http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Fabrication of coarse grain yttria composite and its corrosion resistance to molten titanium
Jingkun Yu,Chengwan Cui,Xinzhong Tian,Chun Wang,Xinli Wang,Wenbin Dai 한양대학교 세라믹연구소 2016 Journal of Ceramic Processing Research Vol.17 No.10
To fabricate coarse yttria grain with closed pores for improving the thermal shock resistance of yttria, a proper additive wasfirstly selected among calcium nitrate, cerium nitrate, and neodymium nitrate. Then, the appropriate amount of calcia addedinto yttria was investigated. Finally, the corrosion resistance of the fabricated yttria crucible was compared with pure calcia,and magnesia crucible. The results reveled that by adding 1 mol% calcia, lots of closed pores were distributed in coarse yttriagrains and the composite has superior thermal shock resistance and excellent corrosion resistance with titanium alloy. Thenewly fabricated yttria might fit for the melting and casting of pure titanium and its alloys.
Shiwei Liu,Jingkun Yu,Lu Han,Beiyue Ma 한양대학교 세라믹연구소 2018 Journal of Ceramic Processing Research Vol.19 No.3
Nanoporous thermal insulation materials prepared with fumed SiO2 possess excellent thermal insulation property, and havebeen attracted much attention, but their mechanical properties are poor. Adding a small amount of fiber materials as atoughening material can improve the mechanical properties of the nanoporous thermal insulation materials. However, toomuch fiber materials additives will seriously affect the thermal insulation property. In this study, SiO2-based nanoporousthermal insulation materials were prepared, and the effects of addition amounts of xonotlite and forming pressure on themechanical performance and thermal insulation performance of as-prepared thermal insulation materials were investigated. It was found that addition of 10% xonotlite and forming pressure of 2MPa were proper for the preparation of SiO2-basednanoporous thermal insulation materials. The compressive strength and thermal conductivity of as-prepared materials were0.34 MPa and 0.031 W·m−1·K−1, respectively.
Fabrication of self-reinforcement of porous mullite ceramic using NH4F as additive from kaolinite
Lei Yuan,Jingkun Yu,Rutao Ye,Shaowei Zhang 한양대학교 세라믹연구소 2013 Journal of Ceramic Processing Research Vol.14 No.4
Self-reinforcement of porous mullite ceramics containing needle-liked whiskers were fabricated from a powder mixture of kaolinite, Al(OH)3 and starch with NH4F as additive. The effects of the sintering temperature and the content of NH4F on porosity, phase composition, strength and microstructure of ceramics were investigated. The formation mechanism of needleliked mullite whiskers by in situ synthesis in ceramic body was discussed. The results indicated that lots of large aspect ratio needle-liked mullite whiskers, especially in the 15% NH4F additive sample, were observed. An interlocking structure was formed by needle-liked mullite whiskers to enhance the mechanical strength of porous mullite ceramic. And as the content of NH4F increasing, the bending strength increased. Comparing to the samples without NH4F additive, porous ceramic fabricated by adding NH4F showed a higher degree of mullitization. The formation mechanism of the needle-liked mullite in the ceramic was attributed to the reaction among NH4F and raw materials.
Effect of solvents on the properties of co-precipitated MgO-ZrO2 nano powders
Lei Yuan,Dong Xiang,Jingkun Yu 한양대학교 세라믹연구소 2013 Journal of Ceramic Processing Research Vol.14 No.4
8 mol% MgO-ZrO2 nano-sized powders have been synthesized through the coprecipitation route using ammonia as precipitant. In order to investigate the agglomeration of the nano powders during synthesis, water, butyl alcohol, and a mixture of butyl alcohol and ethanol were utilized as the solvents to precipitate and wash. The characteristics of the different powders were estimated by FT-IR, TG-DSC, XRD and SEM. It has been demonstrated that uniformly dispersed and soft agglomerates containing MgO-ZrO2 nano-sized powders can be obtained when the butyl alcohol, especially the butyl alcohol and ethanol mixture are used. It has been found that the hydroxyl group on the particle surface is replaced by the alkoxy group to alleviate the hard agglomerate.
Gas sensors based on Pd-decorated and Sb-doped SnO2 for hydrogen detection
Xingtai Chen,Tao Liu,Ran Wu,Jingkun Yu,Xitao Yin 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.115 No.-
Pd-modified Sb-doped SnO2 nanomaterials were prepared by a simple hydrothermal reaction and reductionmethod. The as-obtained samples were characterized by X-ray diffraction, scanning electron microscopy,X-ray phosphorescence, and elemental mapping analysis. The extracted results demonstrated evendoping of Sb within the SnO2 lattice, and Pd was successfully incorporated on the surface of samples. Compared with the pristine SnO2, 3 mol% Sb doping with 7 wt% Pd decorating exhibited the highestresponse of 9.7 to 100 ppm H2 at 320 C and revealed excellent selectivity and cycling stability to hydrogen. The mechanism of the enhanced sensing performance of Pd@Sb-SnO2 can be attributed to the changein the energy band structure by Sb doping, the energy-band bending, and depletion layer generated withthe Pd loading. The increased oxygen vacancy caused by the lattice distortion generated by the Sb doping,and the strong metal-support interaction effect between the Pd and SnO2 also plays an important role.
Tianpeng Wen,Lei Yuan,Chen Tian,Yao Jin,Tao Liu,Jingkun Yu 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.106 No.-
A new strategy for preparing a novel CaO-Al2O3 auxiliary electrode coating for sulfur sensor by infiltratingCa2+ and Al3+ into the porous ZrO2(MgO) backbone was proposed in this work. The phase composition andmicrostructure of the auxiliary electrode was detected and correlated to the electrochemical performance,while the application of the sulfur sensor in the liquid iron was presented. It is demonstrated thatthe CaO-Al2O3 particles were homogenously coated on the ZrO2(MgO) backbone and formed well connectednetwork, which could effectively improve the reaction area between CaO-Al2O3 and [S] as wellas enhancing the ionic conductivity and bonding strength of the auxiliary electrode. The assembled sulfursensor possessed a superior sensing performance of theoretical response, simultaneously the Nernst relationshipbetween the sensor EMF output and the linearity of the sulfur concentration occurred along withthe stable, continuous, and reproducible response.
Wen Tianpeng,Yuan Lei,Yan Zhengguo,Jin Yao,Liu Zhaoyang,Yu Jingkun 한국물리학회 2022 Current Applied Physics Vol.39 No.-
The present work looked at the co-doping effect of the typical trivalent metal oxides on the electrochemical performance of 8 mol% of MgO stabilized ZrO2 (Mg-PSZ) electrolyte ceramics used for oxygen sensors. An appreciable increase in the ionic conductivity occurred on substituting MgO with trivalent metal oxides except La2O3 in the Mg-PSZ electrolyte ceramics across the measured temperature range. The conductivity was related to the co-dopant ionic radius and the ionic conductivity increased with the co-dopant ionic radius of the trivalent metal oxides, reached a maximum at about 1.02 Å, and thereafter decreased. Through comparison and analysis, the Y2O3 exhibited excellent superiority than other trivalent metal oxides and the oxygen sensor assembled by 1Y7Mg-PSZ electrolyte possessed more excellent response speed and stability.