低密度非金属装饰材料表面金属化的工艺研究

:分析了传统非金属表面金属化工艺的局限性 ,探讨了采用真空镀膜法实现低密度非金属装饰材料表面金属化的主要工艺环节 .研究表明 ,采用磁控和蒸发装饰镀可镀制大面积的非金属浮雕式装饰材料 。

基于金属非金属增材制造适用材料及产品机械性能研究

增材制造技术的发展,促使传统制造领域无法实现的复杂结构件制造变为可能。文章基于金属/非金属增材制造使用材料及其加工产品的机械性能进行了研究。文章首先对增材制造技术的原理进行了综述;其次分析了增材制造技术适用材料及加工产品的机械性能;再次分析了在增材制造工艺中产品机械性能变化的主要原因;最后针对增材制造加工产品性能改进的方法进行了总结,从金属、非金属两个角度总结了性能改进的具体方法。最终结果表明,可以通过添加填充材料、材料熔融共混、改变轮廓宽度等方式能够有效提升非金属材料进行增材制造时的产品性能;通过调节材料配比、激光融化沉积技术、添加稀土氧化物、调节激光功率和扫描率等方式能够有效提升金属材料进行增材制造时的产品性能。

Analysis of Through-the-Thickness Stress Distribution in Thick Laminate Multi-Bolt Joints Using Global-Local Method

The stress distribution surrounding the fastener hole in thick laminate mechanical joints is complex. It is time-consuming to analyze the distribution using finite element method. To accurately and efficiently obtain the stress state around the fastener hole in multi-bolt thick laminate joints, a global-local approach is introduced. In the method, the most seriously damaged zone is 3D modeled by taking the displacement field got from the 2D global model as boundary conditions. Through comparison and analysis there are the following findings: the global-local finite element method is a reliable and efficient way to solve the stress distribution problem; the stress distribution around the fastener hole is quite uneven in through-the-thickness direction, and the stresses of the elements close to the shearing plane are much higher than the stresses of the elements far away from the shearing plane; the out-of-plane stresses introduced by the single-lap joint cannot be ignored due to the delamination failure; the stress state is a useful criterion for further more complex studies involving failure analysis.

Effect of Oil Shale on Na^+ Solidification of Red Mud-Fly Ash Cementitious Material

Red mud-fly ash based cementitious material mixed with different contents of oil shale calcined at 700 ℃ is investigated in this paper. The effect of active Si and A1 content on the solidification of Na＋ during the hydration process is determined by using X-ray diffraction （XRD）, 27A1 and 29Si magic-angle-spinning nuclear magnetic resonance （MAS-NMR）, infrared （IR）, scanning electronic microscopy （SEM） and X-ray photoelectron spectroscopy （XPS）. It is shown that the content of oil shale has a remarkable effect on the solidified content of Na＋. The hydration process generates a highly reactive intermediate gel phase formed by co-polymerisation of individual alumina and silicate species. This kind of gel is primarily considered as 3D framework of Si04 and A104 tetrahedra interlinked by the shared oxygen atoms randomly. The negative charges and four-coordinated A1 inside the network are mainly charge-balanced by Na＋. The solidifying mechanism of Na＋ is greatly attributed to the forming of this kind of gel.

Non-noble metal single-atom catalyst of Co_(1)/MXene(Mo_(2)CS_(2))for CO oxidation

MXene is a variety of new two-dimensional(2D)materials with early transition metal carbides,nitrides,and carbonitrides.Quantum chemical studies have been carried out on the geometries,electronic structures,stability and catalytic properties of a non-noble metal single-atom catalyst(SAC)with single Co atom anchored on MXene materials of Mo_(2)CS_(2).The Co adatom anchored on top of the Mo atom of this MXene is found to be rather stable,and this SAC is appropriate for CO oxidation.The charge transfers from the surface to the adsorbed CO and O2 play a significant role in the activation of these molecules on Co_(1)/Mo_(2)CS_(2).With this catalyst,the Eley-Rideal(ER),Langmuir-Hinshelwood(LH),and Termolecular Eley-Rideal(TER)mechanisms are explored for CO oxidation.We find that,while all the three mechanisms are feasible at low temperature,Co_(1)/Mo_(2)CS_(2) possesses higher catalytic activity for CO oxidation through the TER mechanism that features an intriguing OC(OO)CO intermediate(IM)adsorbed on Co single atom.The calculated activation energy barriers of the rate-limiting step are 0.67 eV(TER),0.78 eV(LH)and 0.88 eV(ER),respectively.The present study illustrates that it is promising to develop and design low-cost,non-noble metal SACs using MXene types of 2D materials.

Research on Online Texture Measurements in Metal Rolling Field

In rolled strip material,the orientation of the crystallites,known as texture,is influenced by various kinds of thermo-mechanical processes,such as casting,plastic deformation,annealing and phase transformation. The modern industry production requires stable product performance,real-time monitoring and full controlling of the quality.The online texture measurement in metal rolling can be used to real-time monitor the whole process, and then feedback control to the production process can be implied to adjust the process parameters to ensure the stability of the products.The principles,advantages and disadvantages of related detection methods(2D X-ray diffraction,neutron diffraction,laser-ultrasonics and electromagnetic acoustic transducers(EMAT)) and the possibility of online measurement are discussed.Finally,2D X-ray diffraction and laser-ultrasonics are employed on online texture measurement,and the schemes of online texture measurement are proposed.

Exceptionally shear-stable and ultra-strong Ir-Ni-Ta high-temperature metallic glasses at micro/nano scales

Ir-Ni-Ta metallic glasses(MGs)exhibit an array of superior high-temperature properties,making them attractive for applications at high temperatures or in harsh environments.However,Ir-Ni-Ta bulk MGs are quite brittle and often fracture catastrophically even before plastic yielding,significantly undercutting their high-strength advantage.Here,we show that the Ir-Ni-Ta MGs are not intrinsically brittle,but rather malleable when the feature size is reduced to micro/nano-scales.All tested Ir-Ni-Ta MG micropillars with a diameter ranging from~500 nm to~5μm display a large plastic strain above 25%(the maximum up to 35%),together with a yield strength up to 7 GPa,well exceeding the strength recorded in most metallic materials.The intrinsic shear stability of Ir-Ni-Ta MGs,as characterized by the normalized shear displacement during a shear event,is much larger than those malleable Zr-and Cu-based MGs.Our results suggest that Ir-Ni-Ta MGs are excellent candidates for micro/nanoscale structural applications used at high-temperature or extreme conditions.