为了解湖泊沉积物研究领域现状和未来发展趋势,采用信息可视化、网络分析的研究方法,以Web of Science(WoS)和中国知网(CNKI)数据库中近35年(1985—2019年)湖泊沉积物研究领域的论文作为数据来源绘制社会网络图谱,剖析湖泊沉积物研究领...为了解湖泊沉积物研究领域现状和未来发展趋势,采用信息可视化、网络分析的研究方法,以Web of Science(WoS)和中国知网(CNKI)数据库中近35年(1985—2019年)湖泊沉积物研究领域的论文作为数据来源绘制社会网络图谱,剖析湖泊沉积物研究领域的发展动态、研究热点及前沿趋势。结果表明:WoS数据库近35年来湖泊沉积物研究领域的发文量呈显著上升趋势,发文量位居前3的国家依次为美国、中国和德国;近5年中国发文量较高,但发文总被引频次相对较低;Bindler R、Birks H J B和Bakke J为该领域以第一作者发文量排名前3的作者,Journal of Paleolimnology、Hydrobiologia和Limnology and Oceanography为发文量排名前3的期刊。CNKI数据库的发文量滞后于WoS数据库,国内研究者有偏向于投稿国外期刊的趋势;CNKI数据库中湖泊沉积物研究领域发文量最高的期刊为《湖泊科学》,张恩楼、金章东和薛斌为发文量排名前3的作者。国内外湖泊沉积物研究领域的研究热点大致相同,主要包括沉积物重金属和有机物的污染与风险评估、湖泊沉积物与气候变化研究等方面,未来该领域在正定矩阵因子分析模型和多元统计方法包括相关性分析、聚类分析、因子分析等方向的研究有待进一步加强。展开更多
SiC porous ceramics were prepared at 1 400 ℃ for4 h with crystalline silicon cutting waste and activated carbon as main starting materials and NH4HCO3 as the pore-forming agent. Effects of NH4HCO3 additions( 0,20%,30...SiC porous ceramics were prepared at 1 400 ℃ for4 h with crystalline silicon cutting waste and activated carbon as main starting materials and NH4HCO3 as the pore-forming agent. Effects of NH4HCO3 additions( 0,20%,30%,40%,by mass) on the phase composition,microstructure,sintering properties,cold compressive strength and thermal shock resistance of as-prepared Si C porous ceramics were investigated. The results show that:( 1) addition of NH4HCO3 remarkably influences the apparent porosity and cold compressive strength of specimens. The apparent porosity achieves its maximum value( 63. 40%) when 40% NH4HCO3 is added,while the minimum cold compressive strength is 4. 77 MPa;( 2) the specimen with 40% NH4HCO3 has the best thermal shock resistance. The thermal cycling times between1 000 ℃ to room temperature reach 62;( 3) the addition of NH4HCO3 does not remarkably affect the phase composition of the specimens;( 4) the specimens include a large number of SiC particles and a small amount of SiC whiskers.展开更多
SiC powder was rapidly synthesized in an induction furnace with crystalline silicon cutting waste and active carbon as raw materials,and then SiC porous ceramics were prepared at 1600 t for 4 h with carbon embedded us...SiC powder was rapidly synthesized in an induction furnace with crystalline silicon cutting waste and active carbon as raw materials,and then SiC porous ceramics were prepared at 1600 t for 4 h with carbon embedded using the powder as raw material,the starch and the graphite as pore-forming agents.Effects of additions of different pore-forming agents on the phase composition,microstructures,physical properties,and cold crushing strength of the porous ceramics were investigated.The results show that the main crystalline phases of the synthetic powder areα-S iC(6H-SiC)andβ-SiC(3C-SiC).The phase composition of the porous ceramics includesα-S iC(6H-SiC),β-SiC(3C-SiC),FeSi,quartz and Si2N20.The apparent porosity and closed porosity of the porous ceramics prepared by adding starch are higher,and the cold compressive strength of the porous ceramics added with graphite is higher.As increasing the additions of the starch,the apparent porosity,closed porosity and linear shrinkage ratio of the porous ceramics increase,and the bulk density decreases correspondingly.When 20 mass%starch is added,the apparent porosity,closed porosity,linear shrinkage ratio and cold compressive strength are 57.05%,2.03%,5.10%and 10.20 MPa,respectively.展开更多
In order to fabricate porous ceramics with good properties and proper production cost,SiC-Al2 O3 porous ceramics were prepared at 1 450 ℃ for 2 h from the powders of commercial silicon carbide and white fused corundu...In order to fabricate porous ceramics with good properties and proper production cost,SiC-Al2 O3 porous ceramics were prepared at 1 450 ℃ for 2 h from the powders of commercial silicon carbide and white fused corundum via a polymeric replication method. Effects of the mass ratio of SiC powder to white fused corundum powder（ 1 ∶ 3,1 ∶ 1 and 3 ∶ 1） on the appearance,phase composition,sintering properties and thermal shock resistance were investigated. The research results indicate that the as-prepared Si C-Al2 O3 porous ceramics have uniform pores,and their linear shrinkage ratio,apparent porosity and bulk density reach 4. 70%,67. 17%and 0. 83 g·cm-3,respectively. The thermal shock cycles from 1 400 ℃ to room temperature reach 23 including 15 cycles in air cooling condition and then 8 cycles in water cooling condition. Their main phases areα-Al2 O3 and Al6 Si2 O13 as well as a small amount of SiC and free SiO2. The as-prepared porous ceramic with the ratio of m（ SiC） ∶ m（ Al2 O3） = 1∶ 1 possesses prior comprehensive properties.展开更多
文摘为了解湖泊沉积物研究领域现状和未来发展趋势,采用信息可视化、网络分析的研究方法,以Web of Science(WoS)和中国知网(CNKI)数据库中近35年(1985—2019年)湖泊沉积物研究领域的论文作为数据来源绘制社会网络图谱,剖析湖泊沉积物研究领域的发展动态、研究热点及前沿趋势。结果表明:WoS数据库近35年来湖泊沉积物研究领域的发文量呈显著上升趋势,发文量位居前3的国家依次为美国、中国和德国;近5年中国发文量较高,但发文总被引频次相对较低;Bindler R、Birks H J B和Bakke J为该领域以第一作者发文量排名前3的作者,Journal of Paleolimnology、Hydrobiologia和Limnology and Oceanography为发文量排名前3的期刊。CNKI数据库的发文量滞后于WoS数据库,国内研究者有偏向于投稿国外期刊的趋势;CNKI数据库中湖泊沉积物研究领域发文量最高的期刊为《湖泊科学》,张恩楼、金章东和薛斌为发文量排名前3的作者。国内外湖泊沉积物研究领域的研究热点大致相同,主要包括沉积物重金属和有机物的污染与风险评估、湖泊沉积物与气候变化研究等方面,未来该领域在正定矩阵因子分析模型和多元统计方法包括相关性分析、聚类分析、因子分析等方向的研究有待进一步加强。
文摘SiC porous ceramics were prepared at 1 400 ℃ for4 h with crystalline silicon cutting waste and activated carbon as main starting materials and NH4HCO3 as the pore-forming agent. Effects of NH4HCO3 additions( 0,20%,30%,40%,by mass) on the phase composition,microstructure,sintering properties,cold compressive strength and thermal shock resistance of as-prepared Si C porous ceramics were investigated. The results show that:( 1) addition of NH4HCO3 remarkably influences the apparent porosity and cold compressive strength of specimens. The apparent porosity achieves its maximum value( 63. 40%) when 40% NH4HCO3 is added,while the minimum cold compressive strength is 4. 77 MPa;( 2) the specimen with 40% NH4HCO3 has the best thermal shock resistance. The thermal cycling times between1 000 ℃ to room temperature reach 62;( 3) the addition of NH4HCO3 does not remarkably affect the phase composition of the specimens;( 4) the specimens include a large number of SiC particles and a small amount of SiC whiskers.
文摘SiC powder was rapidly synthesized in an induction furnace with crystalline silicon cutting waste and active carbon as raw materials,and then SiC porous ceramics were prepared at 1600 t for 4 h with carbon embedded using the powder as raw material,the starch and the graphite as pore-forming agents.Effects of additions of different pore-forming agents on the phase composition,microstructures,physical properties,and cold crushing strength of the porous ceramics were investigated.The results show that the main crystalline phases of the synthetic powder areα-S iC(6H-SiC)andβ-SiC(3C-SiC).The phase composition of the porous ceramics includesα-S iC(6H-SiC),β-SiC(3C-SiC),FeSi,quartz and Si2N20.The apparent porosity and closed porosity of the porous ceramics prepared by adding starch are higher,and the cold compressive strength of the porous ceramics added with graphite is higher.As increasing the additions of the starch,the apparent porosity,closed porosity and linear shrinkage ratio of the porous ceramics increase,and the bulk density decreases correspondingly.When 20 mass%starch is added,the apparent porosity,closed porosity,linear shrinkage ratio and cold compressive strength are 57.05%,2.03%,5.10%and 10.20 MPa,respectively.
文摘In order to fabricate porous ceramics with good properties and proper production cost,SiC-Al2 O3 porous ceramics were prepared at 1 450 ℃ for 2 h from the powders of commercial silicon carbide and white fused corundum via a polymeric replication method. Effects of the mass ratio of SiC powder to white fused corundum powder（ 1 ∶ 3,1 ∶ 1 and 3 ∶ 1） on the appearance,phase composition,sintering properties and thermal shock resistance were investigated. The research results indicate that the as-prepared Si C-Al2 O3 porous ceramics have uniform pores,and their linear shrinkage ratio,apparent porosity and bulk density reach 4. 70%,67. 17%and 0. 83 g·cm-3,respectively. The thermal shock cycles from 1 400 ℃ to room temperature reach 23 including 15 cycles in air cooling condition and then 8 cycles in water cooling condition. Their main phases areα-Al2 O3 and Al6 Si2 O13 as well as a small amount of SiC and free SiO2. The as-prepared porous ceramic with the ratio of m（ SiC） ∶ m（ Al2 O3） = 1∶ 1 possesses prior comprehensive properties.
