X.L.Gong
,
Y.Liu
,
S.Y.He
,
J.Lu
材料科学技术（英）
Three types of metal porous polymer composite (MPPC) were produced by infiltrating different polymers into a porous Al structure. This type of interpenetrating microstructure allows for a better combination of mechanical and physical properties. The low velocity impact response of these composites was investigated by conducting drop-weight impact tests. Impact parameters such as the peak load, the time to peak load, the deflection at peak load, and the absorbed energy were evaluated and compared for Al, MPPC and pure Al foam. The influence of the volume fraction of polymer was also investigated for the above impact parameters. The experimental results indicate that the inlaid polymer has a very important positive effect on the impact behavior and improves the characteristics of the composite in comparison with conventional foam and pure Al.
关键词:
MPPC
,
null
,
null
T.Rol
,
M.Ya
,
D.Retraint
,
K.Lu
,
J.Lu
材料科学技术（英）
Surface mechanical attrition treatment (SMAT) can produce a nanometer-grained surface layer without porosity and contamination on a bulk stainless steel. The nanostructured layer has high strength that contributes to an overall increase in the mechanical properties of the nanostructured sample. In this study, a new nanostructured composite was developed by assembling three SMA-treated thin plates. An FEM model based on nanoindentation data was established to simulate the stress-strain relationship. The simulation and the experimental tension curve correspond well. Moiré interferometry was used to observe the tensile behavior of the new composite in real time. A tension test conducted on a specimen consisting of three 500~μm thick SMA-treated sheets showed that the yield stress is much higher than that of a bulk-treated sample of the same total thickness. Based on these results, the new multilayer composite would seem to be a promising structural material due to its high strength/weight ratio.
关键词:
Nanostructures
,
null
,
null
,
null
G.Montay
,
A.Cherouat
,
A.Nussair
,
J.Lu
材料科学技术（英）
Residual stress in coatings is the result of individual particle stress. Their effects may be either beneficial or detrimental, depending upon the magnitude, sign and distribution of the stresses with respect to the external load. Tensile stress which exceeds the elastic limit causes cracking in surface coatings or at the interface between the substrate and the coat. Compressive stress, in general, has a beneficial effect on the fatigue life, crack propagation, coating adhesion and on the durability of the top coat during service. Compressive residual stresses can increase the number of cycles before crack initiation begins through a mean stress effect. Temperature gradients which occur during solidification and subsequent cooling are the principal mode of internal stresses generation. Some parameters influence the residual stress field of both the coating and the substrate. Substrate nature, spraying temperature, thickness of the coat layer, substrate preparation (grit blasting conditions), and velocity of the splats are in the relation with the quality of the coating. In this work, we will describe the role playing by the ceramics coating elaboration on the residual stress gradient in depth of the component. The incremental hole drilling technique has been developed to determine the residual stress gradient in depth of the coat and substrate which must be used with particularly conditions. This new technology has been employed on zirconia, alumina and tungsten carbide plasma sprayed coating.
关键词:
Coating
,
null
,
null
,
null
孙智
,
谢建军
,
王宇
,
施鹰
,
雷芳
人工晶体学报
采用溶胶-凝胶法结合旋涂工艺在单晶硅(111)上制备了Tb3+离子不同掺杂浓度的硅酸镥光学薄膜(Tb∶Lu2SiO5),利用热重差热分析(TG-DSC)、X射线衍射(XRD)、傅里叶红外光谱仪(FTIR)、原子力显微镜(AFM)和紫外可见荧光光谱(PL)对Tb∶Lu2SiO5薄膜的不同温度热处理的结构演变和发光性能进行了表征.研究结果表明Tb∶Lu2SiO5光学薄膜表面均匀、平整、无裂纹,薄膜样品从800℃开始晶华,1100 ℃时晶化完全.Tb∶Lu2SiO5的发光性能表现为Tb3+离子的4f→5d和5D4(5D3)→7FJ(J =6,5,4,3)跃迁结果(监测波长分别为480～650 nm和350～470 nm),激发主峰位于～240 nm,发射光谱主峰为542 nm的绿光发射.研究表明Tb3掺杂浓度对Tb∶Lu2SiO5光学薄膜的发光强度会产生明显影响,掺杂15mol％的Tb3+时,Tb∶Lu2SiO5薄膜的发光强度最强.
关键词:
Sol-gel法
,
Tb∶Lu2SiO5光学薄膜
,
结构演变
,
发光性能
张炳涛
,
滕冰
,
钟德高
,
曹丽凤
,
李建宏
,
人工晶体学报
采用提拉法生长出Ybb0.005Y0.708Lu0.287VO4晶体.在室温下,对Yb0.005Y0.708Lu0.287VO4晶体进行了XRPD测试,计算了晶格常数(a=b=0.7091 nm,c=0.6273 nm)和密度(4.826 g/cm3).对混晶的(100)面进行了腐蚀,腐蚀坑呈四棱锥形状.平均线膨胀系数α1=1.285×10-6 K-1,α3=7.030 ×10-6 K-1,温度在330.15 K和570.15 K之间变化时,比热为0.494 ～0.617 J/g·K.
关键词:
钒酸盐晶体
,
腐蚀坑
,
膨胀系数
,
比热
,
热导率
Physical Review B
The Hamiltonian for a four-sublattice Heisenberg ferrimagnet or ferromagnet with different exchange constants (J(ab) = J(cd) not equal J(bc) = J(da)) was established. An extended Bogoliubov transformation was developed by solving an equation group, consisting of 20 equations and 20 unknowns. The procedure for solving the equation group was carried out by introducing a simple way of reducing the numbers of the equations and the unknowns. The spin-wave spectra in the present system have been determined by performing the standard Holstein-Primakoff transformation and the Bogoliubov one. It has been found that the spin-wave spectra of the present system depend on the exchange constants and that the degeneracy of the spin-wave spectra remains. The results for a special case (J(ab) = J(bc)) i.e., an antiferromagnet are discussed briefly. The spin-wave spectra of the four-sublattice Heisenberg antiferromagnet are found to be degenerative also and they are linear in k for small k.
关键词:
model
Y.G. Cao
,
X.Y. Sun
金属学报(英文版)
J-integral and crack opening displacement δ(COD) were important parameters for characterization of fractures in engineering materials. The relationship between J-integral and COD has been investigated for a long time and was enerally represented as J = m σyδ, where σy is the yield strength and m is a function of specimen geometry and material properties. To determine the value of m, extensive studies and experiments have been performed. The method that used the fracture-surface topography analysis (FRASTA) for determining J-integral from fracture surfaces of materials was introduced. On the basis of the relationship between COD and fracture surface average profile, the relationship between J-integral and COD was deduced and compared with the generally used equation. The method was experimentally confirmed to be able to provide a new way to determine the relationship between J-integral and COD.
关键词:
FRASTA
,
null
,
null
洪智亮
,
成来飞
,
鲁琳静
,
张立同
,
王一光
无机材料学报
doi:10.3724/SP.J.1077.2010.00186
采用溶胶-凝胶法制得三种镥硅酸盐体系粉体材料. 以氧化物的摩尔比来表示此三种粉体, 分别为：Lu2O3·SiO2、Lu2O3·2SiO2和Lu2O3·2.26SiO2. 在1400℃、50%H2O-50%O2静态常压气氛下, 研究了它们的耐水蒸气腐蚀性能.以单位面积重量变化率表征材料的耐水蒸气腐蚀性能, 结合X射线衍射（XRD）、傅里叶红外光谱（FTIR）和扫描电镜能谱分析（SEMEDS）等分析手段, 揭示了镥硅酸盐体系在高温水蒸气环境中的腐蚀机制和反应机理. 结果表明：三种原始粉体主要物相依次为：Lu2SiO5+Lu2Si2O7、 Lu2Si2O7+SiO2和Lu2Si2O7+SiO2. 在水蒸气作用下, Lu2SiO5相与Al2O3反应生成新相Lu3Al5O12, 而Lu2Si2O7相并未受到水蒸气的作用而发生任何反应, 表现出优异的化学稳定性.
关键词:
Lu2SiO5
,
Lu2Si2O7
,
environmental barrier coating (EBC)
,
water vapor corrosion
洪智亮
,
成来飞
,
鲁琳静
,
张立同
,
王一光
无机材料学报
doi:10.3724/SP.J.1077.2010.00186
采用溶胶-凝胶法制得三种镥硅酸盐体系粉体材料.以氧化物的摩尔比来表示此三种粉体,分别为:Lu_2O_3·SiO_2、Lu_2O_3·2SiO_2和Lu_2O_3·2.26SiO_2.在1400℃、50%H_2O-50%O_2静态常压气氛下,研究了它们的耐水蒸气腐蚀性能.以单位面积重量变化率表征材料的耐水蒸气腐蚀性能,结合X射线衍射(XRD)、傅里叶红外光谱(FTIR)和扫描电镜能谱分析(SEM-EDS)等分析手段,揭示了镥硅酸盐体系在高温水蒸气环境中的腐蚀机制和反应机理.结果表明:三种原始粉体主要物相依次为:Lu_2SiO_5+Lu_2Si_2O_7、Lu_2Si_2O_7+SiO_2和Lu_2Si_2o_7+SiO_2.在水蒸气作用下,Lu_2SiO_5相与Al_2O_3反应生成新相Lu_3Al_5O_(12)而Lu_2Si_2O_7相并未受到水蒸气的作用而发生任何反应,表现出优异的化学稳定性.
关键词:
Lu_2SiO_5
,
Lu_2Si_2O_7
,
环境障碍涂层
,
水蒸气腐蚀
