| Large quantities of silicon scraps will occur in each wafer preparation procedure,especially in wafer cutting process. How to take advantage of these wastes and makeit profitable has been becoming the focus of the researchers’attention. Generally, thesilicon sawdust has a very fine particle size, which exhibits high activity without anyneed of additional activating treatment after simple recycle.In recent years, the crucible coating materials have been the hot subject due tothe rapid development of the solar photovoltaic industry on a global scale. It will beof great practical significance to explore an economical and easy way to synthesizehigh-purity silicon nitride-oxide powder materials.In this thesis, a gas-solid method was employed to synthesize Si2N2O usingsilicon sawdust purified by acid pretreatment and solid oxygen source SiO2withdifferent forms as the raw materials. On this basis, quartz was further used as thesolid oxygen source in the thermal explosive synthesis experiments, and thecorresponding thermodynamic and kinetic analyses were also investigated. Toprepare the desired Si2N2O powder, the molar ratio of SiO2and sawdust, reactiontemperature, reaction time and other parameters were adjusted. After then, theobtained Si2N2O powder was used to prepare coatings under the optimized enterprisecoating process. The coating performances were measured by Cross-Cut Tester,Pencil Hardness Tester, LSCM, ESEM and so on.The results show that the favorable oxynitride products can be obtained underthe following two groups of conditions:1380°C/4h, the ratio of wafer cutting sawdustand fumed silica2.0:1-2.6:1and1450°C/4h, the ratio of wafer cutting sawdust andcrystalline quartz1.5:1. By using the optimized recipe,(0.975-1.300)gSi2N2O:2mlH2O:1.25mlsol:(1-3)wt%PVA, the as-obtained coatings of Si2N2O andSi3N4-Si2N2O have a uniform appearance, together with the hardness greater than HB,and adhesion strength of grade2, which satisfy the application in crucible coatings. |
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