VOCs는 인체에 치명적인 질환을 유발하는 물질로써 도장공정중 발생되는 양이 가장 큰 비 중을 차지하고 있다. 일반적으로 소형 도장시설에서 발생되는 VOCs를 처리하는 방법으로 활성탄 흡착 또는 흡착 후 연소 및 촉매 산화법 등을 사용하고 있다. 하지만 활성탄 교체주기, 재생시설 및 재생주기 등을 예측하기 어려워 새로운 처리방법이 필요하다. 비이송식 플라즈마 시스템을 이용한 VOCs 제거방 법은 일반 연소과정이 아닌 고전압 아크 방전에 의한 고온 플라즈마 유동 발생 기술을 이용한 제거방법 으로 화학반응이나 오염이 없는 고순도의 고온 열처리 및 열분해가 가능하다. 본 연구에서는 고온 아크 플라즈마 시스템을 이용하여 특수 환경오염물 및 VOCs 가스 열처리 공정의 핵심기술로 활용하여 작동 가스 유량 변화에 따른 VOCs 처리 효율 및 플라즈마 전력량에 따른 처리 효율을 측정하였다. 또한 유 해가스 처리효율성 증대를 위해 플라즈마 반응기를 최적화하여 제작하였으며 성능을 파악하였다.

In this study, the synthesis of nickel nanoparticles and copper nanospheres for the potential applications of MLCC electrode materials has been studied by plasma arc evaporation method. The change in the broad distribution of the size of nickel and copper nanopowders is successfully controlled by manifesting proper mixture of gas ambiance for plasma generation in the size range of 20 to 200 nm in diameter. The factors affecting the mean diameter of the nanopowder was studied by changing the composition of reactive gases, indicating that nitrogen enhances the formation of larger particles compared to hydrogen gas. The morphologies and particle sizes of the metal nanoparticles were observed by SEM, and ultrathin oxide layers on the powder surface generated during passivation step have been confirmed using TEM. The metallic FCC structure of the nanoparticles was confirmed using powder X-ray diffraction method.

Electricity is generated by the combined reactions of hydrogen oxidation and oxygen reduction which occur on the Pt/C catalyst surface. There have been lots of researches to make high performance catalysts which can reduce Pt utilization. However, most of catalysts are synthesized by wet-processes and a significant amount of chemicals are emitted during Pt/C synthesis. In this study, Pt/C catalyst was produced by arc plasma deposition process in which Pt nano-particles are directly deposited on carbon black surfaces. During the process, islands of Pt nano-particles were produced and they were very fine and well-distributed on carbon black surface. Compared with a commercialized Pt/C catalyst (Johnson & Matthey), finer particle size, narrower size distribution, and uniform distribution of APD Pt/C resulted in higher electrochemical active surface area even at the less Pt content.

In this study, SAP (Sliding Arc Plasma) was applied to remove ammonia, an odor causing substance under various conditions. From the study, it was found that the SAP angle is related with the plasma radius. As the angle became narrower, the radius became shorter while the plasma became stronger. Results within 30° angle of the electrode and the electrode length of 10 cm or more and the electrode spacing shows high efficiency at 2mm. In short, it was empirically proved that the ammonia removal efficiency increased at the limited plasma range.

The present study focused on the synthesis of a bismuth-antimony-tellurium-based thermoelectric nanopowders using plasma arc discharge process. The chemical composition, phase structure, particle size of the synthesized powders under various synthesis conditions were analyzed using XRF, XRD and SEM. The powders as synthesized were sintered by the plasma activated sintering. The thermoelectric properties of sintered body were analyzed by measuring Seebeck coefficient, specific electric resistivity and thermal conductivity. The chemical composition of the synthesized Bi-Sb-Te-based powders approached that of the raw material with an increasing DC current of the are plasma. The synthesized Bi-Sb-Te-based powder consist of a mixed phase structure of the , and phases. This powder has homogeneous mixing state of two different particles in an average particle size; about 100nm and about 500nm. The figure of merit of the sintered body of the synthesized 18.75 wt.%Bi-24.68 wt.%Sb-56.57 wt.%Te nanopowder showed higher value than one of the sintered body of the mechanically milled 12.64 wt.%Bi-29.47 wt.%Sb-57.89 wt.%Te powder.

The present study was focused on the synthesis of a zirconium-based alloyed nanopowder by the plasma arc discharge process. The chemical composition, phase structure, particle size and hydrogen sorption property of the synthesized powders under various synthesis conditions were analyzed using XRF, XRD, SEM, XPS and the ASTM-F798 method. The chemical composition of the synthesized Zr-V-Fe-based powders approached that of the raw material with an increasing hydrogen fraction in the powder synthesis atmosphere. The synthesized powder consist of a mixed phase structure of the phases. This powder has an average particle size of about 20 nm. The synthesized nanopowder showed getter characteristics, even though it had a lower hydrogen sorption speed than the getter powder. However, the synthesized Zr nanopowder with an average particle size of 20 nm showed higher hydrogen sorption speed than the getter powder.

In the present study, ultrafined Zr-V-Fe based alloy powder prepared by a plasma arc discharge process with changing process parameters. The chemical composition of synthesized powder was strongly influenced by the process parameters, especially the hydrogen volume fraction in the powder synthesis atmosphere. The synthesized powder had an average particle size of 50 nm. The synthesized Zr-V-Fe based particles had a shell-core structure composed of metal in the core and oxidse in the shell.

The nano-sized Fe powders were prepared by plasma arc discharge process using pure Fe rod. The microstructure and the sintering behavior of the prepared nanopowders were evaluated. The prepared Fe nanopowders had nearly spherical shapes and consisted of metallic core and oxide shell structures. The higher volume shrinkage at low sintering temperature was observed due to the reduction of surface oxide. The nanopowders showed 6 times higher densification rate and more significant isotropic shrinkage behavior than those of micron sized Fe powders.

Nano sized FeAl intermetallic particles were successfully synthesized by plasma arc discharge pro-cess. The synthesized powders shouted core-shell structures with the particle size of 10-20 nm. The core was metallic FeAl and shell was composed of amorphous Because of the difference of Fe and Al vapor pressure during synthesis, the Al contents in the nanoparticles depended on the Al contents of master alloy.

Iron-carbon nanocapsules were synthesized by plasma arc discharge (PAD) process under various atmosphere of methane, argon and hydrogen gas. Characterization and surface properties were investigated by means of HRTEM, XRD, XPS and Mossbauer spectroscopy. Fe nanocapsules synthesized were composed of three phases with core/shell structures. The surface of nanocapsules was covered by the shell of graphite phase in the thickness of nm.

Fe nanopowders were successfully synthesized by plasma arc discharge (PAD) process using Fe rod. The influence of chamber pressure on the microstructure was investigated by means of X-ray Diffraction (XRD), Field Emission Scanning Electron Microscope (FE-SEM), Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). The prepared particles had nearly spherical shapes and consisted of metallic cores (a-Fe) and oxide shells (FeO), The powder size increased with increasing chamber pressure due to the higher dissolution and ejection rate of H and gas density in the molten metal.

To investigate the effect of the parameters of the plasma arc discharge process on the particle formation and particle characteristics of the iron nano powder, the chamber pressure, input current and the hydrogen volume fraction in the powder synthesis atmosphere were changed. The particle size and phase structure of the synthesized iron powder were studied using the FE-SEM, FE-TEM and XRD. The synthesized iron powder particle had a core-shell structure composed of the crystalline -Fe in the core and the crystalline in the shell. The powder generation rate and particle size mainly depended on the hydrogen volume fraction in the powder synthesis atmosphere. The particle size increased simultaneously with increasing the hydrogen volume fraction from 10% to 50%, and it ranged from about 45nm to 130 nm.

As the decommissioning of domestic nuclear power plants (Gori Unit 1 and Wolseong Unit 1) becomes more visible, many research projects are being conducted to safely and economically decommissioning of domestic nuclear power plants (NPPs). After permanent shutdown, decommissioning of NNPs proceeds through decontamination, cutting of main equipment, waste disposal and site restoration stages. And various technologies are applied at each stage. In particular, remote cutting of neutron induced structures (RV, RVI, etc.) is a technology used in developed countries in the cutting stage, and remote cutting has been evaluated as a core technology for minimizing workers’ radiation exposure. Generally, remote cutting technologies are divided into mechanical/thermal/electrical cutting. Among various thermal cutting technologies, plasma arc cutting (PAC) is more economical and easily to remote control than other cutting technologies, and is also effective in cutting STS304 plates. PAC is a thermal cutting technology that melts the base material at the cutting area with a plasma arc heat source and removes melted material by blowing it out with cutting gas. The cutting quality depends on the stand-off distance and power (current), material thickness, cutting speed, etc., while double arcing will occur if the cutting conditions are not suitable. A monitoring system that can confirm double arcing during remote cutting is necessary because double arcing can reduce cutting quality, increase secondary waste (increase kerf and aerosol), and cause non-cutting. In this study, we used an ultrahigh-speed camera equipped with a band-pass filter to capture clear arc shapes, and measured voltage waveforms with a data acquisition system. We studied a monitoring method that can confirm the occurrence of double arcing by synchronizing the obtained arc shape and voltage waveform, and the effects of double arcing on the STS304 plates. The results of this study are expected to be helpful in the development of the remote cutting process using plasma arc cutting when decommissioning of domestic NPPs.

Metals such as stainless steel and alloy 600 are used as structures and materials in nuclear power plants due to their excellent mechanical properties and heat resistance. And recently thermal and mechanical cutting technologies are being actively researched and developed for dismantling NPP. Among them, the mechanical cutting method has the advantage of less secondary waste generation such as fume and fine dust, but according to the wider the cutting range, the reaction force and the cutting device size are increased. In this paper, plasma assisted milling has been proposed to reduce the reaction force and device size, and the plasma efficiency was measured for SUS 316L. The plasma torch was operated at the level of 3 to 4 kW so that it was heated only without cutting. And the feedrate was set at 150 to 250 mm/min. The test confirmed that the plasma efficiency was 35% about SUS 316L, and it is expected that the numerical analysis using these test results can be used as basic data for plasma assisted milling.