- 學位論文
液鐵觸媒槽中生產石墨技術研究
Production of Graphite from Catalytic Liquid Cast Iron Bath
摘要
本研究利用鐵碳平衡圖及鑄鐵內有關碳的石墨化理論，探討一種新的、連續、有效與環保的石墨生產技術。結論為: (1)依本法可有效將非晶碳轉變成石墨，且所得石墨之石墨化度，可達傳統Acheson 法工業石墨的標準(即93%以上)，且在過共晶成份的觸媒液鐵中，石墨化程度是可製程控制的，且與碳來源無關。(2)觀察到熔融鑄鐵內石墨的上浮現象，表示可以利用流體化床，製造石墨。 研究第一部份，以感應熔煉爐，將鐵、碳、矽合金，在1600oC充分熔融後，降至1500oC 進行4 h 持溫，使之在共晶點溫度以上，有足夠的時間，進行石墨化反應後，爐冷至室溫，製成試片，與球墨鑄鐵與灰鑄鐵，一同進行XRD 及OM 觀察，並將試片進行鹽酸酸洗，過濾取得石墨粉，再對石墨粉進行XRD 及OM 觀察，並進行ICP 分析。 第二部份是取第一部份的試片，以真空電弧熔煉法多次重熔，觀察重熔次數，與加入人造石墨，對於提昇石墨化程度的效應。所得試片，皆以OM 觀察微結構變化。酸洗後取得的石墨，作產率分析，並作XRD 以比較石墨化度，並以ICP 法作成份分析。
並列摘要
Via the use of iron-carbon phase diagram and the theory of graphitization of carbon in cast irons, this study investigates an innovative method for continuously, effectively and efficiently, as well as environment-friendly producing graphite in a catalytic cast iron bath. It is concluded that the transformation from amorphous carbon to graphite via the method is available, and the degree of graphitization (DOG) described in this study reaches a high value of more than 93% like that of Acheson’s. Furthermore, the DOG is process-controlled and is independent of carbon source in the hypereutectic catalytic cast iron melt. The observance of graphite flotation in liquid catalytic cast iron bath manifests the production of graphite is achievable by the fluidized bed method. The first part of this study describes the inductive melting (IM) of alloys of iron, carbon, and silicon at 1600oC for full melting; holding at temperatures higher than the eutectic temperature of 1500oC for 4 h for graphitization of carbon; and then lower the temperature to 25oC for test specimens. The IM specimens, being XRD and OM-checked firstly, are further pickled to obtain graphite that is also XRD-, OM- and ICP-analyzed to compare with graphite obtained from nodular cast iron and gray cast iron. The second part is about the vacuum arc re-melting (VAR) experiment of the specimens that are obtained in the first part. The effects of the number of VAR process and the addition of synthetic graphite on the DOG are checked with OM. The graphite samples of VAR specimens after pickled are checked with graphite production yield analysis, XRD for the comparison of the DOG, and ICP for the composition analysis.