Synthesis and characteristics of large-scale ZnO rods by wet chemical method

The large-scale ZnO rods of submicrometer were prepared on the bare glass using a wet chemical method under different experimental parameters, such as the reactant concentration and the growth time. The microstructure of the ZnO rods was characterized by X-ray diffractometry（XRD） and field emission scanning electron microscopy （FESEM） with the energy dispersive X-ray spectroscopy（EDX）, and the optical property was investigated by the room-temperature photoluminescence （PL） spectra. XRD and FESEM results show that the wurtzite structure and rod-like ZnO is obtained. The length （3-8 μm） and the diameter （400 nm- 3 μm） vary with the experimental parameters. A strong UV emission at 384 nm and a weak visible yellow-green emission around 570 nm are observed in the PL spectrum. After annealing at 600 ℃ in air, the UV peak intensity increases obviously and the yellow-green peak intensity decreases greatly. The near-band-edge UV emission is attributed to the exciton recombination; the yellow-green emission can be associated with the defect recombination; and some defect complexes may be responsible for the latter emission.     

LY12CZ 铝合金超塑性孔洞长大及其对断裂的影响~*

供应状态 LY12CZ 铝合金具有超塑性,平均晶粒尺寸为15.3μm,在490℃,(?)_0=1.67×10~(-4)s~(-1)时,延伸率为346%,m 值为0.52—0.6。该材料为孔洞敏感材料,孔洞长大规律可用本文提出的二阶段孔洞模型描述。同时考虑材料的应变速率敏感性(m)和孔洞长大效应,可从理论上预测该材料的延伸率。     

碳化物分布及基体均匀性对Cr12MoV钢机械性能的影响

一前言Cr12MoV是一种莱氏体型高合金冷作模具钢。经锻轧后的棒材,碳化物分布不均匀,带状组织严重。淬火及低温回火后,这种粗大带状分布的碳化物,不仅降低钢的强度,而且由于碳化物或碳化物与基体界面易     

球化钢损伤和断裂的实验与理论研究

对４５，Ｔ８和ＧＣｒ１５三种球化钢的力学性能，断裂及微观损伤机理进行了研究，结果表明，碳化物粒子的存在引起的孔洞形核及长大是导致这类材料断裂破坏的主要原因；材料的孔洞体积分数随应变而增加，且有较多碳化物粒子的材料孔洞体积分数增长较快；孔洞损伤可导致材料的软化，推导出碳化物粒子和孔洞损伤影响的等效应硬化指数以及断裂应变的解析表达式，断裂应变的解析表达式为ε＝ｎｍ（１－ｆｖ）（１－ｆｐ）／βｆｖ（１＋     

对于Pb—Sn共晶合金超塑性流动方程中K常数的讨论

超塑性流动方程σ=Kε~m 中的K 一直被认为是一材料常数。本文用Pb—Sn 共晶合金的实验结果证明了K 不是常数,而是随应变速率变化的函数。在最佳趣塑性应变速率下具有最大的K 值,随着应变速率引起超塑能力的减弱而减小,和m 值的变化关系吻合。同时还表明,应力的晶粒尺寸指数也不是常数,隧应变速率的变化而变化,在最佳超塑性应变速率区具有最大值,随着应变速率引起超塑性能力的减弱而减小。