Molten salt reactors represent a promising advancement in nuclear technology due to their potential for enhanced safety, higher efficiency, and reduced nuclear waste. However, the development of structural materials that can survive under severe corrosion environments is crucial. In the present work, pure Ni was deposited on the surface of 316H stainless steel using a directed energy deposition (DED) process. This study aimed to fabricate pure Ni alloy layers on an STS316H alloy substrate. It was observed that low laser power during the deposition of pure Ni on the STS316H substrate could induce stacking defects such as surface irregularities and internal voids, which were confirmed through photographic and SEM analyses. Additionally, the diffusion of Fe and Cr elements from the STS316H substrate into the Ni layers was observed to decrease with increasing Ni deposition height. Analysis of the composition of Cr and Fe components within the Ni deposition structures allows for the prediction of properties such as the corrosion resistance of Ni.
Molten salt reactors have several advantages over conventional light water reactors. These include producing less nuclear waste, operating at higher power efficiency and inherent safety due to the low operating pressure. NaCl-MgCl2 eutectic salt is one of the candidates for the molten salt reactor coolant. However, because the salt is very hygroscopic, structural material corrosion occurs resulting in the high cost to maintain. To mitigate corrosion there have been many studies for the dehydration of the salt, especially focusing on the magnesium chloride. The reason is that the moisture adsorbed to the magnesium chloride undergoes hydrolysis over 200 degrees Celsius and decomposes to MgOHCl while the moisture associated with the NaCl is easily liberated during the heating procedure without chemical reaction. As the operating temperature of the molten salt is between 500 and 700 degrees Celsius, the MgOHCl is believed as the main cause for the structural corrosion. In this research, thermal dehydration of the salt with elemental Mg, for the NaCl-MgCl2 eutectic, was studied based on the previous dehydration methods and considering scalable and easy to handle. The MgOHCl was removed both through the thermal decomposition and the reduction by Mg metal. After the removal of MgOHCl, based on the difference between the freezing points and the density, the salt cooled down very slowly to ensure the separation between the purified salt and the disposals such as MgO and remaining Mg metals. The efficiency of the dehydration method was determined by the concentration of the MgOHCl. The concentration was determined by cyclic voltammetry and the result was compared with undehydrated salt and salt dehydrated thermally without the addition of Mg metal. To qualify and quantify the MgOHCl content through the cyclic voltammetry, it was necessary to observe the signal by adding MgOHCl to each sample. Based on the thermogravimetric analysis result of MgCl2· 6H2O, MgOHCl powder was formed through heating the MgCl2·6H2O.
The semiconductor industry faces physical limitations due to its top-down manufacturing processes. High cost of EUV equipment, time loss during tens or hundreds of photolithography steps, overlay, etch process errors, and contamination issues owing to photolithography still exist and may become more serious with the miniaturization of semiconductor devices. Therefore, a bottom-up approach is required to overcome these issues. The key technology that enables bottom-up semiconductor manufacturing is area-selective atomic layer deposition (ASALD). Here, various ASALD processes for elemental metals, such as Co, Cu, Ir, Ni, Pt, and Ru, are reviewed. Surface treatments using chemical species, such as self-assembled monolayers and small-molecule inhibitors, to control the hydrophilicity of the surface have been introduced. Finally, we discuss the future applications of metal ASALD processes.
An options study was performed for the treatment of residual elemental sodium in driver plenums following the chopping operation during the pyroprocessing of used nuclear fuel. Given the pending availability of a multi-function furnace for distillation and consolidation operations in the Fuel Conditioning Facility, the furnace was considered for the processing of driver plenums. Although two options (oxidation and distillation) could be performed in the multi-function furnace, neither option has been developed sufficiently to date to warrant the use of the furnace for treatment operations. Thus, it was decided to defer the treatment of elemental sodium from driver plenums in the multi-function furnace until more developed technologies and/or furnaces become available. In the interim, storage of the plenums and characterization efforts are recommended.
The objective of this study is to reveal the sintering mechanism of mixed Ti-6Al-4V powders considering the densification and the homogenization between Ti and Al/V particles. It is found that the addition of master alloy particles into Ti enhances densification by the migration of Al into the Ti matrix prior to the self-diffusion of Ti. However, as Ti particles become coarser, sintering of the powders appears to be retarded due to slower inter-diffusion of the particles due to the reduced surface energies of Ti. Such phenomena are confirmed by a series of dilatometry tests and microstructural analyses in respect to the sintering temperature. Furthermore, the results are also consistent with the predicted activation energies for sintering. The energies are found to have decreased from 299.35 to 135.48 kJ·mol-1 by adding the Al/V particles because the activation energy for the diffusion of Al in α-Ti (77 kJ·mol-1) is much lower than that of the self-diffusion of α-Ti. The coarser Ti powders increase the energies from 135.48 to 181.16 kJ·mol-1 because the specific surface areas of Ti decrease.
Seafood is attracting attention as a future food industry. In recent years, the demand for fishery equipment of mechanization, automation, and unmanned was increased due to the environment affected by seafood processing, stricter regulations on safety, decline and aging of fishery worker. Ark shell (Scapharca subcrenata) was being produced in many steps in the production process. The process has been made such as collection–landing–washing–first sort (goods/non-goods)–transports– second sort (size). It was undergone first and second steps by delivering to the consumer. Here, the first step is to sort goods to collection and the second step is to sort by size. The fishery workers need ten people in first step and six people in second step. The workload of one hour per kg is 4,247 kg/h in first step and 2,213 kg/h in second step. In addition, the goods ratio by work process was 79% in first step and 98% in the second step. In this process, a lot of fishery worker and working time is needed. Therefore, this study developed elemental techniques for an automated size sorting system considering the working process problem, time and situation for washing and sorting of ark shell.
A Ni-Ti-B alloy powder prepared by mechanical alloying (MA) of individual Ni, Ti, and B components is examined with the aim of elucidating the phase transitions and crystallization during heat treatment. Ti and B atoms penetrating into the Ni lattice result in a Ni (Ti, B) solid solution and an amorphous phase. Differential thermal analysis (DTA) reveals peaks related to the decomposition of the metastable Ni (Ti, B) solid solution and the separation of equilibrium Ni3Ti, TiB2, and τ-Ni20Ti3B6 phases. The exothermal effects in the DTA curves move to lower temperatures with increasing milling time. The formation of a TiB2 phase by annealing indicates that the mechanochemical reaction of the Ni-Ti-B alloy does not comply with the alloy composition in the ternary phase diagram, and Ti-B bonds are found to be more preferable than Ni-B bonds.
The paper focuses on the four conditions of earth, water, air, and fire identified by the pre-Socratic philosopher Empedocles, and alchemy. Yeats used concepts he learned from alchemy on the level of words and images and in distinctive tonal qualities. He also took from it concepts that energised his work, especially issues of opposition and desire, and the work towards transfiguration.
In this work, nanoporous carbons (NPCs) were prepared by the self-assembly of polymeric carbon precursors and block copolymer template in the presence of tetraethyl orthosilicate and colloidal silica. The NPCs' pore structures and total pore volumes were analyzed by reference to N2/77 K adsorption isotherms. The porosity and elemental mercury adsorption of NPCs were increased by activation with carbon dioxide. It could be resulted that elemental mercury adsorption ability of NPCs depended on their specific surface area and micropore fraction.
People have been concerned about mercury emissions for decades because of the extreme toxicity, persistence, and bioaccumulation of methyl Hg transformed from emitted Hg. This paper presents an overview of research related to mercury control technology and identifies areas requiring additional research and development. It critically reviews measured mercury emissions progress in the development of promising control technologies. This review provides useful information to scientists and engineers in this field.
In rapidly changing circumstances, the construction industry shows tendency to be more complicated and expanded and these changes are becoming the main factors aggravating uncertainty in straightening construction costs in the industry. The most important process in preliminary phase is calculation of appropriate construction sum and accurate estimation is required to accomplish it. Currently, local constructors draw up estimates by using the ‘per square meter’ calculation method or by applying of previous cases as they are. These methods become suppressive cause for making clear decisions by occurring errors in quantity survey in a way of data emission, replication and so on. Therefore, in this study, approximate estimation model of finishing construction shall be proposed to assist people to make prompt decisions in initial design stage. To develop this research, the existing quoting practices shall be presented and categorized by usage of space. To achieve this, information on performance, furnishings and unit price according to space definition has been collected in advance, which again enable ontology knowledge classification scheming database of space unit to be utilized and presented as knowledge information.
The present paper gives an overview about the Atom Probe Tomography technique and its application to powder materials. The preparation of needle-shaped Atom Probe specimens from a single powder particle using focused-ion-beam milling is described. Selected experimental data on mechanically alloyed (and sintered) powder materials are presented, giving insight into the atomic-scale elemental redistribution occurring under powder metallurgical processing.
Public concern has recently increased over the potential risk of toxic elements emitted from anthropogenic sources. Among these, mercury has drawn special attention owing to its increasing level of bioaccumulation in the environment and in the food chain, with potential risks for human health. This paper presents an overview of research related to mercury control technology and identifies areas requiring additional research and development. It critically reviews measured mercury emissions progress in the development of promising control technologies, including catalytic oxidation, sorbent injection, photochemistry oxidation, and air pollution control devices.
본 논문에서는 물질의 원소 분석법 가운데 하나인 레이저 유도 플라즈마 분광법을 이용한 해양 환경 오염을 감시 기술의 적용 가능성 을 제시한다. 제주도 근해에서 채취한 백화시료에 포함되어 있는 칼슘 원소와 수돗물에 포함되어 있는 소듐, 칼슘 원소들을 레이저 유도 플라즈 마 분광법을 통해서 검출하였다. 또한 해수에 용해되어 있는 다양한 무기 원소들을 레이저 유도 플라즈마 분광법을 통해서 정량적으로 측정하 고자 할 때 사용할 수 있는 새로운 정량화 기법을 제안한다.
황해와 북동중국해에는 중국의 황하와 양쯔강 그리고 한국의 강들로부터 많은 양의 부유물질이 공급되어 대륙붕 해역에 여러 개의 니질 퇴적체가 발달하고 있으나, 이들 퇴적체에서 두 기원을 설명할 수 있는 퇴적-지화학적 요인은 아직까지 명확하게 제시되고 있지 않다. 본 논문에서는 한국과 중국 기원 강 퇴적물의 주성분 원소의 함량 특성을 비교 연구하고, 그 결과를 토대로 황해와 북동중국해 퇴적물에 적용 가능한 기원지 추적자를 제시하였다. 본 연구를 위해 총 102개의 강과 연안 퇴적물에 대한 주성분 원소(Al, Fe, Mg, K, Ca, Na, Ti)들의 함량을 유도결합플라즈마 분석기를 이용하여 분석하였으며, 이와 함께 입도효과를 최소화하기위해 원시료를 실트(60∼20μm)와 점토 구간(<20μm)으로 분리하여 주성분 원소 함량과 스트론튬 동위원소 비(87Sr/86Sr)를 분석하였다. 연구결과, 새로운 방법의 입도보정을 통한 Fe/Al과 Mg/Al 함량 비는 매우 유용한 잠재적 추적자로 제시되며, 이러한 결과는 입자 분리된 실트와 점토 퇴적물에서 더욱 뚜렷하다. 또한 실트 구간의 퇴적물에서 한국 기원의 87Sr/86Sr 비는 0.7229∼0.7253(평균 0.7243) 범위로 중국 기원 퇴적물(0.7169∼0.7189, 평균 0.7179)과 뚜렷한 차이를 보여, 황해와 북동중국해에서 한국과 중국 기원의 퇴적물을 구분할 수 있는 중요한 지화학적 성분으로 평가된다. 이러한 잠재적 추적자들에 근거할 때, 한국 서남해에 발달하고 있는 니질 퇴적대의 전퇴적물은 한국과 중국의 혼합 기원으로 해석되나, 실트와 점토 구간의 퇴적물로 나누어 볼 때 그기원이 각각 다르게 나타났다. 즉, 점토 퇴적물은 한국과 중국의 혼합 기원으로, 실트 퇴적물은 한국 기원이 우세한 것으로 해석된다.
In order to obtain specific magnetic properties, it is of paramount importance to increase the alloy density of components fabricated by powder metallurgy. An alternative to increase the density of alloys such as Fe-49Co-2V would be the use of elemental Fe and Co instead of the pre-alloyed powder. Trying to give some insight on the industrial application of this strategy, this paper investigates the replacement of more conventional pre-alloyed Fe-49Co-2V powders with elemental Fe and Co. A previous analysis shows that it is possible to achieve higher densities and leads to a noticeable improvement in some important magnetic properties.
Titanium alloys and Titanium alloy-based particulate composites were synthesized using the blended elemental P/M route. First, processing conditions such as the fabrication of master alloy powder were investigated. Ti-6Al-4V, Ti-5Al-2.5Fe, Ti-6Al-2Sn-4Zr-2Mo, IMI685, IMI829, Timetal 1100 and Timetal 62S, and Ti-6Al-2Sn-4Zr-2Mo/ 10%TiB and Timetal 62S/10%TiB were then synthesized using the optimal processing conditions obtained. The microstructures and mechanical properties such as tensile strength and high cycle fatigue strength were evaluated.