威尼斯娱人城官网

Title： 1. Improving fatigue performance of additive manufactured metal structures by ultra-stable microstructures
             2. 3D freeze assembling printing of graphene aerogel
Time：9:30 to 12:00, Wednesday, Aug 9, 2017
Place：A701, School of Mechanical Engineering
 
 

Title 1：
Improving fatigue performance of additive manufactured metal structures by ultra-stable microstructures.
 
Abstract: Currently, additive manufacturing is a popular topic, while laser based additive manufacturing is the most applied technique for metal based additive manufacturing. Laser based additive manufacturing can be used to print complex, hard machining materials and large components. However, the major issue for laser based additive manufacturing is that it introduces thermal tensile stress, which decreases fatigue life of metal components. Fatigue is responsible for 90% of metal failure. In order to improve fatigue life of metal component, a two-step manufacturing technology, including laser sintering plus laser shock peening (LSP), was proposed. First, 0D (Nanoparticles), 1D (carbon nanotube) and 2D (graphene or graphene oxide) nanomaterials were integrated into metal matrix by laser sintering. Then laser shock peening was performed to introduce high density of dislocations and novel microstructures. Compressive residual stress and surface work hardening were also introduced by LSP. The interaction between dislocations with nanomaterials helped block dislocation movement, thus stabilizing residual stress and work hardening. The stabilized work hardening and residual stress increased the resistance for crack initiation and crack propagation, so that we can greatly improve fatigue life.
 
Title 2：
3D freeze assembling printing of graphene aerogel
 
Abstract: The surging field of graphene aerogels (GA) provides a promising methodology for transferring inherent properties of graphene into macroscopic applications for composite materials, energy storage, stress sensor, thermal insulator, and shock damping. However, fabrication of GA with tailored macrostructures by scalable and controllable methods remains a significant challenge. The vision of tailoring macroarchitecture of GA for specific applications, including separation, all-solid-state batteries, micro pressure sensors, flexible electrodes, and electrochemical catalyst templates, has stimulated the research on 3D printing of GA. Here, we propose a printing methodology that contines multinozzle drop-on-demand inkjet printing of pure graphene oxide (GO) suspension with freeze casting for rapid printing of 3D GA architectures to achieve several key qualities, namely, pure, continuous, boundary free, controlled microstructure, and truly 3D architectures (e.g., 3D truss with overhang structures). To date, we have successfully printed world’s lightest material via 3D printing through the proposed technique.