Preparation and properties of ZrB2-YAG-Al2O3 ceramics

Jie-Guang Song,Gang-Chang Ji,Shi-Bin Li,Yang-Liang Li,Da-Ming Du,Lian-Meng Zhang,Yin-Yan Ju 한양대학교 세라믹연구소 2009 Journal of Ceramic Processing Research Vol.10 No.4

ZrB2, YAG and Al2O3 are widely applied because of some excellent properties, but ZrB2 is easily oxidized in high-temperature air. To achieve better properties in ZrB2 ceramics, high-density ZrB2-YAG-Al2O3 ceramics were prepared. Below 1000℃, the shrinkage of ZrB2-YAG-Al2O3 ceramics is less than that of ZrB2-YAG ceramics. From 1000℃ to 1600℃, the second largest shrinkage occurs. Above 1600℃, the shrinkage of ZrB2-YAG-Al2O3 ceramics is more than that of ZrB2-YAG ceramics. The fracture toughness of sintered ceramics from coated raw materials is higher than that of sintered ceramics with mixed raw materials with the same phases and phase content, the fracture toughness of ZrB2-YAG-Al2O3 ceramics is higher than that of ZrB2-YAG ceramics with the same raw materials. The weight gain of all types of ceramics is increased with all increase in the oxidation temperature, the weight gain of ceramics is reduced with all increase in the YAG-Al2O3 content and Al2O3 proportion, especially above 1500℃. ZrB2, YAG and Al2O3 are widely applied because of some excellent properties, but ZrB2 is easily oxidized in high-temperature air. To achieve better properties in ZrB2 ceramics, high-density ZrB2-YAG-Al2O3 ceramics were prepared. Below 1000℃, the shrinkage of ZrB2-YAG-Al2O3 ceramics is less than that of ZrB2-YAG ceramics. From 1000℃ to 1600℃, the second largest shrinkage occurs. Above 1600℃, the shrinkage of ZrB2-YAG-Al2O3 ceramics is more than that of ZrB2-YAG ceramics. The fracture toughness of sintered ceramics from coated raw materials is higher than that of sintered ceramics with mixed raw materials with the same phases and phase content, the fracture toughness of ZrB2-YAG-Al2O3 ceramics is higher than that of ZrB2-YAG ceramics with the same raw materials. The weight gain of all types of ceramics is increased with all increase in the oxidation temperature, the weight gain of ceramics is reduced with all increase in the YAG-Al2O3 content and Al2O3 proportion, especially above 1500℃.

The effect of a reinforcement phase on the oxidation mechanism of ZrB2-YAG-Al2O3 ceramcis

Jie-Guang Song,Fang Wang,Ming-Han Xu,Shi-Bin Li,Gang-Chang Ji 한양대학교 세라믹연구소 2012 Journal of Ceramic Processing Research Vol.13 No.3

ZrB2 and YAG are widely applied because of some excellent properties, but ZrB2 is easily oxidized in high-temperature air. To make ZrB2 ceramics have a better oxidation resistance, high-density ZrB2-YAG-Al2O3 ceramics were prepared. The effect of a reinforcement phase on the oxidation mechanism of ZrB2-YAG-Al2O3 ceramics is investigated at different high temperature ranges. The results show that the overall tendency of the weight gain of ZrB2-YAG ceramics and ZrB2 ceramics are similar, but the weight gain of ZrB2-YAG ceramics is less than that of ZrB2 ceramics. The weight gain tendency of three types of ceramics are similar below 1000, the weight gain of ZrB2-YAG and ZrB2-YAG-Al2O3 ceramics have a mild tendency between 1000 and 1300, the weight gain tendency of ZrB2-YAG ceramics and ZrB2 ceramics are similar at 1300, however, the weight gain tendency of ZrB2-YAG-Al2O3 ceramics became mild at 1300 due to the Al18B4O33 coating on the ceramic surface. The weight gain rapidly increased for 1h, then the weight gain tendency became mild after 1 h. The weight gain tendency of ZrB2-YAG-Al2O3 ceramics is similar by contrast with ZrB2-YAG ceramics and ZrB2 ceramics for 1 h, the weight gain tendency of ZrB2-YAG-Al2O3 ceramics is extremely mild at a higher oxidation temperature after 1 h. ZrB2 and YAG are widely applied because of some excellent properties, but ZrB2 is easily oxidized in high-temperature air. To make ZrB2 ceramics have a better oxidation resistance, high-density ZrB2-YAG-Al2O3 ceramics were prepared. The effect of a reinforcement phase on the oxidation mechanism of ZrB2-YAG-Al2O3 ceramics is investigated at different high temperature ranges. The results show that the overall tendency of the weight gain of ZrB2-YAG ceramics and ZrB2 ceramics are similar, but the weight gain of ZrB2-YAG ceramics is less than that of ZrB2 ceramics. The weight gain tendency of three types of ceramics are similar below 1000, the weight gain of ZrB2-YAG and ZrB2-YAG-Al2O3 ceramics have a mild tendency between 1000 and 1300, the weight gain tendency of ZrB2-YAG ceramics and ZrB2 ceramics are similar at 1300, however, the weight gain tendency of ZrB2-YAG-Al2O3 ceramics became mild at 1300 due to the Al18B4O33 coating on the ceramic surface. The weight gain rapidly increased for 1h, then the weight gain tendency became mild after 1 h. The weight gain tendency of ZrB2-YAG-Al2O3 ceramics is similar by contrast with ZrB2-YAG ceramics and ZrB2 ceramics for 1 h, the weight gain tendency of ZrB2-YAG-Al2O3 ceramics is extremely mild at a higher oxidation temperature after 1 h.

Oxidation behavior of YAG-ZrB2 ceramics prepared by spark plasma sintering

Jie-Guang Song,Da-Ming Du,Yin-Yan Ju,Yang-Liang Li,Shi-Bin Li,Gang-Chang Ji 한양대학교 세라믹연구소 2010 Journal of Ceramic Processing Research Vol.11 No.4

ZrB2 and YAG are widely applied because of some excellent properties, but ZrB2 is easily oxidized in high-temperature air. To make ZrB2 ceramics have better oxidation resistance, high-density YAG-ZrB2 ceramics were prepared. The oxidation behavior of YAG-ZrB2 ceramics is investigated at different temperatures. The results indicate that the enhanced weight change differs according to the temperature range, slightly in the temperature 900-1000oC, sharply from 1100-1300 and smoothly above 1300oC. The weight change rate of YAG-ZrB2 ceramics is increased by prolonging the oxidation time, but the weight change rate of YAG-ZrB2 ceramics is gradually reduced. The oxidation layer is porous as compared to the YAG-ZrB2 ceramics layer.

Infuluence of sintering technology on microstructure and mechanical properties of YAG/ZrB2 ceramics

Jie-Guang Song 한양대학교 세라믹연구소 2013 Journal of Ceramic Processing Research Vol.14 No.3

Because ZrB2 has some excellent physical performance and chemical stability, it has been widely applied in a lot of fields, but sintering of ZrB2 is too difficult to be densified and easy oxidation at high temperature. To keep advantages and improve disadvantages of ZrB2, the shell-core structure A12O3-Y2O3/ZrB2 composite powders are prepared by the co-precipitation methods, the high density YAG/ZrB2 ceramics is prepared by the spark plasma sintering (SPS). The increasing ratio of mehanical properties is faster at sintering temperature from 1300o C to 1700o C, the increasing ratio of mehanical properties is faster under sintering pressure from 5 MPa to 20 MPa, the increasing ratio of mehanical properties is faster for holding time from 1 minute to 4 minutes. When the sintering conditons is 1700o C, 20 MPa and 4 minutes, the Young’s modulus and the fracture toughness are 430 GPa and 3.76 MPam1/2, respectively. The YAG is coated on the surface of ZrB2 crystal, that is to say, the YAG is show on the crystal boundary, which is help for the densification and the oxidation resistance at hightemperature condition.

Preparation and sintering behavior of Al2O3-Y2O3/ZrB2 composite powders

Jie-Guang Song,Fang Wang 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.5

Zirconium diboride (ZrB2) has some excellent physical properties and chemical stability, it has been widely applied in many fields, but the sintering densification of ZrB2 is very difficult, and it is easily oxidized at high temperature. In order to improve the disadvantages of ZrB2, Al2O3-Y2O3/ZrB2 composite powders were prepared by a co-precipitation methods. When the pH is 9, the encapsulted structure of A1(OH)3-Y(OH)3/ZrB2 composite powders is best. Through analyzing ZrB2 surface status with SEM, EDS, TEM and XRD, the A12O3-Y2O3/ZrB2 composite powders were prepared by calcining at 600 oC in argon. The density of ZrB2-YAG ceramics with Al2O3-Y2O3 composite powders added is higer than that of ZrB2-YAG ceramics, which indicates the A12O3-Y2O3/ZrB2 composite powders are more easily prepared than high density ZrB2-YAG ceramics.

Isoindolin-1-ones from the stems of Nicotiana tabacum and their antiviral activities

Guang-Yu Yang,Jia-Meng Dai,Zhen-Jie Li,Jin Wang,Feng-Xian Yang,Xin Liu,Jing Li,Qian Gao,Xue-Mei Li,Yin-Ke Li,Wei-Guang Wang,Min Zhou,Qiu-Fen Hu 대한약학회 2022 Archives of Pharmacal Research Vol.45 No.8

In previous studies, several isoindolin-1-oneanalogs that exhibited signifi cant anti-tobacco mosaic virus(anti-TMV) activities were isolated from Nicotiana tabacum . Since gene-editing mutants provide a new sample for thediscovery of active metabolites, we focused on the stems ofYN-18–23 (a mutant N. tabacum for gene editing with thealkaloid metabolic pathway cultivated by Yunnan TobaccoCompany), which led to the isolation of four new ( 1–4 )and four known ( 5–8 ) isoindolin-1-ones. To the best of ourknowledge, nicindole C ( 3 ) is the fi rst subclass of isoindolin-1-one bearing a pentacyclic ketone, while nicindole D ( 4 )is the fi rst example of isoindolin-1-one bearing a methylpyridin-2-(1 H )-one moiety. Compounds 1–4 were testedfor their anti-TMV activities, and the results revealed thatcompounds 1 , 3 , and 4 exhibited high anti-TMV activities atconcentrations of 20 μM with inhibition rates of 48.6, 42.8,and 71.5%, respectively. These rates are higher than the inhibitionrate of the positive control (33.2%). The mechanisticstudy of compound 4 , which had the highest anti-TMV activityrevealed that increased potentiation of defense-related enzyme activities and downregulation of expression of theNtHsp70 protein may induce resistance in tobacco againstthe viral pathogen TMV. Molecular docking studies alsorevealed that the isoindolin-1-one substructure is fundamentalfor anti-TMV activity. The methyl-pyridin-2-(1 H )-onemoiety in compound 4 and the 2-oxopropyl groups in compounds1 and 3 at the N -2 position may increase inhibitoryactivities. This study of the structure–activity relationshipis helpful for fi nding new anti-TMV activity inhibitors. Tostudy whether the isoindolin-1-ones have broader antiviralactivities, compounds 1–4 were also tested for their antirotavirusactivities. Compound 4 exhibited high anti-rotavirusactivity with a therapeutic index (TI) value of 20.7. This TI value is close to that of the positive control (20.2).

Effect of raw materials on the properties of ZrB2-YAG-Al2O3 multi-phase ceramics

Jie-Guang Song,Fang Wang,Da-Ming Du,Yin-Yan Ju,Shi-Bin Li,Gang-Chang Ji,Lian-Meng Zhang 한양대학교 세라믹연구소 2014 Journal of Ceramic Processing Research Vol.15 No.2

ZrB2 belongs to a class of ceramics defined ultra-high-temperature ceramics with extremely high melting temperatures, but ZrB2 ceramics is difficultly sintered and easily oxidized. To make ZrB2 ceramics possess the high relative density and the better oxidation resistance. The effects of raw materials on the properties of ZrB2 composite were investigated. YAG and Al2O3 help for the densification of ZrB2 ceramics. Fracture toughness of sintered ceramics with coated powder is higher than that of sintered ceramics with mixed powder. The mechanical property of ZrB2-YAG-Al2O3 materials is higher than that of ZrB2-YAG materials. Oxidation layer thickness of sintered ceramics with coated powder is thinner than that of sintered ceramics with mixed powder. These results show the sintered ZrB2 based multi-phase ceramics with coated microstructure help to increase the mechanical properties and oxidation resistance. The oxidation resistance of ZrB2-YAG-Al2O3 ceramics is better than that of ZrB2-YAG materials.

Effect of synthesis conditions on the particle size and morphology of YAG powder

Jie-Guang Song,Fang Wang,Ming-Han Xu,Yin-Yan Ju,Yang-Liang Li,Shi-Bin Li,Gang-Chang Ji 한양대학교 세라믹연구소 2012 Journal of Ceramic Processing Research Vol.13 No.2

Yttrium aluminum garnet (YAG) is currently a widely applied structural and functional material. To prepare highperformance YAG ceramics we prepared pure YAG powder, after calcining the precursor at 1100 ºC, by co-precipitation with ammonia as the precipitant and aluminum nitrate as well as yttrium nitrate as raw materials. The preparation conditions for the YAG precursor were a pH of 9, a titration rate of 10 ml/ minute and a reaction time of 60 minutes. The mean paricle size of the YAG powder was 11ìm. The mean particle size for the YAG powder increased with an increase in the pH and at a higher pH the YAG particles were more irregular in shape. The mean particle size and particle size distribution range of the YAG powder increased with an increase in the titration rate. For the YAG powder with a higher mean particle size, the particle size distribution range was wider but the size of most YAG particles was still small and the YAG particles were nearly spherical.

Effect of the sintering technology on the properties of fired brick from quartz sands

Jie-Guang Song,Fang Wang,Xiao-Bo Bai,Da-Ming Du,Yin-Yan Ju,Ming-Han Xu,Gang-Chang Ji 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.4

River sands as low grade natural raw materials are used to prepare the fired brick to replace clay fired bricks, which aims to save land resources and use low grade natural resources to realize high cost performance. In this paper, the effect of sintering technology of bricks on their performance is discussed. The compressive strength of fired bricks is first increased and then decreased with an increase in the sintering temperature, the compressive strength of bricks prepared by the isostatic compaction shaping is higher than that of bricks prepared by the plastic shaping under the same conditions. The compressive strength of bricks reaches 28 MPa when sintered at 1150 oC by using a 20MPa isostatic compaction shaping method. The compressive strength of bricks is first increased and then decreased by prolonging the holding time, the compressive strength of bricks reaches 28.9MPa when sintered at 1150 oC for 2 h.

The effect of the oxidation conditions on the surface microdomains of ZrB2-YAG ultra-high temperature ceramics

Jie-Guang Song,Min-Han Xu,Da-Ming Du,Fang Wang,Shi-Bin Li,Gang-Chang Ji 한양대학교 세라믹연구소 2013 Journal of Ceramic Processing Research Vol.14 No.4

Zirconium diboride is widely applied because of some excellent properties. The effect of the oxidation temperature on the surface microdomain of ZrB2-YAG multi-phase ceramics was studied, it helps to improve the performance of ultra-hightemperature ceramics. The results show the oxidation layer thickness is increased with an increase in the oxidation temperature, the oxidation layer thickness is decreased by increasing the density of multi-phase ceramics at the same oxidation temperature. The ceramic surface shows the (m)ZrO2, YAG, B2O3 and ZrB2 phases below the the oxidation temperature at 1300 ο C, but the ceramic surface do not show the ZrB2 phase above the oxidation temperature at 1300 ο C that is to say, the ZrB2 phase of the ceramic suface is entirely oxidized. The oxidation layer thickness is increased with an increase in the oxidation time, however, the ratio of increasing thickness is less and less. The oxidation layer shows a loose structure during the initial stage of the oxidation, which lacks a barriers for the diffusion of the oxygen.