• Title/Summary/Keyword: microstructure

Search Result 8,091, Processing Time 0.037 seconds

All-Solid-State Electrochromic Film with WO3/NiO Complementary Structure (WO3/NiO 상호 보완적인 구조의 전고체 전기변색 필름)

  • Shin, Minkyung;Lee, Sun Hee;Seo, Intae;Kang, Hyung-Won;Han, Seung Ho
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.35 no.3
    • /
    • pp.275-280
    • /
    • 2022
  • An all-solid-state electrochromic film was fabricated by laminating tungsten oxide (WO3) and nickel oxide (NiO) thin films deposited by a reactive DC magnetron sputtering on flexible ITO films. The influence of oxygen partial pressure on the crystal structure, microstructure, optical properties, and electrochromic properties of WO3 and NiO thin films were investigated. WO3 and NiO films showed the best electrochromic properties under the flow of Ar:O2=80:20 and Ar:O2=90:10, respectively. The EC film fabricated with an optimized WO3 and NiO films showed a high coloration efficiency, a fast response time, and a stable optical modulation. It is expected that flexible EC window films will pave the way for the next-generation energy-saving windows.

Non-aqueous Zinc(Zn) Plating to Prevent Hydrogen Release from Test Specimens in Hydrogen Embrittlement Test (수소 취성 시험 평가를 위한 수소 방출 방지용 비수계 아연(Zn) 도금)

  • Jeon, Jun-Hyuck;Jang, JongKwan
    • Journal of the Korean Institute of Gas
    • /
    • v.26 no.3
    • /
    • pp.21-26
    • /
    • 2022
  • Zinc is emerging as a environment-friendly plating material to replace cadmium, which is harmful to the human body, to prevent hydrogen gas penetration or release from metal materials. Electroplating of Zn and Zn alloys, which is usually performed in an aqueous acidic atmosphere, has disadvantages such as low coulombic efficiency, corrosion, and hydrogen release, resulting in industrial use difficult. In this study, a deep-eutectic solvent was synthesized using choline chloride and ethylene glycol. Using this as a solvent, an electrolyte for Zn plating was prepared, and then zinc was plated on the STS 304 substrate. The surface microstructure and roughness were observed using SEM and AFM. The crystal structure of the electro-plated film was analyzed using XRD. Finally, the preventing effects of hydrogen release through Zn-based deep-eutectic plating on the STS 304 substrate were compared with the uncoated substrate.

Effects of pulsed laser surface remelting on microstructure, hardness and lead-bismuth corrosion behavior of a ferrite/martensitic steel

  • Wang, Hao;Yuan, Qian;Chai, Linjiang;Zhao, Ke;Guo, Ning;Xiao, Jun;Yin, Xing;Tang, Bin;Li, Yuqiong;Qiu, Shaoyu
    • Nuclear Engineering and Technology
    • /
    • v.54 no.6
    • /
    • pp.1972-1981
    • /
    • 2022
  • A typical ferritic/martensitic (F/M) steel sheet was subjected to pulsed laser surface remelting (LSR) and corrosion test in lead-bismuth eutectic (LBE) at 550 ℃. There present two modification zones with distinct microstructures in the LSRed specimen: (1) remelted zone (RZ) consisting of both bulk δ-ferrite grains and martensitic plates and (2) heat-affected zone (HAZ) below the RZ, mainly composed of martensitic plates and high-density precipitates. Martensitic transformation occurs in both the RZ and the HAZ with the Kurdjumov-Sachs and Nishiyama-Wassermann orientation relationships followed concurrently, resulting in scattered orientations and specific misorientation characteristics. Hardnesses of the RZ and the HAZ are 364 ± 7 HV and 451 ± 15 HV, respectively, considerably higher than that of the matrix (267 ± 3 HV). In oxygen-saturated and oxygen-depleted LBE, thicknesses of oxide layers developed on both the as-received and the LSRed specimens increase with prolonging corrosion time (oxide layers always thinner under the oxygen-depleted condition). The corrosion resistance of the LSRed F/M steel in oxygen-saturated LBE is improved, which can be attributed to the grain-refinement accelerated formation of dense Fe-Cr spinel. In oxygen-depleted LBE, the growth of oxide layers is very low with both types of specimens showing similar corrosion resistance.

Multi-scale Process-structural Analysis Considering the Stochastic Distribution of Material Properties in the Microstructure (미소 구조 물성의 확률적 분포를 고려한 하이브리드 성형 공정 연계 멀티스케일 구조 해석)

  • Jang, Kyung Suk;Kim, Tae Ri;Kim, Jeong Hwan;Yun, Gun Jin
    • Composites Research
    • /
    • v.35 no.3
    • /
    • pp.188-195
    • /
    • 2022
  • This paper proposes a multiscale process-structural analysis methodology and applies to a battery housing part made of the short fiber-reinforced and fabric-reinforced composite layers. In particular, uncertainties of the material properties within the microscale representative volume element (RVE) were considered. The random spatial distribution of matrix properties in the microscale RVE was realized by the Karhunen-Loeve Expansion (KLE) method. Then, effective properties of the RVE reflecting on spatially varying matrix properties were obtained by the computational homogenization and mapped to a macroscale FE (finite element) model. Morever, through the hybrid process simulation, a FE (finite element) model mapping residual stress and fiber orientation from compression molding simulation is combined with one mapping fiber orientation from the draping process simulation. The proposed method is expected to rigorously evaluate the design requirements of the battery housing part and composite materials having various material configurations.

Electrical Properties and Phase Transition Behavior of Lead-Free BaTiO3-Modified Bi1/2Na1/2TiO3-SrTiO3 Piezoelectric Ceramics (BaTiO3 첨가에 따른 Bi1/2Na1/2TiO3-SrTiO3 무연 압전 세라믹스의 전기적 특성 및 상전이 거동 연구)

  • Kang, Yubin;Park, Jae Young;Devita, Mukhllishah Aisyah;Duong, Trang An;Ahn, Chang Won;Kim, Byeong Woo;Han, Hyoung-Su;Lee, Jae-Shin
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.35 no.5
    • /
    • pp.516-521
    • /
    • 2022
  • We investigated the microstructure, crystal structure, dielectric, and elecromechanical strain properties of lead-free BaTiO3 (BT)-modified (Bi1/2Na1/2)TiO3-SrTiO3 (BNT-ST) piezoelectric ceramics. Samples were prepared by a conventional ceramic processing route. Temperature dependent dielectric properties confirmed that a phase transition from a nonergodic relaxor to an ergodic relaxor was induced when the BT concentration reached 1.5 mol%, interestingly, where the average grain size reached a maximum value of 4.5 ㎛. At the same time, enhanced electromechanical strain (Smax/Emax = 600 pm/V) was obtained. It is suggested that the induced ferroelectric-relaxor phase transition by the BT modification is responsible for the enhancement of electromechanical strain in 1.5 mol% BT-modified BNT-ST ceramics.

Degradation Evaluation of High-Pressure Superheater Tube in Heat Recovery Steam Generator (배열회수보일러 고압 슈퍼히터 튜브 열화도 평가)

  • Song, Min Ji;Choi, Gahyun;Chae, Hobyung;Kim, Woo Cheol;Kim, Heesan;Kim, Jung-Gu;Lee, Soo Yeol
    • Corrosion Science and Technology
    • /
    • v.21 no.2
    • /
    • pp.130-137
    • /
    • 2022
  • In this work, the degradation of high-pressure superheater tubes exposed to the flame of a duct burner in a heat recovery steam generator of a district heating system was evaluated. To assess the deterioration of the used superheater tube, the microstructure, microhardness, and tensile properties were investigated by comparison to an unused tube. The study found that a fin bound at the outer surface of the used tube became fragile only in the location facing the flame. This indicates that the tube was directly exposed to the flame from the duct burner or underwent abnormal overheating. While the unused tube showed a uniform value in hardness and equiaxial grain structure, the used tube revealed a decrease in hardness up to 105 HV and an increase in grain size with a plate-like morphology in the location facing the flame. The coarsening of the grain structure by the flame weakened the mechanical properties of yield strength, tensile strength, and elongation.

Evaluation of Weathering Durability of Waterborne Preservative Treated Wood by Accelerated Weathering (수용성 방부처리재의 기상열화 저항성 평가)

  • Lee, Myung-Jae;Lee, Dong-Heub;Kim, Gyu-Hyeok
    • Journal of the Korean Wood Science and Technology
    • /
    • v.31 no.4
    • /
    • pp.44-49
    • /
    • 2003
  • This study was carried out to evaluate the weathering durability of waterborne preservative (AAC, ACQ, CCA, CuAz) treated Japanese red pine (Pinus densiflora S. et Z.) sapwood samples by accelerated weathering, and to find out the factor of stability. When considered the color changes, weight losses, surface degradation, and microstructure changes due to weathering, ACQ-, CCA-, and CuAz-treated samples were durable against weathering; the weathering durability of AAC-treated samples was poor and similar to untreated controls. The lignin content in aqueous extracts collected from ACQ-, CCA-, and CuAz-treated samples during weathering was lower than that from untreated and AAC-treated ones. From these findings, we might concluded that weathering durability of ACQ-, CCA-, and CuAz-treated samples was enhanced by the fixation of preservative component(s) onto the lignin structure, which is very susceptible to weathering.

Effect of Initial Solidification Condition During Directional Solidification on the Grain Growth and the Tensile Properties of Superalloy CM247LC (초내열합금 CM247LC의 조직 및 인장특성에 미치는 초기 일방향응고 조건의 영향)

  • Jeong, Jae Jun;Kwon, Seok Hwan;Jeong, Eui Seok;Jo, Chang Yong;Lee, Je Hyun
    • Journal of Korea Foundry Society
    • /
    • v.42 no.2
    • /
    • pp.77-82
    • /
    • 2022
  • Initial solidification condition during directional solidification of superalloy CM247LC was controlled with various cooling methods such as insertion of alumina disc or Ni foil or inoculant, and direct pouring of melt onto chill plate. Rapid cooling with direct pouring of melt onto chill plate resulted in generation of many fine grains and precipitation of fine γ' particles, as well as small dendrite arm spacing. Tensile properties of directionally solidified superalloy CM247LC were closely related to microstructure which was governed by initial solidification conditions. Directionally solidified CM247LC with small dendrite arm spacing and fine precipitates showed good tensile properties.

Carburizing Behavior of AISI 4115 Steel with a Flow Rate of Acetylene and Specimen Location in an 1 ton-class Mass Production-type Vacuum Carburizing Furnace (1 톤급 양산형 진공 침탄로에서 아세틸렌 유량과 로 내 위치에 따른 AISI 4115 강의 침탄 거동)

  • Kwon, Gi-hoon;Moon, Kyoungil;Park, Hyunjun;Lee, Young-Kook;Jung, Minsu
    • Journal of the Korean Society for Heat Treatment
    • /
    • v.34 no.6
    • /
    • pp.272-280
    • /
    • 2021
  • The influence of acetylene flow rates on the carburizing behavior of an AISI 4115 steel in 1 ton-class mass production-type vacuum carburizing furnace has been studied through microstructure, carbon concentration, hardness analyses. The AISI 4115 steels were carburized with various flow rates (20, 32.7, 60 l/min) and locations in the furnace (top, center, bottom) at 950℃. The acetylene flow rate played an important role in controlling the carburizing properties of carburized samples, such as effective case depth and uniformity carburizing according to location in the furnace. At an acetylene flow rate of 20 l/min, the carburized samples had a shallow average hardened layer (0.645 mm) compared to the target hardening depth (1 mm) due to low carbon flux and spatial uniformity of carburization (17.8%) in the furnace. At a flow rate of 60 l/min, the carburized samples showed an average hardened layer (1.449 mm) deeper than the target hardening depth and had the spatial uniformity of carburization (98.8%). In particular, at a flow rate of 32.7 l/min, the carburized samples had an average hardened layer (1.13 mm) close to the target hardening depth and had the highest carburizing uniformity (99.1%). As a result, an appropriate flow rate of 32.7 l/min was derived to satisfy the target hardening depth and to have spatial uniform hardened layer in the furnace.

Effect of Microstructure on Piezoelectric Properties and TCC Behavior in PZT-PZN Ceramics (PZT-PZN 세라믹의 미세구조가 압전 특성 및 TCC 거동에 미치는 영향)

  • Seo, Intae;Choi, Yongsu;Cho, Yuri;Kang, Hyung-Won;Kim, Kang San;Cheon, Chae Il;Han, Seung Ho
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.35 no.5
    • /
    • pp.445-451
    • /
    • 2022
  • Ultrasonic sensor is suitable as a next-generation autonomous driving assist device because its lower price compared to that of other sensors and its sensing stability in the external environment. Although Pb(Zr, Ti)O3 (PZT)-relaxor ferroelectric system has excellent piezoelectric properties, the change in capacitance is large in the daily operating temperature range due to the low phase transition temperature. Recently, many studies have been conducted to improve the temperature stability of ferroelectric ceramics by controlling the grain size and crystal structure, so it is necessary to study the effect of the grain size on the piezoelectric properties and the temperature stability of PZT-relaxor ferroelectric system. In this study, the piezoelectric properties, phase transition temperature, and temperature coefficient of capacitance (TCC) of 0.9 Pb(Zr1-xTix)O3-0.1 Pb(Zn1/3Nb2/3)O3 (PZTx-PZN) ceramics with various grain sizes were investigated. PZTx-PZN ceramics with larger grain size showed higher piezoelectric properties and temperature stability, and are expected to be suitable for ultrasonic devices in the future.