Oxidation Behavior of CoCrFeMnNi High-Entropy Alloy Fabricated by Selective Laser Melting

Xiquan Jia,Zhenlin Xu,Yizhu He,Shengxuan Zhou,Xiaojie Du,Hui Zhang,Aiqin Mao 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.10

The present study investigated the microstructure and oxidation behavior of the CoCrFeMnNi high-entropy alloy (HEA) prepared by selective laser melting (SLM). The microstructure of the as-built sample comprised layer-by-layer overlapping melt pools, columnar grains, and cellular structures. The melt pool boundaries (MPBs) and cellular structures disappeared, and the dislocation density decreased after annealing at 900 °C. The high-temperature oxidation behavior of the CoCrFeMnNi HEA was investigated via oxidation kinetics, morphology observation, and oxidation product analysis. The oxidation kinetics followed the parabolic law at 800 to 1000 ℃. There were three layers of oxide scale at all temperatures. At 800 to 1000 °C, the inner oxide layer was Cr2O3; the intermediate layer consisted of Cr-oxides and Mn-oxides. The outer oxide layer mainly consisted of Mn2O3 at 800 to 900 °C and Mn3O4 at 1000 °C. At 1000 °C, the fast diffusion channels provided by MPBs led to preferential oxidation in the as-built HEA. And the preferential oxidation behavior in the annealed HEA was inhibited due to the removal of MPBs by annealing. At each temperature, the annealed HEA showed relatively better oxidation resistance than the as-built sample.

The Polynomial Matrix Method of Governor Designing for Speed Governing System

Zhao Xiquan 대한전자공학회 1991 ICEIC:International Conference on Electronics, Inf Vol.1991 No.8

Endovascular Repair of Blunt Popliteal Arterial Injuries

Shan Zhong,Xiquan Zhang,Zhong Chen,Peng Dong,Yequan Sun,Wei Zhu,Xiaolin Pan,Deming Qi 대한영상의학회 2016 Korean Journal of Radiology Vol.17 No.5

Objective: To evaluate the feasibility and effectiveness of endovascular repair for blunt popliteal arterial injuries. Materials and Methods: A retrospective analysis of seven patients with clinical suspicion of popliteal arterial injuries that were confirmed by arteriography was performed from September 2009 to July 2014. Clinical data included demographics, mechanism of injury, type of injury, location of injury, concomitant injuries, time of endovascular procedures, time interval from trauma to blood flow restoration, instrument utilized, and follow-up. All patients were male (mean age of 35.9 ± 10.3 years). The type of lesion involved intimal injury (n = 1), partial transection (n = 2), complete transection (n = 2), arteriovenous fistula (n = 1), and pseudoaneurysm (n = 1). All patients underwent endovascular repair of blunt popliteal arterial injuries. Results: Technical success rate was 100%. Intimal injury was treated with a bare-metal stent. Pseudoaneurysm and popliteal artery transections were treated with bare-metal stents. Arteriovenous fistula was treated with bare-metal stent and coils. No perioperative death and procedure-related complication occurred. The average follow-up was 20.9 ± 2.3 months (range 18–24 months). One patient underwent intra-arterial thrombolysis due to stent thrombosis at 18 months after the procedure. All limbs were salvaged. Stent migration, deformation, or fracture was not found during the follow-up. Conclusion: Endovascular repair seems to be a viable approach for patients with blunt popliteal arterial injuries, especially on an emergency basis. Endovascular repair may be effective in the short-term. Further studies are required to evaluate the long-term efficacy of endovascular repair.

Analytical Solution of Magnetic Field in High Speed Surface Mounted Permanent Magnet Machine With Parallelly Magnetized Magnet Segments

Shilei Xu,Xiquan Liu 한국자기학회 2018 Journal of Magnetics Vol.23 No.2

Due to some limitations of permanent-magnet (PM) production and magnetizing technology, it is difficult to construct the large magnetic poles of high-power surface-mounted PM machines by using integral magnets. One simple solving scheme is that the large magnetic poles can be formed by several parallelly magnetized magnet segments. For the surface-mounted PM machines with parallelly magnetized magnet segments, this paper gives an accurate analytical solution of the magnetic field. First, in 2-D polar coordinates, the PM machine model is divided into three subdomains, and the magnetic field governing equations are established in each region. By adopting the theory of Fourier’s series and the method of separating variables, the solutions of the magnetic field are determined according to associated boundary conditions. Then, the proposed analytical model is compared with finite element method, and the results show that they have a good agreement. Based on the obtained magnetic field solution, the induced electromotive force of a designed PM machine is calculated, and the result is verified by experiment.

Nonlinear Increase of Spatial Noise for Ultrashort Pulses with Different Temporal Widths

Lifu Zhang,Xiquan Fu,Jianqin Deng,Hua Yang,Youwen Wang,Shuangchun Wen,Huiwen Xu,Jinggui Zhang,Jin Zhang,Dianyuan Fan 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.55 No.2

In this paper, the dynamic evolution of the spatial noise modulation of ultrashort laser pulses in carbon disulfide (CS2) is investigated experimentally, and different temporal widths of the stretched pulse are analyzed for spatial noise gain. The spatial noise evolution (i.e., small-scale self-focusing) of ultrashort laser pulses with different temporal widths as a function of the length of the CS2 has been observed. If the spectral bandwidth is invariant, the experimental results show that a stretched pulse with a broader temporal width can postpone the small-scale self-focusing of spatial noise for longer medium length with constant input power or for greater input power with the same medium length. In this paper, the dynamic evolution of the spatial noise modulation of ultrashort laser pulses in carbon disulfide (CS2) is investigated experimentally, and different temporal widths of the stretched pulse are analyzed for spatial noise gain. The spatial noise evolution (i.e., small-scale self-focusing) of ultrashort laser pulses with different temporal widths as a function of the length of the CS2 has been observed. If the spectral bandwidth is invariant, the experimental results show that a stretched pulse with a broader temporal width can postpone the small-scale self-focusing of spatial noise for longer medium length with constant input power or for greater input power with the same medium length.

Geometric Modeling by Blending Hermite Interpolation

Benyue Su,Jieqing Tan,Xiquan Shi,Fengshan Liu (사)한국CDE학회 2007 한국CAD/CAM학회 국제학술발표 논문집 Vol.2007 No.8

Uniform Microstructure and Excellent Corrosion Resistance of HVOF-Sprayed CoCrNi Medium-Entropy Alloy Coating in Fluoride Ion Environment

Dongbao Huang,Zhenlin Xu,Xiquan Jia,Haitao Yu,Yizhu He,Zhenqi Dong,Shenshen Li,Hui Zhang 대한금속·재료학회 2024 METALS AND MATERIALS International Vol.30 No.1

To solve the corrosion problem of the copper plates caused by fluoride ions, the Ni55 and CoCrNi medium-entropy alloycoatings were prepared via high-velocity oxygen fuel technology. The corrosion resistance of the Ni55 and CoCrNi coatingsin NaF solution was compared through electrochemical experiments and immersion corrosion experiments. The Ni55coating contained complex precipitated phases, resulting in preferential corrosion at the phase boundaries between the γ-Nisolid solution and the precipitated phases. The composition of the CoCrNi coating was more homogeneously distributed,and mainly uniform corrosion occurred. The corrosion products of the two coatings in the NaF solution were both complexescomposed of metal oxides and fluorides. Compared with the Ni55 coating, the passive film formed on the CoCrNi coatinghad a more uniform and protective property; therefore, the CoCrNi coating had better corrosion resistance. This researchcan pave a pathway for developing coating on copper and its alloys with excellent corrosion resistance.

Quadratic Nonlinear Technologies for Femtosecond Lasers

Liejia Qian,Guang Xu,Hang Luo,Heyuan Zhu,Peng Yuan,Tao Wang,Xiquan Fu 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.46 No.2

Quadratic optical nonlinearity (2) can be exploited in femtosecond lasers and regarded as a significant new degree of freedom for the design of short-pulse sources. We will review our recent progress on developing nonlinear quadratic technologies for femtosecond lasers. Our nonlinear laser technology offers new properties for femtosecond lasers, including optical parametric amplifier with novel working regime, efficient second harmonic generation, and time telescope.

Optical Properties of Leaky Modes of Photonic Crystal Waveguides

Hao Zhang,Liejia Qian,Dianyuan Fan,Heyuan Zhu,Xiquan Fu 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.5I

We used the scattering-matrix numerical method to calculate the reflectivity and the polarization conversion efficiency of multilayered photonic crystal waveguide (PhCW) and the surface-coupling technique to plot its leaky bands. Because of the vertical confinement of PhCW, a TE-polarized incident wave is partially transferred into a reflected wave containing a TM-polarized component, however, the conversion efficiency is weak, and such a conversion vanishes for waves incident along directions possessing reflection symmetry. By comparing the reflection spectrum with the polarization conversion efficiency curves, we found that their resonance patterns were identical and that dips in the former corresponded to peaks in the latter.

Genome wide association study on feed conversion ratio using imputed sequence data in chickens

Jiaying Wang,Xiaolong Yuan,Shaopan Ye,Shuwen Huang,Yingting He,Hao Zhang,Jiaqi Li,Xiquan Zhang,Zhe Zhang 아세아·태평양축산학회 2019 Animal Bioscience Vol.32 No.4

Objective: Feed consumption contributes a large percentage for total production costs in the poultry industry. Detecting genes associated with feeding traits will be of benefit to improve our understanding of the molecular determinants for feed efficiency. The objective of this study was to identify candidate genes associated with feed conversion ratio (FCR) via genome-wide association study (GWAS) using sequence data imputed from single nucleotide polymorphism (SNP) panel in a Chinese indigenous chicken population. Methods: A total of 435 Chinese indigenous chickens were phenotyped for FCR and were genotyped using a 600K SNP genotyping array. Twenty-four birds were selected for sequencing, and the 600K SNP panel data were imputed to whole sequence data with the 24 birds as the reference. The GWAS were performed with GEMMA software. Results: After quality control, 8,626,020 SNPs were used for sequence based GWAS, in which ten significant genomic regions were detected to be associated with FCR. Ten candidate genes, ubiquitin specific peptidase 44, leukotriene A4 hydrolase, ETS transcription factor, R-spondin 2, inhibitor of apoptosis protein 3, sosondowah ankyrin repeat domain family member D, calmodulin regulated spectrin associated protein family member 2, zinc finger and BTB domain containing 41, potassium sodium-activated channel subfamily T member 2, and member of RAS oncogene family were annotated. Several of them were within or near the reported FCR quantitative trait loci, and others were newly reported. Conclusion: Results from this study provide valuable prior information on chicken genomic breeding programs, and potentially improve our understanding of the molecular mechanism for feeding traits.