지지체 및 SPS를 이용하여 제조된 다기공 BCP 생체재료의 특성

이택 전북대학교 일반대학원 2016 국내석사

Ceramic-based biomaterials are useful as implant materials in orthopedic surgery. Among them, HA (hydroxyapatite)/β-TCP (tricalcium phosphate) biomaterial (BCP; biphasic calcium phosphate) is widely used as bone cement or scaffolds due to their superior biocompatibility. However, implants as bone scaffolds also need to consider mechanical properties such as hardness, strength and Young’s modulus. Lower Young’s modulus of BCP is an important factor to reduce the stress-shielding phenomenon. In order to reduce Young’s modulus, NH4HCO3 as space holder (SH) was used and feasibility assessment of porous structured BCP as bone scaffolds was evaluated. In this study, porous HA/β-TCP biomaterials were successfully fabricated using HA/β-TCP powders with 10~30wt% SH, TiH2 as a foaming agent and MgO powder as a binder by using spark plasma sintering (SPS) process at 393K and 1373K under 20MPa load. The effect of SH content on the pore size and distribution of the BCP biomaterial was observed by scanning electron microscopy (SEM) and microfocus X-ray computer tomography system (SMX-225CT). These microstructure observations revealed that the volume fraction of the pores increased with increasing SH content. The elongated pore size of the BCP biomaterials is about 400~500μm. But the relative density of the BCP biomaterial increased with decreasing SH content. The porous BCP biomaterial fabricated with 30%SH exhibited similar elastic modulus to cortical bone, but compression strength is higher than that of cortical bone.

열처리를 통한 Ti-6Al-4V 주조재 합금의 기계적 성질 개선

오성탁 전북대학교 일반대학원 2016 국내석사

Titanium alloys have been used in a number of parts as not only aerospace components but also marine and biomedical applications due to lightweight, high specific strength, and corrosion resistance. Particularly, Ti-6wt%Al-4wt%V alloy which is one of α+β titanium alloys has been utilized in the various applications due to its excellent combination of strength and ductility. In addition, Ti-6Al-4V alloy is heat-treatable to develop a variety of microstructure and mechanical property combinations. Thus, in wrought Ti-6Al-4V alloy, the improvement of their mechanical properties by a heat treatment has been studied for a long time. However, in cast Ti-6Al-4V alloy, it is still required to study on heat treatment process and strengthening mechanism to derive the increased strength and ductility of cast Ti-6Al-4V alloy. From the above viewpoint, in this study, the microstructure refinement which is one of the strengthening mechanisms is applied to improve the mechanical properties by the heat treatment on cast Ti-6Al-4V alloy. Additionally, the effect of the heat-treatment condition and stabilizer partitioning (Al,V) on the microstructure control and phase transformation of the β phase was investigated. Moreover, the further strengthening mechanism was investigated to obtain the improvement of the strength and ductility. The precipitation strengthening by α2 (Ti3Al) precipitates is well known in Ti-6Al-4V alloy to improve the further mechanical properties. However, it needs a long time to precipitate the α2 phase. To overcome this disadvantage, the short-time aging treatment was performed after the solution treatment in present study. With the relatively short aging time, the further strengthening mechanism of the retained β phase on microstructure and mechanical properties was investigated. From the results in present study, the microstructure of cast Ti-6Al-4V alloy was greatly refined through the solution and subsequent aging treatments due to α and β phases decomposed from α' martensite. As well as, the microstructure control was determined by the prior solution treatment. The solution heat-treated microstructure and phase transformation of the β phase was strongly dependent on the concentration of vanadium in the β phase in cast Ti-6Al-4V alloy. Furthermore, although the short-aging treatment for 5 minutes was conducted, its combination of tensile strength and elongation was further improved, relatively compared to that of aged specimen for 1440 minutes. Its effects and reasons were discussed in present study.

Co-Cr-Mo합금의 미세조직, 기계적 성질과 생체적합성에 미치는 접종제 첨가의 효과 : Effect of Inoculant Addition on Microstructure, Mechanical Properties and Biocompatibility of Co-Cr-Mo Alloy

이해철 전북대학교 일반대학원 2016 국내석사

The developments for artificial biomaterials have been progressed since the beginning of the 20th century to satisfy a lot of demands for substitute of a body. Especially, as-cast Co-Cr-Mo alloy(ASTM F75) has been widely used as biomaterial in orthopedic implant due to its excellent mechanical properties, good corrosion resistance and biocompatibility. As-cast Co-Cr-Mo alloy consists of mainly Co, Cr, Mo and C elements. The mechanical properties of this alloy depended on the phase state of Co, the size of grains, the shape of precipitate and some defects formed during casting. Actually, some casting defects such as porosity, pinhole make some problems for application. So, these casting defects mainly cause the destruction and breakage during usage. Therefore, it is an important for Co-Cr-Mo alloys to decrease the casting defects. Many authors are trying to decrease these defects in as-cast Co-Cr-Mo alloy by heat treatment such as solution heat treatment and aging treatment, by addition of inoculant and by application of hot isostatic pressing(HIP). In this paper, inoculant(Cobalt-aluminate, CoAl2O4) was added to Co-Cr-Mo alloy to decrease casting defects and reduce the grain size. This method is very useful to decrease the casting defects and to refine the grain size. We confirmed that the microstructure of Co-Cr-Mo alloy consists of ε-Co(HCP) phase, γ-Co(FCC) phase, σ(CoCr) phase, carbides and lamellar structure(Co phase+carbide). Also, the grain size of this alloy was refined without a change of phase transformation according to inoculant addition. So, mechanical properties of as cast Co-Cr-Mo alloys were improved by addition of inoculant. Inoculant was also known to act as the grain refinement and act as degassing of Co-Cr-Mo alloy. In addition, microstructure and mechanical properties of inoculant added Co-Cr-Mo alloy were changed by conducting heat treatment.

Ti 합금의 조직, 기계적 성질 및 생체 적합성에 미치는 Mo, Mn, Nb 첨가의 영향

이응범 전북대학교 일반대학원 2016 국내박사

In order to study the effect of Mo, Mn, Nb addition on the structures, mechanical properties, corrosion behavior and biocompatibility of commercially pure titanium (CP-Ti), Ti-5∼20 wt.% (Mo, Mn, Nb) alloys were investigated. The phases and structures were characterized by X-ray diffraction, optical microscopy, scanning electron microscopy and transmission electron microscopy. The results indicated that the Ti-5wt.%Mo alloy was mainly composed of ɑʹ phase with a small fraction of ɑʹʹ phase. The orthorhombic ɑʹʹ phase in the Ti-10wt.%Mo alloy was dominated. The structure of Ti-15wt.%Mo alloy was mainly composed of ɑʹʹ phase with a small fraction of β phase. The volume percentage of the β phase increased with increasing Mo content. The structure of Ti-20wt.%Mo alloy was mainly composed of β phase. The effect of Mo in pure Ti on the hardness and corrosion behavior of Ti-xMo (x=5, 10, 15, 20 wt.%) alloys has been investigated. The addition of Mo in CP-Ti increased hardness. But the hardness of Ti-20wt.% alloy was decreased. Electrochemical results showed that the Ti-xMo alloys improved corrosion resistance. Elastic modulus obtained by compression test of Ti-15wt.%Mo alloy was 261.94 GPa. In XRD result of Ti-5wt.%Mn alloy, ɑ-Ti was dominant phase with a weak shoulder peak of β-TiMn. In the higher Mn added Ti-Mn alloys, eutectoid structures, ɑ-Ti + β-TiMn and/or α-TiMn intermetallic compound, were observed with primary ɑ-Ti. Moreover, Ti-20wt.%Mn alloy showed amorphous phase peaks by XRD results. Vickers hardness of Ti-xMn alloys were significantly increased compared to that of CP-Ti(156 VHN) (p<0.05), and hardness increased with increasing Mn content. In all of Ti-Mn alloys, Ti-20wt.%Mn alloy showed the highest hardness (561 VHN). Ti-15wt.%Mn alloy showed more anodic Ecorr(-475.1mV vs SCE). Widmanstӓtten structure was observed in the Ti-5wt.%Mn and Ti-10wt.%Mn alloys. In Ti-10wt.%Mn alloy, the length of ɑ-Ti lamellar was shorter than that of Ti-5wt.%Mn alloy. Martensite structure was observed in the Ti-15wt.%Mn alloy, and the structure tended to become more single phase. Elastic modulus obtained by compression test of Ti-15wt.%Mn alloy was 293.79 GPa. In the XRD results of the Ti-5wt.%Nb and Ti-10wt.%Nb alloys, ɑ-Ti phase with weak appearance of β-Ti peak were observed. The intensities of β-Ti peaks increased with increasing Nb content. Basket weave patterned lamellar structures were formed in the Ti-xNb alloys. As the Nb content increased, the lamellar became thicker and the portions of β-Ti phase increased. The Vickers hardness of Ti-xNb alloys showed two times higher values than CP-Ti(p<0.05). All the Ti-xNb alloys showed higher Ecorr values compare to CP-Ti(p<0.05, except of Ti-10wt.%Nb), and Ti-5wt.%Nb showed the highest Ecorr value among all of specimens. Elastic modulus obtained by compression test of Ti-15wt.%Nb was 242.38 GPa. Biocompatibility of Ti-15wt.%Mo(or Mn or Nb) alloys was good.

전자기 펄스 스폿 용접을 이용한 이종 판재 접합부의 미세조직과 기계적 성질에 미치는 공정조건의 영향

김인봉 전북대학교 일반대학원 2016 국내석사

Melt-welding (spot welding, arc welding, etc.) is more than 80% of a typical vehicle body welding the welding process to be applied to the automotive industry. The recent worldwide international oil and energy prices and environmental regulation has been the case in the automotive industry, which is closely related to strengthening the use of lightweight materials for automotive fuel efficiency, led by the developed countries as the automobile body reduce this important increase. In general, the weight material being applied to the car high strength steel, aluminum, magnesium, which has the problem of bonding properties, particularly in the case of a typical aluminum of light weight material spot frequent defects caused during welding, low resistivity and high electrical conductivity the result can affect the decrease in the strength and durability of the vehicle body weld a new bonding process technology which can compensate for this is required because welding is a very demanding for a short time high current conduction is required, solid phase welding to solve the problem kinds of electromagnetic pulse welding process (Magnetic Pulse Spot Welding) technique has been reported as an ideal alternative. The purpose of this experiment was to affect the Magnetic pulse welding using the Magnetic pulse spot welding (Magnetic Pulse Spot Welding) offer and the high strength steel plate that is being applied to the actual car weight material aluminum two kinds of sheet material using conventional Magnetic pulse welding the arguments to the charging energy, cable length, Air gap according to the process conditions, such as the surface characteristics and mechanical properties of the joint and to examine how the impact. In order to study the above the process condition such as the charge energy of 4.9kJ~26.7kJ and the weld distance of the 1.0, 1.5, 2.0mm in a welding test it was performed. Using a Bonding material of Al 1050 0.5mm, Al 5052 0.5mm and the base material of TRIP 590 Steel was subjected to the welding test. Each process specific specimens were analyzed using optical microscopy, scanning electron microscopy, shearing test, peel test, etc. In order to examine the microstructure and mechanical properties.

Space holder를 첨가하여 급속소결법으로 제조된 다공성 Ti-Zr 생체재료의 미세조직 및 기계적 성질

곽승미 전북대학교 일반대학원 2017 국내석사

티타늄 합금은 우수한 기계적 성질 및 생체 적합성 때문에 생체재료로서 널리 사용되어져 왔다. 그러나 Ti의 탄성계수는 100 ~ 120 GPa로 생체 내 뼈의 탄성 계수 (10 ~ 30 GPa)보다 높은 값을 갖는다. 이러한 경우, Ti과 생체 내 뼈의 탄성계수의 차이로 인한 응력 차폐 효과가 발생하게 된다. 따라서 인체 내 뼈와 유사한 탄성계수를 갖는 Ti 생체 재료를 개발 해야 할 필요성이 있다. 본 연구에서는 Ti 분말에 인체 내에서 독성을 유발하지 않는 Zr 분말을 첨가하여 우수한 생체 적합성을 갖는 동시에 탄성계수가 낮은 Ti-Zr 합금을 제조 하였다. Space holder 법은 Ti-Zr 생체재료에 기공을 형성하여 탄성계수를 낮추는데 사용되었으며, 본 실험에서는 NaCl이 Space holder로 사용되었다. NaCl 분말은 200rpm, 350rpm으로 4h 동안 고에너지 밀링기로 밀링한 Ti-10wt%Zr 분말에 각각 5wt%, 15wt%, 30wt%의 비율로 혼합 하여 24h동안 혼합하였으며, 혼합 분말을 SPS (Spark Plasma Sintering)를 사용하여 973K 및 35MPa에서 소결하였다. 소결 된 시편은 293K의 증류수에 하루 동안 담가 NaCl을 녹여내었으며, NaCl이 녹은 자리에 기공에 형성됨으로서 다공성 Ti-Zr 합금을 제조하는 데 성공하였다. 형성된 기공의 형태는 광학 현미경 및 3D-CT촬영에 의해 관찰되었으며, 압축 강도 및 탄성계수는 압축 시험에 의해 측정되었다. 실험 결과 Space holder로 사용된 NaCl 분말을 첨가한 비율이 높아짐에 따라 기공률 또한 증가하였으며, 기공의 증가함으로 인해, 압축강도 및 탄성계수는 감소하였다. 200rpm으로 밀링한 분말과 350rpm으로 밀링한 분말을 비교해 보았을 때 350rpm으로 밀링한 분말로 실험을 진행한 경우 미세해진 분말입자로 인해 소결성이 증가하여 압축강도가 우수한 소결체를 제조할 수 있게 되었으며, 그 값은 인체 내 경골과 유사한 값을 나타내었다. Titanium alloys have been widely used as biomaterials because of their excellent mechanical properties and biocompatibility. However, the elastic modulus of Ti and Ti alloys are 100 ~ 120 GPa, which is higher than the elastic modulus of cortical bone (10 ~ 30 GPa) and trabecular bone(0.04-1GPa). In this case, the stress shielding effect was occurred due to the difference in elastic modulus between Ti and the human bone. Therefore, there is a need to develop a Ti biomaterial having elastic modulus similar to that of a human. In this study, Ti-Zr alloys with adequate biocompatibility and low elastic modulus were prepared by adding Zr powder which did not cause poisoning when the Ti powder eluted in the human body. The space holder method is one of methods to lower the elastic modulus by forming pores in the biomaterials. In this study, NaCl which is no toxic materials in the body was used as a space holder. NaCl powders were mixed at ratio of 5 wt%, 15 wt%, and 30 wt% for 24 h with Ti-10 wt% Zr high energy ball milled powder for 4h. The mixed powders were sintered at 973K for 5min under 35 MPa by SPS (Spark Plasma Sintering). The sintered specimen was immersed into 293K of the distilled water for one day to dissolve NaCl, and the porous Ti-Zr alloy was successfully produced by forming pores in the warm water. The shape of the formed pores was observed by optical microscopy and 3D-CT. The compressive strength and elastic modulus were measured by compression test. As a result, the porosity increased with increasing NaCl amount as space holder. The compressive strength and elastic modulus of the porous Ti-Zr alloy decreased with decreasing the porosity. By increasing the milled speed from 200rpm to 350rpm, the sinter-ability of milled Ti-Zr powders was increased due to the fine powder particles. The sintered the porous Ti-Zr alloy has excellent compressive strength indicated with similar values to the cortical bone in the human body.

마찰교반공정으로 제작된 강재의 표면개질부의 기계적 성질과 미세조직 관찰

김상혁 전북대학교 일반대학원 2016 국내박사

In many industries, surface modification methods as carburizing, nitriding and surface heat-treatment by laser or high frequency induction were used. By surface modification, surface of press mould, auto parts and other metallic materials were hardened with ductile matrix. However, the such methods need high processing temperature and long manufacturing time. Therefore, friction stir process (FSP) is one of methods to dissolve these problems. Because surface modified by FSP method improves mechanical properties such as strength, hardness and wear resistance by using frictional heat and plastic deformation. In this study, the surface modification of commercial steels was conducted by friction stir process. In the chapter 3.1, sound FSP conditions to modify the surface without defect were founded through observations of microstructure and mechanical properties of FSP zone. Optical microscope and scanning electron microscopy were used to observed microstructure. Mechanical properties such as tensile strength, hardness and impact energy were measured by tensile test, hardness tester and impact tester respectively. In the chapter 3.2, surface modification of SUS 409 steel was conducted by FSP. The SUS 409 steel is not phase transformation during FSP. But microstructure was changed by FSP due to frictional heat and plastic deformation. The residual stress of FSP zone was similar to that of base metal (BM) due to release the stress by dynamic recrystallization. And compressive residual stress was formed at thermal-mechanical effected zone (TMAZ). Therefore, fatigue property of FSPed specimen was improved to the BM. In the chapter 3.3, the effect of carbon content on phase transformation of mild steel (SS400 steel) and carbon steel (SM45C steel) by FSP was observed. The phase transformation of FSP zone was analysed by using XRD and EBSD. And the mechanical properties of FSP zone was measured by hardness test and impact test. The microstructure of FSP zone of SS400 steel was ferrite like BM. However, the FSP zone of SM45C steel consisted of ferrite, pearlite and martensite unlike BM. Also, the hardness, impact properties of FSP zone of SM45C steel were higher than that of FSP zone of SS400 steel. Those are because FSPed SM45C was the formation of martensite phase and smaller grain size than FSPed SS400. In the chapter 3.3~4, the addition effect of WC powder in SM45C steel on microstructure of friction stir processed zone was observed. Friction stir process (FSP) was conducted, 400 RPM and 100~150 mm/min. The mechanical properties and microstructure of friction stir processed zone of SM45C steel were analyzed. Mechanical properties as hardness, tensile and abrasion properties of FSPed specimen with WC powder were measured by Rokwell hardness test, tensile test and abrasive wear test. And optical microscope and scanning electron microscopy was used to observed microstructure. By addition of WC powder in SM45C steel, hardness and wear property og FSPed specimen improved.

기계적 혼합에 의한 플라즈마 용사용 ZrO2-8%Y2O3 분말의 제조 및 특성

한진원 전북대학교 일반대학원 2013 국내석사

Thermal barrier coatings (TBCs) are being applied in many industry fields such as thermal power generation, aviation sector, and seasonal field. Stabilizers of ZrO2 are CaO, MgO, Y2O3, CeO2 and full stablized ZrO2 are being used on material of thermal barrier coating. ZrO2-8%Y2O3 thermal spray powders are commercially used for thermal barrier coating materials. Materials used in the thermal barrier coating need to low thermal conductivity and the thermal stability at high temperature. In order to improvement an efficient productivity, a high operating temperature is needed in the field of thermal power when power is being produced by gas turbine. The gas turbine blade materials are high heat-resistant alloys, but these materials i can be oxidized and corrided for long time usage. Therefore thermal barrier coatings are used to protect oxidation and corrosion of heat-resistance alloys at high temperature. Currently ZrO2-8%Y2O3 thermal spray powder is made ​​through the following processes in industry. Main method used in industry is coprecipitation method using yttria-stabilized zirconia powder synthesis. And the spherical granules manufactured by calcination, crushing, spray drying and heat treatment process. However the process might be introduced impurities during fabrication process. And this process is very complex and needs to a lot of time. In this study, orthorhombic ZrO2 and Y2O3 powders have been fabricated easily by the mechanical mixing method instead of using complex powder synthesis through existing coprecipitation method. ZrO2 granular powder mixed with Y2O3 was produced through spray drying method during plasma spraying process. These composite powders can be solid solution state by solid-solid reaction exposed at high temperature. Thies experimental results can use in the industry economically. Because there is no necessary to make ZrO2-8%Y2O3 composite powder by liquid phase and gas phase methods.

급속소결로 제조한 Ti-Nb-X(Zr,Mo)/CPP 생체재료의 조직, 기계적 성질 및 생체 특성

김상미 전북대학교 일반대학원 2013 국내석사

Ti-6Al-4V ELI (Extra Low Interstitial) alloy have been widely used as alternative bone due to its excellent biocompatibility, although it still has some problems such as high elastic modulus and toxic. Al and V elements are known as harmful elements on biomaterials. Therefore, biomaterials with low elastic modulus and non-toxic elements has to be developed. Non-toxic elements such as Nb, Ta, Zr, Mo, Pt and Sn are appropriate selections for designing new Ti alloys with low elastic modulus. The aim of this study is to fabricate two types (Ti-Nb-Zr-CPP and Ti-Nb-Zr-Mo-CPP) of biocomposite. And to improve the reaction between Ti-Nb-Zr-CPP composite and body tissue, surface of composite was made porous by several kinds of leaching solution at room temperature for 24h. In this study, the raw materials of Ti, Nb, Zr with or without CPP and Ti, Nb, Zr, Mo with or without CPP were blended in a mixing machine for 24h and milled in a high energy mechanical ball milling of 1h, 4h, 6h and 8h respectively. Ti-Nb-Zr-CPP and Ti-Nb-Zr-Mo-CPP composites were successfully fabricated by spark plasma sintering (SPS) at 1000˚C under 60MPa using mixed and milled powders. The effects of CPP contents and milling time on biocompatibility and mechanical property have been investigated. By X-ray diffraction (XRD), chemical reaction during the sintering was occurred and formed new phases, Ti2O, CaO, CaTiO3, and TixPy. Vicker's hardness of composites increased with increase of milling time and addition of CPP contents. Biocompatibility of Ti-Nb-Zr-(Mo) alloys was improved by addition of CPP.

고대 정련 및 단야 공정 슬래그의 금속학적 연구 : 나주 복암리 유적을 중심으로

송정일 전북대학교 일반대학원 2012 국내석사

The iron production in the Honam region from 3rd century to 6th century, carry out the refining and forging of iron which utilized smelt material imported from outside the Honam region. Naju Bogam-ri remains of iron production facilities and slag found in the first time Honam region is significant. Iron production technology in the development of ancient societies played an important role. Therefore, we analyzed slag of the remains of iron manufactured on ancient times using modernized analysis tools. Iron was obtained in ancient times by what is known as the low temperature reduction process, reduction takes place at a lower temperature than that at which iron fluxes (1,536℃). The conditions in the ancient smelting furnace had to be very reductive and this was achieved by filling the furnace with charcoal (with iron oxide and fluxes). It had to have an exit to evacuate the slag from the gangue (1,100∼1,200℃). The result of this operation is the bloom iron. This product was not very homogenous and contained a lot of slag so hammering was necessary to build up the metal. Thus, Slag generated from low-temperature reduction will remain in the iron production process. From The contents of Fe and The modified rate (SiO2+Al2O3+CaO+MgO) containing to the iron slag, we can presume the extent of refinement technology of ancient times. It is possible to distinguish smelting ash, forging ash and casting ash using a metallurgical microscope. The use of scanning electron microscopy (SEM) is proposed to observe surface images of the slag to determine their morphological, microstructural and topographic characteristics to obtain valuable information on the materials studied. The study also proposes chemical analysis of the elements in the slag by X-ray microanalysis(EDS) which provides both qualitative and quantitative information. And X-ray diffraction analysis recognize the chemical compound of slag. This study contain analysis result of slag excavated from No.1 Irregular pits and No.3 Smithery hearth, No.4 Pit. We can know the characterization of the slag excavated from the Purifing and forging remains in Bogam-ri, Naju The total Fe content of Bogam-ri, Naju, can be observed most 58∼64% and The modified rate is most 6∼17% by chemical analysis results. Ancient the total Fe content is 30∼50% is, The modified rate is 17∼40%. the product of low temperature reduction process was not very homogenous and contained a lot of slag so hammering was necessary to build up the metal. In this process, Iron content in the slag was increased higher. Because of this, total Fe content is the increased higher. The modified rate is an ingredient that helps the fluidity of slag and the separation of metals. The modified rate in refining and forging processes is not necessary for function. For this reason, the content of The modified rate is low. As a result of XRD and the microstructure analysis, Fayalite,Magnetite, W&uuml;stite was widely detected in the slags (slag 1, slag 3, slag 4, slag 7, slag 8, slag 9). We could know the refining ash and the forging ash produced during refining and forging work from these results. Microstructure of iron ore 10 was observed in the magnetite and glassy. Microstructure of Furnace wall 6 and 11 was observed in the magnetite and glassy. In the XRD results, Cristobalite and Mullite of temperature minerals were detected. Due to this reason, the furnace temperature of 900 degrees or more would have been. The microstructures of oxide layer in the hammer scale 2 and 5 were found to have crucial information about ancient iron forging process treatment. The microstructure observed in hammer scale can be distinguished by the forging process. First, the microstructure of the oxide layer in the hammer scale 2 created by the forging process is W&uuml;stite (FeO) in the form of leaves. Latterly, the microstructure of the W&uuml;stite(FeO) in the hammer scale 5 is observed to be in the form of a flat shape formed by a repeating forging process. These results, Naju Bogam-ri remains were the production technology of iron refining process and forging processes. 3∼6세기의 고대 호남지역은 외부에서 유입된 철 소재에 대한 정련 및 단야 공정을 중심으로 철기생산이 이루어진 것으로 보고 있다. 나주 복암리 유적의 정련 및 단련단야 공정 슬래그 및 단야노지(鍛冶爐址)의 발굴은 호남 지역 최초로 철기 생산과 관련된 노가 발견되었다는 점에서 그 의미가 크다. 제철기술은 고대 사회의 발전에 중요한 역할을 하는 기술적 요소이다. 따라서 나주 복암리 정련 및 단야 관련 유적 슬래그를 현대적인 금속학적 분석을 통하여 살펴보았다. 고대 철은 저온환원법이라고 알려진 방식으로 얻어졌는데, 이때 철의 환원은 철의 융점(1535℃)보다 낮은 온도에서 발생한다. 고대 제철로의 철생산은 노에 목탄(산화철, 융제와 함께)을 넣어 환원분위기 조성한다. 철광석로부터 슬래그를 배출한다. 이러한 결과물로서 괴련철을 얻는다. 괴련철은 균질하지 않고 내부에 많은 슬래그를 포함하고 있어 순수한 금속 철을 만들기 위해선 담금질이 필요하다. 이러한 저온환원법에서 생성된 슬래그에는 철 생산 과정이 남게 된다. 슬래그에 함유된 전철량 (Total-Fe) 및 조재량(SiO2+Al2O3+ CaO+MgO)을 통해 고대 철 생산의 효율을 추정할 수 있고 금속현미경의 미세조직에 따라 제철 슬래그, 주물슬래그, 단야 슬래그로 구분하여 고대 철 생산 공정을 파악할 수 있다. 또한, 주사전자현미경(SEM)은 샘플의 표면 이미지를 관찰하고 원료를 연구할 때 중요한 정보가 되는 원료의 형태, 구조, 표면관찰을 하였고, 에너지분산분광계(EDS)를 통하여 슬래그의 성분을 파악였다. X선 회절분석(XRD)를 이용하여 화합물상태를 구분할 수 있다. 본 연구는 5∼7세기 나주 복암리 유적에서 나온 단야공정슬래그(폐기장의 1호 부정형 수혈, 3호 단야 로와 4호 주구(周溝))를 대상으로 금속학적 분석을 실시하였다. 고대 철 생산의 전철량은 30∼50%, 조재량은 17∼40%으로 나주 복암리 슬래그의 성분 분석 결과와 비교했을 때 나주 복암리 슬래그의 전철량이 더 높고, 조재량은 더 낮은 결과 치를 나타낸다. 나주 복암리의 철 생산 공정은 정련 및 단련단야의 철 생산 과정으로 저온환원법에서 생산된 괴련철(sponge iron, 塊鍊鐵) 또는 선철(pig iron, 銑鐵)의 빈공간 사이에 있는 슬래그를 제거한다. 이러한 정련 공정을 통하여 다량의 철 성분이 슬래그에 잔류되어 전철량이 높게 된 것으로 사료된다. 나주 복암리의 전철량 성분은 58∼64%이다. 조재 성분(SiO2+Al2O3+CaO+MgO)은 슬래그의 유동성을 좋게 해주어 슬래그와 금속 철의 분리를 원활하게 하고, 제철시 용융온도를 낮춰주어 작업을 쉽게 이루어 질 수 있도록 한다. 나주 복암리의 철 생산 과정은 정련 및 단야 공정으로 제철 공정과 같은 철광석에서 금속철을 분리하기 위한 조재 성분의 보충이 불필요하여 고대 조재량에 비해 낮아 진 것으로 사료된다. 나주 복암리의 조재량 성분은 6∼17%이다. 화합물과 미세조직을 관찰한 결과,슬래그 1, 슬래그 3, 슬래그 4, 슬래그 7, 슬래그 8, 슬래그 9의 미세조직은 회색장주상의 Fayalite가 나타나고 Magnetite와 입상의 W&uuml;stite 상이 나타나 는 것으로 보아 정련 및 단야 작업 중에 발생 한 정련 및 단야슬래그로 판단된다. 철광석 10의 미세조직은 다각형의 마그네타이트(Fe3O4)와 기지 조직으로는 유리질이 관찰되었다. 노벽 6, 노벽 11의 미세 조직에서도 다각형의 마그네타이트의 자철광 일부가 노벽의 유리질 기지에서 관찰되었다. 또한, XRD 결과에서 뮬라이트(3Al2O3·2SiO2)와 크리스토발라이트(SiO2)의 고온 지시 광물이 확인되었다. 900℃이상의 고온지시 광물을 통해 노의 소성온도가 높았을 것으로 추정해 볼 수 있다. 단조박편 2와 단조박편 5는 단조박편으로 단련단야 작업 과정에 중요한 정보를 나타낸다. 미세조직 관찰 결과에서 단조박편 2의 단조박편은 내부층에 나뭇잎 형태의 뷔스타이트 조직이 뚜렷하게 나타나는데, 이는 단련단야 전반 단계에 해당한다. 단조박편 5의 단조 박편의 미세조직은 단련단야 후반 단계로 반복 단조가 진행 되면서 내부층의 뷔스타이트가 응집되어 압착된 형태의 미세조직이 관찰된다. 이상의 결과를 통해 나주 복암리 유적에서는 철 소재를 정련 하여 생산된 중간 소재를 가지고 단련단야 가공하여 최종 철제품을 생산하였던 철 생산 기술이 시행하였던 것으로 보여 진다.