Microstructural Stability and Creep Performance of a Novel Low-Cost Single Crystal Superalloy

Z. H. Tan,X. G. Wang,Y. L. Du,Y. M. Li,Y. H. Yang,J. L. Liu,J. D. Liu,J. G. Li,Y. Z. Zhou,X. F. Sun 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.7

The increasing pursuit of advanced aero-engines with lower ratio between the cost and performance has greatly promotedthe demanding of single crystal superalloys characterized by low cost and outstanding temperature capability. In this study,a novel low-cost single crystal superalloy was designed and the creep tests as well as micro-characterization were carried outon the experimental alloy. The results illustrated that the novel single crystal alloy exhibited an ideal microstructural stabilitywithout precipitating TCP phases, after long-term thermal exposure at the ultimate service temperature of third generationsingle crystal superalloys. Moreover, the experimental alloy with only 3 wt% Re addition demonstrated remarkable creepresistance and maintained a very low minimum creep rate at 1100 °C/137 MPa and 1120 °C/137 MPa, while the accumulationand coalescence of micro-pores had eventually led to the alloy fracture. Apart from that, the compact interfacial dislocationnetworks the 2nd γ′ phase were observed after high-temperature creep rupture, and the typical a < 010 > superdislocationswith relatively poor mobility was found at 1120 °C. At 760 °C/800 MPa, both the minimum creep velocity and entire creepstain was increased evidently, however, the ultimate creep rupture life of the alloy had still reached 200 h. The correspondingdeformation mechanism was identified as the combination of superdislocation pairs shearing and a/3 < 121 > partial dislocationcutting the γ′ phase with a SISF being generated. In general, the novel single crystal alloy characterized by remarkablemechanical properties and cost reduction possesses a great potential for future application in the advanced aircraft engines.

Enhanced energy storage properties in PbZrO3 thin films via the incorporation of NiO

Wang X.W.,Chen J.Y.,Hu S.Y.,Yu K.X.,Yang F.,Shi Y.J.,Li J.H.,Hou M.Z.,Liu A.D.,Zheng M.M.,Yin S.Q.,Hu Y.C.,Shang J. 한국물리학회 2023 Current Applied Physics Vol.52 No.-

In this study, NiO–PbZrO3 composite films were deposited on SiO2/Si substrates buffered with LaNiO3 films via the sol-gel coating technique. The effects of NiO addition in PZO thin films on the microstructure, dielectric properties, leakage mechanism, ferroelectric properties and energy storage properties have been discussed. The dielectric constant increased with the addition of NiO, while the leakage current density decreased. Compared with pure PZO films, the maximum polarization of the composite films was improved. For the composite films prepared using the NiO precursor solution with 0.05 mol/L, the recoverable energy storage density of the NiO-PZO composite film is up to 19.6 J/cm3 under the electric field of 1038 kV/cm, which is 30% higher than that of the pure PZO film under the same conditions. Also, the energy storage efficiency of the composite film reaches 48%. Accordingly, we demonstrate a simple and convenient method by adding NiO to fabricate thin films with high energy storage performance.

Response of plasma rotation to resonant magnetic perturbations in J-TEXT tokamak

Yan, W,Chen, Z Y,Huang, D W,Hu, Q M,Shi, Y J,Ding, Y H,Cheng, Z F,Yang, Z J,Pan, X M,Lee, S G,Tong, R H,Wei, Y N,Dong, Y B IOP 2018 Plasma physics and controlled fusion Vol.60 No.3

<P>The response of plasma toroidal rotation to the external resonant magnetic perturbations (RMP) has been investigated in Joint Texas Experimental Tokamak (J-TEXT) ohmic heating plasmas. For the J-TEXT’s plasmas without the application of RMP, the core toroidal rotation is in the counter-current direction while the edge rotation is near zero or slightly in the co-current direction. Both static RMP experiments and rotating RMP experiments have been applied to investigate the plasma toroidal rotation. The core toroidal rotation decreases to lower level with static RMP. At the same time, the edge rotation can spin to more than 20 km s<SUP>−1</SUP> in co-current direction. On the other hand, the core plasma rotation can be slowed down or be accelerated with the rotating RMP. When the rotating RMP frequency is higher than mode frequency, the plasma rotation can be accelerated to the rotating RMP frequency. The plasma confinement is improved with high frequency rotating RMP. The plasma rotation is decelerated to the rotating RMP frequency when the rotating RMP frequency is lower than the mode frequency. The plasma confinement also degrades with low frequency rotating RMP.</P>

재래 흑돼지와 중국 재래돈간의 Melanocortin Receptor 1(MC1R) 유전자의 유전자형 분석

이성수,양보석,정진관,고서봉,오성종,양영훈,김규일,이찬동,풍서당 한국동물자원과학회 2001 한국축산학회지 Vol.43 No.1

PCR-RFLP analysis of Melanocortin receptor 1 (MC1R) gene was carried out to investigate the genotype distribution in Korean-Native and Chinese-Native pig breeds(Neijiang, Putian, Wannanhua and Jinhua). Allelic variants of MC1R in pigs were analyzed by digestion of BspH I , AccII and Hha I . Ncijiang. Wannanhua and Jinhua had only MC1R*2 allele which is considered to be typical genotype for Meishan and Large Black. Among 20 Korean-Native Pigs and 5 Putian pigs, 10 and 2 heads had the MC1R*3 allele (*2/3 or 3/3), respectively, which was detected in European pig breeds such as Hampshire, Large White, and Pietrain. The remaining animals possessed the genotype MC1R*2/2, probably reflecting the genetic introgression of MC1R*3 allele into Korean-Native and Putian pig breeds by the crossbreeding for improvement. The alleles MC1R*l and MC1R*4, which are considered to be typical allele for European Wild Boar with wild-type coat color and Duroc with red coat color, respectively, were not detected in pig breeds used in this experiment. These results indicate that the analysis of genotype frequencies of MC1R gene may be a useful tool for the conservation of Korean-Native and Chinese-Native pig breeds.

Al_(2)O_(3)-MgO계 캐스터블 내화물의 내침식성 향상

전명곤,연상흠,양정훈,김재준,황규홍,정두화 慶尙大學校 經營行政大學院 2004 工學硏究院論文集 Vol.20 No.-

To improve the mechanical and chemical properties of unfired Al_(2)O_(3) castables which is widely used in metal line of steel-making ladle, the ρ-Al_(2)O_(3) and /or fine MgO was added as a matrix powders and the degree of spinel formation was studied. Because the spinel was formed at the contact areas between Al_(2)O_(3) and MgO particles and the volume of in-situ formed spinel increased more abnormally at the site of Al_(2)O_(3) particles than MgO side, Al_(2)O_(3) aggregates was more recommendable than MgO aggregates. And to compare the degree of spinel formation in the Al_(2)O_(3)-MgO castable refractories, ultrafine SiO_(2) and Al_(2)O_(3) powders were added and their effects on physical properties such as permanent volume expansion and cold crushing strength were examined. For ρ-Al_(2)O_(3) binder, it could be replaced the alumina cement so that the CaO content could be reduced, but low compressive strength and firing shrinkage inhibit it's application to castables. But MgO powders should be added and the finer the MgO powder, the better the residual expansion and in-situ Spinel formation was observed. And due to Spinel formation and dense microstructure, CA_(6) phase would not formed around alumina aggregates during corrosion so that the corrosion resistance was much more increased.

Leakage Currents of a Fast Switching Thyristor Made by Proton Irradiation Method

E.D. Kim,C.L. Zhang,S.C. Kim,N.K. Kim,J.Z. Zhu,B.F. Yang 전력전자학회 2004 ICPE(ISPE)논문집 Vol.- No.-

A thyristor with a VRRM of 1,600V was made with 200μm of N-base width from 60Ω·cm NTD-Si wafer and the proton irradiation was employed for improving its switching performance. This study showed that 4.7MeV-proton irradiation gives a narrow distribution of induced defects in the middle of N-drift region with its width of 10μm, which resulted in a superior trade-off relation between its static and dynamic characteristics. It was found that 3.7MeV and 5.9MeV protons remarkably increased the forward leakage current IDRM and the reverse leakage current IRRM, respectively. The increased IDRM and IRRM are attributed to the induced defects in the depletion layers of thyristor junctions J2 and J1, respectively.

Luminescence characteristic of RE (RE = Pr, Sm, Eu, Tb, Dy) and energy levels of lanthanide ions in Gd₅Si₃O₁₂N

Zhang, Z.J.,Yang, W. Elsevier 2017 SOLID STATE SCIENCES Vol.72 No.-

Polycrystalline Gd<SUB>5</SUB>Si<SUB>3</SUB>O<SUB>12</SUB>N: RE (RE = Pr, Sm, Eu, Tb and Dy) phosphors have been synthesized via a solid-state reaction method at high temperature, and their photoluminescence properties were studied. The absorption peak at about 230 nm is attributed to the host absorption. For the Pr<SUP>3+</SUP>-doped sample, the typical excitation lines located at 273 nm originating from the <SUP>8</SUP>S<SUB>7/2</SUB> → <SUP>6</SUP>I<SUB>J</SUB> (J = 5/2, 7/2) transitions of the Gd<SUP>3+</SUP> ions were observed in the excitation spectra. Upon excitation at 227 nm UV light, the 4f<SUP>1</SUP>5d → 4f<SUP>2</SUP> emission band (350-450 nm) and typical 4f<SUP>2</SUP> → 4f<SUP>2</SUP> emission lines (450-700 nm) assigned to Pr<SUP>3+</SUP> were observed. The Sm<SUP>3+</SUP>-doped sample exhibits a bright red emission owing to the <SUP>4</SUP>G<SUB>5/2</SUB> → <SUP>6</SUP>H<SUB>J</SUB> (J = 5/2, 7/2 and 9/2) transitions. However, the charge transfer band of Sm<SUP>3+</SUP> was not observed in the excitation spectrum. There is a broad band from 200 to 350 nm originating from the charge transfer transition (CT) of the Eu<SUP>3+</SUP> (O<SUP>2-</SUP>/N<SUP>3-</SUP> → Eu<SUP>3+</SUP>) in the excitation spectra, and the strongest peak in the emission spectra located at 615 nm is due to the electric-dipole <SUP>5</SUP>D<SUB>0</SUB> → <SUP>7</SUP>F<SUB>2</SUB> transition of Eu<SUP>3+</SUP>. For the Tb<SUP>3+</SUP>-doped sample, it shows <SUP>5</SUP>D<SUB>3</SUB> →<SUP>7</SUP>F<SUB>J</SUB> (J = 5, 4, 3, 2) blue line emissions and <SUP>5</SUP>D<SUB>4</SUB> → <SUP>7</SUP>F<SUB>J</SUB> (J = 6, 5, 4, 3) green line emissions under the excitation of Tb<SUP>3+</SUP>. The Dy<SUP>3+</SUP>-activated sample upon excitation at 349 and 386 nm UV light shows blue-green and orange-red emission lines originating from <SUP>4</SUP>F<SUB>9/2</SUB> → <SUP>6</SUP>H<SUB>J</SUB> (J = 15/2, 13/2) transitions. In addition, the energy transfer from the host lattice to the luminescence activators (i.e. Pr<SUP>3+</SUP>, Sm<SUP>3+</SUP>, Eu<SUP>3+</SUP>, Tb<SUP>3+</SUP>, Dy<SUP>3+</SUP>) has been confirmed. In addition, the energy level diagram including the 4f and 5d energy levels of all Ln<SUP>2+</SUP> and Ln<SUP>3+</SUP> ions relative to the valence and conduction band of Gd<SUB>5</SUB>Si<SUB>3</SUB>O<SUB>12</SUB>N were constructed and discussed.

IMC and creep behavior in Lead-free solder joints of Sn-Ag and Sn-Ag-Cu alloy system by SP method

Yang, Z. J.,Yang, S. M.,Yu, H. S.,Kang, S. J.,Song, J. H.,Kim, K. J. Springer Science + Business Media 2014 International journal of automotive technology Vol.15 No.7

Drug-clay nanohybrids as sustained delivery systems

Yang, J.H.,Lee, J.H.,Ryu, H.J.,Elzatahry, A.A.,Alothman, Z.A.,Choy, J.H. Elsevier 2016 Applied clay science Vol.130 No.-

<P>Biocompatible 2-dimensional layered compounds such as clays and layered double hydroxides (anionic clays) have been explored and utilized in drug delivery system for therapeutic application because they can safely encapsulate drug molecules via intercalation reaction. Therefore, various kinds of drug molecules and bio-functional molecules with cationic or anionic charge have been incorporated into clay delivery carriers, giving rise to the heterostructured layered nanohybrids with chemo-therapeutic and gene-therapeutic functions. Recently, such inorganic delivery systems have received growing attention because their inertness and low toxicity gives rise to safety and stability in bio-systems. Furthermore, the hybridization of drug with clays offers the fascinating features such as controlled and sustained release, improved water-solubility, and even protective and targeted delivery. Unique release behaviors of drugs from the drug-clay nanohybrids are originated from molecular level incorporation, and strong interaction between drug and inorganic layers including electrostatic and hydrogen bonding interactions. In the present review, various drug-clay nanohybrids will be introduced, and their recent development will be highlighted in the viewpoint of oral administration drugs with controlled and sustained release. (C) 2016 Elsevier B.V. All rights reserved.</P>

NON-NATURAL EQUILIBRIUM CONTOUR DESIGN FOR RADIAL TIRE AND ITS INFLUENCE ON TIRE PERFORMANCE

J. YANG,G. L. WANG,Z. J. WAN,C. LIANG,H. C. ZHOU 한국자동차공학회 2016 International journal of automotive technology Vol.17 No.4

Two types of radial tire 11.00R20 and 385/65R22.5 are chosen as the research objects, and their carcass contours are redesigned by using Sakai Hideo’s, Frank’s and the new non-natural equilibrium contour design theories, which were based on analyzing the current non-equilibrium contour design theories of radial tire. Then the tire wear, rolling resistance and grip performance of the two radial tires designed by different non-natural equilibrium contour design theories are comprehensively analyzed with the finite element software ABAQUS. The results show that Frank’s contour design theory can reduce tire wear; the new non-natural equilibrium contour design theory can enhance tire wear, rolling resistance performance, etc. It is also found that the tire carcass contour has great influence on tire performance, especially on the tire rolling resistance. The new non-natural equilibrium contour theory provides a guidance to reduce the tire rolling resistance, and it can break through the target conflicts in tire performance. The tire with the new non-natural equilibrium carcass contour can enhance its comprehensive performance.