TiO2对CaO陶瓷烧结和抗水化性能的影响

研究了TiO2添加剂对CaO陶瓷抗水化性能的影响.结果表明:TiO2与CaO反应生成的Ca3(TiO7)连结CaO晶粒,促进固相烧结,增大了陶瓷的烧结密度,同时TiO2能促进CaO晶粒长大,提高了CaO陶瓷的抗水化性能.提高烧结温度,能提高陶瓷密度,从而提高CaO陶瓷的抗水化性能,实验中TiO2最佳添加量为3%.     

Al2O3透明陶瓷显微结构的研究

采用高纯Al2O3(＞99.9%)粉末为原料,用无压烧结工艺制备Al2O3透明陶瓷.研究了添加剂Y2O3、烧结温度、保温时间等对Al2O3透明陶瓷显微结构和光学性能的影响.实验结果表明,适量的Y2O3能够抑制Al2O3晶粒的生长,改善烧结性能,但添加量过多会使Al2O3陶瓷气孔略有增加.在1800℃烧结的样品密度接近理论密度,具有较好的光学性能.延长保温时间能够使晶粒长大的同时有效排除晶界处少量气孔.     

铬掺杂对PZN-PZT陶瓷微观结构和电学性能的影响

研究了Cr2O3掺杂对0．2Pb（Zn1／3Nb2/3）O3-Pb（Ti0.5Zr0.5）03（PZN-PZT）陶瓷结构和电学性能的影响。结果表明,Cr2O3掺杂量小于0．3wt％时,Cr2O3能引起三方-四方相变,四方相含量诸加,晶粒尺寸和烧结密度上升;掺杂量高于0．3wt％时,Cr2O3掺杂能抑制晶粒长大并降低烧结密度。同时,Cr2O3掺杂表现出硬性掺杂特征：εr变小,Qm值增加。而tanδ,kp和d33随Cr2O3掺杂量增加而表现出极值特征。最佳的压电性能出现在Cr2O3掺杂量为0．3wt％处。     

MgO和烧结温度对Al_2O_3透明陶瓷显微结构和性能的影响

采用高纯Al2O3粉末为原料,在氢气气氛中烧结了氧化铝透明陶瓷。研究了添加剂MgO和烧结温度对Al2O3透明陶瓷致密化过程、显微结构和性能的影响。实验结果表明,适量掺杂MgO能够抑制晶粒生长,改善烧结性能,提高致密度,0.05%(质量分数)是MgO最佳含量;随着烧结温度的升高,晶粒发育完全,透光率增加,1850℃为最佳烧结温度;在最佳条件下获得的氧化铝透明陶瓷,相对密度为99.72%,平均晶粒尺寸约20μm,总透光率达到93%,显微硬度(HV5)为20.75GPa,抗弯强度达到320MPa。     

MnO2-TiO2-MgO复相添加剂对氧化铝陶瓷烧结温度的影响

用注浆成型方法,通过加入MnO2-TiO2-MgO复相添加剂,在1300℃下获得了相对密度为95%的氧化铝陶瓷。研究了MnO2-TiO2-MgO复相添加剂对氧化铝陶瓷力学性能、显微结构的影响。通过比较在添加相同质量MnO2、MgO的情况下,添加不同质量的TiO2对氧化铝陶瓷烧结性能的影响。结果表明,该复相添加剂能有效降低氧化铝陶瓷的烧结温度,尤其Al2O3+0.5%MgO+3%MnO2+3%TiO2体系烧结效果最好,晶粒分布均匀,几乎无晶粒异常现象,平均粒径为1μm,烧结体密度达到3.78g/cm3。     

烧结助剂种类对Si_3N_4/SiC陶瓷力学与摩擦性能的影响（英文）

分别以Y2O3-Al2O3(YA)和Y2O3-MgO(YM)为烧结助剂,采用气压烧结工艺制备了Si3N4/SiC陶瓷,研究了两种不同的烧结助剂对陶瓷的力学和摩擦性能的影响。研究结果表明:添加不同种类的烧结助剂对制备陶瓷的相对密度、抗弯强度、断裂韧性、硬度、摩擦系数和磨损率影响很大;与添加烧结助剂YM相比较,添加烧结助剂YA的Si3N4/SiC陶瓷在烧结过程中表现出了更好的烧结性能,得到的陶瓷样品最终显示了更好的力学和摩擦性能,尤其是SiC添加量为20wt%的Si3N4/SiC陶瓷。这主要归因于烧结助剂YA的添加使Si3N4/SiC陶瓷呈现出了更高的相对密度,获得的晶粒长径比更小。     

空心阴极等离子烧结AlN陶瓷

将空心阴极效应运用于AlN陶瓷的烧结,选用自蔓延高温合成的AlN粉体为原料,用Y2O3-CaO-Li2O作为烧结助剂,制备出了致密度高,导热性能好的AlN陶瓷.在添加5.5wt％的Y2O3-CaO-Li2O(Y2O3:Li2O:CaO=44:6:5wt％)作为烧结助剂,在1700℃,保温3h的烧结条件下,获得相对密度为98.89％,热导率为93.8 W/(m·K)AlN烧结体.烧结体的断口SEM照片显示烧结试样的晶粒生长发育完善,晶粒轮廓清晰呈尖锐的多面体形状,晶粒大小均匀,气孔和晶界相少,断裂模式为穿晶断裂.TEM表明:晶界相少,且大部分都缩至三角晶界,AlN颗粒与颗粒接触紧密.     

Y2O3和B2O3对莫来石低温烧结的影响

由于Si4+和Al3+离子在莫来石晶界处扩散速率低,莫来石陶瓷难以烧结.为了降低莫来石陶瓷的烧结温度,在莫来石中添加Y203.B2O3为烧结助剂,研究了添加剂在单独和混合添加情况下对莫来石陶瓷体积密度、抗弯强度以及微观形貌等的影响.同时,研究了烧结温度及保温时间对莫来石陶瓷性能的影响.研究表明,添加剂显著地降低了莫来石的烧成温度,添加Y2O3充当烧结助剂比添加B2O3具有更好的效果,随着温度的提高,陶瓷强度由37.39MPa增至77.89MPa,体积密度由1.99g/cm3增至2.60g/cm3.     

纳米复合助剂对氮化铝陶瓷烧结特性的影响

如何获得理想的氮化铝陶瓷是电子陶瓷材料研究领域的重要课题。本研究采用纳米复合添加剂Y2O3-La2O3,分别在1600℃、1650℃、1700℃、1750℃和1800℃下,无压烧结氮化铝陶瓷。测定并分析了AlN陶瓷的性能和微观结构。实验结果表明:烧结温度达到1750℃,就可获得致密烧结,此时AlN晶粒细小均匀,第二相Al2Y4O9、LaAlO3和Y2O3分布在AlN晶界,AlN晶粒内的氧含量很低,AlN陶瓷样品的热扩散率较高。     

微波和常规烧结制备纳米Al_2O_3/3Y-TZP陶瓷

采用共沉淀法制备Al2O3/3Y-TZP纳米粉体,粉体压制后通过微波和常规烧结制备Al2O3/3Y-TZP陶瓷,并研究两种烧结方法对Al2O3/3Y-TZP陶瓷相对密度、抗弯强度、断裂韧性和断口形貌等的影响。结果表明,共沉淀法制得的Al2O3/3Y-TZP纳米粉体晶粒细小、均匀,近似球形,尺寸为40~60nm;随烧结温度的升高,两种烧结方法制备的陶瓷试样相对密度、抗弯强度和断裂韧性均先升高后降低;与常规烧结相比,Al2O3/3Y-TZP陶瓷的微波烧结温度明显降低,时间显著缩短,且晶粒更细小,相对密度、抗弯强度和断裂韧性显著提高。     

Chromium behavior during cement-production processes: a clinkerization, hydration, and leaching study

The behavior of chromium during the production of cement clinker, during the hydration of cement and during the leaching of cement mortars was investigated. The microstructures of clinker and mortar properties were investigated using free lime, XRD, SEM/EDS, and TG/DTA techniques. Chromium was found to be incorporated in the clinker phase. The formation of new chromium compounds such as Ca(6)Al(4)Cr(2)O(15), Ca(5)Cr(3)O(12), Ca(5)Cr(2)SiO(12), and CaCr(2)O(7), with chromium oxidation states of +3, +4.6, +5, and +6, respectively, was detected. After the hydration process, additional chromium compounds were identified in the mortar matrix, including Ca(5)(CrO(4))(3)OH, CaCrO(4)·2H(2)O, and Al(2)(OH)(4)CrO(4), with chromium oxidation states of +4.6, +6, and +6, respectively. Additionally, some species of chromium, such as Cr(3+) from Ca(6)Al(4)Cr(2)O(15) and Cr(6+) from CaCr(2)O(7), CaCrO(4)·2H(2)O, and Al(2)(OH)(4)CrO(4), were leached during leaching tests, whereas other species remained in the mortar. The concentrations of chromium that leached from the mortar following U.S. EPA Method 1311 and EA NEN 7375:2004 leaching tests were higher than limits set by the U.S. EPA and the Environment Agency of England and Wales related to hazardous waste disposal in landfills. Thus, waste containing chromium should not be allowed to mix with raw materials in the cement manufacturing process.     

ZnO－MgO－Al_2O_3陶瓷性能研究

ＺｎＯ－ＭｇＯ－Ａｌ２Ｏ３陶瓷是一种复合烧结体，其主晶相为ＺｎＯ与ＺｎＡｌ２Ｏ４，且均以晶粒存在．ＭｇＯ能调节电阻温度系数，使之由负变为正．Ａｌ２Ｏ３能调节电阻率．慢的降温速度能提高线性及耐浪涌能量，降低电阻温度系数．     

微波烧结和常压烧结对Al2O3-ZrO2陶瓷磨损行为的影响

采用多模微波烧结系统和常压烧结，对Al2O3-ZrO2复合材料的基本性能进行了研究，提出了相关的磨损机理，与常压烧相比，微波烧结可以提高ZTA陶瓷的密度，强度和韧，使其结构均匀，耐磨性提高，常压吉样品的磨损主要是晶粒铲平，磨屑填充体内气孔形成光滑的磨损界面；而向波烧结ZTA陶瓷主要是界面晶粒剥离脱落磨损，载荷的增加使磨损量增大。     

纳米Al2O3对纳米4YSZ复相陶瓷结构和性能的影响

以纳米4YSZ和纳米Al2O3粉末为原料,对掺少量Al2O3的4YSZ无压烧结体的烧结特性、结构和性能进行了研究.掺适量的Al2O3可降低烧结温度,减缓4YSZ晶粒的长大.少量的交接渗透强化了晶界,烧结体断裂倾向于穿晶断裂,提高了烧结体硬度.     

ZnO和CaO含量对CaO-Al2O3-SiO2系泡沫微晶玻璃析晶与发泡的影响

以CaO-Al2O3-SiO2玻璃为基体,以石墨为发泡剂,制备硅灰石基泡沫微晶玻璃,研究了玻璃中引入ZnO和增加CaO含量对析晶与发泡的影响.结果表明,ZnO可降低发泡过程中假硅灰石晶相的析出量,促进玻璃粉与发泡剂混合物的烧结,降低发泡剂在较低温度下的损耗.提高CaO含量,样品结晶度增大,相同温度下玻璃的粘度增加,发泡效率降低.原料中ZnO加入量6wt%、CaO含量为18wt%的CaO-Al2O3-SiO2玻璃粉,较低温度下烧结充分,发泡剂损耗相对较少,在1000℃的发泡温度下可获得气孔率高的泡沫微晶玻璃.     

NiMn2O4热敏材料纳米粉体烧结过程研究

本文采用溶胶－凝胶法（ｓｏｌ－ｇｅｌ）制备ＮｉＭｎ２Ｏ４纳米粉体。将ＮｉＭｎ２Ｏ４纳米粉体压制成型,进行烧结。对ＮｉＭｎ２Ｏ４的米粉体烧结过程进行研究。实验结果表明：ＮｉＭｎ２Ｏ４纳米粉体的烧结温度比传统烧结方法低２００℃左右。在１１００℃以下的温度范围,烧结试样的相结构均为尖晶石结构。ＮｉＭｎ２Ｏ４纳米粉体烧结过程分为三个过程：（１）烧结前期（≤８００℃）;（２）烧结初中期（８００℃￣１０００℃     

铬掺杂对PZT-PMN陶瓷材料性能的影响

采用ＴＥＭ、ＳＥＭ、ＥＳＲ（电子自旋共振）结合常规压电性能测试手段研究了Ｃｒ_２Ｏ_３掺杂对ＰＺＴ－ＰＭＮ陶瓷的压电性能、微结构及畴态的影响．压电性能测试结果表明,当Ｃｒ_２Ｏ_３含量低于０．０６Ｗｔ％时,可使Ｋ_ｐ和Ｑ_ｍ同时提高,这说明铬掺杂同时兼具“软掺杂”与“硬掺杂”的双重特性．此外,还发现随着烧结温度的提高,材料性能“硬化”明显．ＥＳＲ谱分析表明,Ｃｒ离子主要以Ｃｒ^３＋和 Ｃｒ^５＋的方式共存,随着烧结温度的提高,它有从高价态 Ｃｒ^５＋或Ｃｒ^６＋向低价态转变的趋势,这一价态变化被认为是材料性能随烧结温度提高而“变硬”的主要原因之一．ＴＥＭ图片显示,随着掺杂的Ｃｒ_２Ｏ_３的浓度的增大,由于氧空位或受主离子与氧空位构成的缺陷复合体对畴壁的钉扎,电畴将从正规带状畴向波纹状畴转变．     

Effects of Kaolinite additions on sintering behavior and dielectric properties of CaCu3Ti4O12 ceramics

Commercial Kaolinite was employed as sintering aid to reduce the sintering temperature of CaCu₃Ti₄O₁₂ (CCTO) ceramics. The effects of Kaolinite content and sintering temperature on the densification, microstructure and dielectric properties of CCTO ceramics have been investigated. The density characterization results show that the addition of Kaolinite significantly enhanced the relative density of CCTO ceramics to about 92 %. X-ray diffraction results show CCTO ceramics with a low amount of Kaolinite exhibited perovskite-like structure, but 1.0 wt% Kaolinite additions resulted in the formation of a secondary phase, CaO–TiO₂–Al₂O₃–SiO₂ glass phase was formed and improved the dielectric constant of ceramics, which was supported by scanning electron microscopy–energy dispersive X-ray results. CCTO ceramic with 1.0 wt% Kaolinite addition possessed well temperature and frequency stability of dielectric constant. It was found that Kaolinite lowered the dielectric loss of the samples.     

Ho掺杂对Bi4-xHoxTi3O12陶瓷结构与铁电性能的影响

以Ho为掺杂元素,采用热压烧结方法制备Bi4-xHoxTi3O12陶瓷,重点研究了Ho掺杂量对其物相组成、致密度、微观结构和铁电性能的影响.首先以Bi2O3、TiO2和Ho2O3微粉为原料,利用固相反应在900℃合成出主晶相为Bi4Ti3O12的Bi4-xHoxTi3O12(x=0～0.8)粉体;然后,将合成粉体在850℃、30 MPa条件下热压烧结,当Ho掺杂量x=0～0.4得到了物相单一、整体致密(>99%)的Bi4-xHoxTi3O12陶瓷.随Ho掺杂量的增加,Bi4-xHoxTi3O12陶瓷的剩余极化强度呈现先增大后减小的趋势,主要与氧空位浓度和不同掺杂浓度引起的掺杂位置的不同有关.在Ho掺杂量x=0.4时,其剩余极化强度最大(2Pr=13.92μC/cm2),远大于未掺杂的Bi4Ti3O12陶瓷,说明适量Ho掺杂能有效改善其铁电性能.     

Preparation of slaking resistant CaO aggregate from lightweight CaCO3 with oxide addition

CaO aggregate was sintered from reagent-grade lightweight CaCO₃ powder by the addition of 0-20% (molar ratio) MgO and ZrO₂, respectively. The results showed that the CaO derived from lightweight CaCO₃ was highly sinterable and compact CaO aggregate with relative density above 96% was obtained after sintering at 1400 °C for 2 h, but further increase of compactness was restrained due to the occurrence of abnormal grain growth. The densification of the aggregate was promoted due to the behavior of oxide addition on restraining the grain growth of CaO. With increasing the amount of oxide addition, the microstructure of CaO aggregate underwent a restructuration process. Homogeneous microstructure, with well growing MgO grains occupying most of the boundary triple points of CaO grain, formed by the addition of 20% MgO. Especially when 20% ZrO₂ was added, CaZrO₃ layer formed around CaO grains. The slaking resistance of the aggregate was appreciably improved due to the promotion of densification, the formation of CaO solid solution (while MgO added) and the modification of microstructure.