Al-Cr-Zr nanocomposite metal powders were prepared by mechnical alloying (MA) in order to develop aircraft structure materials with lighter weight and lower cost than the conventional Ti and Ni alloys. The morphological changes and microstrutural evolution of Al-6wt.%Cr-3wt.%Zr nanocomposite metal powders during MA were investigated by SEM, XRD and TEM. The approximately 50m sized Al-Cr-Zr nanocomposite metal powders has been formed after 20 h of MA. The individual X-ray diffraction peaks of Al, Cr and Zr were broadened and peak intensitied were decreased as a function of MA time. The observed Al crystallite size by TEM was in the range of 20 nm, which is a simliar value calculated by Scherrer equation. The microhardness of Al-Cr-Zr nanocomposite metal powders increases alomost linearly with increase of the processing time, reaching a saturation hardness value of 127 kg/ after 20 h of processing. The intermetallic compound phase of in the matrix was identifed by XRD and TEM.

Three mixtures of elemental powders of Al-25at.%Ti, 48at.%Ti and 70at.%Ti were offered to ball milling process for the formation of intermetallic compounds of , AlTi and . Ballmilling or attrition process were carried out at the condition of rotaing speed of 110 or 350 rpm at torr vacuum or argon atmospheres. phases were fully obtained by heat treatment for 1 hors at with Al-25at.%Ti composition mixtures milled by 100 hours. The amorphous phase was completely formed at the composition of Al-48at.%Ti mixed powders by milling 100hours at the 50 to 1 weight ratio of ball to powder, and AlTi compounds were obtained by heat treament. In the case of Al-70at%Ti mixed powders milled for 100 hours, and intermetallic compounds were formed by heat treatment for 1 hour at . By attrition milling of 350rpm for 10 hours, phase was formed completley after heat treatment for 1 hour at .

The synthesis of titanium silicides (, , , and TiSi) by mechanical alloying has been investigated. Rapid, self-propagating high-temperature synthesis (SHS) reactions were observed to produce the last three phases during room-temperature high-energy ball milling of elemental powders. Such reactions appeared to be ignited by mechanical impact in an intimate, fine powder mixture formed after a critical milling period. During the high-energy ball milling, the repeated impact at contact points leads to a local concentration of energy which may ignite a self-propagating reaction. From in-situ thermal analysis, each critical milling period for the formation of , and TiSi was observed to be 22, 35.5 and 53.5 min, respectively. and , however, have not been produced even till the milling period of 360 min due to lack of the homogeneity of the powder mixtures. The formation of titanium silicides by mechanical alloying and the relevant reaction rates appeared to depend upon the critical milling period, the homogeneity of the powder mixtures, and the heat of formation of the products involved.

환원.확산법에 의해 Sm2Fe17Nx 계 희토류 영구자석을 제조하기 위한 기초연구로서, 우선 Sm2Fe17 금속간화합물의 제조를 위하여, 금속 Ca에 의한 Sm2O3의 환원반응과 Fe분말중에 Sm의 확산반응을 검토하였다. 그 결과 전자는 1000˚C이상의 고온의 경우에 매우 빠르게 완료되지만, 후자의 Fe분말의 중심까지 Sm의 확산반응의 완료(완전한 균질화조건)는 1100˚C에서 3h 정도의 R-D 반응이 필요하며, 이 확산반응이 전체반응에 있어서 율속단계임을 알았다. Sm-Fe 계의 금속간화합물들의 성장은 1000˚C이하에서는 SmFe2, SmFe3,Sm2Fe17금속간화합물의 3개의 상이 관찰되었으나, 1100˚C에서는 Sm2Fe17 금속간화합물의 상만이 관찰되었다. 본 연구에서 얻어진 최종시료의 산소 및 Ca량은 각각 0.72wt% 및 0.11wt%이었다.

Surface active properties of these aqueous Gemini surfactant solutions including surface tension, critical micelle concentration(cmc), foaming power, foam stability, emulsifying power and Krafft point were measured at given conditions. They showed excellent properties, being compared with conventional single-chain surfactants such as sodium dodecyl sulfonate(SDS). Their surface tensions in the aqueous solutions were decreased to 30~38 mN/m, which is lower than 39 mN/m of SDS, and their cmc values evaluated by surface tension method were 2.8×10-5~3.3×10-4 mol/L. These values were also much lower than that of SDS, 9.8×10-3 mol/L. The foaming power and foam stability, especially decyl and dodecyl compounds, were good and the emulsifying power in benzene or soybean oil was also excellent. All of the synthesized Gemini surfactants possessed good water solubility and their Krafft points were all below 0℃. As results, DDED and DDOD, Gemini surfactants which were synthesized are expected to be applied as foamers, emulsifiers and so on.

The catalytic oxidations of several cycloolefins in CH2Cl2 were been investigated using Mn(III)-, Fe(III)-porphyrin complexes as a catalyst and sodium hypochlorite as a terminal oxidant. Porphyrins were (p-CH3O)TTP, (p-CH3)TTP, TPP, (p-F)TPP, (p-Cl)TPP and (F20)TPP (TPP = tetraphenylporphyrin), and olefins were cyclopentene, cyclohexene and cycloheptene. The substrate conversion yield was discussed according to the substituent effects of metalloporphyrin. The conversion yield of substrate by changing the substituent of TPP increased in the order of p-CH3O 〈 p-CH3 〈 H 〈 p-F 〈 p-Cl, which was consistent with the sequence of 4Σ values of TPP. The conversion of cycloalkene followed the order of C5 < C6 < C7.

Novel type surfactants containing two long-chain hydrophobic alkyl groups and two hydrophilic sulfonate groups were successfully synthesized by reactions of ethylene glycol diglycidyl ether with long-chain fatty alcohols, after then by reactions with 1,3-propane sultone and sodium hydride under THF solvent. All these compounds, so called Gemini surfactants, were purified by thin layer chromatography and column chromatography. Their structures were identified by FT-IR and 1H-NMR.

Ti-45at%AI-1.6at%Mn 조성을 갖는 금속간화합물의 장시간 및 반복산화 거동을조사하기 위하여 반응소결법 및 플라즈마 아크 용해법으로 제조한 시편에 대하여 800˚C에서는 반응소결재와 용제재 모두 등온 및 반복산화에 대하여 우수한 저항성을 나타내었다. 900˚C에서는 반응소결재의 경우에는 등온 및 반복산화에 대하여 우수한 저항성을 보였으며, 중량변화와 산화피막의 박리는 극히 적었다. 이에 비해 용제재의 경우에는 등온 및 반복산화에 의해 중향이 크게 변하였으며 피막의 박리도 극심하였다. 900˚C에 있어서 두 재료간의 이러한 산화거동 차이는 기지/산화물 계면 부근에 형성된 산화층의 차이에 기인하는 것으로 간주하였다. 반응소결재의 경우에는 계면 부근에 연속적인 AO3O3층이 형성되며, 이러한 층이 산화에 대한 보호막으로 작용하는데 비하여 용제재에 있어서는 계면 부근에 AO3O3와 TiO2의 혼합층이 형성되었다. 용제재의 반복산화시에 보여진 피막의 박리는 냉각시에 TiO2와 기지간의 열팽창계수 차이에 기인하여 발생하는 열응력을 TiO2가 견디지 못하고 박리를 초래한 것으로 해석하였다.

intermetallics containing 0-6 wt% of Cu were made by reactive sintering (RS) under vacuum using elemental powder mixtures (Process 1), electro-pressure sintering (EPS) using RS'ed materials (Process2), and EPS using elemental powder mixtures (Process 3). Relatively low dense titanium silicides were gained by process 1, in which porosity decreased with increasing Cu content. For example, porosity changed from 42 to 19.4% with the increase in Cu content from 0 to 6 wt%, indicating that Cu is a useful sintering aid. The titanium silicides fabricated by Process 2 had a higher density than those by Process 1 at given composition, and porosity decreased with increasing Cu content. For example, porosity decreased from 38 to 6.8% with the change in Cu content from 0 to 6 wt%. A high dense titanium silicides were obtained by Process 3. In this Process, porosity decreased a little by Cu addition, and was almost insensitive to Cu content. Namely, about 9 or 7% of porosity was shown in 0 or 1-6 wt% Cu containing silicides, respectively. The hardeness increased by Cu addition, and was not changed markedly with Cu content for the silicides fabricated by Process 3. This tendency was considered to be resulted from porosity, hardening of grain interior by Cu addition, and softening of grain boundary by Cu-base segregates. All these results suggested that EPS using elemental powder mixtures (Process 3) is an effective processing method to achieve satisfactorily dense titanium silicides.

Engine valve-shaped TiAl-Mn intermetallics containing 43.5 to 47.5at%Al (Mn/Al=0.036) are successively fabricated by reactive sintering the elemental powder mixtures near-net shaped by extrusion and die forging. A duplex structure consisted of lamellar grains and equiaxed grains is developed for all compositions, and the areal fraction of the lamellar grains(or equiaxed grains) decreases (or increases) with increasing Al content. As Al content increased, the elongation increases with accompanying decrease in yield strength and ultimate tensile strength at both room temperature and 80. This indicates that the suitable composition is Ti-45at%Al-1.6at%Mn in considering the balance of ambient and elevated tensile properties. The reactive-sintered Ti-45Al-1.6Mn alloy shows superior oxidation resistance not only to the plasma arc melted one but also to the heat resistance steel STR35(representative exhaust valve head material for automotive engine). The reactive-sintered Ti-45Al-1.6Mn alloy coated with an oxidizing scale exhibits a better wear resistance than induction hardened martensitic steel STR11(representative exhaust valve tip material for automotive engine).

This study was carried out in order to analyze the changes in nitrogen containing taste compounds of traditional Korean soy sauce with varying Meju concentrations (Meju-water ratios of 1:4 and 1.3:4) and ripening periods (up to 2 years), and to investigate correlation between sensory characteristics and taste compound contents via contents assay and sensory evaluation of soy sauce samples. Nitrogen compound contents were higher in 1.3:4 than in 1:4 for all nitrogen compounds. Free amino acid contents were highest in soy sauce ripened for 210 days. Among amino acids, glutamic acid was highest concentration. Nucleotides and their related compound contents did not vary with concentrations and were highest in the sample ripened for 210 days. In direct sensory evaluation of soy sauce, overall taste preference showed positive correlation to sweet taste. Likewise, overall taste preference showed positive correlation to umami, nutty, sweet taste in the sensory evaluation of seaweed soup seasoned with soy sauce. Sensory evaluation score was higher in 1.3:4 than in 1:4. According to the correlation assay of taste compound contents and sensory evaluations, nitrogen compounds (such as amino type nitrogen), amino acids (such as glutamic acid, aspartic acid, and lysine, and etc.), nucleotides (such as AMP, IMP, and etc) had significant influence on the sensory characteristics of soy sauce, and therefore we can conclude that these compounds affect the taste and quality of soy sauce.