Microstructure and Electrical Properties of Pb[(Mg,Mn)Nb]O₃-Pb(Zr,Ti)O₃ Piezoelectric Ceramics

Kim, Jin-Ho,Kim, Jong-Hwa,Baik, Seung-Woo The Korean Institute of Electrical and Electronic 2005 Transactions on Electrical and Electronic Material Vol.6 No.5

Phase evolution, microstructure and the electrical properties such as $k_p$ and $Q_m$ of $Pb(Mg_{1/3}Nb_{2/3})O_3[PMN]-Pb(Mn_{1/3}Nb_{2/3})O3[PM'N]-PbZrO_3[PZ]-PbTiO_3[PT]$ quaternary system were investigated within the compositional ranges $0{\leq}y{\leq}0.125$, y+z=0.125, and $0.39{\leq}x{\leq}0.54$ of the formula $Pb_{0.97}Sr_{0.03}[Mg_{1/3}Nb_{2/3})_y\;(Mn_{1/3}Nb_{2/3})_z\;(Zr_{x}Ti_{1-x})_{1-(y+z)}]O_3$. In the case of increasing Mn/(Mg+Mn) ratio for a fixed Zr/Ti ratio of 47.5/52.5, phase relation remained unchanged but the grain size drastically decreased, and the electrical properties changed as following: both $k_P$ and $Q_m$ reached the peak values at $Mn/(Mg+Mn)\cong0.3l7$ and gradually decreased; $\varepsilon33^T$ showed a monotonic decrease; P-E hysteresis loop gradually changed to asymmetrical one, and $E_i$ increased in correspondence. With increasing Zr/Ti ratio for a fixed Mn/(Mg+Mn) ratio of 0.317, on the contrary, the cell parameter $(\alpha^2c)^{1/3}$ gradually increased, and tetragonal-rhombohedral morphotropic phase boundary appeared in the range of $51/49{\leq}Zr/Ti{\leq}54/46$. the meantime, the grain size substantially increased, and the electrical properties changed as following: $k_P$ and $\varepsilon33^T$ reached peak values at Zr/Ti=51/49 and 48/52, respectively, and then gradually decreased; change of $Q_m$ was adverse to $k_P$; both $E_C\;and\;E_i$ considerably decreased while $P_S$ moderately increased. For the system 0.125(PMN+PM'N)-0.875PZT studied, the composition Mn/(Mg+Mn)=0.3l7 and Zr/Ti=51/49 revealed some promising electrical properties for piezoelectric transformer application such as $k_P=0.58,\;Q_m\cong1000$, and $\varepsilon^T_{33}=970$, as well as dense and fine-grained microstructure.

Microstructure and Electrical Properties of Pb[(Mg,Mn)Nb]O3-Pb(Zr,Ti)O3 Piezoelectric Ceramics

김진호,Jong-Hwa Kim,Seung-Woo Baik 한국전기전자재료학회 2005 Transactions on Electrical and Electronic Material Vol.6 No.5

Phase evolution, microstructure and the electrical properties such as kP and Qm of Pb(Mg1/3Nb2/3)O3[PMN]-Pb(Mn1/3Nb2/3)O3[PM΄N]-PbZrO3[PZ]-PbTiO3[PT] quaternary system were investigated within the compositional ranges 0≤y≤0.125, y+z=0.125, and 0.39≤x≤0.54 of the formula Pb0.97Sr0.03[(Mg1/3Nb2/3)y (Mn1/3Nb2/3)z (ZrxTi1-x)1-(y+z)]O3. In the case of increasing Mn/(Mg+Mn) ratio for a fixed Zr/Ti ratio of 47.5/52.5, phase relation remained unchanged but the grain size drastically decreased, and the electrical properties changed as following: both kP and Qm reached the peak values at Mn/(Mg+Mn)@0.317 and gradually decreased; e33Tshowed a monotonic decrease; P-E hysteresis loop gradually changed to asymmetrical one, and Ei increased in correspondence. With increasing Zr/Ti ratio for a fixed Mn/(Mg+Mn) ratio of 0.317, on the contrary, the cell parameter (a2c)1/3 gradually increased, and tetragonal-rhombohedral morphotropic phase boundary appeared in the range of 51/49≤Zr/Ti≤54/46. In the meantime, the grain size substantially increased, and the electrical properties changed as following: kP and e33T reached peak values at Zr/Ti=51/49 and 48/52, respectively, and then gradually decreased; change of Qm was adverse to kP; both EC and Ei considerably decreased while PS moderately increased. For the system 0.125(PMN+PM΄N)-0.875PZT studied, the composition Mn/(Mg+Mn)=0.317 and Zr/Ti=51/49 revealed some promising electrical properties for piezoelectric transformer application such as kP=0.58, Qm@1000, and eT33=970, as well as dense and fine-grained microstructure.

Preparation of Porous Ni–Cu Alloy Electrodes and their Electrocatalytic Performance as Cathode for Hydrogen Evolution Reaction in Alkaline Solution

Li Yuan,Chen Gao,Chunyan Zeng,Yue Lu,Xuzheng Qian,Fuyi Chen 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.10

Porous Ni–Cu alloy electrodes were conveniently fabricated by galvanic displacement reaction (GDR) between Ni foam and copper ion in copper ion solutions, followed by cyclic voltammetry (CV) treatment to form a hierarchical microstructure. The electrocatalytic performance of prepared electrodes in terms of the hydrogen evolution reaction (HER) was investigated in a 1 mol/L KOH solution at room temperature. Different copper ion solutions were tested to determine the best copper ion solution and the optimum GDR time, and experimental results show that all cathodes obtained by GDR between Ni foam and copper ion exhibit a superior HER activity over the pure Ni foam cathode, while the HER activity of electrode obtained by GDR between Ni foam and copper ion in 0.5 mol/L CuCl2 solutions for 1 h is the highest. Furthermore, it is found that the HER activity of electrode obtained by GDR between Ni foam and copper ion in 0.5 mol/L CuCl2 solutions for 1 h can be further enhanced through a CV treatment and the optimal number of CV cycles is 3, which can be attributed to a hierarchical microstructure (a needle-like nano–microstructure formed on the surface of the electrode during the CV treatment process).

Effects of Sintering Conditions on Microstructure and Characteristics of Screen-Printed Ag Thin Film

김광석,Woo-Ram Myung,정승부 대한금속·재료학회 2012 ELECTRONIC MATERIALS LETTERS Vol.8 No.3

Direct printing techniques can provide a shorter manufacturing time, lower cost, and greater environmental friendliness compared to conventional photolithography. The electrical and mechanical characteristics of directly printed films are determined by their microstructure. This research focuses on the microstructural evolution of silver (Ag) thin films screen-printed onto a silicon (Si) wafer passivated with SiO2. To investigate the effect of heat treatment on the microstructure of the thin film, various sintering conditions were used: temperatures of 150°C, 200°C, 250°C, and 300°C, atmospheres of air, vacuum, N2, and Ar and rates of increase of temperature of 10°C/min, 20°C/min, 30°C/min, 40°C/min, and 50°C/min. Each parameter plays an important role in determining the density and microstructural evolution, which affect the densification of and void distribution inside the thin film. The electrical resistivity of the Ag thin film was measured by a four-point probe method. The oxygen concentration profiles on the Ag film surface were investigated using Auger electron spectroscopy (AES). The film sintered in air showed the highest oxygen concentration. At higher sintering temperatures, the film showed a denser microstructural evolution and void growth resulting in a lower electrical resistivity of 2.88 μΩ·cm.

Hardness prediction based on microstructure evolution and residual stress evaluation during high tensile thick plate butt welding

Zhou, Hong,Zhang, Qingya,Yi, Bin,Wang, Jiangchao The Society of Naval Architects of Korea 2020 International Journal of Naval Architecture and Oc Vol.12 No.-

Two High Tensile Strength Steel (EH47) plates with thickness of 70 mm were butt-welded together by multi-pass Submerged Arc Welding (SAW), also the hardness and welding residual stress were investigated experimentally. Based on Thermal-Elastic-Plastic Finite Element (TEP FE) computation, the thermal cycles during entire welding process were obtained, and the HAZ hardness of multi-pass butt welded joint was computed by the hardenability algorithm with considering microstructure evolution. Good agreement of HAZ hardness between the measurement and computational result is observed. The evolution of each phase was drawn to clarify the influence mechanism of thermal cycle on HAZ hardness. Welding residual stress was predicted with considering mechanical response, which was dominantly determined by last cap welds through analyzing its formation process.

Hardness prediction based on microstructure evolution and residual stress evaluation during high tensile thick plate butt welding

Zhou, Hong,Zhang, Qingya,Yi, Bin,Wang, Jiangchao The Society of Naval Architects of Korea 2020 International Journal of Naval Architecture and Oc Vol.12 No.1

Two High Tensile Strength Steel (EH47) plates with thickness of 70 mm were butt-welded together by multi-pass Submerged Arc Welding (SAW), also the hardness and welding residual stress were investigated experimentally. Based on Thermal-Elastic-Plastic Finite Element (TEP FE) computation, the thermal cycles during entire welding process were obtained, and the HAZ hardness of multi-pass butt welded joint was computed by the hardenability algorithm with considering microstructure evolution. Good agreement of HAZ hardness between the measurement and computational result is observed. The evolution of each phase was drawn to clarify the influence mechanism of thermal cycle on HAZ hardness. Welding residual stress was predicted with considering mechanical response, which was dominantly determined by last cap welds through analyzing its formation process.

Particle Size versus Grain Size Relation in the Sprayformed Al-18Si Composites

석현광,박경원,이재철 대한금속·재료학회 2009 METALS AND MATERIALS International Vol.15 No.4

Various hypereutectic Al-18Si-X composites with different average Si particle sizes ranging from 0.2~30 μm were produced by varying process parameters of spray forming. The effect of the Si particle size in determining the matrix grain size was investigated in order to design the optimum process for producing hypereutectic Al-18Si-X composites with fine microstructures. The experimental results suggested that the Si particle size greater than 2 μm is desirable for retarding the grain coarsening during subsequent forming processes, resulting in the fine microstructure. The observed results on the coarsening behavior of grains during spray-forming were analyzed from the free energy viewpoint.

Effect of ruthenium on high-temperature creep rupture life of a single crystal nickel-based superalloy

Tan, X.P.,Liu, J.L.,Jin, T.,Hu, Z.Q.,Hong, H.U.,Choi, B.G.,Kim, I.S.,Jo, C.Y. Elsevier Sequoia 2011 Materials science & engineering. properties, micro Vol.528 No.29

The addition of 3wt% ruthenium (Ru) has been found to improve the creep rupture lives of a single crystal Ni-based superalloy under both conditions of 1100<SUP>o</SUP>C/150MPa and 1000<SUP>o</SUP>C/310MPa. Creep curve analysis indicates that the creep mechanisms are different from each condition. The improvement of creep rupture lives by 3wt% Ru addition is discussed not only from the view of dislocation movement but also the γ' phase evolution. The change of γ/γ' lattice misfit in the initial microstructure is believed to be the key role of Ru on the high-temperature creep deformation. The larger negative lattice misfit caused by an addition of 3wt% Ru induces smaller and more regular γ' particles in the initial state, as well as denser dislocation networks at the γ/γ' interface during creep. These two aspects are crucial to the high-temperature creep rupture life. In addition, a little topologically close-packed (TCP) phases are observed after creep rupture in the two experimental alloys.

저온 열처리로 제작된 1.5 mol% 이트리아 안정화 지르코니아 세라믹스의 상 안정성 및 소결물성

김경태,최한철,박정식,이종국 한국열처리공학회 2024 熱處理工學會誌 Vol.37 No.1

Phase stability of tetragonal crystals in yttria-stabilized zirconia ceramics is dependent on the content of yttria and the heat-treatment condition, related with mechanical properties. In this study, we fabricated the 1.5 mol% yttria-stabilized zirconia (1.5Y-YSZ) ceramics by cold isostatic pressing (CIP) and post-sintering at temperature range of 1200 to 1350oC for 2 hours and investigated the sintered properties and microstructural evolution. Sintered and microstructural parameters, i.e, apparent density, grain size and phase composition of 1.5Y-YSZ ceramics were mainly dependent on the sintering temperature. Maximum sintered density of 99.4 % and average grain size of 200-300 nm could be obtained from the heat-treatment condition above sintering temperature at 1300oC for 2 hours, possessing the superior mechanical hardness with 1200 Hv. However, phase stability of tetragonal grains in 1.5 YSZ ceramics is very low, inducing the phase transformation to monoclinic crystals on specimen surface during cooling after heat-treatment.

Influence of the Welding Speeds and Changing the Tool Pin Profiles on the Friction Stir Welded AA5083-O Joints

M. M. El-Sayed,A. Y. Shash,M. Abd Rabou 대한용접·접합학회 2017 대한용접·접합학회지 Vol.35 No.3

In the present study, AA 5083-O plates are joined by friction stir welding technique. A universal milling machine was used to perform the welding process of the work-pieces which were fixed on the proper position by a vice. The joints were friction stir welded by two tools with different pin profiles; cylindrical threaded pin and tapered smooth one at different rotational speed values; 400 rpm and 630 rpm, and different welding speed values; 100 mm/min and 160 mm/min. During FSW of each joint, the temperature was measured by infra-red thermal image camera. The welded joints were inspected by visually as well as by the macro- and microstructure evolutions. Furthermore, the joints were tested for measuring the hardness and the tensile strength to study the effect of changing the FSW parameters on the mechanical properties. The results show that increasing the rotational speed results in increasing the peak temperature, while increasing the welding speed results in decreasing the peak temperature for the same tool pin profile. Defect free welds were obtained at lower rotational speed by the threaded tool profile. Moreover, the threaded tool pin profile gives superior mechanical properties at lower rotational speed.