Papers by Author: Dao Ren Gong

Abstract: Iron silicide films with two different structures were fabricated by electron beam evaporation (EBE) technique. X-ray diffraction (XRD), Fourier transform infrared (FTIR) and scanning electron microscope (SEM) were carried out to describe the characteristics and structures of the films. It was found that after annealing at 800oC for 5 h, the β-FeSi2 film formed in the sample with the structure of Si/Fe film on silicon substrate, while only FeSi film generated in the sample with the structure of Si/Fe/Si films on silicon substrate. It is considered that the different iron silicides may be due to the different reaction of iron with crystal silicon or amorphous silicon, which is related to diffusion of iron or silicon atoms.

Abstract: In the present work, TZ-3Y20A/Mo multilayer composites were prepared by sedimentation method. Appropriate settling parameters were chosen and green bodies of multilayer composites were obtained by settling TZ-3Y20A powder and Mo powder in turn according to the designed individual layer thickness. Then green laminates were hot pressed at 1773K for an hour under the pressure of 20MPa. Three-point Bending and Single Edge Notched Beam (SENB) tests were adopted to evaluate the flexure strength and fracture toughness of the samples. The results showed that, compared to TZ-3Y20A ceramics, the fracture toughness and the work of fracture increased due to the layered structure. The microstructure and crack deflection of the fracture surface of the laminated composites was also observed by optical microscopy.

Abstract: From the process of sedimentation the mathematical relationship between deposition volume and powder properties as well as sedimentation parameters was deduced in this paper. The relationship was expressed by using indirect method. Based on the formula, design model and prediction model were set up. The models can be used to design powder properties and predict the volume fraction of FGM. Programs to solve the models were developed in numerical methods. As examples, TiC-Ni system FGM were designed and predicted. The prediction results fit well with the design. Experiment of Mo-Ti system FGM was used to validate the prediction model.