철탄화물의 분해속도에 미치는 Si , Mn 및 Cr 의 영향

김동의 ( Dong Ui Kim ) 한국주조공학회 1985 한국주조공학회지 Vol.5 No.3

Decarburization phenomena were investigated at 800 ℃ by the PH₂O/PH₂+Ar gas mixture in the case iron range which contains Si, Mn and Cr as an alloying elements. Dissociation of cementite in a matrix which contains graphitizer as Si begins at the carbon rich cementite dendrite arms. Several primary austenite (γ) skeletons are surrounded by those nucleated graphite nodules, and that forms a limited area of nucleation region. Decarburization reactions at 800℃ in Fe-C, Fe-Mn-C and Fe-Cr-C alloy are followed by parabolic rate law under the gas mixture of PH₂O/PH₂=0.01 and the modified rate const. k were in the range of 1∼6×10^(-10)㎠/s.

Ar-CO2 Plasma 에 의한 강의 (鋼) 정련 (精鍊)

장석영,김동의 ( Sek Young Chang,Dong Ui Kim ) 한국주조공학회 1986 한국주조공학회지 Vol.6 No.4

Decarburization phenomena have been studied by plasma in stainless steel, plain carbon steel and cast iron. It was also investigated the movement of impurity element P,S in the plasma jet metal pool. The plasma jet was obtained by Ar - CO₂ gas mixture with 5 kVA DC power source. It produced enough temperature to dissociate into activated oxygen atom by reaction of CO₂↔ CO + O^+ and it reacted with C_ in metal pool. Decarburization rate was increased about 5 times in comparing with the conventional induction melted metal pool by CO₂gas decarburization. Even under the Ar plasma jet, decarburization was obtained by agitation of metal bath by Ar^+ bombardment and dilution phenomena of carbon atom under the very high plasma temperature. But heavy element P and S are not much removed because they are too heavy in mass to be activated by Ar^+ ion bombardment. Desulphurization was achieved by Ar - CO₂ plasma in plain carbon steel and cast iron by the reaction of SO₂(S_ + O^+). But dephosphorization could not be obtained by Ar- CO₂ plasma, because gaseous reaction of phosphorous oxide (P_ + O^+) was not existed.

TPV 소재 웨더스트립 2D 형상 최적설계 자동화해석 기법연구

박상철(Sangcheol Park),박정원(Jungwon Park),신종현(Jonghyun Shin),김성술(Sungsool Kim),김동의(Dong-ui Kim) 한국자동차공학회 2017 한국자동차공학회 부문종합 학술대회 Vol.2017 No.5

Fe-Mn-C 삼원계 합금에서 Mn 과 C 원자의 확산

김동의 대한금속재료학회(대한금속학회) 1984 대한금속·재료학회지 Vol.22 No.10

Interdiffusion coefficients of manganese D~ were investigated as the functions of solute atom of Mn in FCC-γ phase of Fe-Mn-C ternary alloy at 950℃ and 1000℃ by using the vapour-solid couple method. D~ are gradually increased by the addition of Mn and the values are in the range of D~=0.040-0.240x10^(-10)㎠/s. Diffusion of Mn atoms are accelerated in the matrix which has contained C atoms, but the increment in D~_(Mn) with increasing Mn concentration is lessened in the matrix which has contained C and Mn atoms. In order to study the intrinsic diffusion phenomena, the diffusivity of Mn atoms D_(Mn) were calculated by the equation of Darken and Manning with the thermodynamic factor and structure factor. The difference between D~_(Mn) and D were in the range of 10-40%, and it's tendency was increased with the concentration of Mn.

熔融狀態에서 크롬鋼의 脫炭反應

金哲弘,金東義 慶北大學校 産業開發硏究所 1995 硏究報告 Vol.13 No.-

This study has been undertaken to clarify the decarburization phenomena of liquid chrome steel under reduced pressure. The study has been especially directed toward determining the rate-controlling steps of decarburization reaction. Chrome melts containing 0.20∼0.30% carbon decarburized by blowing the different oxygen potential gases such as CO_2, Ar-O_2 gas mixture and pure O_2 gas at 1620℃ under 100∼400 Torr and also the change of C, Cr and O contents was observed. The aspects of the mechanism of decarburization of molten chrome steel under the reduced atmosphere are summarized as follow; The decarburization by CO_2 blowing that is low oxygen potential, is controlled by the mass transfer in gas site. The decarburization by blowing Ar-O_2 gas mixture and O_2 are conceived to be carried on according to following reaction model. C+1/2O_2(g)→CO(g) xM+y/2O_2(g)→MxOy MxOy→xM+yO C+O→CO(g)

철탄화물의 생성에 미치는 합금원소의 영향

김동의 대한금속재료학회(대한금속학회) 1985 대한금속·재료학회지 Vol.23 No.2

The diffusion of silicon and carbon atoms was studied in γphase of Fe-Si-C ternary alloy at 1000℃ under the steady-state condition. Diffusion cell assembly, essentially, consisted of a thin sheet of pure iron and a silicon powder (60 mesh) which was packed on one side of the membrane, while the other side was packed with manganese powder. Both sides of the pure iron membrane, were packed with 0.7 mm φcarbon rods to maintain the equal carbon potentials. Atomic rnobilitics of silicon were measured along each of the steady-state diffusion concentration profiles. Diffusion coefficient of silicon D_(22) was found to be, 39∼5.79×10^(-11) ㎠/s in Fe-2.8∼1.5 at. pct Si-2.2∼1.5 at, pct C system, where the diffusivity of silicon was increased by the addition of silicon and carbon atoms. Interstitial carbon atoms diffuse more rapidly than the substitutional silicon atoms. The carbon atoms on the gradient of slow moving component, will easily become a state of a transient equilibrium. The ratios of diffusivity of carbon D_(11) and cross term D_(12) were calculated by D_(12)/D_(11) ∼ 0.1∼0.19 at Yc=0.019∼0.021 in a Fe-Si-C alloy.

금속산화물 (W, Fe, Cr-Oxide) 의 In-Flight Plasma 에 의한 환원

김종대,김동의,최덕순 대한금속재료학회(대한금속학회) 1988 대한금속·재료학회지 Vol.26 No.12

The oxides of tungsten, iron, chromium are very strong carbide forming elements, therefore, it is a very useful method that their oxides are reduced by carbothermic In- Flight Plasma reduction. The experimental apparatus in the present study used a secondary nozzle and an electromagnet so that the plasma flame could rotate in the secondary nozzle. The variables of experiment were the amount and the sort of the reductants, size of feeding materials and the powder feeding rate. The reduced particles were collected in water cooled pipe and paper filter. By increasing the reductant ratio and the reduction ratio the fixed carbon content and free carbon content were increased. By increasing the powder feeding rate and the size of feeding material the reduction rates were decreased. The reduction rate of WO_(2.9) Fe₂O₃and Cr₂O₃were 80%, 90% and 20%, respectively, by the in-flight plasma process. The reduced particle size were below 0.03㎛ ; therefore, an ultra-fine powder could be obtained by the present in-flight plasma process.

Ar/H2 Plasma 에 의한 철산화물의 용융환원

김동의,정권표,조용환 대한금속재료학회(대한금속학회) 1988 대한금속·재료학회지 Vol.26 No.1

Reduction of molten iron oxide with Ar-H₂ plasma was studied using a DC 15KW power sourse. 50g of sample was melted by Ar plasma and reduced in a stream of Ar-H₂ gas, the flow rate of which was 17ℓ/min. Degree of reduction (R) was reached as much as 95% within 12 min by Ar-H₂(14%) plasma, and it was linearly propotional to both the reduction time and the partial pressure of hydrogen. Additives such as CaO, MaO, SiO₂ and A1₂O₃charged in the range of 1-20% showed only trivial effects, however in case of charging serpentine which contained same ratio of acid and basic components, there was a tendence to increase in the reduction degree Kch. Reduction rate constant was calculated, as a function of hydrogen concentration in the Ar-H₂Plasma, the 0.512. Reduction rate and gas utilization % were increased with the increase in plasma temperature, dissociation of H₂and gas ionization such as H→H^+ + e.

소결광의 하중연화 및 용융적하거동 (2)

김동의,조용환,김태동,신형기 대한금속재료학회(대한금속학회) 1992 대한금속·재료학회지 Vol.30 No.9

As an alternative way to investigate how iron ore sinter in a blast furnace behaves in the process of reduction and mineral formation during softening and melting, tests under loading of iron ore sinter in temperature ranges of 800℃ and 1515℃ have been made. It was found that iron ore sinter at basicity of 1.8 behaved fairly good, while that of 1.6 shrinked rapidly as compared with that at higher basicity. It was also found that metallic iron was readily reduced from Fe0 in temperatures below 1100℃ and over 1400℃, whereas the reduction was retarded in temperature ranges between 1100℃ and 1400℃, whereas the reduction was retarded in temperature ranges between 1100℃ and 1400℃. A mechanism on the formation of mineral phase and its transfer into slag were confirmed and analyzed from the phase diagram of CaO-SiO₂-MgO-10%Al₂O₃. The magnesio-wustite phase was found to be melted into a slag in temperature ranges of 1300℃ and 1400℃, thereby raising a dripping start temperature of the melt and enhancing a blast furance operation.

소결광의 하중연화 및 용융적하 거동

김동의,조용환,김태동,신형기 대한금속재료학회(대한금속학회) 1991 대한금속·재료학회지 Vol.29 No.4

The effects of bascity and MgO in iron ore sinter on softening and melting down behaviors under load were investigated. The optmum range of basicity in iron ore sinter for softening and melting down properties under load was considered 1.7∼1.8, which was confirmed on the phase diagram of CaO-SiO₂-MgO-10% Al₂O₃ system. Mineral phases melting at high temperature were formed with the increase of MgO in iron ore sinter, which affected the enhancement of starting temperature for softening and melting down, and the optimum concentration of MgO was confirmed at the vicinity of 1.8wt.% The melting down phenomena of iron ore sinter of homogeneous slagmelt processes during softening and melting down were able to be analyzed on the phase diagram of CaO-SiO₂-MgO-10% Al₂O₃ system.