Y.Ma
,
Y.Hao
,
S.Z.Kou
,
X.N.Lu
金属学报(英文版)
Based on the experiment and the thermodynamics analysis for CuO/Al system, it is founded that the compounding reaction of CuO/Al under low temperature is available. The general equation of adiabatic temperature of the system is set up, and the influence of resultant concentration and temperature on adiabatic temperature is theoretically analyzed. The values of heat effect of CuO/Al system under different temperature are also caculated.
关键词:
composite in situ
,
null
,
null
Pengfei Zhang Litong Zhang Xiaowei Yin
材料科学技术（英文）
To improve the corrosion resistance of porous Si3N4 used in the high temperature environments, which contain water vapor and volatile species, porous Si3N4-Lu2Si2O7 composite ceramics were fabricated by a process of oxidation bonding and pressureless sintering in flowing N2 atmosphere at the temperatures lower than 1550°C. The pores in ceramics were formed by removing the pore-forming agent (phenolic resin). SiO2 derived by the oxidation of Si3N4 at 1250°C in air reacted with Lu2O3 at various sintering temperatures, leading to the formation of Lu2Si2O7 with excellent oxidation and corrosion resistance. The phase composition, microstructure, and mechanical properties of the porous ceramics depended on the sintering temperatures. Si3N4-Lu2Si2O7 composite ceramics with the porosity of 52% and the pore size of 0.2μm were obtained by oxidation bonding at 1250°C for 1 h and pressureless sintering at 1550°C for 2 h using 4 wt pct Lu2O3 additive.
关键词:
Porous ceramics
,
氮化硅
,
焦硅酸镥
,
无压烧结
魏绍娟
,
邾强强
,
季巍巍
,
郝绿原
,
徐鑫
中国稀土学报
doi:10.11785/S1000-4343.20160502
采用高温固相反应法合成系列Lu2.92 Ce0.08Al5-ySiyO12-yNy(LuAG-CSN)荧光粉,研究了利用CeSi3 N5实现Si-N在Lu3Al5O12∶Ce(Lu-AG)荧光粉中的均匀有序掺杂,以优化和调控荧光粉的光致发光特性.首先合成了高纯度的CeSi3N5原料,然后采用CeO2和CeSi3 N5的组合实现优化Ce浓度(Lu∶ Ce=2.92∶0.08)下的Si-N可控均匀掺杂.从荧光粉的激发发射光谱,发现适量的Si-N共掺可以明显增强荧光粉的荧光性能,而且使发射光谱宽化,450 nm蓝光激发的发射峰可从524.2 nm连续调节到556.4 nm,从而能有效优化白光LED的发光效率和调节色坐标,同时发现,所获LuAG荧光粉具有一定的余辉性能.而利用Si3N4作起始原料的掺杂虽然也可以使发射波长宽化,但会显著减低发射强度,且几乎没有余辉特性.
关键词:
荧光粉
,
LuAG
,
荧光性能
,
Si-N
,
余辉性能
于俊杰
,
郭伟明
,
林华泰
人工晶体学报
研究了二元助剂Al2O3-Re2O3(Re=La,Nd,Y,Lu)对无压烧结Si3N4陶瓷的相对密度、显微结构及力学性能的影响.结果表明:经1800℃无压烧结后,Si3N4陶瓷试样的相对密度均达到97％以上;以Al2O3-Lu2O3为烧结助剂的Si3N4陶瓷试样具有最高的维氏硬度和抗弯强度,分别为15.2±0.18 GPa和920±5 MPa.
关键词:
Si3N4陶瓷
,
无压烧结
,
相对密度
,
显微结构
,
力学性能
蒋强国
,
古尚贤
,
刘伟
,
周茂鹏
,
郭伟明
,
伍尚华
人工晶体学报
利用球盘式摩擦磨损试验机,研究了含MgO-Lu2O3-Re2O3(La2O3,Sm2O3,Gd2O3,Er2O3)三元添加剂Si3 N4陶瓷的摩擦磨损性能.结果表明:机械磨损和摩擦化学反应为主要磨损机理.在三元添加剂中,随着第二稀土离子Re3+半径的增加,粘附层增加,Si3N4摩擦系数降低.基于横向断裂理论模型,Si3N4陶瓷单位磨损率随着1/(KB1/2H5/8)的增加而增加,其中含有第二相Lu4Si2N2O7的样品SN-LuSm和SN-LuEr优于此线性关系,表现出更好的抗磨损性能.
关键词:
Si3N4
,
三元添加剂
,
摩擦磨损
,
横向断裂模型
郭伟明
,
吴利翔
,
马提
,
游洋
,
伍尚华
,
林华泰
人工晶体学报
研究了MgO-Al2O3-Re2O3(Re=Lu,Y)三元烧结助剂体系对无压烧结Si3N4陶瓷显微结构和力学性能的影响.研究结果表明,添加MgO-Al2O3-Lu2O3三元助剂制备的Si3N4陶瓷显微结构具有明显的双峰分布,晶粒较粗化,致密度、硬度、弯曲强度、断裂韧性分别为96.4％、14.59 GPa、964 MPa、7.64 MPa·m1/2;而添加MgO-Al2O3-Y2O3三元助剂制备的Si3N4陶瓷具有细化的显微结构,致密度、硬度、弯曲强度、断裂韧性分别为99.9％、15.29 GPa、758 MPa、6.60 MPa·m1/2.
关键词:
Si3N4陶瓷
,
无压烧结
,
显微结构
,
力学性能
,
双峰分布
丁栋舟
,
陆晟
,
潘尚可
,
张卫东
,
王广东
,
任国浩
无机材料学报
doi:10.3724/SP.J.1077.2008.00434
采用提拉法制备了LuxY1-xAlO3:Ce晶体样品, 通过XRD物相分析和成分分析, 并结合Lu2O 3-Al2O3二元体系相图以及LuxY1-x AlO3:Ce结构稳定性方面的分析与讨论, 结果表明: 随着熔体中Lu元素含量的增加, 熔体分层加剧, 析晶LuxY1-xAlO3:Ce相的熔体组成区间将向富Lu一侧偏移, 这使得晶体上部易伴生(Lu,Y)3Al5O12:Ce相; 而随着Lu元素含量的提高, LuxY1-xAlO3:Ce晶体的热稳定性降低, 氧空位的存在则使晶体的热稳定性进一步降低, 在接种过程中籽晶表面易发生相分解反应生成(Lu,Y)3 Al5O12:Ce和(Lu,Y) 4 Al2O9:Ce, 籽晶表面相分解产物(Lu,Y)3Al5O12:Ce提供了诱导析晶(Lu,Y)3Al5O12 :Ce相所需的晶核, 这使得晶体的外
表面处易伴生(Lu,Y)3Al5O12:Ce相. 调整配料组成使 n(Lu,Y)2O3 ): n (Al2O3)=1.17～1.00, 加大熔体内部和固液界面处的温度梯度以改善熔体对流、抑制熔体分层以及籽晶表面处的相分解等有助于高Lu元素含量LuxY1-xAlO3 :Ce晶体的获得.
关键词:
铝酸钇镥晶体
,
perovskite
,
garnet
,
accompany
Journal of Materials Science
Mn(3+x) Ga(1-x) N compounds with x = 0.0 and 0.1 were prepared by re-sintering Mn(2)N(0.86), Ga bulk and Mn powders. These compounds are deduced to be the N-deficiency ones. In Mn(3)GaN, a step-like magnetic transition, from frustrated antiferromagnetism to paramagnetism with increasing temperature, occurs at 370 K, while the same magnetic transition of Mn(3.1)Ga(0.9)N is far above 380 K. The enhanced magnetization of Mn(3)GaN at low temperatures is ascribed to the fast lowering of antiferromagnetism. The electrical resistivity of Mn(3)GaN exhibits a typically metallic conducting behavior with a positive magnetoresistance of 4-7%.
关键词:
perovskites;heat;manganese;mn3znn;phase
Quan Li
材料科学技术（英文）
Porous silicon nitride ceramics (Si3N4) were fabricated by pressureless sintering using different particle size of silicon nitride powder. Lu2O3 was used as sintering additive. According to phase relationships in the ternary system Si3N4-SiO2-Lu2O3, porous Si3N4 ceramics with different phase composition were designed through the change of the content of SiO2 which was formed by the oxidation at 800°C in air. Porous Si3N4 with different phase compositions was obtained after sintering at 1800°C in N2 atmosphere. A small content of SiO2 favored the formation of secondary phase Lu4Si2O7N2, while large content of SiO2 favored the formation of secondary phase Lu2Si2O7 and Si2N2O. Porous Si3N4 ceramics with secondary phase Lu4Si2O7N2 had a flexural strength of 207 MPa, while that with secondary phase Si2N2O and Lu2Si2O7 had lower flexural strength.
关键词:
Porous silicon nitride ceramics
Materials Science-Poland
Mn(4-x)Ag(x)N compounds (x = 0.0, 0.3, 0.6, 1.0) were prepared by milling and subsequently annealing the mixture of Mn(2)N(0.86), Mn, and Ag powders. All compounds display good single-phase characteristics. Both Mn(4)N and Mn(3.7)Ag(0.3)N exhibit ferrimagnetism, and a little Ag replacement of Mn can improve the saturation magnetization. The magnetic transition of Mn(3.4)Ag(0.6)N and Mn(3)AgN below 15 K is from triangular antiferromagnetism to non-coplanar ferrimagnetism, while the ones at 256 and 275 K (Mn(3.4)Ag(0.6)N and Mn(3)AgN, respectively) have been ascribed to the gradual transition, as temperature increases, from the triangular antiferromagnetic structure Gamma(5g) to a ferrimagnetic-like one. Two minima appear on the rho(T) curves for Mn(3)AgN, with the observation of a positive magnetoresistance throughout the whole tempeature-dependent change.
关键词:
antiferromagnetism;spin reorientation;magnetoresistance;metallic perovskite-type;mn4n;manganese;antiferromagnet;phase
