SiC is a material with excellent strength, heat resistance, and corrosion resistance. It is generally used as a material for SiC invertors, semiconductor susceptors, edge rings, MOCVD susceptors, and mechanical bearings. Recently, SiC single crystals for LED are expected to be a new market application. In addition, SiC is also used as a heating element applied directly to electrical energy. Research in this study has focused on the manufacture of heating elements that can raise the temperature in a short time by irradiating SiC-I2 with microwaves with polarization difference, instead of applying electric energy directly to increase the convenience and efficiency. In this experiment, Polydimethylsilane (PDMS) with 1,2 wt% of iodine is synthesized under high temperature and pressure using an autoclave. The synthesized Polycarbosilane (PCS) is heat treated in an argon gas atmosphere after curing process. The experimental results obtain resonance peaks using FT-IR and UV-Visible, and the crystal structure is measured by XRD. Also, the heat-generating characteristics are determined in the frequency band of 2.45 GHz after heat treatment in an air atmosphere furnace.

It is known that bones get damaged by accidents and aging. Since the discovery of Bioglass, various kinds of ceramics have been also found to bond to living bone; some of these ceramics are already being clinically used as bone-repairing materials. In the present study, antibacterial calcium silicate gel (Ag-30CaO·70SiO2 gel) was prepared by sol-gel method in order to control the microstructure, which is related to the dissolution rate and induction period of apatite formation in body environment. In addition, biological Ag-30CaO·70SiO2 is tested. This was done to impart antimicrobial activity to the 30CaO·70SiO2. Ag ion was added during sol-gel synthesis to replace the H2O added during the making of the 30CaO·70SiO2 gel, which has silver solutions of various concentration. After the sol-gel process, 1N-HNO3 solution was used to wash the gel when synthesizing the gel, in order to maintain the porous structure and remove PEG, water soluble polymers. Then, the apatite forming ability of the sol-gel derived CaO-SiO2 gels was investigated using simulated body fluid (SBF), which had almost the same ion concentration as that of human blood plasma. The gels were analyzed by FT-IR spectroscopy, SEM observation, XRD, and fluorescent microscopy. The apatite was successfully created even after washing the gel; apatite is present in an amorphous state, and was found to affect the concentration of the Ag ion in cells in MC3T3 live & dead assay results. From these results, it is suggested that a good material that can be used to repair defects of nature bone is Ag-30CaO·70SiO2 gel.

Pure zirconia and x mol% calcia partially stabilized zirconia (x = 1.5, 3, and 8) nanopowders were synthesized by hydrothermal method with various reaction temperatures for 24 hrs. The precipitated precursor of pure zirconia and x mol% calcia doped zirconia was prepared by adding NH4OH to starting solutions; resulting sample was then put into an autoclave reactor. The optimal experimental conditions, such as reaction temperatures and times and amounts of stabilizer CaO, were carefully studied. The synthesized ZrO2 and x mol% CaO-ZrO2 (x = 1.5, 3, and 8) powders were characterized by XRD, SEM, TG-DTA, and Raman spectroscopy. When the hydrothermal temperature was as low as 160˚C, pure ZrO2 and x mol% CaO-ZrO2 (x = 1.5 and 3) powders were identified as a mixture of monoclinic and tetragonal phases. However, a stable tetragonal phase of zirconia was observed in the 8 mol% calcia doped zirconia nanopowder at hydrothermal temperature above 160˚C. To observe the phase transition, the 3 mol% CaO-ZrO2 and 8 mol% CaO-ZrO2 nanopowders were heat treated from 600 to 1000˚C for 2h. The 3 mol% CaO-ZrO2 heat treated at above 1000˚C was found to undergo a complete phase transition from mixture phase to monoclinic phase. However, the 8 mol% calcia doped zirconia appeared in the stable tetragonal phase after heat treatment. The result of this study therefore should be considered as the preparation of 8 mol% CaO-ZrO2 nanopowders via the hydrothermal method.

The industrial manufacturing of YSZ products can be summarized as a three step process: a) hydrolysis of zirconyl chloride and mixing of other solutions, b) precipitation, and c) calcination. The addition of ammonia or OH- is essential in the precipitation process. However, a strong agglomeration was observed in the results of an ammonia or OH- addition. Thus, it is necessary to disperse the powders smoothly in order to improve the mechanical strength of YSZ. In this study, YSZ was synthesized using the urea stabilizer and hydrothermal method. YSZ powders were synthesized using a hydrothermal method with Teflon Vessels at 180˚C for 24 h. The mole ratio of urea to Zr was 0, 0.5, 1, and 2. The crystal phase, particle size, and morphologies were analyzed. Rectangular specimens (33 mm×8 mm×1±0.5 mm) for three-point bend tests were used in the mechanical properties evaluation. The crystalline of YSZ powders observed a tetragonal phase in the sample with a ratio of Zr:urea = 1:2 addition and a hydrothermal reaction time of 24 h. The average primary particle size of YSZ was measured to be 9 nm to 11 nm. The agglomerated particle size was measured from 15 nm to 30 nm. The three-point bending strength of the YSZ samples was 142.47 MPa, which is the highest value obtained for the Zr:urea = 1:2 ratio addition YSZ sample.

In this study, partially stabilized zirconia was synthesized using a chemical Y2O3 stabilizer and hydrothermal method. First, YCl3-6H2O and ZrCl2O-8H2O was dissolved in distilled water. Y-TZP (a Y2O3-doped toughened zirconia polycrystalline precursor) was also prepared by conventional co-precipitates in the presence of an excess amount of NH4OH solution under a fixed pH of 12. The Y-TZP precursors were filtered and repeatedly washed with distilled water to remove Cl- ions. ZrO2-Xmol%Y2O3 powder was synthesized by a hydrothermal method using Teflon Vessels at 180˚C for 6 h of optimized condition. The powder added with the Xmol%- Y2O3 (X = 0,1,3,5 mol%) stabilizer of the ZrO2 was synthesized. The crystal phase, particle size, and morphologies were analyzed. Rectangular specimens of 33mm×8mm×3 mm for three-point bend tests were used in the mechanical properties evaluation. A teragonal phase was observed in the samples, which contains more than 3 mol% Y2O3. The 3Y-ZrO2 agglomerated particle size was measured at 7.01μm. The agglomerated particle was clearly observed in the sample of 5 mol % Y2O3-ZrO2, and and the agglomerated particle size was measured at 16.4 um. However, a 20 nm particle was specifically observed by FE-SEM in the sample of 3 mol% Y2O3-ZrO2. The highest bending fracture strength was measured as 321.3 MPa in sample of 3 mol% Y2O3-ZrO2.

The friction characteristics of automotive brake friction materials that contained different ceramic content were investigated. Several kinds of raw materials, such as resin-based binder, reinforcing fiber, friction restraint, abrasive, and filling materials were mixed, pressed, and heated in order to make the brake friction materials. The contents of SiC and BaSO4 changed from 5 vol% to 20 vol%, respectively. In addition to this, the content of Al2O3 adjusted from 1 vol% to 16 vol%. The surface morphology of the SiC containing sample appeared rough while more debris was observed when the contents of SiC increased. This implies that the SiC containing brake composite was not adequate for the automobile. However, the relatively smooth surface was observed in samples that contained the Al2O3. But the roughness was low with a content of 11 vol% Al2O3 compared to the other samples. This is consistent with the abrasive properties of the samples. In the case of BaSO4 containing samples, the smoothes surface was observed in the contents of 15 vol% BaSO4. Thus, it was concluded that the 11 vol% Al2O3 and 15 vol% BaSO4 containing composite would be the optimum content for the brake composite. Similar to the results of the surface morphology, the abrasion resistance consistently decreased when the content of SiC increased. On the contrary, the sample that contained 11 vol% Al2O3 and 15 vol% BaSO4 showed the highest abrasion resistance compared to the other samples.

Non-sintering cement was manufactured with briquette ash. Alkali activator for compression bodies used a NaOH solution. In order to apply alkali-activated briquette ash and the non-sintering cement to concrete, several experimental studies were performed. It was necessary to study the binder obtained by means of a substitute for the cement. This study concentrated on strength development according to the concentration of NaOH solution, the curing temperature, and the curing time. The highest compressive strength of compression bodies appeared as 353kgf/cm2 cured at 80˚C for 28 days. This result indicates that a higher curing temperature is needed to get a higher strength body. Also, geopolymerization was examined by SEM and XRD analysis after the curing of compression bodies. According to SEM and XRD, the main reaction product in the alkali activated briquette ash is aluminosilicate crystal.

The bricks in Myung Dong Cathedral Church are now deteriorated by the weather such as temperature, humidity, and winds. Thus it is necessary to replace the old bricks to the restored bricks for the load bearing capacity as well as to prevent the penetrations of rains from outside. However the mortar composition is not well defined at this moment and there are literary about the mortar completions. Thus it is necessary to verify the mortar compactions between old bricks and results to bring the restoring the mortar for the replace of new bricks. The particles of mortar was collected from Myung Dong Cathedral Church and particle size was analyzed by the mortar and pestle and mechanicle floater. The X-ray diffraction and XRF of each particles are analyzed. The quartz and feldspar such as albite, kaolinite are observed in large particles(>1mm). However, the clicite was observed at lower than $43{\mu}m$ particles. In XRF analysis, the $SiO_2\;and\;K_2O$ are observed at large particles$(1mm-208{\mu}m)\;and\;CaCO_3$ is observed at small particles$(208-43{\mu}m)\;and\;CaCO_3$ is observed at small particles($208-43{\mu}m$). This is well coincide with XRD results. The optimum volume ratio of lime mortar would be 1: 2 ($CaO: SiO_2$).