Papers by Keyword: Carbon Deposit

Abstract: The provision of carbon reducing agents for the direct reduction process of iron ore is carried out by immersing the iron ore in a tar solution and then proceeding with the pyrolysis/ carbonization process to obtain carbon deposits on the surface of the iron ore. The purpose of this study is to investigate the characterization and reduction behavior of Fe compounds resulting from impregnation and carbonization processes. In this study, iron ore is immersed in the pine flower tar with immersion time varying from 0 - 12 hours and a fixed ratio of tar / ore 1: 1. The soaking mixture is then carbonized in a vertical tube reactor covered by furnace with N₂ gas flowed during the carbonization/pyrolysis process. The carbonization runs with a temperature variation of 450-550°C, for 1 hour, and a heating rate of 10°C/min. From SEM-EDX-Mapping result shows that the immersion method in tar followed by carbonization caused the carbon content in iron ore to increase by 86.68% in a 1: 1 tar/ore ratio, the impregnating time of 6 hours, and a pyrolysis temperature of 450°C. Effect of impregnation duration evidence that immersion times of 6 and 12 hours are sufficient to produce the magnetite phase after the carbonization process. Furthermore, the 6 hours’ duration provides a more optimal peak intensity. Meanwhile, the effect of temperature on the carbonization process shows that 450°C is the optimal temperature to obtain the magnetite phase in the carbonized ore.

Abstract: Two thirds of all examined defect cases present on rolled steel strips appeared to be chemical in nature. They are characterized by a modification in surface chemistry. Chemistry-based defects on the steel strips can vary in composition and generally consist of reaction products with the steel substrate. First big category of widely occurring chemistry-based defects is corrosion or oxidation, second contamination with alien matter and third defect category is related to carbon sediments. A number of different surface chemistry-based defects are related to annealing process. Common problem, that occurs in communication is, that identical defects are often indicated by different names and identical names are given for different defects. In the present study an overview including possible causes of three types of the continuous chemistry-based defects situated on the steel strip edges, that appeared to be the same at first glance, is presented: carbon edge deposit, low reflectivity band and annealed border.

Abstract: Flame sprayed ceramic coatings on the wall of coke oven are characterized before and after melting. The attempt has been made to investigate thermal shock resistant, carbon deposit resistant, wear resistant of the coated and melted samples. The techniques used are SEM and XRD. The results show that: 1) Presence of quartz, corundum and mullite are identified in the surface of the coated specimen. Good adhesion between the coating and the substrate is caused by presence of quartz which is the same content as the substrate.2) The thermal shock resistance cycles of the coating samples are 15 ~ 30 times, but uncoated samples are only 1~2 times. The main reason is that he coating–substrate interface shows no gaps or cracks, and it has a characteristic feature of good adhesion between the coating and the substrate. 3) The wear resistance of the coated samples are better than that of the uncoated samples because glass-coating is more smooth than the uncoated specimen and the mullite and corundum in the coating have the high hardness value that makes the hardness of the coating increased.

Abstract: Nanocrystalline cobalt was carburised with ethylene in the range 340– 500°C to obtain Co(C) nanocapsules. The carbon deposit was reduced by a flow of hydrogen in the range 500– 560°C. The reduction kinetics were studied using thermogravimetry, described by the equation: α = Α[1-exp(-kt)n]. The apparent activation energy of the reduction process of the carbon deposit was determined. After carburisation and reduction the samples were examined by XRD and HRTEM.