Zirconium boride is an artificial or which is rarely found in the nature. ZrB2 is popular in the hard material industry because it has a high melting point, excellent mechanical properties and chemical stability. There are two known methods to synthesize ZrB2. The first involves direct reaction between Zr and B, and the second is by reduction of the metal halogen. However, these two methods are known to be unsuitable for mass production. SHS(Self-propagating High-temperature Synthesis) is an efficient and economic method for synthesizing hard materials because it uses exothermic reactions. In this study, ZrB2 was successfully synthesized by subjecting ZrO2, Mg and B2O3 to SHS. Because of the high combustion temperature and rapid combustion, in conjunction with the stoichiometric ratio of ZrO2, Mg and B2O3; single phase ZrB2 was not synthesized. In order to solve the temperature problem, Mg and NaCl additives were investigated as diluents. From the experiments it was found that both diluents effectively stabilized the reaction and combustion regime. The final product, made under optimum conditions, was single-phase ZrB2 of 0.1-0.9μm particle size.

Due to their unique properties, tungsten borides are good candidates for the industrial applications where certain features such as high hardness, chemical inertness, resistance to high temperatures, thermal shock and corrosion. In this study, conditions were investigated for producing tungsten boride powder from tungsten oxide(WO3) by self-propagating high-temperature synthesis (SHS) followed by HCl leaching techniques. In the first stage of the study, the exothermicity of the WO3-Mg reaction was investigated by computer simulation. Based on the simulation experimental study was conducted and the SHS products consisting of borides and other compounds were obtained starting with different initial molar ratios of WO3, Mg and B2O3. It was found that WO3, Mg and B2O3 reaction system produced high combustion temperature and radical reaction so that diffusion between W and B was not properly occurred. Addition of NaCl and replacement of B2O3 with B successfully solved the diffusion problem. From the optimum condition tungsten boride(W2B and WB) powders which has 0.1~0.9 um particle size were synthesized.

In this study, green barium strontium silicate phosphor (BaSrSiO4:Eu3+, Eu2+) was synthesized using a solid-statereaction method in air and reducing atmosphere. Investigation of the firing temperature indicates that a single phase of BaSrSiO4is formed when the firing temperature is higher than 1400oC. The effect of firing temperature and doping concentration onluminescent properties are investigated. The light-emitting property was the best when the molar content of Eu2O3 was 0.025mol. Also, the luminescent brightness of the BaSrSiO4 fluorescent substance was the best when the particle size of the bariumwas 0.5µm. BaSrSiO4 phosphors exhibit the typical green luminescent properties of Eu3+ and Eu2+. The characteristics of thesynthesized BaSrSiO4:Eu3+, Eu2+ phosphor were investigated using X-ray diffraction (XRD) and scanning electron microscopy.The maximum emission band of the BaSrSiO4:Eu3+, Eu2+ was 520nm.

The effect of BaF2 flux in Y3Al5O12:Ce3+(YAG:Ce) formation was investigated. Phase transformation ofY3Al5O12(YAG) was characterized by using XRD, SEM, and TEM-EDS, and it was revealed that the sequential formation ofthe Y4Al2O9(YAM), YAlO3(YAP) and Y3Al5O12(YAG) in the temperature range of 1000-1500oC. Single phase of YAG wasrevealed from 1300oC. In order to find out the effect of BaF2 flux, three modeling experiments between starting materials(1.5Al2O3−2.5Y2O3, Y2O3−BaF2, and Al2O3−BaF2) were done. These modeling experiments showed that the nucleationprocess occurs via the dissolution-precipitation mechanism, whereas the grain growth process is controlled via the liquid-phasediffusion route. YAG:Ce phosphor particles prepared using a proposed technique exhibit a spherical shape, high crystallinity,and an emission intensity. According to the experimental results conducted in this investigation, 5% of BaF2 was the bestconcentration for physical, chemical and optical properties of Y3Al5O12:Ce3+(YAG:Ce) that is approximately 10-15% greaterthan that of commercial phosphor powder.

[ Zn2(1-x)MnxSiO4 ]0.07≤x≤0.15) green phosphor was prepared by solid state reaction. The first heating was at 900˚C-1250˚C in air for 3 hours and the second heating was at 900˚C in N2/H2(95%/5%) for 2 hours. The size effect of SiO2 in forming Zn2SiO4 was investigated. The temperature for obtaining single phase Zn2SiO4 was lowered from 1100˚C to 1000˚C by decreasing the SiO2 particle size from micro size to submicro size. The effect of the activators for the Photoluminescence (PL) intensity of Zn2SiO4:Mn2+ was also investigated. The PL intensity properties of the phosphors were investigated under vacuum ultraviolet excitation (147 nm). The emission spectrum peak was between 520 nm and 530 nm, which was involved in green emission area. MnCl2·4H2O, the activator source, was more effective in providing high emission intensity than MnCO3. The optimum conditions for the best optical properties of Zn2SiO4:Mn2+ were at x = 0.11 and 1100˚C. In these conditions, the phosphor particle shape was well dispersed spherical and its size was 200 nm.

Spherical Ag powder was prepared in the system of by wet chemical reduction method. The size of Ag powder was increased as the reaction temperature and the concentration of reducing agent was decreased in the constant concentration of dispersion agent. Optimum conditions of producing Ag powder having of D50 was 1M of , 0.5M of , 1.5g of Gelatine in the room temperature.

In this study, high purity fine powders were prepared by SHS (Self-propagating High-temperature Synthesis). We would examinate the study of sintering properties and characteristics as a function of temperature with various additives (binder, sintering agent). In separately binder addition, the green and sintered density of specimen were increased as binder content increases. The increased porosity resulted in fine grain size due to the inhibition of grain boundary moving. The and MgO playa role of increasing dielectric constants at room temperature. These values were decreased at curie temperature. In case of , the Curie temperature was decreased. In this study, a high dielectric ceramic capacitor material with temperature stability was synthesized by using various additives

Ag powder was prepared from by wet chemical reduction method using various reduction agent system involving , (AgCl) and Ag complex ion aqueous solution. The pure Ag powder could be prepared regardless of reaction system but the particle shape and distribution were affected very much according to the kind of reduction agents and reaction systems. The optimum reaction system for the preparation of the silver powder having the uniform particle shape and size distribution was Ag complex ion aqueous solution-reduction agent system and in particular, and as a reduction agent leaded the more uniform particle shape and size distribution

Submicron nickel powders were prepared from aqueous solution under hydrothermal condition. The experimental conditions including the types of protective agents, concentration of the solution and the pH were studied in detail. Starting concentration of nickel ion is a dominant factor affecting particle size. It was shown that the subsequent addition of Poly Vinyl Pyrrolidone(PVP) and Sodium Dodecyle Sulfate(SDS) can help to disperse the nickel powder. X-ray diffraction and SEM were employed to characterize the products.

Fe-Al계 금속간화합물이 FACS (Field-Activated Combustion Synthesis) 법에 의해 제조되었다. 이 계의 반응에 있어서 조성 (Fe:Al=3 : 1,2 : 1, 1 : 1.1 : 2, 1 : 3) , 성형압력 (150, 250, 350MPa), 저항 등이 조사되었는데. Al의 몰비, 성형압력, 전기장의 세가가 증가함에 따라서 연소온도와 연소속도는 증가하였다. 또한 이 계에 있어서 전류적용방식에 따른 반응에 대한 영향이 조사되었다. 전기장이 적용되지 않는 경우, 반응이 일어나기 위해서는 예열이 필요하였고, 예열을 하였을 경우라도 그 반응은 불안정연소파를 나타내어 완전한 반응이 이루어지지 않았다. 생성물은 X-ray, SEM, EDXS를 사용하여 그 구조와 조성을 관찰하였다

금속기지 복합물은 구조용 재료로서 매우 우수한 성질을 지니고 있어 광범위하게 연구되어져 왔다. Al2O3와 SiC는 그들의 우수한 기계적 특성 때문에 일반적인 보강재로서 사용되어져 왔다. 그러나 이들 세라믹 보강재는 비싼 재조 비용 때문에 특별한 목적을 위해서만 한정되어 사용되어져 왔다. 본 연구에서는 우리는 Al 합금기지 복합물에서 SHS법에 의해 합성된 Al2O3-SiC 분말의 보강재로서의 응용 가능성을 살펴보았다. 또한 Al2O3단섬유를 Al기지 하이브리드 복합물에 적용하기 위하여 합성된 분말과 함께 첨가하였다. 25vol% 강화재의 복합물을 제조하기 위하여 용탕단조법을 사용하였다. 미세구조와 결정구조는 SEM, OM 그리고 XRD로 관찰하였고 압축시험과 마모시험으로 기계적인 성질들을 조사하였다.

TiN은 기상반응법으로 티타늄판과 질소가스의 질화반응에 의해 제조되었다. δ-TiN은 약 1100-1400˚C의 온도 범위에서만 형성되는데 반해, 1100˚C이하의 온도에서는 ε-TiN 상도 관찰할 수 있었다. δ-TiN의 미소정도값은 3000±300kg/mm2였고, 격자상수는 0.4226μm였다. 가스의 유동속도가 0.7ℓ/min의 속도이하에서는 확산과정에 의해 지배됨을 알 수 있었다. 활성화에너지가 1100˚C이상에서는 67.6Kcal/mol이었고 1100˚C이상에서는 13.9Kcal/mol이었던 것으로 보아 반응메커니즘이 1100˚C를 기점으로 변한다는 것을 명백히 관찰할 수 있었다. 그리고 증착속도가 확산과정에 의해 지배되는 영역에서 TiN의 증착속도는 전체 유량의 제곱근에 비례하였다.