Ag对Cu-Ti-PILC结构和催化性能的影响

采用离子交换法制备了Cu-Ti-PILC样品,采用浸渍法制备了Ag/Cu-Ti-PILC样品。采用X射线衍射谱(XRD)、程序升温还原(TPR)、NO程序升温脱附(NO-TPD)研究银物种对Cu-Ti-PILC结构的影响,以无机物NO为催化反应模型降解物,研究银物种对Cu-Ti-PILC催化性能的影响。结果表明:Ag物种破坏了钛柱层粘土(TiPILC)的有序排列性,未改变Ti-PILC的层间结构及铜物种的分散度,改变了铜物种在催化剂表面的分配并提高了Cu2+的比例,改变了NO的反应途径并提高了中间产物的产生量,故导致N2收率提高了约20%,在SO2和H2O存在的条件下,N2收率提高了约12%。

Ag-Cu-Ti活性法封接AlN陶瓷与Mo-Cu合金

用AgCu—Ti焊料在真空条件下活性法封接了AIN陶瓷和Mo—Cu合金，用EBSD，EDS，XRD等手段分析了界面结构，对封接件进行了强度和气密性测试。结果显示：焊料中的活性组元Ti与陶瓷反应，形成厚2～3μm，紧邻陶瓷连续分布的反应层；靠近AlN一侧，焊层为AgCu共晶组织，靠近合金一侧，焊层以富Cu相为主。整个界面产物主要有TiN，Cu2Ti，AgTi3，AgTi，Ni3Ti等化合物。连接件的剪切强度στ=172．94MPa，弯曲强度στ=69．59MPa，气密性1．0×10^-11=Pa·m^3／s。

Ag对Fe/Al-PILC的SCR-C3H6脱硝特性的影响

为提高低温段(<300℃)铝柱撑蒙脱土负载铁基催化剂的脱硝效率,采用银离子对其进行修饰。通过超声浸渍法合成银-铁双金属催化剂,并于固定床反应器中评价催化剂性能。结果表明,Ag的引入显著改善了Fe/Al-PILC催化剂的低温催化活性。在250℃时,Ag-Fe/Al-PILC催化剂的NO转化率达到60%以上,高于Fe/Al-PILC催化剂20%的NO的转化率,其中,2.1Ag-Fe/Al-PILC在250℃时NO转化率达到82%,N2选择性达到100%。而且,引入银离子后的双金属催化剂保持了铁基催化剂较好的抗H2O和SO2性能。通过多种技术探究催化剂的微观结构和物理化学性质。根据N2吸附-脱附测试结果表明,双金属催化剂形成了稳定的整体结构,并具有较大的内比表面积。同时,XRD和UV-vis表征结果显示,在催化剂表面形成的银-铁固溶体、Ag+和Agn^δ+物种是影响其低温活性的关键因素。Ag-Fe/Al-PILC的低温活性与形成的银-铁固溶体有关,同时在催化剂表面形成的Ag+和Agn^δ+物种是影响其低温活性的关键因素。XPS结果表明,Ag和Fe之间存在电子转移,形成了双金属协同作用,改变了催化剂表面的银、铁成分含量及其价态。H2-TPR结果表明,Ag促使Fe/Al-PILC还原特征峰出现在低温区,提高了其低温还原性能。表面酸性的Py-FTIR分析结果表明,Ag-Fe/Al-PILC催化剂同时存在Lewis酸和Bronsted酸,且Ag提高了Bronsted酸的稳定性。

Ultrahigh strength and improved electrical conductivity in an aging strengthened copper alloy processed by combination of equal channel angular pressing and thermomechanical treatment

In this paper,equal channel angular pressing and thermomechanical treatment was employed to improve the strength and electrical conductivity of an aging strengthened Cu-Ti-Cr-Mg alloy,and the microstructure and properties of the alloy were investigated in detail.The results showed that the samples deformed by the combination of cryogenic equal channel angular pressing(ECAP)and rolling had good comprehensive properties after aging at 400℃.The tensile strength of the peak-aged and over-aged samples was 1120 MPa and 940 MPa,with their corresponding electrical conductivity of 14.7%IACS and 22.1%IACS,respectively.ECAP and cryogenic rolling introduced high density dislocations,leading to the inhibition of the softening effects and refinement of the grains.After a long time aging at 400℃,the alloy exhibited ultra-high strength with obvious increasing electrical conductivity.The high strength was attributed to the synergistic effect of work hardening,grain refinement strengthening and precipitation strengthening.The precipitation of a large amount of Ti atoms from the matrix led to the high electrical conductivity of the over-aged sample.

TiN颗粒增强AgCuTi合金钎焊CBN磨粒的界面微结构

向Ag-Cu-Ti合金中加入TiN颗粒组成复合钎料。在加热温度920℃和保温时间5min的工艺下进行立方氮化硼(CBN)磨粒与45#钢基体的连接实验。运用三维视频显微镜、扫描电镜、能谱仪和X射线衍射仪分析TiN颗粒、Ag-Cu-Ti合金、CBN磨粒和钢基体之间的结合界面的微观组织结构。结果表明:加入的TiN颗粒在结合剂层中分布均匀、致密,且显著细化了结合剂层(复合钎料层)显微组织,提高了结合剂层的显微硬度;加入TiN颗粒后仍可确保结合剂层与钢基体之间的良好结合;复合钎料对CBN磨粒有好的润湿性,TiN颗粒未对CBN磨粒与结合剂层的界面化学反应造成负面影响,实现了对CBN磨粒的牢固连接。

Microstructure and properties of Cu-3Ti-1Ni alloy with aging process

The effects of Ni addition and aging treatment on the microstructure and properties of Cu?3Ti alloy were investigated. Themicrostructure and phase constituents were characterized by optical microscopy, scanning electron microscopy, X-ray diffractometerand high-resolution transmission electron microscopy, and the hardness and electrical conductivity were measured as well. Theresults show that NiTi phase forms with addition of Ni into as-cast Cu-3Ti alloy during solidification, and the as-cast microstructureevolves from dentrite to equiaxial structure. After aging treatment, coherent metastable β′-Cu4Ti precipitates from the Cu matrix.However, β′-Cu4Ti precipitation phase transforms into equilibrium, incoherent and lamellar Cu3Ti phase after overaging. Meanwhile,aging treatment results in appearance of annealing twins in the residual NiTi phase, and dislocation lines exist in the Cu matrix. Niaddition enhances the electrical conductivity, but decreases the hardness of Cu?3Ti alloy. In the range of experiments, the optimumaging treatment for Cu?3Ti?1Ni alloy is 300 °C for 2 h and 450 °C for 7 h. The hardness and electrical conductivity were HV 205and 18.2%IACS (international annealed copper standard), respectively.

A new ordered phase forming during ageing in Cu-Ti alloys

AGE-hardened Cu-Ti has been an important alloy of investigation in the field of continuousphase transformation due to its complicated transformation processes which involve short rangeordering (SRO), spinodal decomposition (SD), long range ordering (LRO), etc. So far, ithas been a controversial topic whether each process exists, and in what sequence they pro-ceed.