Papers by Author: Chao Li

Abstract: Usually, the teaching courseware that based on Web having a tree menu and can easily browse and links chapter and section. We study the development of a software system that can automatically generate courseware framework system with the menu tree. Here to generate static pages with dynamic page technology method, the key code of software framework system with the general characteristics stored in the database, and identify the dynamic location will be update. During the background program, according to the user input the information of chapter and section header, create the object code that can generate the directory tree structure; Finally, the teaching courseware framework system will be created that based on user input basic information and choose the courseware page template with the program stored in advance.

Abstract: The new metal-cored wires with Fe-Si-Mn-Ti-B microalloyed series were prepared to meet demands of GMAW surfacing rapid forming technology. The microstructure and performance characteristics of parts produced with them are both investigated. Its continuous metallographic microstructure along the deposition height direction shows obvious layered characteristic due to the special thermal cycles and cooling conditions. The microhardness values of intermediate sections of the part are higher than those of surface sections, which closely relates to their microstructure. The tensile strength, yield strength and broken elongation percentage of the part are 575MPa, 530 MPa and 10.14%, respectively. The fracture mechanism of the part belongs to quasi-cleavage crack. Therefore, the self-made metal cored wires are acceptable for forming some structure parts.

Abstract: The self-made metal cored wires with Fe-Si-Mn-Ti-B microalloyed series were adopted to directly form a part by gas metal arc welding (GMAW) surfacing rapid prototyping technology. The microstructure and microhardness of the part are both investigated. Its continuous metallographic microstructure along and vertical to the deposition direction shows layered characteristic, due to the special thermal cycles and cooling conditions. The microhardness values of intermediate sections of the part are much higher and stabler than those of surface sections. It is necessary to deposit a wear-resistant metal layer for enhancing the surface abradability. Among the microstructures of the part, the average nanohardness of acicular ferrite is 1.28 times than that of massive ferrite, but their Young’s modulus values are almost equivalent, which indicates acicular ferrite possesses excellent mechanical property. Therefore, achieving acicular ferrite microstructures is an appropriate means to enhance the combination property of the formed parts.

Abstract: The Cu-coated nano SiC composite particles were prepared by heterogeneous nucleation method. For the heterogeneous nucleation process, the dispered nano SiC particles and the active Cu2O precipitation were both prefabricated. The composite particles were characterized by means of XRD, SEM, EDS, TEM and ED analysis technics. It is found that Cu layers are coated on the nano SiC particles, which are continuous and dense, and partly oxidized to Cu2O, and the oxidation rate can be reduced by improving experimental processes. The investigation on reaction mechanism shows the disproportionating reaction speed of Cu+ can be controlled by adjusting the pH value of reaction solution, which makes the degree of supersaturation of Cu crystallites accord with the conditions of heterogeneous nucleation.