Preparation Mechanism And Property Of C-Si System Composite In Different Conditions

With the development of Silicon steel production, Carbon casing and Quartz casing used on the furnace bottom roll in continuous annealing furnace cannot satisfy the production requirement. So in this thesis, the problem was solved by a complex casing, which was prepared by industrial Carbon and Silicon powders.The samples, whose starting materials was carbon black and industrial Si with the different ratios, were fired at different temperatures immerged Carbon powders or put in nitrogen atmosphere, respectively. By using XRD analyzing technique, the phase compositions of the sintered samples have been detected. Such important issues as influence of formula and synthesized temperature on synthesis were investigated. Hence the related dynamic mechanism has been tentatively explained. And the properties and agglomerating mechanism of C-Si system composites has been investigated.In the samples immerged Carbon powders, there was SiC phase, quartz and cristobalite, and there was hardly the phase of Si₃N₄ and Si₂N₂O. The reaction processes were that SiO₂, SiC were produced by the reaction between Si and O₂, Si and C, or Si and CO, respectively. When the synthesized temperature was above 1450℃, SiC phase were produced by the reaction between SiO₂ and the rest C in the samples.In the samples in nitrogen atmosphere, the final phases were SiC,α-Si₃N₄ andβ-Si₃N₄, and Si₂N₂O also stayed when the percentage compsition of Si is large. And quartz and cristobalite appeared as intermediate product. Silicon Nitride could be produced not only by the reaction between Si and N2, but also among SiO₂, C and N2, or Si₂N₂O, C and N2. In addition,α-Si₃N₄ always appeared earlier thanβ-Si₃N₄, and transformed intoβ-Si₃N₄ with the temperature rising. When the synthesized temperature was above 1500℃, SiC phase was produced by the reaction between Si₃N₄ and the rest C in the samples.The sintered temperature and the starting materials compositions were some keys to influence synthetic products of the sintered samples.Whether in the condition immerged Carbon powders, or in nitrogen atmosphere, the sintered composites showed the characteristic of keeping away from Fe's erosion. The sintered composites immerged Carbon powders showed very good compressive strength, and was universally better than the ones sintered in nitrogen atmosphere.