烧温度和保温时间对纳米粒子尺寸的影响.结果表明,制备SnO2-CuO的最佳PH值范围是7.60～9.24.随着煅烧温度升高和保温时间延长,纳米粒子逐渐长大.其中,温度作用更为明显.     

硼铝酸锶长余辉发光玻璃的制备及发光性能研究

采用一步合成法制备了硼铝酸锶长余辉发光玻璃,系统研究了热处理温度、热处理时间、冷却制度等条件对长余辉玻璃发光性能的影响.结果表明:在N2气氛下,热处理温度为1300℃、保温时间为3h、试样随炉冷却的制备工艺可得到发光性能优良的长余辉玻璃,该玻璃的长余辉特性源自在玻璃基体中均匀分布的Eu2 、Dy3 共掺杂的SrAl2O4微晶.     

SnO2气敏元件烧结工艺与电性能关系的复阻抗分析

采用平面丝网印刷工艺制备SnO2厚膜气敏试样,分别在不同烧结温度和保温时间下于空气中烧成,测量试样的灵敏度和稳定性,并通过复阻抗分析方法,研究SnO2气敏元件烧结工艺和电性能的关系,探讨烧结工艺对敏感材料微结构的影响．结果表明,适当调整烧结工艺参数可以使元件既有较高的气体灵敏度又有良好的长期稳定性;复阻抗分析表明, 随保温时间延长, 试样的电阻--电抗曲线半圆弧的弥散角逐渐减小至零, 说明适当延长保温时间使晶粒间界处的弛豫时间分布趋向一致,晶界处晶粒的接触形态以及开口气孔和缺陷的分布等更趋均一和稳定．     

落锤试验试样的冷却方式和冷却效果相关性分析

由于在API，ASTM以及国标等相关标准中，对试样在气体介质中的保温时间等无具体规定，在一定程度上限制了冷却介质的选用范围。通过对试样在冷却中物理过程的分析和计算，给出了气体介质冷却条件下落锤试样的保温时间，使气体介质条件下的冷却有初步的依据。同时，给出了试样温度测试的关键之处。     

基于RAINBOW结构的反铁电陶瓷研究

还原制备了基于RAINBOW结构的反铁电陶瓷．给出了试样还原层微观结构及其还原规律;测试了试样的驱动性能并讨论了影响因素。研究结果表明：反铁电陶瓷还原性能较好．理想的还原条件为870℃保温2～3h;RAINBOW试样在相对较低的电场强度下即可发生反铁电-铁电相变．并得到很大的轴向位移(约190／μm);承载方向对试样的驱动性能具有决定性的影响。     

高温氮化法制备z=3的β-Sialon材料

以Al2O3粉、Al粉和Si粉为主要原料,经高温氮化反应制备β-Sialon材料。研究了TiO2烧结助剂、烧结温度和保温时间对制备β-Sialon材料的影响。结果表明,添加TiO2作烧结助剂,在N2气氛中于1500℃保温5h后烧成的试样耐压强度达到76.94MPa、体积密度达到2.86g/cm3;试样以β-Sialon为主晶相,晶粒发育较好,呈棱柱状,直径约为1μm,长度约为2μm,且分布比较均匀,提高了材料的强度。     

不同形态低维ZnO晶须的制备及表征

采用热蒸发法制备出高纯度线状、棒状、多脚状的不同形态ZnO晶须材料.研究了氮气流量、反应温度、反应时间(保温时间)等因素对产物规整率、转化率及长径比的影响.利用SEM对产物形态进行表征.结果表明:采用不同条件的热蒸发法可制备出高质量不同形态的ZnO晶须.反应过程中锌蒸压气对产物形态的影响较大.以陈化锌粉为原料,在1000～1100℃保温较短的时间,并始终以0.2m3/h通入高纯氮气,得到棒状晶须;保温时间较长,得到线状晶须.而多脚状ZnO晶须则是在通入高纯氮气时间较短的情况下得到的.     

热处理工艺参数对超高强度钢性能的影响

目的 研究热处理工艺参数对BR1500HS超高强度钢的微观组织、拉伸断口以及力学性能的影响,并且研究保温时间和加热温度对淬火后的硬度、抗拉强度、微观组织以及伸长率等的影响规律.方法 将BR1500HS加热到一定温度,并保温使得试样充分奥氏体化,随后在水中冷却,并测试冷却后的材料力学性能.此外,将克立金模型引入用于近似加热温度、保温时间与硬度、抗拉强度、伸长率之间的关系,用NSGA-Ⅱ多目标遗传算法优化代理模型.结果 当保温时间一定时,硬度随着加热时间的增加先增加后减小、抗拉强度先增加后减小最后趋于平稳;当加热温度一定时,硬度随保温时间的增加先增加后减小.当加热温度不同时,抗拉强度随保温时间的变化规律不同;当加热温度在950℃以下时,随着保温时间的增加而增加;当加热温度在950～1000℃时,随着保温时间的增加先增加后减小.结论 采用实验和代理模型的优化结果的误差较小,对BR1500HS超高强度钢的热处理工艺具有一定的指导作用.     

La0.5Y0.5Ni4.8Mn0.1Al0.1和La0.5Y0.5Ni4.8Al0.2合金的储氢性能研究

针对两种新型稀土型储氢合金La0.5Y0.5Ni4.8Mn0.1Al0.1和La0.5Y0.5Ni4.8Al0.2的储氢特性进行研究分析。实验表明,相同温度下,La0.5Y0.5Ni4.8Mn0.1Al0.1和La0.5Y0.5Ni4.8Al0.2合金的PCT曲线基本重合,且都具有优良的吸氢动力学性能;相比之下,后者的滞后系数要小于前者,吸氢量较大,吸氢速率也较快,故其储氢性能较优。300次吸放氢循环实验结果表明,La0.5Y0.5Ni4.8Al0.2合金的吸氢动力学性能虽然略有下降,但抗粉化性能较好。     

Dy0.6Tb0.3Pr0.1(Fe0.95Mn0.05)x取向晶体的结构与磁致伸缩

采用Ｃｚｏｃｈｒａｌｓｋｉ方法生长了Ｄｙ０．６Ｔｂ０．３Ｐｒ０．１（Ｆｅ０．９５Ｍｎ０．０５）ｘ（１．８５≤ｘ≤１．９５）取向合金。所有合金主相为立方Ｌａｖｅｓ相结构,择优取向不完整择优取向的方向与Ｘ的大小有关。研究了沿着这些样品的生长方向的磁致伸缩性能以及磁致伸缩性能与压力之间的关系。     

Thermal Stability of Amorphous Hydride Mg_(50)Ni_(50)H_(54) and Mg_(30)Ni_(70)H_(45)

The thermal stability of amorphous ternary hydrides Mg_(50)Ni_(50)H_(54) and Mg_(30)Ni_(70)H_(45) and their corre-sponding amorphous binary alloys Mg_(50)Ni_(50) and Mg_(30)Ni_(70) were studied with X-ray diffraction(XRD) and differential scanning calorimetry(DSC). Samples of the amorphous alloys were preparedby mechanical alloying and the amorphous hydrides were obtained by charging the alloys with gas-eous hydrogen at 3.0 MPa and 423 K. It was found that the amorphous hydrides released most oftheir hydrogen before the crystallization of the essentially hydrogen depleted amorphous alloy. Thecrystallization temperature of amorphous Mg_(50)Ni_(50)H_(54) elevated and that of amorphousMg_(30)Ni_(70)H_(45) did not change in relation to the original binary amorphous alloy. This is very excep-tional for amorphous hydrides. The reason for the effects of hydrogen absorption/desorption on thecrystallization of amorphous alloys was discussed.     

Zr65Al7.5Ni10Cu15Co2.5合金的玻璃转变温度

根据Ｚｒ６５Ａｌ７。５Ｎｉ１０Ｃｕ１５Ｃｏ２。５合金的纳米晶，晶体，液体和玻璃比热的测量结果，研究了合金的玻璃转变温度与全金的热力学函数，动力学参数以及加热速度的关系。结果表明，非晶态合金玻璃转变所需转变激活能很小，玻璃转变温度实际上是由于加热速度引起的不同状态的玻璃与液体的热力学平衡温度。     

Natural Passivity of Amorphous Fe_(40)Ni_(40)P_(14)B_6 and Fe_(54.6)Ni_(38)Si_(4.1)B_(2.3)V_1 Alloys

The natural passive films forrned on Fe_(40)Ni_(40)P_(14)B_6 and Fe_(54.6)Ni_(38)Si_(4.1)B_(2.3)V_1 amorphous alloys long-term exposed in air have been studied by X-ray photoelectron spectroscopy (XPS) and Auger electron (including Ar+ ion depth profiling) spectroscopy (AES). The following aspects have been investigated: (1) chemical states of the elements in the films. binding energies and the chemical shifts measured by XPSf (2) structure and composition of the films fand (3) thickness of the passive films determined by AES depth profiling and XPS analysis.     

Acousto-optic interaction in alpha-BaB(2)O(4)and Li(2)B(4)O(7) crystals

Experimental studies and analysis of acousto-optic diffraction in alpha-BaB(2)O(4) and Li(2)B(4)O(7) crystals are given. Ultrasonic wave velocity, elastic compliance and stiffness coefficients, and piezo-optic and photoelastic coefficients of alpha-BaB(2)O(4) and Li(2)B(4)O(7) crystals are determined. The acousto-optic figure of merit has been estimated for different possible geometries of acousto-optic interaction. It is shown that the acousto-optic figures of merit for alpha-BaB(2)O(4) crystals reach the value M(2)=(270 +/- 70) x 10(-15) s(3)/kg for the case of interaction with the slowest ultrasonic wave. The directions of propagation and polarization of those acoustic waves are obtained on the basis of construction of acoustic slowness surfaces. The acousto-optic diffraction is experimentally studied for alpha-BaB(2)O(4) and Li(2)B(4)O(7) crystals.     

Nanomechanical characterization of one-step combustion-synthesized Al(4)B(2)O(9) and Al(18)B(4)O(33) nanowires

Two kinds of aluminum borate nanowires, Al(4)B(2)O(9) and Al(18)B(4)O(33), were successfully synthesized by a one-step combustion method through control of the Al:B atomic ratio and synthesis temperature. Both nanowires are single crystalline but have distinguishing growth habits. Nanoindentation tests were performed directly on individual nanowires to reveal their mechanical properties. A 70% reduction in elastic modulus was found in Al(18)B(4)O(33) nanowires compared with their bulk counterpart. Al(18)B(4)O(33) nanowires exhibited higher hardness and elastic modulus than Al(4)B(2)O(9) nanowires.     

Plasma surface treatments of poly(l-lactic acid) (PLLA) and poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV)

The surfaces of poly(l-lactic acid) (PLLA) and poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) were modified by oxygen and nitrogen plasma treatments. The physical and chemical surface characteristics were evaluated by contact angle tests, scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). The plasma treatments caused an increase in both contact angle and roughening, altered the surface morphology, inserted polar groups, and, consequently, enhanced the hydrophilicity for both PLLA and PHBV polymers.     

An SANS Study of Decomposition Kinetics in Amorphous Cu_(12.5)Ni_(10)Zr_(41)Ti_(14)Be_(22.5)

Phase decomposition in amorphous Cu12.5Ni10Zr411Ti14Be22.5 alloy as annealed in the super-cooled liquid range was studied by applying small angle neutron scattering (SANS). As annealed between 600 K and 700 K, the alloy was observed to decompose into two new amorphous phases,with the second phase precipitates embedded in the matrix of the first. Long time annealing of the alloy results in crystallization in addition to evolution of the decomposed microstructure.The kinetic diagram of the decomposition and crystallization for this alloy is given. The second phase precipitates have several nanometers in size and occupy a quite low volume fraction. The decomposition of the supercooled liquid in overall temperature range exhibits the features of spinodal reaction.