Microstructures of Sintered Mo-Cu Alloys with Mechanically Activated Powder

Mechanical activation and liquid phase sintering were used to manufacture high performance Mo-Cu alloy and develop new processes. The microstructures and properties of the alloy were investigated. The experimental results showed that: (1) the ball milled Mo/Cu powder has lamellar structure, (2) the microstructures of the sintered Mo-Cu alloy were homogenous compound structures of adhesive phase Cu linking Mo grains, (3) Mo grains frequently strung or ga thered in Cu phase, and (4) the full densities of Mo-Cu alloy was achieved through sintering and special densification process. As a result, the properties of the alloy are good enough to satisfy various requirements.     

新型白光LED用SrMg_2(PO_4)_2单-基质荧光粉

本文通过高温固相法合成了紫外光LED用SrMg2(PO4)2为基质Eu2+,Tb3+和Mn2+为激活剂的白色荧光粉。采用XRD对荧光粉的结构和相纯度进行分析,Eu2+、Tb3+及Mn2+的加入对其结构没有明显的影响,且无杂相生成;当用Ca部分取代Sr时Eu2+和Mn2+的发射带分别发生红移和蓝移且二者之间存在着明显的能量传递;当引入共激活剂Tb3+时对其荧光光谱进行了详细研究,发现Eu2+和Tb3+,Eu2+和Mn2+之间存在部分的能量传递,通过调整它们的相对掺杂浓度可以得到发白光的荧光粉。     

钼酸盐基白色荧光粉的制备及性能研究

采用溶胶-凝胶法合成了紫外光激发的钼酸盐基白色荧光粉。用粉末X射线衍射(XRD)和荧光光谱对其结构、发光性能进行了表征,并对其发白光的原理进行了分析。同时详细研究了煅烧温度对所得荧光粉的组成及发光性能的影响,计算了不同温度下得到的荧光粉的色坐标、显色指数和色温。     

Eu2+激活的Ga2S3-CaS体系的发光性能研究

采用高温固相法合成了Eu2 激活的不同镓含量的CaS-Ga2S3系列荧光粉.随镓含量的增加荧光粉的体色由红色过渡到黄色,其发射光谱由红光到黄光.通过XRD和漫反射谱测试得到,当Ga/Ca值＜2时,其成份为CaS与CaGa2S4的混合物;当Ga/Ca值＞2时,其成份为CaGa2S4与Ga2S3的混合物.当Ga/Ca值＞0.5时红光已基本上测不到,且Ga适当的过量可使CaGa2S4:Eu2 在可见光区的激发和发光效率提高.     

Preparation of Stable CaS： Eu^2＋ , Tm^3＋ Phosphor

Different fluxes were used to synthesize long persistence phosphors, calcium sulfides activated by Eu^2 and Tm^3 , by convenient solid-state method. The phosphor using NH4F as a flux has good crystallinity and large particle size, its stability against water and other atmospheric components is enhanced, and its afterglow is longer and fluorescent inten-sity is more intense than those of the phosphor using NH4Cl as flux. Their PL intensities varied with time in moist air were measured, no remarkable change was found for those prepared with NH4F flux in contrast with NH4Cl as flux. So using NH4F as flux is a good method to enhance the stability of alkaline earth sulfides.     

实现机械工程的可靠性优化设计

自改革开放之后,中国的工程机械行业得到了前所未有的发展,经过30多年的不懈努力,机械工程制造业取得了巨大的发展成果,在国民经济中占有很大的比重。在机械工程行业里面,对其可靠性进行优化设计是十分必要的。在本文中,深入探讨了工程机械可靠性优化设计中的问题,以便参考。     

Preparation of Stable CaS∶Eu~(2+), Tm~(3+) Phosphor

Alkalineearthsulfides (AES)havebeenfoundtobeexcellentandversatilephosphor ,andrareearthsasactivatorshavebeenintensivelyinvestigated[1～ 7] .Theyholdpromiseforapplicationsinphoto ,electro ,cathoderay ,fieldemissiondisplaysandluminescencepaints[8,9] .However ,alkalineearthsulfidesasaphos phorhosthavebeenfoundtobelimitedinapplica tion ,duemainlytoitssensitivetomoistureandotheratmosphericcomponents .Theirchemicalstabilityagainstatmosphericcarbondioxideandmoisturecouldbeenhancedthroughthegoodcryst…     

Ca4Y6(SiO4)6O∶Eu纳米晶与微米晶发光对比研究

通过控制实验条件,合成了Ca4Y6(SiO4)6O∶Eu纳米晶和微米晶,经1000℃灼烧后,纳米晶的粒径约为50nm,提高灼烧温度并延长灼烧时间,可使其粒径达到几百个纳米.研究了纳米晶Ca4Y6(SiO4)6O∶Eu的发光特性,发光强度与灼烧温度的关系,灼烧温度及材料制备方法对Eu3+在Ca4Y6(SiO4)6O中的猝灭浓度的影响,并发现纳米晶的激发光谱中,Eu3+-O2-电荷迁移带蓝移的特性.     

锶铝比例对铝酸锶长余辉发光材料性能的影响

系统研究了Eu²⁺、Dy³⁺共激活的铝酸锶长余辉发光材料的发光特性与Al/Sr比例的关系.采用高温固相法合成了Al/Sr从1.0到12.0的一系列样品,对其进行了XRD和荧光光谱测试,当Al/Sr＝2.0、3.5、10.0时,分别得到了SrAl₂O₄:Eu²⁺,Dy³⁺、Sr₄Al₁₄O₂₅:Eu²⁺,Dy³⁺、SrAl₁₂O₁₉:Eu²⁺,Dy³⁺的纯相,其它比例时得到的是不同铝酸锶化合物的混合物,样品的相组成呈明显的过渡性变化,导致样品的发光颜色随Al/Sr比例的增大,从蓝绿光向短波长方向移动,最终到达紫光.     

Green up-conversion luminescence in Yb^3＋-Pr^3＋ co-doped BaRE2ZnO5（RE=Y,Gd）

Yb3＋and Pr3＋co-doped BaRE2 ZnO5（RE=Y,Gd） up-conversion（UC） phosphors were successfully synthesized by a modified sol-gel method.The processing parameters and optimal concentration of Pr3＋and Yb3＋were determined.The structures and luminescent properties of samples were characterized by X-ray diffraction（XRD） and photoluminescence spectra（PL）.With the excitation of 980 nm laser diode,UC spectra showed five prominent emission bands centered at 484,514,546,656 and 670 nm,which were attributed to the1I6 →3H4,3P1 →3H4,3P0 →3H5,3P0 →3F2 and3P0 →3F3 transitions of Pr3＋,respectively.In the light of the pump power dependence,the possible UC mechanism in Yb3＋and Pr3＋co-doped BaRE2 ZnO5（RE=Y,Gd） was proposed and discussed.