以稻壳为硅源和碳源制备多孔堇青石陶瓷的研究

稻壳是以C、O、H和Si为主要元素组成的一种农业废弃物。本文以稻壳为硅源和碳源合成了多孔堇青石陶瓷载体,讨论了多孔堇青石的最佳烧成温度、碳质组分含量对堇青石微观结构和性能的影响。实验结果表明:以稻壳中碳质成份为造孔剂,当其添加量为堇青石原料总量的8 wt%、烧成温度为1300℃时,可获得性能较好的多孔堇青石陶瓷。经测试,此样品的显气孔率为37.18%、抗折强度为19.48 MPa、热膨胀系数为3.1×10-6℃-1,可满足工业载体的要求。     

堇青石陶瓷烧结工艺及机理研究

本文利用DSC、XRD技术，研究了MgO、Al2O3，和SiO2反应烧结制备堇青石陶瓷的机理。结果表明MgO和Al2O3在1155℃反应合成镁铝尖晶石(MgAl2O4)，进而在1317℃长时间保温与SiO2反应生成堇青石。     

添加Li2CO3和BaCO3对合成堇青石性能的影响

采用煤系高岭土、滑石和镁砂为主要原料,在化学组成(w)为MgO13.23%,Al2O333.78%,SiO251.16%的研究配方(试样A)的基础上,分别添加1.0%、1.5%、2.0%的Li2CO3(对应试样编号为L1、L2、L3)或1.0%、2.0%、3.0%的BaCO3(对应试样编号为B1、B2、B3),以100MPa压制成36mm×50mm的圆柱状试样,在110℃干燥4h后,以3~5℃·min-1的升温速度升至1340℃保温3h烧成,然后检测试样的烧后体积收缩率及体积密度、显气孔率和热膨胀系数,并采用XRD分析矿物成分,K值法测量烧后试样的堇青石相含量,以探讨添加Li2CO3和BaCO3对合成堇青石性能的影响。结果表明:随着Li2CO3添加量的增加,烧后试样的体积收缩率和体积密度逐渐增大,显气孔率逐渐减小,而添加BaCO3对堇青石合成过程中的烧结性影响不大;烧后试样A和B2中除分别含有为90%和95%的堇青石外未检测到其他晶相,但L1中还存在一定量的LiAlSi2O6相;添加剂Li2CO3或BaCO3均能降低合成堇青石的热膨胀系数。     

Bi_2O_3对堇青石陶瓷的烧结行为、相变和热膨胀性能的影响

采用X射线衍射仪、差热分析仪和热膨胀仪等手段研究了由氧化物粉末 (MgO、Al2 O3 和SiO2 )制备堇青石陶瓷时 ,添加Bi2 O3 对堇青石陶瓷相变和性能的影响 ,分析了Bi2 O3 在烧结过程中的作用机理是低温产生液相促进烧结。试验表明 ,Bi2 O3 能明显降低烧结温度 ,在 12 5 0℃烧成 3h后的陶瓷是由α堇青石和少量的 μ堇青石组成。随着Bi2 O3 含量增加 ,陶瓷的致密度和热膨胀系数逐渐升高。Bi2 O3 的添加量 (质量分数 )为 0 .0 4 ,原料相石英消失。Bi-O膨胀系数较Si-O的大和Bi3 + 离子进入堇青石晶格中是引起堇青石陶瓷热膨胀系数升高的主要原因。     

Bi2O3对堇青石陶瓷的烧结行为、相变和热膨胀性能的影响

采用X射线衍射仪、差热分析仪和热膨胀仪等手段研究了由氧化物粉末(MgO、Al2O3和SiO2)制备堇青石陶瓷时，添加Bi2O3对堇青石陶瓷相变和性能的影响，分析了Bi2O3在饶结过程中的作用机理是低温产生液相促进烧结。试验表明，Bi2O3能明显降低饶结温度，在1250℃烧成3h后的陶瓷是由α堇青石和少量的μ堇青石组成。随着Bi2O3含量增加，陶瓷的致密度和热膨胀系数逐渐升高。Bi2O3的添加量(质量分数)为0．04，原料相石英消失。Bi—O膨胀系数较Si—O的大和Bi^3 离子进入堇青石晶格中是引起堇青石陶瓷热膨胀系数升高的主要原因。     

堇青石质多孔陶瓷的制备及性能研究

采用氧化铝、烧高岭、烧滑石为原料,可溶于水的有机物质尿素作为造孔剂,TiO2为添加剂,于6MPa压力下干压成形,1350℃下保温60min进行烧成,制备出以堇青石为主晶相的多孔陶瓷体。通过XRD分析手段对不同温度合成堇青石主晶相进行了分析,并用SEM观察了烧结后多孔陶瓷的微观结构。探讨了可溶性造孔剂用量、TiO2添加量、烧成制度等因素对堇青石质多孔陶瓷性能的影响。制备的多孔陶瓷体气孔率接近于70%,抗压强度达到3.310MPa。     

碳化硅/堇青石复相多孔陶瓷的制备及性能研究

采用碳化硅、烧高岭土、氢氧化铝、滑石为主要原料,石墨为造孔剂制备了碳化硅/堇青石复相多孔陶瓷.研究了烧结温度和烧结助剂二氧化铈对碳化硅/堇青石复相多孔陶瓷气孔率和强度的影响,并分别用XRD和SEM分析晶相组成和断面显微结构表明:制备出的SiC多孔陶瓷的主相是SiC,结合相是堇青石与方石英,多孔陶瓷具有相互连通的开孔结构;在1350℃烧结,并保温3h,当造孔剂含量为15％时,碳化硅/堇青石复合多孔陶瓷性能最佳,其气孔率31.80％,相应的弯曲强度为63.74 MPa.在1200℃下,添加不同含量的CeO2,对烧结样品的相组成有影响,能够降低生成堇青石的温度,在CeO2含量为3％的样品中,堇青石的峰最明显,但是过量的氧化铈会抑制了堇青石的生成;随着CeO2加入量的增加,其气孔率和弯曲强度也会随之变化,1200℃下,在CeO2加入量为4％时其弯曲强度最优.但随着CeO2的含量的增加,其气孔率逐渐下降.     

化学组成对合成堇青石显微结构和高温性能的影响

研究了化学组成对合成堇青石材料显微结构和高温性能的影响。研究发现 ,当配料中的Al2 O3含量在理论组成的 5 %范围内变化时 ,对合成堇青石材料的显微结构和高温性能产生明显影响。其中Al2 O3与SiO2 或Al2 O3与MgO的质量比的增大有利于改善堇青石材料的显微结构和提高其高温性能。合成的堇青石材料在 12 5 0℃下的高温抗折强度为 16～ 18MPa ,0 .2MPa荷重下 10h后的蠕变率为 - 0 .0 79%。     

锂辉石对堇青石多孔陶瓷性能的影响

通过堇青石颗粒料制得的堇青石多孔陶瓷,与加入一定比例锂辉石制得的堇青石多孔陶瓷,在不同的温度下烧成,对气孔率、抗折强度、热膨胀系数等性能进行测试对比研究,对比实验数据表明加入锂辉石对堇青石多孔陶瓷的性能起到了优化作用。结果表明加入5%锂辉石烧成温度1280℃制得堇青石多孔陶瓷气孔率45.83%、抗折强度22.64MPa、热膨胀系数1.73×10-6/℃。     

锂辉石对堇青石多孔陶瓷性能的影响

通过堇青石颗粒料制得的堇青石多孔陶瓷,与加入一定比例锂辉石制得的堇青石多孔陶瓷,在不同的温度下烧成,对气孔率、抗折强度、热膨胀系数等性能进行测试对比研究,对比实验数据表明加入锂辉石对堇青石多孔陶瓷的性能起到了优化作用。结果表明加入5%锂辉石烧成温度1280℃制得堇青石多孔陶瓷气孔率45.83%、抗折强度22.64MPa、热膨胀系数1.73×10-6/℃。     

石棉尾渣和粉煤灰制备堇青石多孔陶瓷及其理化性能

低成本制备堇青石多孔陶瓷一直是专家学者们研究的热点,本文以石棉尾渣、粉煤灰、高岭土为原料,在不添加发泡剂的情况下,采用直接烧结法成功制备了堇青石多孔陶瓷,系统研究了堇青石多孔陶瓷的物相演化、显微结构及理化性能。结果表明:烧结温度的升高和配方中高岭土含量的增加有助于样品中堇青石的合成,高岭土的添加可以有效降低样品发泡的温度和提高样品的孔隙率;当烧结温度为1 240 ℃,焙烧后的石棉尾渣、焙烧后的粉煤灰和高岭土质量比为5∶5∶3时,制备的堇青石多孔陶瓷的体积密度仅为0.6 g/cm³,孔隙率高达76.94%;当烧结温度为1 220 ℃,焙烧后的石棉尾渣、焙烧后的粉煤灰和高岭土质量比为5∶5∶5时,制备的堇青石多孔陶瓷吸水率达到最大值34.57%;此外,制备的堇青石多孔陶瓷还表现出良好的耐碱性能。     

堇青石多孔陶瓷的制备与性能表征

以粉煤灰和碱式碳酸镁为主要原料制得了堇青石多孔陶瓷材料.烧结温度在1 100～1 350℃时,样品的弯曲强度由50 MPa增加至65 MPa,热膨胀系数由8.07×10-6℃-1下降至4.21×10-6℃-1.优化的烧结工艺为1 300℃保温4 h.样品的孔隙率和孔径随原料中淀粉含量的增加而增加.在原料中添加40%(质量分数)的造孔剂(淀粉)可使样品的孔隙率、平均孔径为和氮气通量分别达到41.7%,2.35μm和0.225 m·h-1Pa-1.     

脱硝催化剂用堇青石多孔陶瓷的制备与性能研究

以偏高岭土、氧化铝和滑石为原料,利用压制成型制备出堇青石多孔陶瓷并采用浸渍涂覆法制备锰基低温脱硝催化剂.通过气孔率、抗折强度、热膨胀系数、SEM、BET等测试探究了碳粉和淀粉两种造孔剂及添加量、不同酸处理时间等因素对堇青石性能的影响并考察了不同浸渍次数的催化剂在80~200 ℃间的脱硝性能.结果表明:造孔剂为碳粉且添加量为4%时,得到的堇青石具有良好的性能,此时气孔率达31.12%,热膨胀系数为3.10×10-6/K,抗折强度为21.41 MPa;适当的酸处理有助于堇青石表面孔结构的丰富且能大幅提升其比表面积,最佳处理时间为2 h;当浸渍次数为4次时,整体式催化剂的性能最佳,牢固度可达90.18%,140 ℃时的脱硝率可达74.5%以上.     

Fabrication and characterization of porous cordierite ceramics prepared from fly ash and natural minerals

Low cost, single-phase porous cordierite ceramics are successfully synthesized by in-situ solid-state reactions from fly ash, quartz, and magnesite. The effects of sintering temperature and magnesite content on phase transformation, open porosity, bulk density, mechanical properties, and microstructure are carefully investigated. Factsage analyses are carried out to calculate the isopleth diagrams, and the results agree well with the experimental outcomes. Thermal gravimetric and differential scanning calorimeter analyses (TG-DSC) are performed to characterize the weight loss and transient behaviors of the raw materials. Linear thermal expansion properties are also studied. The α-cordierite phase is the only phase observed in S-3 (magnesite content 25%) sintered at 1300 °C for 2 h, and its linear thermal expansion coefficient (2.71 × 10⁻⁶ K⁻¹) is close to that of typical cordierite. Both the compressive strength (72.64 MPa) and flexural strength (23.92 MPa) of the as-synthesized samples are high with an open porosity of 33.16% and a bulk density of 1.61 g/cm³.     

造孔剂种类对粉煤灰多孔陶瓷性能的影响研究

以工业废弃物粉煤灰为主要原料,采用添加造孔剂法,分别以淀粉和煤粉为造孔剂,模压成型,在1000℃固相烧结制备粉煤灰多孔陶瓷,用SEM测试分析手段表征不同条件下粉煤灰多孔陶瓷的微观结构变化,研究了造孔剂种类及用量对显气孔率、抗弯强度、吸水率、体积密度、耐酸碱性能的影响.     

Recycling of harmful waste lead-zinc mine tailings and fly ash for preparation of inorganic porous ceramics

The porous ceramics were prepared by directly sintering of lead-zinc mine tailings and fly ash as the raw materials without any additional sintering and foaming agent. The effects of fly ash addition on the crystalline phases, pore structure, physical–chemical porosities and mechanical strength were investigated. The results showed that the bulk density decreased firstly and then increased while the porosity and water absorption presented the opposite tendency with the increase of fly ash content. Meanwhile, the chemical stability improved and the flexural strength had the same variation tendency of the bulk density. The phase evolution of sample with 60 wt% fly ash addition indicated that anorthite phase was formed at low temperature (1000 °C). The thermal behavior illustrated that the foaming process was initiated by the reaction of internal constituents in the lead-zinc mine tailings. Different pore structures indicated different foaming mechanisms that probably occurred at different temperatures. The porous ceramics with 60 wt% fly ash addition exhibited excellent properties, including bulk density of 0.93 g/cm³, porosity of 65.6%, and flexural strength of 11.9 MPa.     

Recycling bagasse and rice hulls ash as a pore-forming agent in the fabrication of cordierite–spinel porous ceramics

Bagasse and rice hulls ash are both waste materials. In recent years, in order to meet environmental protection, these materials have been recycled in the production of porous ceramics. A solid-state reaction mechanism of calcined alumina and talc was used to prepare cordierite–spinel porous ceramics. Talc was added from 30 to 60 wt.% at the expense of alumina and sintered at 1400°C for 2 h. The effect of bagasse and rice hulls ash (as a pore forming agent) on the densification parameters, cold crushing strength (CCS), and pore size distribution was also studied. The phase composition (X-ray diffraction) and microstructure (scanning electron microscopy) of sintered samples were investigated. The results showed that the main phases present in the samples are cordierite, corundum, spinel, and sapphirine. In the sample with a higher amount of talc additions (60 wt.%), only the formation of the cordierite and spinel phases was observed. The bulk density of the samples and the apparent porosity ranged from 1.77 to 2.26 g/cm³ and from 28.6% to 48.21%, respectively. The CCS of the samples ranges from 13.9 to 36.3 MPa. The microstructures of the sintered samples were observed for the formation of cordierite phase, alumina phase, and spinel phase in an excellent crystallization and phase arrangement.     

燃煤飞灰化学成分随粒度分布规律的试验研究

在对国内几家电厂电除尘器收集的燃煤飞灰进行混配、筛分及全灰化等处理后，采用常量法对分电场、分粒径灰样的化学成分进行了分析。结果发现：飞灰中SiO2,Al2O3,TFeO,CaO和MgO等化学成分的含量随电场及飞灰的粒度呈一定规律分布，Al2O3含量则随着粒度的减小而逐渐增加，CaO和MgO的含量随粒度变细也有增加的趋势，针对造成这种分布规律的机理进行了初步的分析。     

粉煤灰细粉添加量对多孔莫来石材料的影响

为了提高粉煤灰的资源化利用,在m(漂珠):m(氢氧化铝):m(V2O5):m(AlF3)=45:55:4:3的混合料中分别添加不同量(每100 g混合料分别添加0、5、10、20、30 g)的粉煤灰细粉,以PVA溶液为结合剂,经干料混匀、泥料搅拌、泥料陈腐、挤制成型、1100℃保温2 h烧成制备莫来石试样,然后检测其致...