Study On Monolayer/Multi-layers Porous Silicon Prepared By Anodized Method And Its Explosive Performance

To improve energy and reduce pollution is the ultimate goal of energetic materials researching. With the rapid development of environmental pollution and the increase of people's awareness to environment protection, researching new energetic materials is a matter with great reality and economic significance. Energetic materials of porous silicon attract extensive attention for their higher explosive properties and lower environment pollution. Porous silicon owns very high porosity and strong adsorption, sodium perchlorate were mixed into its holes to form energetic composite. Based on the former work of our team, n-type silicon wafer is used as the start material to prepare monolayer porous silicon film and multi-layers porous silicon film by electrochemical anodic oxidation. The preparation of porous silicon/NaClO4 composite as well as the effect of different factors on the explosive performance of the composite were researched. The main points of this dissertation are as following:(1) It is summarized that the current studies situation and perspective orient of energetic materials of porous silicon, preparation mechanism and applied research status of porous silicon.(2) N-type silicon wafer of 6.6520~8.3260Ω·cm is used to prepare monolayer porous silicon by DC electrochemical anodic oxidation. N-type silicon wafer of 0.008~0.020Ω·cm is used to prepare multi-layers porous silicon by pulse electrochemical anodic oxidation. The fresh etched porous silicon is immerged in inorganic acid and alcohol solution for 30min by UV-irradiation.(3) The structure, physical and chemical properties of porous silicon were characterized, including the porosity, film depth, surface and cross-sectional micrograph of porous silicon. The results show that the porosity of porous silicon increases with the increasing current density, and to be stable at current density 50mA·cm-2. With increasing hydrofluoric acid concentration, the porosity of porous silicon decreases; but accompanied by the increase of anodizing time, the porosity increases firstly and then decreases; the porosity reaches the maximum when the anodizing time is 30min. Film depth is thicker when anodizing time is longer, and its growth speed is about 2μm·min-1. Monolayer porous silicon cracks on surface and contains silicon columns internal which are 40μm long and 2~3μm wide. The film depth of multi-layers porous silicon is 4~50μm. (4) Porous silicon/NaClO4 composites were prepared. The effect of anodized conditions, sodium perchlorate concentration and storage methods on the explosive performance of composite were researched.