New 3D stratified Si-Ca-P porous scaffolds obtained by sol-gel and polymer replica method: Microstructural,mineralogical and chemical characterization

The aim of this research was to develop and characterize a novel stratified porous scaffold for future uses in bone tissue engineering. In this study, a calcium silicophosphate porous scaffold, with nominal composition 29.32 wt% SiO₂ – 67.8 wt% CaO – 2.88 wt% P₂O₅, was produced using the sol-gel and polymer replication methods. Polyurethane sponges were used as templates which were impregnated with a homogeneous sol solution and sintered at 950 °C and 1400 °C during 8 h. The characteristics of the 3D stratified porous scaffolds were investigated by Scanning Electron Microscopy, X-Ray Diffraction, Fourier Transform Infrared Spectrometry, Diametric Compression of Discs Test and Hg porosimetry techniques. The result showed highly porous stratified calcium silicophosphate scaffolds with micro and macropores interconnected. Also, the material has a diametrical strength dependent on the number of layers of the stratified scaffolds and the sintering temperature.     

内衬316L双金属复合管环焊焊缝失效原因分析

针对双金属机械复合管对接环焊缝的刺漏问题,对某油田现场服役的内衬316L双金属复合管问题管段进行取样,并从焊缝横截面各区域微观组织、化学成分、抗晶间腐蚀性能等方面进行了研究。研究结果表明,对接环焊缝打底焊道的热影响区晶粒粗大,对接环焊缝打底焊道熔合线附近区域主要耐腐蚀合金元素被稀释是双金属机械复合管对接环焊缝发生刺漏的主要原因。最后给出了预防刺漏发生的措施,即通过降低打底焊热输入量,提高管端尺寸精度,增加过渡层厚度且减小第一层填充焊热输入量的方法可有效预防刺漏问题的发生。     

A Modified Co-precipitation Method to Prepare Cu/ZnO/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Catalyst and Its Application in Low Temperature Water-gas Shift (LT-WGS) Reaction

A modified co-precipitation method for the production of Cu/ZnO/Al₂O₃ complex was studied. The modification was that part of Al was introduced by adding Al³⁺ into Cu²⁺/Zn²⁺ solution, and the rest of Al was added after co-precipitation step in the form of pseudo-boehmite. The prepared samples were characterized by different techniques such as X-ray diffraction, N₂ adsorption, H₂-N₂O titration, temperature programmed reduction and scanning electron microscopy. X-ray diffraction characterizations revealed that Al³⁺ can be doped in aurichalcite lattice, and the maximum doping amount of Al³⁺ was 5.0% of total Cu and Zn atoms. The Cu/ZnO/Al₂O₃ sample produced by the modified method, in which co-precipitated Al³⁺ was 2.5% of total Cu and Zn atoms showed much better activity and stability in water-gas shift reaction than commercial sample. The high Cu surface area (26.1 m²/g) obtained by decompositon of doped aurichalcite is believed to be responsible for the activity enhancement. The stability was enhanced mainly because of the support effect of γ-Al₂O₃, which was decomposed from pseudo-boehmite in the calcination step.     

Reel-lay铺设对机械式双金属复合管性能的影响

为了探究机械式双金属复合管进行Reel-lay海底管道铺设的可行性,模拟Reel-lay铺管过程,采用全尺寸静态弯曲试验机对Φ219.1 mm×（14.3+3.2） mm L450Q+316L机械式双金属复合管进行了循环弯曲试验。通过复合管弯曲应力应变测试,证明本试验装置完全可以模拟复合管Reel-lay铺设过程的弯曲变形。同时,对复合管弯曲前后的金相组织、拉伸性能、硬度和冲击性能进行检测,结果表明Reel-lay铺设过程中弯曲变形对该管材的理化性能影响较小,采用Reel-lay铺设方式是可行的。