Fabrication and characterization of highly transparent Y₂O₃ ceramics by hybrid sintering: A combination of hot pressing and a subsequent HIP treatment

Zhu, Lin-Lin,Park, Young-Jo,Gan, Lin,Kim, Ha-Neul,Ko, Jae-Woong,Kim, Hai-Doo Elsevier 2018 Journal of the European Ceramic Society Vol.38 No.9

<P><B>Abstract</B></P> <P>We succeeded in the optimization of highly transparent Y<SUB>2</SUB>O<SUB>3</SUB> ceramics with a submicrometer grain size approximately 0.6 μm by hot pressing (1300–1550 °C) and a subsequent HIP (1450 °C) treatment using commercial Y<SUB>2</SUB>O<SUB>3</SUB> powders as starting powders and ZrO<SUB>2</SUB> as a sintering additive. The optimum microstructure for the HIP treatment was prepared by hot pressing at a temperature as low as 1400 °C for 3 h with a relative density of 99.3%. The thus HIP-treated specimen showed the best transmittance (2 mm thick) ever reported of 83.4% and 78.3% at 1100 and 400 nm, respectively. Specifically, the transmittance using this hybrid sintering method improved substantially in the visible range compared to that of the counterpart using hot pressing only. A simulation of the transmittance based on the Beer-Lambert law and Mie scattering theory has proved that this improvement is mainly due to the elimination of nanopores below 15 nm in size.</P>

Fabrication of transparent MgAl₂O₄ from commercial nanopowders by hot-pressing without sintering additive

Zhu, Lin-Lin,Park, Young-Jo,Gan, Lin,Go, Shin-Il,Kim, Ha-Neul,Kim, Jin-Myung,Ko, Jae-Woong North-Holland 2018 Materials letters Vol.219 No.-

<P><B>Abstract</B></P> <P>Transparent magnesium aluminate spinel (MgAl<SUB>2</SUB>O<SUB>4</SUB>) ceramics were successfully fabricated for the first time using commercially available nanopowders without sintering additive by a single hot-press step process. This method does not involve all the complexity of powder, green body pre-treatment and post-treatment, which are commonly used in the fabricating process. Effects of holding time (3–12 h) at the sintering temperature 1500 °C on the transmittance, microstructure and Vickers microhardness are investigated. The highest transmittance is achieved for the sample hot pressed at 1500 °C for 12 h, which exhibits 80.2% at the wavelength of 1100 nm. These results may provide a guide for understanding the microstructural development of transparent spinel without sintering additive.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Pure MgAl<SUB>2</SUB>O<SUB>4</SUB> transparent ceramic was prepared by a single hot-press step. </LI> <LI> The transmittance of the sample at 1500 °C for 12 h reached 80.2% at 1100 nm. </LI> <LI> The Vickers microhardness decreases from 15.1 to 12.5 GPa with holding time from 3 to 12 h. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Fabrication of transparent Y₂O₃ ceramics with record-high thermal shock resistance

Zhu, Lin-Lin,Park, Young-Jo,Gan, Lin,Kim, Ha-Neul,Ko, Jae-Woong,Kim, Hai-Doo Elsevier 2018 Journal of the European Ceramic Society Vol.38 No.11

<P><B>Abstract</B></P> <P>Sintering-additive-free fine-grained highly transparent Y<SUB>2</SUB>O<SUB>3</SUB> ceramics featuring record-high thermal shock resistance were fabricated using commercial powders via vacuum pre-sintering (1375–1550 °C) followed by hot-isostatic pressing (1450 °C). The sample pre-sintered at 1450 °C provides the optimum microstructure for post HIPing, which resulted in a grain size of 0.64 μm. The transmittance, microhardness and fracture toughness of the thus HIPed sample are 80.8% at 1100 nm and 65.5% at 400 nm (1.2 mm thick), 8.0 ± 0.02 GPa and 1.00 ± 0.06 MPa m<SUP>1/2</SUP>, respectively. The thermal conductivity increases from 13.1 to 16.5 W/m/K with increasing vacuum pre-sinterin Proc. SPIE-Int. Soc. Opt g temperature from 1450 to 1550 °C. This hybrid sintering method realized high thermal conductivity and high strength simultaneously. Consequently, the thermal shock resistance of the HIPed specimen vacuum pre-sintered at 1450 °C in this work is the highest ever reported to the best of our knowledge, which makes the developed material a promising candidate for high-power laser host and IR dome.</P>

Fabrication and characterization of highly transparent Er:Y₂O₃ ceramics with ZrO₂ and La₂O₃ additives

Zhu, Lin-Lin,Park, Young-Jo,Gan, Lin,Go, Shin-Il,Kim, Ha-Neul,Kim, Jin-Myung,Ko, Jae-Woong Elsevier 2017 CERAMICS INTERNATIONAL Vol.43 No.16

<P><B>Abstract</B></P> <P>In this study, we report highly transparent Er:Y<SUB>2</SUB>O<SUB>3</SUB> ceramics (0–10at% Er) fabricated by a vacuum sintering method using compound sintering additives of ZrO<SUB>2</SUB> and La<SUB>2</SUB>O<SUB>3</SUB>. The transmittance, microstructure, thermal conductivity and mechanical properties of the Er:Y<SUB>2</SUB>O<SUB>3</SUB> ceramics were evaluated. The in-line transmittance of all of the Er:Y<SUB>2</SUB>O<SUB>3</SUB> ceramics (1.2mm thick) exceeds 83% at 1100nm and 81% at 600nm. With an increase in the Er doping concentration from 0 to 10at%, the average grain size, microhardness and fracture toughness remain nearly unchanged, while the thermal conductivity decreases slightly from 5.55 to 4.89W/mK. A nearly homogeneous doping level of the laser activator Er up to 10at% in macro-and nanoscale was measured along the radial direction from the center to the edge of a disk specimen, which is the prominent advantage of polycrystalline over single-crystal materials. Based on the finding of excellent optical and mechanical properties, the compound sintering additives of ZrO<SUB>2</SUB> and La<SUB>2</SUB>O<SUB>3</SUB> are demonstrated to be effective for the fabrication of transparent Y<SUB>2</SUB>O<SUB>3</SUB> ceramics. These results may provide a guideline for the application of transparent Er:Y<SUB>2</SUB>O<SUB>3</SUB> laser ceramics.</P>

Enhancement of the thermal shock resistance of transparent Y₂O₃ ceramics by reducing the content of sintering additive

Zhu, Lin-Lin,Park, Young-Jo,Gan, Lin,Kim, Ha-Neul,Ko, Jae-Woong,Lee, Jae-Wook,Kim, Hai-Doo Elsevier 2018 Ceramics international Vol.44 No.14

<P><B>Abstract</B></P> <P>It is known that 1.0 at.% is the lowest amount of ZrO<SUB>2</SUB> which can be used for the sintering of well-balanced Y<SUB>2</SUB>O<SUB>3</SUB> ceramics to ensure both transparency and strength. In this work, a highly transparent Y<SUB>2</SUB>O<SUB>3</SUB> ceramic material doped with a reduced amount of ZrO<SUB>2</SUB> (0.5 at.%) was fabricated by means of a hot-press sintering method at a temperature as low as 1600°C using commercial powders. The in-line transmittance of the 0.5 at.% ZrO<SUB>2</SUB>-doped Y<SUB>2</SUB>O<SUB>3</SUB> sample (2 mm thick) is 80.8% at 1100 nm and 72.2% at 400 nm with an average grain size of 1.06 μm. By reducing the ZrO<SUB>2</SUB> content from 1.0 to 0.5 at.%, the thermal conductivity is increased by 18.2% with only a slight decline in the strength and the band gap becomes broader. Consequently, the Hasselman mild-thermal-shock figure of merit of the developed specimen increases by 13.0% overall. These results indicate that this Y<SUB>2</SUB>O<SUB>3</SUB> ceramic has potential for use as a laser host or an infrared window material used on Mach-speed applications.</P>

Effects of ZrO₂-La₂O₃ co-addition on the microstructural and optical properties of transparent Y₂O₃ ceramics

Zhu, Lin-Lin,Park, Young-Jo,Gan, Lin,Go, Shin-Il,Kim, Ha-Neul,Kim, Jin-Myung,Ko, Jae-Woong Elsevier 2017 CERAMICS INTERNATIONAL Vol.43 No.11

<P><B>Abstract</B></P> <P>Commercial Y<SUB>2</SUB>O<SUB>3</SUB> powder was used to fabricate Y<SUB>2</SUB>O<SUB>3</SUB> ceramics sintered at 1600°C and 1800°C with concurrent addition of ZrO<SUB>2</SUB> and La<SUB>2</SUB>O<SUB>3</SUB> as sintering aids. One group with different contents of La<SUB>2</SUB>O<SUB>3</SUB> (0–10mol%) with a fixed amount of 1mol% ZrO<SUB>2</SUB> and another group with various contents of ZrO<SUB>2</SUB> (0–7mol%) with a fixed amount of 10mol% La<SUB>2</SUB>O<SUB>3</SUB> were compared to investigate the effects of co-doping on the microstructural and optical properties of Y<SUB>2</SUB>O<SUB>3</SUB> ceramics. At low sintering temperature of 1600°C, the sample single doped with 10mol% La<SUB>2</SUB>O<SUB>3</SUB> exhibits much denser microstructure with a few small intragranular pores while the samples with ZrO<SUB>2</SUB> and La<SUB>2</SUB>O<SUB>3</SUB> co-doping features a lot of large intergranular pores leading to lower density. When the sintering temperature increases to 1800°C, samples using composite sintering aids exhibit finer microstructures and better optical properties than those of both ZrO<SUB>2</SUB> and La<SUB>2</SUB>O<SUB>3</SUB> single-doped samples. It was proved that the grain growth suppression caused by ZrO<SUB>2</SUB> overwhelms the acceleration by La<SUB>2</SUB>O<SUB>3</SUB>. Meanwhile, 1mol% ZrO<SUB>2</SUB> acts as a very important inflection point with regard to the influence of additive concentration on the transmittance, pore structure and grain size. The highest in-line transmittance of Y<SUB>2</SUB>O<SUB>3</SUB> ceramic (1.2mm in thickness) with 3mol% of ZrO<SUB>2</SUB> and 10mol% of La<SUB>2</SUB>O<SUB>3</SUB> sintered at 1800°C for 16h is 81.9% at a wavelength of 1100nm, with an average grain size of 11.2µm.</P>

Bio-inspired Fabrication of Cu-Ni Coatings onto Mercerized Flax Fabric by Electroless Plating

Lin Zhu,Hang Zhao,Bijian Lan,Lei Hou,Siyi Bi,Yumeng Xu,Yinxiang Lu 한국섬유공학회 2020 Fibers and polymers Vol.21 No.2

This research mainly prepared a bio-friendly electromagnetic interference (EMI) shielding fabric, and discussed the influence of the grammage (i.e. 120 g/m2, 160 g/m2 and 210 g/m2, etc) of fabric substrate on the preparation of metalbased EMI shielding conductive fabric by electroless plating. A series of steps involved mercerization, dopamine (DoPA) modification, Ni0 seeding and electroless copper-nickel (Cu-Ni) plating were carried out to fabricate ideal EMI shielding fabric. The prepared Cu-Ni fabric endowed relatively high EMI shielding effectiveness (SE) (34.80-42.00 dB) ranging from 30 to 4500 MHz, which made it a huge potential in the field of wearable EMI shielding. Moreover, another discovery was that a relative higher grammage may lead to a lower total metal loading. Furthermore, Fourier transformation infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) measurements were conducted to verify the introduction of functional groups in mercerization, modification and activation procedures. The crystalline phases and morphologies of resulting Cu-Ni coatings were characterized by X-ray diffraction (XRD) and field emission-scanning electron microscopy (FE-SEM) measurements. The atomic ratio (at.%) of Cu and Ni in the sample was determined by Energy Dispersive X-ray Spectroscopy (EDX) measurements. Overall, the Cu-Ni alloy fabric prepared in this research met the requirements of health, coating lining and EMI shielding.

Bile Acid Transporters Are Expressed and Heterogeneously Distributed in Rat Bile Ducts

Zhu-lin Luo,Long Cheng,Tao Wang,Li-jun Tang,Fu-zhou Tian,Ke Xiang,Lin Cui 거트앤리버 소화기연관학회협의회 2019 Gut and Liver Vol.13 No.5

Background/Aims: Cholangiocytes are capable of reabsorbing bile salts from bile, but the pathophysiological significance of this process is unclear. To this end, we detected the expression and distribution of bile acid transport proteins in cholangiocytes from normal rat liver and analyzed the possible pathophysiological significance. Methods: Bile duct tissues of Sprague-Dawley rats were isolated by enzymatic digestion and mechanical isolation, and then divided into large and small bile duct tissues. Immunohistochemistry, real-time polymerase chain reaction and Western blotting were used to determine the expression of the apical sodium-dependent bile acid transporter (ASBT), ileal bile acid binding protein (IBABP), and basolateral organic solute transporter α (Ostα) in the biliary tract system of rats. Differences in the expression and distribution of these proteins were analyzed. Results: In cholangiocytes, ASBT and IBABP were mainly expressed in cholangiocytes of the large bile ducts, in which the expression of both was significantly higher than that in the small ducts (p<0.05). Ostα was simultaneously expressed in cholangiocytes of both the large and small bile ducts, showing no significant difference in expression between the two groups of bile ducts (p>0.05). Conclusions: Bile acid transporters are expressed and heterogeneously distributed in rat bile ducts, indicating that bile acid reabsorption by cholangiocytes might mainly occur in the large bile ducts. These findings may help explore the physiology of bile ducts and the pathogenesis of various cholangiopathies.

An improved horizontally reversible plow design based on virtual assembly semantics and constraint

Lin Zhu,Shuang-Shuang Peng,Yin-Yin Qi,Xi Cheng,Wen-Feng Zhang,Liang-Yuan Xu,De-Quan Zhu 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.1

There exit model errors in the constructed Horizontally reversible plough (HRP) structure through Interference check technique (ICT). This is basically due to missing parts and geometric interference and, hence, has significantly adverse effects in improving HRP. In thispaper an improved design to refine the three dimensional (3D) model of HRP is implemented by using Virtual assembly technology(VAT). To achieve this, the authors propose a combined virtual assembly semantics and constraint for assembly planning and simulationof HRP in the commercial software, e.g., SolidWorks. First, the assembly planning of HRP was captured with a semantics-based model,including spatial position, assembly orientation, type and parameters of the semantic entities; secondly, the assembly simulation of HRPwas performed by using constraint-based VAT, e.g. component grasping, moving and releasing; finally, the obtained HRP model wasverified through ICT again. The results demonstrate that not any model error exists in the refined 3D HRP model any longer and thatsemantics and constrain based VAT can support the interactive operation more effectively and accurately than those with geometric constraints. This technique was previously used for HRP model. Based on the refined 3D HRP model, the design improvement of Remotecylinder base (RCB), an important component of HRP, will be forthcoming in a future paper.

Bilateral Thoracodorsal Neuromas: A Cause of Persistent Breast Pain after Bilateral Latissimus Dorsi Breast Reconstruction

Lin Zhu,Niles J Batdorf,Annie L Meares,William R. Sukov,Valerie Lemaine 대한성형외과학회 2015 Archives of Plastic Surgery Vol.42 No.4