간행물
한국재료학회지 KCI 등재 SCOPUS Korean Journal of Materials Research
- 발행기관 한국재료학회
- 자료유형 학술지
- 간기 월간
- ISSN 2799-8525 (Print)2799-8681 (Online)
- 수록기간 1991 ~ 2024
- 주제분류 공학 > 재료공학 공학 분류의 다른 간행물
- 십진분류KDC 530DDC 620
권호리스트/논문검색
제29권 제11호 (2019년 11월) 12건
1.
2019.11
구독 인증기관 무료, 개인회원 유료
In this work, we study physical and mechanical properties of oxide films formed on AZ91D magnesium alloy by plasma anodization at different temperatures. It is found that the higher the electrolyte temperature, the lower is the breakdown voltage of oxide layer. This is probably because films formed at higher temperatures are thinner and denser. Moreover, electrolyte temperature plays an important role in the physical properties of the films. As the electrolyte temperature increases from 20 to 50℃, the hardness of the oxide layer increases. Friction test against steel balls indicates that wear scars become narrower for films formed at higher temperatures because the films are harder, as indicated by the Vickers hardness. The thinner and denser nature of the oxide film formed at 50°C is also advantageous for heat transfer when film is used as a heat sink. Laser flash test results show very fast heat transfer for AZ91D with plasma anodized oxide layer formed at higher temperatures.
29,000원
2.
2019.11
구독 인증기관 무료, 개인회원 유료
In this paper, a water-based green polymer mud is synthesized by simple compounding method. Effects of different kinds of tackifiers, their molecular weight on the viscosity of polymer mud and the effects of different fluid loss additives on mud fluid loss are studied. The results show that when polystyrene and anionic polyacrylamide with molecular weight of 8 ~ 10 million are used as the main thickening ingredient, polymer mud with high viscosity and high stability can be obtained. When the prepared polymer mud is formulated as NPAM: PEO: Hydroxypropyl cellulose(HPC) :Water = 42:10:10:100000 (unit: kg), the viscosity can reach 20.6 s, the filtration loss in 7.5 min is 24 mL, and the sand content is only 0.1%. Compared with traditional bentonite mud, the green environment-friendly polymer mud has the advantages of small amount of waste, low environmental pollution, and low pulping cost, and can meet the construction needs for most topography and geomorphology drilling engineering
4,000원
3.
2019.11
구독 인증기관 무료, 개인회원 유료
We study substrate support structures and materials to improve uptime and shorten preventive maintenance cycles for chemical vapor deposition equipment. In order to improve the rolling of the substrate support, the bushing device adopts a ball transfer method in which a large ball and a small ball are mixed. When the main transfer ball of the bushing part of the substrate support contacts the substrate support, the small ball also rotates simultaneously with the rotation of the main ball, minimizing the resistance that can be generated during the vertical movement of the substrate support. As a result of the improvement, the glass substrate breakage rate is reduced by more than 90 ~ 95 %, and the equipment preventive maintenance and board support replacement cycles are extended four times or more, from once a month to more than four months, and the equipment uptime is at least 15 % improved. This study proposes an optimization method for substrate support structure and material improvement of chemical vapor deposition equipment.
4,000원
4.
2019.11
구독 인증기관 무료, 개인회원 유료
In this paper, nitrogen-doped reduced graphene oxide(rGO) is obtained by thermal annealing of nitrogen-containing compounds and graphene oxide (GO) manufactured by modified Hummers' method. We use melamine as a nitrogen-containing compound and treat GO thermally with melamine at over 800 ~ 1,000℃ and 1 ~ 3 hr under Ar atmosphere. The electrical conductivity of doped rGO is measured by 4-point probe method. As a result, nitrogen contents on rGO are found to be in the range of 2.5 to 12.5 at% depending on the doping conditions after thermal annealing. The main doping site on graphene oxide is changed from pyridinic-N and pyrrolinic N to the graphitic site as the heat treatment temperature increases. The electrical conductivity of doped rGO increases as the N doping content increases. As the thermal treatment time increases, the change of both total doping contents and doping sites is slight and the surface resistance is remarkably reduced, which is caused by healing effects of doped graphene oxide at high temperature.
4,000원
5.
2019.11
구독 인증기관 무료, 개인회원 유료
Single crystals, which have complexed composition, are fabricated by solid state grain growth. However, it is hard to achieve stable properties in a single crystal due to trapped pores. Aerosol deposition (AD) is suitable for fabrication of single crystals with stable properties because this process can make a high density coating layer. Because of their unique features (nano sized grains, stress inner site), it is hard to fabricate single crystals, and so studies of grain growth behavior of AD film are essential. In this study, a BaTiO3 coating layer with ~ 9 μm thickness is fabricated using an aerosol deposition method on (100) and (110) cut SrTiO3 single crystal substrates, which are adopted as seeds for grain growth. Each specimen is heat-treated at various conditions (900, 1,100, and 1,300℃ for 5 h). BaTiO3 layer shows different growth behavior and X-ray diffraction depending on cutting direction of SrTiO3 seed. Rectangular pillars at SrTiO3 (100) and laminating thin plates at SrTiO3 (110), respectively, are observed.
4,000원
6.
2019.11
구독 인증기관 무료, 개인회원 유료
Geopolymer is an alumina silicate-based ceramic material that has good heat-resistance and fire-resistance; it can be cured at room temperature, and thus its manufacturing process is simple. Geopolymer can be used as a reinforcement or floor finish for high-speed curing applications. In this manuscript, we investigate a high-speed curing geopolymer achieved by adding calcium to augment the curing rate. Metakaolin is used as the main raw material, and aqueous solutions of KOH and K2SiO3 are used as the activators. As a result of optimizing the high bending strength as a target factor for geopolymers with SiO2 / Al2O3 ratio of 4.1 ~ 4.8, the optimum ranges of the active agent are found to be 0.1 ≤ K2O / SiO2 ≤ 0.4 and 10 ≤ H2O / K2O ≤ 32.5, and the optimum range of the curing accelerator is found to be 0.82 Ca (OH)2 / Al2O3 2.87. The maximum flexural strength is found to be 1.35 MPa at Ca (OH)2 / Al2O3 = 2.82, K2O / SiO2 = 0.3, and H2O / K2O = 11.3. The physical and thermal properties are analyzed to validate the applicability of these materials as industrial insulating parts or repairing·finishing materials in construction.
4,000원
7.
2019.11
구독 인증기관 무료, 개인회원 유료
In this study, using a wet chemical process, we evaluate the effectiveness of different solution concentrations in removing layers from a solar cell, which is necessary for recovery of high-purity silicon . A 4-step wet etching process is applied to a 6-inch back surface field(BSF) solar cell. The metal electrode is removed in the first and second steps of the process, and the anti-reflection coating(ARC) is removed in the third step. In the fourth step, high purity silicon is recovered by simultaneously removing the emitter and the BSF layer from the solar cell. It is confirmed by inductively coupled plasma mass spectroscopy(ICP-MS) and secondary ion mass spectroscopy(SIMS) analyses that the effectiveness of layer removal increases with increasing chemical concentrations. The purity of silicon recovered through the process, using the optimal concentration for each process, is analyzed using inductively coupled plasma atomic emission spectroscopy(ICP-AES). In addition, the silicon wafer is recovered through optimum etching conditions for silicon recovery, and the solar cell is remanufactured using this recovered silicon wafer. The efficiency of the remanufactured solar cell is very similar to that of a commercial wafer-based solar cell, and sufficient for use in the PV industry.
4,000원
8.
2019.11
구독 인증기관 무료, 개인회원 유료
In this study, we investigate the relationship between the peeling behavior of the backsheet of a photovoltaic(PV) module and its surface temperature in order facilitate removal of the backsheet from the PV module. At low temperatures, the backsheet does not peel off whereas, at high temperatures, part of the backsheet remains on the surface of the PV module after the peeling process. The backsheet material remaining on the surface of the PV module is confirmed by X-ray diffraction(XRD) analysis to be poly-ethylene(PE). Differential scanning calorimetry(DSC) is also performed to investigate the interfacial characteristics of the layers of the PV module. In particular, DSC provides the melting temperature(Tm) of laminated ethylene vinyl acetate(EVA) and of the backsheet on the PV module. It is found that the backsheet does not peel off below the Tm of ethylene of EVA, while the PE layer of the backsheet remains on the surface of the PV module above the Tm of the PE. Thus, the backsheet is best removed at a temperature between the Tm of ethylene and that of PE layer.
4,000원
9.
2019.11
구독 인증기관 무료, 개인회원 유료
In order to observe the microstructure and morphology of porous titanium -oxide thin film, deposition is performed under a higher Ar gas pressure than is used in the general titanium thin film production method. Black titanium thin film is deposited on stainless steel wire and Cu thin plate at a pressure of about 12 Pa, but lustrous thin film is deposited at lower pressure. The black titanium thin film has a larger apparent thickness than that of the glossy thin film. As a result of scanning electron microscope observation, it is seen that the black thin film has an extremely porous structure and consists of a separated column with periodic step differences on the sides. In this configuration, due to the shadowing effect, the nuclei formed on the substrate periodically grow to form a step. The surface area of the black thin film on the Cu thin plate changes with the bias potential. It has been found that the bias of the small negative is effective in increasing the surface area of the black titanium thin film. These results suggest that porous titanium-oxide thin film can be fabricated by applying the appropriate oxidation process to black titanium thin film composed of separated columns.
4,000원
10.
2019.11
구독 인증기관 무료, 개인회원 유료
Molybdenum is a low-resistivity transition metal that can be applied to silicon devices using Si-metal electrode structures and thin film solar cell electrodes. We investigate the deposition of metal Mo thin film by plasma-enhanced atomic layer deposition (PE-ALD). Mo(CO)6 and H2 plasma are used as precursor. H2 plasma is induced between ALD cycles for reduction of Mo(CO)6 and Mo film is deposited on Si substrate at 300℃. Through variation of PE-ALD conditions such as precursor pulse time, plasma pulse time and plasma power, we find that these conditions result in low resistivity. The resistivity is affected by Mo pulse time. We can find the reason through analyzing XPS data according to Mo pulse time. The thickness uniformity is affected by plasma power. The lowest resistivity is 176 μΩ·cm at Mo(CO)6 pulse time 3s. The thickness uniformity of metal Mo thin film deposited by PE-ALD shows a value of less than 3% below the plasma power of 200 W.
4,000원
11.
2019.11
구독 인증기관 무료, 개인회원 유료
Recently, research on cost reduction and efficiency improvement of crystalline silicon(c-Si) photovoltaic(PV) module has been conducted. In order to reduce costs, the thickness of solar cell wafers is becoming thinner. If the thickness of the wafer is reduced, cracking of wafer may occur in high temperature processes during the c-Si PV module manufacturing process. To solve this problem, a low temperature process has been proposed. Conductive paste(CP) is used for low temperature processing; it contains Sn57.6Bi0.4Ag component and can be electrically combined with solar cells and ribbons at a melting point of 150℃. Use of CP in the PV module manufacturing process can minimize cracks of solar cells. When CP is applied to solar cells, the output varies with the amount of CP, and so the optimum amount of CP must be found. In this paper, in order to find the optimal CP application amount, we manufactured several c-Si PV modules with different CP amounts. The amount control of CP is fixed at air pressure (500 kPa) and nozzle diameter 22G(outer diameter 0.72Ø, inner 0.42Ø) of dispenser; only speed is controlled. The c-Si PV module output is measured to analyze the difference according to the amount of CP and analyzed by optical microscope and Alpha-step. As the result, the optimum amount of CP is 0.452 ~ 0.544 g on solar cells.
4,000원
12.
2019.11
구독 인증기관·개인회원 무료
In this study, the glass melting properties are evaluated to examine the possibility of using refused coal ore as replacement for ceramic materials. To fabricate the glass, refused coal ore with calcium carbonate and sodium carbonate in it (which are added as supplementary materials) is put into an alumina crucible, melted at 1,200 ~ 1,500℃ for 1 hr, and then annealed at 600℃ for 2 hrs. We fabricate a black colored glass. The properties of the glass are measured by XRD (X-ray diffractometry) and TG-DTA (thermogravimetry-differential thermal analysis). Glass samples manufactured at more than 1,300℃ with more than 60 % of refused coal ore are found by XRD to be non-crystalline in nature. In the case of the glass sample with 40 % of refused coal ore, from the sample melted at 1,200℃, a sodium aluminum phosphate peak, a disodium calcium silicate peak, and an unknown peak are observed. On the other hand, in the sample melted at 1,300℃, only the sodium aluminum phosphate peak and unknown peak are observed. And, peak changes that affect crystallization of the glass according to melting temperature are found. Therefore, it is concluded that glass with refused coal ore has good melting conditions at more than 1,200℃ and so can be applied to the construction field for materials such as glass tile, foamed glass panels, etc.
