• 한국주조공학회지
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• 제3권3호
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• pp.159-166
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• 1983

In order to develope domestic carburizers, the experiment was carried out by applying crystallization heat treatment to domestic anthracites and also to foreign products to compare with domestic anthracites.The present work was mainly concerned with the effect of their degree of crystallization of carbon-bearing materials on carbon pick-up in molten iron.Those effects were evaluated by the measurement of density, chemical composition, specific electric resistivity, and X-ray intensity of carbon-bearing materials. Experimental results thus obtained were summurized as follows. 1. The degree of crystallization of domestic anthracites and foreign products was increased with increasing heat treatment temperature. 2. The more degree of crystallization, the shorter the dissolving time of domestic anthracites in molten iron was obtained, while that of foreign products was remained constant. 3. As the degree of crystallization of domestic anthracites and foreign products was increased, the carbon content as well as carbon recovery in molten iron was increased.

• 한국표면공학회지
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• 제20권4호
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• pp.144-153
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• 1987

In the case of dipping the Ni-Resist cast iron into molten aluminum with iron content, the thickness of intermetallic compound was remarkably increased with increasing iron content. The thickness was shown by following equation in the range of 1-3% iron content; $x=22.5t^{1/2}+4.47{\cdot}t{\cdot}(Fe%)$. where, x is thickness(${\mu}m$), t the time (minute), Fe% the iron w/o. When the Ni-Resist cast iron was dipped into the molten aluminum containing zinc content, the intermetallic compound thickness was also increased with increasing zinc contents. And thickness was represented by the following equation in the range of 2-10% zinc content; $x=3.46t^{1/2}+0.27{\cdot}t{\cdot}(Zn%)$. However, in the case of dipping the Ni-resist cast iron into molten aluminum with silicon content, the thickness of intermetallic compound was decreased with increasing silicon content, as shown in the following equation; $x=7.17t^{1/2}-0.15{\cdot}t{\cdot}(Si%)$. The intermetallic compound formed onto Ni-Resist cast iron was identified to be $FeAl_3\;and\;Fe_3Al$. As the result of hardness measurement, the peak hardness appeared in the intermetallic compound at near interface of the cast iron and the compound.

• 한국표면공학회지
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• 제9권2호
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• pp.1-7
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• 1976

The dissolving and growth kinetics of intermetallic compounds for the reaction between solid iron and molten zinc were studied under nitorgen atmosphere over the temperature range between470$^{\circ}C$ and 680$^{\circ}C$. The rates of dissolution of solid iron into molten zinc were obtained under a static conditon, The amount of dissolution of sold iron and the growth of intermetalic compounds could be determined by means of microscopy. The thickness of intermetallic compound at a given temperature increases with increasing time, whereas for a given time decreases with increasing temperature . The rate of dissolution is controlled by the diffusion process of iron in the effective boundary layer of molten zinc over the temperature range 470$^{\circ}$-530$^{\circ}C$, 570$^{\circ}$-620$^{\circ}C$, and 650$^{\circ}$-665$^{\circ}C$, while by the surface reaction over the range 530$^{\circ}$-570$^{\circ}C$ and 620$^{\circ}$-650$^{\circ}C$.

• 한국주조공학회지
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• 제2권3호
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• pp.16-24
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• 1982

For the purpose of development of domestic carburizer, when the basicity of ash in carburizer was changed from $Na_2O/Al_2O_3+SiO_2$ ; 0.06 to $Na_2O/Al_2O_3+SiO_2$ ; 0,196wt%, using $Na_2O$ as flux for domestic graphite resource (Bong Myung armorphous graphite), carburizing efficiency was improved as basicity increased, optimum basicity value was $Na_2O/Al_2O_3+SiO_2$ ; 0.151. This means that $Na_2O$ contributed to lower viscosity of slag and raise occurence probability of specific reaction surface between molten iron and carburizer. The experiment of effect of general characteristics offecting carburizing ability of this carburizer was performed, the result is that 10/30 mesh was optimum size of the carburizer and as carbon equivalent of molten iron was higher, carburizing ratio was lowered, but when si concentration was below 1.8% in general cast iron melting region, recovery showed 75-85%. As agitation rate of molten iron and temperature interval were higher, Carburizing ratio was increased and showed max, 94%. Desulfurizing phenomena of molten iron by $Na_2O$ in carburizer didn't appear.

• 한국연소학회지
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• 제13권2호
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• pp.33-41
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• 2008

The high permeability of the gas in the molten iron of the dripping zone of the blast furnace is a major factor in achieving the stable operation of a furnace with high productivity. Basic studies of the liquid flow behavior in a packed bed are necessary to grasp the effect of various operational changes on conditions in the dropping zone. Molten iron and slag together playa critical role in the lower zone, transporting mass and energy, while impairing and redistributing the gas flow. In turn, molten iron and slag undergo physical and chemical changes, and are redistributed radially as they descend to the hearth. In this research, mathematical formulations are derived for the gas and the liquid. The solid phase is fixed with constant porosity. The information for the molten iron and slag includes the hold-up, velocity, pressure, and information related to the areas of interaction between the gas and the liquid, and the solid and the liquid. Predictable results include the velocity, pressure and temperature distribution. Additional parameters include the packed particle size and the air blast rate.

• 대한금속재료학회지
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• 제47권2호
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• pp.107-113
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• 2009

Molten iron with 2 mass % carbon content was decarbonized at 1823 K~1923 K by bubbling $Ar+O_2$ gas through a submerged nozzle. The reaction rate was significantly influenced by the oxygen partial pressure and the gas flow rate. Little evolution of CO gas was observed in the initial 5 seconds of the oxidation; however, this was followed by a period of high evolution rate of CO gas. The partial pressure of CO gas decreased with further progress of the decarbonization. The overall reaction is decomposed to two elementary reactions: the decarbonization and the dissolution rate of oxygen. The assumptions were made that these reactions are at equilibrium and that the reaction rates are controlled by mass transfer rates within and around the gas bubble. The time variations of carbon and oxygen contents in the melt and the CO partial pressure in the off-gas under various bubbling conditions were well explained by the mathematical model. Based on the present model, it was explained that the decarbonization rate of molten iron was controlled by gas-phase mass transfer at the first stage of reaction, but the rate controlling step was transferred to liquid-phase mass transfer from one third of reaction time.

• 한국광학회:학술대회논문집
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• 한국광학회 2000년도 제11회 정기총회 및 00년 동계학술발표회 논문집
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• pp.240-241
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• 2000

Sapphire fiber has been used to provide an optical path for the total radiation pyrometry. In measuring the temperature, we use the two-color detector, which consists of a high-performance Silicon detector mounted in a "sandwich" configuration over a Germanium detector. Sapphire fiber can withstand high temperature in the molten steel for two and a half hours. The maximum value of the error is the $\pm$2.5$^{\circ}C$ in the range of 152$0^{\circ}C$~1$600^{\circ}C$. This paper presents the simple scheme for measuring the molten steel temperature in the blast furnace of the iron ＆ steel making process.g process.

• 헤리티지:역사와 과학
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• 제53권2호
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• pp.4-23
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• 2020

이 연구는 우리나라 철 주조기술의 다양성과 기술 체계를 규명하기 위한 목적으로 진행되었으며, 이를 위해 고문헌 조사 및 유물 분석, 제작 도구와 제작 기술에 대한 현지 조사 그리고 주조와 거푸집에 사용된 재료의 과학 분석 등을 실시하였다. 불미기술은 송풍구인 풀무를 이용하여 주철을 녹인 뒤 그 쇳물을 토제 거푸집에 부어 주물을 완성하는 철 주조기술로 현재 유일하게 제주도에서만 전승되고 있는데, 모래 거푸집을 사용하는 육지와 비교해 토제 거푸집을 사용하고 있다는 것이 큰 차이점이라 할 수 있다. 무쇠솥 주조기술에는 석비레, 모래, 점토 등을 섞어 만든 모래 거푸집을 이용한 주물사주조법(鑄物砂鑄造法)과 점토에 볏짚과 갈대 등을 섞어 만든 토제 거푸집을 이용한 도토주조법(陶土鑄造法)이 사용되고 있다. 주물사주조법에 의한 무쇠솥 주조는 거푸집 만들기, 속심 제작, 쇳물 작업, 거푸집에 쇳물 붓기, 완성품 다듬기 등 5단계의 작업공정을 거치며, 도토주조법에 의한 무쇠솥 주조는 거푸집 만들기, 거푸집 굽기, 질먹 입히기, 쇳물 작업, 쇳물 붓기, 완성품 다듬기 등 크게 6단계의 작업 공정으로 이루어진다. 두 주조법은 거푸집의 재료, 거푸집을 불에 굽고 질먹을 입히는 제작 공정에서 차이를 보인다. 이번에 연구한 불미기술은 토제 거푸집 무쇠솥 주조로 진흙 채취 및 반죽, 거푸집 제작, 초벌 굽기, 화적모살 및 질먹 바르기, 건조 및 비얄질, 거푸집 합장, 둑(용광로)제작, 재벌 굽기, 제련, 쇳물 붓기, 주물 다듬기 등 단계별 주조 공정에 사용된 재료 및 도구 분석과 제작 기술에 담겨진 과학 기술 원리를 규명하여 우리 고유 철 주조기술의 기술 체계를 밝혀 보았다. 그리고 무쇠솥 도토주조를 위해 이용한 재료와 완성품을 과학 분석한 결과, 거푸집은 주성분이 SiO₂, Al₂O₃, Fe₂O₃으로 이루어진 진흙과 모래이고, 이형재는 SiO₂, Al₂O₃, Fe₂O₃, K₂O가 함유된 흑연이며, 완성된 무쇠솥의 미세 조직은 시멘타이트(Fe₃C)와 펄라이트(페라이트와 시멘타이트의 층상 구조)로 이루어진 백주철 조직임을 확인하였다.

• 한국재료학회지
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• 제20권1호
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• pp.42-46
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• 2010

Phosphorus exhibits considerable segregation in steelmaking slag. In order to recover phosphorus from slag to $K_3PO_4$ via molten iron, a carbothermic reaction using microwave heating was suggested recently. The carbothermic reduction of phosphorus from slag to molten iron using microwave heating was carried out at 2073K. However, at this temperature the thermodynamic properties of both slag and molten iron cannot be determined experimentally. Therefore, the computational approach of the so-called CALPHAD method is very useful to understand the transfer of phosphorus from slag to metal and to enhance this reaction. In the present investigation, a theoretical study of the reduction behavior of phosphorus in slag was carried out at much lower temperatures using the recently developed thermodynamic database in the FactSage program. The calculated results showed reasonable accordance with the experimental data; namely, the thermodynamic database could be applied successfully to higher temperature reactions. The current study found that higher temperature and high $SiO_2$ concentration are favorable for the recovery of phosphorus from slag.

• 한국표면공학회지
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• 제36권5호
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• pp.364-372
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• 2003

In continuous galvanizing process, dissolution of iron into molten zinc results in a fairly great amount of dross. In order to decrease dross, the amount of dissolved iron of strip in molten zinc was investigated in the range of 0∼0.22%Al content, 440∼$470^{\circ}C$ strip temperature and 3∼60 sec dipping time. Uniform Fe-Al-Zn inhibition layer was formed in the coating layer/strip interface not only in the grain boundary but also in the grain of substrate with the increase of Al content in the zinc pot, while the amount of iron dissolution was decreased. Inhibition layer was unstable as the dipping time and strip temperature increased and the amount of iron dissolution increased.