Improvement of the Microstructure and Microhardness of AQ80 Magnesium Alloy by Repeated Upsetting-Extrusion

Yutian Fan,Liwei Lu,Tao Zhou,Hua Zhang,Fugang Qi,Min Ma,Zhiqiang Wu,Weitao Jia,Sha Zhang,Weiying Huang 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.10

In this work, a novel process of repeated upsetting-extrusion (RUE) was used to fabricate the AQ80 magnesium (Mg) alloy. The effects of deformation passes on the microstructure and microhardness of the RUEed AQ80 Mg alloy were studied. The results showed that {10–12} extension twins appeared in the sample after 1 pass of deformation compared to the initial sample, which divided the coarse grains and achieved the preliminary refinement of the grains. The grains were uniformly refined further with increasing RUE deformation passes, and after 3 passes, the average grain size was reduced from 27.4 to 3.0 μm. The grains were refined mainly by continuous dynamic recrystallization (CDRX), particle-stimulated nucleation (PSN), and discontinuous dynamic recrystallization (DDRX) mechanisms. After RUE deformation, the peak component of the texture was tilted by 0–20° toward the extrusion direction (ED) because of the increased activation of pyramidal < c + a > slip. The microhardness of the 3-pass RUE deformed sample increased by 12.9% compared to the initial sample. This is mainly attributable to fine-grained strengthening and second phase strengthening.

Stability analysis of a novel mobile spray-painting robot for touch-up painting in vehicle repair plant

Ruijie Zhang,Jun Wu,Yutian Wang 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.5

The stability of a mobile robot is important because it may tip over. This work proposes a hybrid spray-painting robot with high stiffness for touch-up painting in vehicle repair plant and investigates its stability. The distribution of the center of mass is studied based on the kinematics model, and the static stability of the mobile spray-painting robot is analyzed. A micro element method is proposed to accurately calculate the inertia force and the action point of each link in the robot. Zero-moment point (ZMP) is calculated, and the dynamic stability of the mobile robot is assessed using the ZMP criterion. The smallest reasonable width of AGV is obtained for the lightweight design of the robot. The static and dynamic stabilities of the mobile robot are compared with a traditional series mobile robot with the same workspace. Several case studies are conduct by ADAMS to verify the theoretical analysis.

Toughness and Strength Coordination in a Low-Alloy Zn–0.5 Mg Alloy via Extrusion and Post-Deformation Annealing

Ruimin Li,Yutian Ding,Hongfei Zhang 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.10

Zn is considered one of the most attractive bioresorbable candidates for metal implants, because it does not exhibit the inherent limitations of Fe and Mg. To explore the coordination of the toughness and strength of Zn alloys via grain size, secondary phase, and texture modification, we designed a micro-alloyed binary Zn–0.5 Mg (wt%) alloy. The sample was processed through hot extrusion at 220 °C with an extrusion ratio of 25:1 and subjected to rapid heat treatment at varying temperatures. Interestingly, the ductility of the low-temperature annealed alloys increased without exhibiting strength loss, in contrast to the known behavior of most other metallic alloys. The mechanical properties were optimized in the sample by thermal deformation and 30 min annealing at 150 °C, exhibiting the following results: yield strength of 240.3 ± 4.3 MPa, ultimate tensile strength of 293.6 ± 3.8 MPa, and elongation to failure of 36.3 ± 4.5%. During the low-temperature annealing of extruded Zn–0.5 Mg rods, the fine Mg2Zn11 phase particles pinning effect and the recrystallization behavior inhibited grain coarsening. The prismatic <a> and pyramidal <c + a> slip systems were activated by a non-basal texture, which contributed to the enhanced toughness. The balance between strength and ductility was mainly attributed to a synergistic effect of grain refinement, unique texture modification, and secondary phases.

Cactus-like double-shell structured SiO2@TiO2 microspheres: Fabrication, electrorheological performances and microwave absorption

Xuqiang Ji,Wenling Zhang,Wenpeng Ji,Xiaoxia Wan,Yutian Wang,Li Deng,Jingquan Liu 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.56 No.-

The cactus-like double-shell structured SiO2@TiO2 microspheres (CDS SiO2@TiO2 microspheres) withhigh dielectric properties were successfully fabricated and utilized as high-performance electrorheological(ER)fluids and microwave absorbing materials. The SiO2 nanospheres with average diametersof 190 nm were synthesized by the hydrolysis of tetraethyl orthosilicate (TEOS), and used as the core forthefirst coating layer of TiO2 achieved by sol-gel method. Thefinal cactus-like TiO2 layer was prepared viaa hydrothermal method. The morphology of the resultant samples was characterized via transmissionelectron microscopy (TEM), scanning electron microscopy (SEM) and scanning transmission electronmicroscopy (STEM). This novel CDS SiO2@TiO2 microspheres based suspension exhibited improved ERproperties compared to conventional bare SiO2 spheres.

Preliminary study of genome-wide association identified novel susceptibility genes for thyroid-related hormones in Chinese population

Huang Liang,Bai Fenghua,Zhang Yutian,Zhang Shanshan,Jin Tianbo,Wei Xingwei,Zhou Xiaoli,Lin Mei,Xie Yufei,He Chanyi,Lin Qi,Xie Tian,Ding Yipeng 한국유전학회 2022 Genes & Genomics Vol.44 No.8

Background: Thyroid hormones are critical regulators of metabolism, development and growth in mammals. However, the genetic association of thyroid-related hormones in the Chinese Han population is not fully understood. Objective: We aimed to identify the genetic loci associated with circulating thyroid-related hormones concentrations in the healthy Chinese Han population. Methods: Genotyping was performed in 124 individuals using Applied Biosystems™ Axiom™ PMDA, and 796,288 single nucleotide polymorphisms (SNPs) were available for the GWAS analysis. For replication, eleven SNPs were selected as candidate loci for genotyping by Agena MassARRAY platform in additional samples (313 subjects). The values of p < 5 × 10- 6 suggest a suggestively significant genome-wide association with circulating thyroid-related hormones concentrations. Results: We identified that rs11178277 (PTPRB, p = 4.88 × 10- 07) and rs7320337 (LMO7DN-KCTD12, p = 1.22 × 10- 06) were associated with serum FT3 level. Three SNPs (rs4850041 in LOC105373394-LINC01249: p = 3.55 × 10- 06, rs6867291 in LINC02208: p = 2.40 × 10- 06 and rs79508321 in WWOX: p = 3.35 × 10- 06) were related to circulating T3 level. Rs12474167 (LOC105373394-LINC01249, p = 1.65 × 10- 06) and rs1864553 (IWS1, p = 2.00 × 10- 06) were associated with circulating T4 concentration. The association with TGA concentration was for rs17163542 in DISP1 (p = 3.46 × 10- 06) and rs12601151 in NOG-C17orf67 (p = 2.72 × 10- 07). Two genome-level significant SNPs (rs2114707 in LINC01314, p = 1.69 × 10- 06 and rs12601151, p = 1.41 × 10- 07) associated with serum TMA concentration were identified. Moreover, rs6083269 (CST1-CST2, p = 3.36 × 10- 06) was a significant locus for circulating TSH level. In replication, rs12601151 in NOG-C17orf67 was still associated with serum TGA level (p = 0.012). Conclusions: The GWAS reported 11 new suggestively significant loci associated with circulating thyroid-related hormones levels among the Chinese Han population. These findings represented suggestively biological candidates for circulating thyroid-related hormones levels and provided new insights into the mechanisms of regulating serum TGA concentration.

A novel recyclable nano-adsorbent for enhanced oil recovery with efficient removal of Ca2+ and Cr6+ from oilfield wastewater

Lei He,Yong Dai,Zhe Wang,Lutao Yang,Luxia Zhang,Pengpeng Hu,Yutian Lei,Hong Mo,Haomiao Zhu,Jun Zhang 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.8

Oilfield wastewater has a significantly negative influence on the recovery efficiency due to its hypersalinity. Therefore, magnetic graphene oxide (GO) modified with ethylene diamine tetraacetic acid (EDTA) and grafted bypolyethylene glycol (PEG) nano-adsorbent was prepared to remove the Ca2+ and Cr6+ in Jidong Oilfield wastewaterspecifically. It was noteworthy that PEG-g-EDTA/Fe3O4/GO nano-adsorbent had excellent adsorption performance,with removal ratios up to 71.6% for Ca2+ and 42.7% for Cr6+ at 30 min. After the fifth recycling run, the nano-adsorbentstill remained with high removal ratios (69.3% for Ca2+ and 30.5% for Cr6+) and high reuse rates (89.4% for Ca2+and 95.2% for Cr6+), indicating that the nano-adsorbent had outstanding adsorption-desorption efficacy and high reusability. The adsorption test results demonstrated that the total salinity of the treated oilfield wastewater decreased byabout 5,000 ppm, and the displacement efficiency further increased by 12.5% by chemical flooding compared with theuntreated wastewater. Therefore, PEG-g-EDTA/Fe3O4/GO nano-adsorbent is an adsorbent with excellent potentialwhich can effectively remove Ca2+ and Cr6+ in oilfield wastewater to enhance oil recovery (EOR).

Periodic solutions for a quasilinear non-autonomous second-order system

Yu Tian,Guosheng Zhang,Weigao Ge 한국전산응용수학회 2006 Journal of applied mathematics & informatics Vol.22 No.1-2

In this paper, a quasilinear second-order system with periodic boundary conditions is studied. By the least action principle and classical theorems of variational calculus, existence results of periodic solutions are obtained.

Oscillation of second order unstable neutraldifference equations with continuous arguments

Yu Tian,Zhenguo Zhang,Weiga Ge 한국전산응용수학회 2006 Journal of applied mathematics & informatics Vol.20 No.1-2