95氧化铝瓷凝胶注模浆料的制备及氧阻聚的抑制

本文研究95氧化铝瓷凝胶注模成型中浆料的流变性.分析了pH值、分散剂用量、球磨时间对浆料粘度的影响.采用L_9(3~4)正交试验,制备出固相含量为58 vol;,粘度为110 mPa · s的95氧化铝瓷浆料.针对表面氧阻聚,本文通过表面改性的方法,既不增加坯体内有机物的含量,也不降低坯体的强度,使坯体表面不起皮、不剥落.结果显示:通过坯体性能参数和显微结构的比较,凝胶注模的95氧化铝瓷坯体性能均优于热压铸成型的坯体性能.     

Y2O3吸附粉对95;氧化铝热压铸瓷坯脱蜡粘粉的控制

95;氧化铝热压铸瓷坯脱蜡粘粉严重影响着产品的合格率及生产效率,本文提出了一种基于Y2O3吸附粉对95;氧化铝热压铸瓷坯脱蜡粘粉的控制方法,并与传统的基于α-Al2O3吸附粉的脱蜡方法进行了对比分析.Y2O3吸附粉脱蜡不仅彻底消除了95;氧化铝热压铸瓷坯脱蜡工艺中的表面粘粉现象,而且获得的烧成95;氧化铝陶瓷的密度、体积电阻率、断裂强度、介电击穿强度等性能均有提升,该方法具有操作简便、工艺研发周期短、成本低等优点,生产推广价值高.此外,基于脱蜡过程中的相变分析,本文讨论了粘粉的形成机制及Y2O3吸附粉控制粘粉的原理.     

烧成温度对高岭土质瓷坯体性能影响与表征

以高岭土为主要原料,少量的透闪石、熔块和钾长石为辅助原料混合制备了高岭土质瓷坯体.通过测试不同烧成温度下坯体吸水率、体积密度、线收缩率和抗折强度,以及借助X射线衍射分析(XRD)和扫描电镜(SEM)等测试表征手段探究了烧成温度对高岭土质瓷坯体的性能的影响.实验结果表明:制备的高岭土质瓷坯体中主晶相为莫来石;相比普通瓷,所制备的高岭土质瓷坯体具有较宽的成瓷温度范围170℃;当烧成温度为1340℃时,所制备的高岭土质瓷坯体的综合性能最优.     

纳米TiO2/蛋白土复合材料的制备与表征

为了解决纳米TiO2在使用过程中分散性差、难以回收等缺点,将纳米TiO2负载在酸浸蛋白土表面,提高光催化效率.以酸浸蛋白土为载体,TiCl4为前驱体,采用水解沉淀法制备了纳米TiO2/蛋白土复合材料.采用XRD、TEM等方法对复合材料性能进行了表征,并进行了复合材料的光催化降解甲醛实验研究.结果表明负载在蛋白土表面的Ti02晶型为锐钛型,晶粒粒度为5～20 nm.对甲醛降解实验研究结果表明,所制备的蛋白土负载纳米TiO2复合材料具有良好的光催化降解性能,其24h对甲醛的降解去除率可以达到90;以上.     

层状C/ZrB2-SiC复合材料素坯成型工艺的研究

采用两种不同素坯成型工艺制备层状C/ZrB2-SiC复合材料,并对其微观结构和力学性能进行研究.结果表明:高温下预压成型制备的层状ZrB2-SiC复合材料层厚均匀,界面平直,弯曲强度和断裂韧性较高,分别达到427MPa和11.3 MPa·m1/2.而室温下预压成型各层厚度不均,界面弯曲,出现界面交叉现象,弯曲强度和断裂韧性较低,分别为277 MPa和9.4 MPa·m1/2.采用素坯高温预压成型制备的层状C/ZrB2-SiC复合材料力学性能较高,主要归因于界面平直,裂纹交替通过基体层和界面层,裂纹的扩展路径变长,断裂功增加.     

微孔HAp-ZrO2生物复合材料的制备及成孔机制研究

本文主要对微孔型HAp基生物材料的制备工艺及成孔机制进行了初步研究.研究发现,经冷压成型、等静压成型后的坯体再用无压烧结可制得孔径不等的微孔型HAp-ZrO2复合材料.在成型压力、烧结温度及保温时间都相同的条件下,添加剂与纳米氧化锆含量越高复合材料的强度越低,但其最低弯曲强度也达到23MPa,大大高于已报道的多孔型材料.添加剂及纳米ZrO2的加入量是材料中孔径大小及孔隙率高低的关键因素,而成型方式、烧结温度及保温时间因素对其也有影响.     

注射成型制备氧化铝陶瓷

采用多组分粘结剂,通过注射成型制备Al2O3陶瓷.讨论了粘结剂中石蜡含量、固含量对喂料粘度及坯体性能的影响.研究了烧结温度对坯体性能及显微结构的影响.结果表明,石蜡含量为粘结剂的40wt;,喂料固含量为52vol;时,喂料粘度合适,坯体性能最好,内部显微结构均匀,抗弯强度为25 MPa,完全满足机械加工的强度要求.1560～1640℃,随着烧结温度的提高,烧结致密性提高.1600℃时,Al2O3抗弯强度最高达(422±40) MPa,致密性较好,晶粒发育较为理想,为最佳烧结温度.     

凝胶注模成型Al2O3陶瓷的显微结构及力学性能研究

以Al2O3粉为原料,TiO2+MgO为烧结助剂,琼脂糖为单体,聚丙烯酸铵为分散剂,利用凝胶注模及无压烧结工艺制备了Al2O3陶瓷.研究了琼脂糖固化机制、烧结助剂作用机理以及琼脂糖含量对Al2O3陶瓷坯体及烧结体的显微结构及力学性能的影响规律.试验结果表明,琼脂糖利用内部氢键的结合,形成三维网络状结构,将Al2O3粉原位凝固成型.TiO2+MgO烧结助剂使材料实现了液相烧结机制,有利于降低材料的烧结温度及促进致密化进程.随着琼脂糖含量增加,坯体的致密度、坯体及烧结体的抗弯强度均呈先增大后减小趋势.当琼脂糖含量为0.5wt;时,Al2O3陶瓷的抗弯强度达到最大值.     

HfO2薄膜反应磁控溅射沉积工艺的研究

采用纯铪(Hf)金属靶,在氧和氩反应气氛中进行了HfO2薄膜反应磁控溅射沉积,研究了电源功率、O2/Ar比例和工作气压对薄膜组成及薄膜沉积过程的影响.对制备的HfO2薄膜进行了退火处理,利用X射线衍射仪(GIXRD)、红外波谱仪(FT-IR)和场发射扫描电子显微镜(FE-SEM)表征了退火前后HfO2薄膜的显微结构、组织组成及红外透过性能.采用胶带测试测定了HfO2薄膜的附着性能.本研究得到了优化的沉积工艺参数.     

Mg3(Si1-xCex)2O7系复合陶瓷微波介电性能研究

采用固相反应法按式Mg3(Si1-xCex)2O7(x=0.2,0.3,0.4和0.5)制备了MgO-SiO2-CeO2系列微波介质陶瓷材料,研究了不同组分体系的相组成与结构、微观结构与微波介电性能之间的影响关系.结果显示:MgO-SiO2-CeO2体系在研究组分范围内的晶相主要由正交相的Mg2SiO4与立方相的CeO2组成;其中,当x=0.5时出现了少量的未知相;经EDS分析可知,该未知相是由Mg、Si、Ce和O元素组成的新相;随着x值的增加,体系εr和τf值在1350～1600℃烧结温度下的变化不明显,而体系的Q×f值则呈先降后升趋势.此外,尽管体系并未能确定形成RP相层状结构,但其研究结果仍对探索新型RP相微波介质材料具有借鉴作用.     

陶瓷微珠直接堆烧制备多孔莫来石陶瓷及性能研究

以高纯石英粉、氧化铝粉以及玻璃粉作为主要原料,首先通过颗粒稳定泡沫法结合离心雾化干燥装置制备得到SiO2-Al2O3陶瓷微珠,然后将其紧密堆积于坩埚中,随后经1500 ℃下直接堆积烧结1 h,利用空心微珠高温下自发泡,成功制备孔分布均匀的多孔莫来石陶瓷.研究了SiO2-Al2O3陶瓷微珠中高纯石英粉、氧化铝粉和玻璃粉组成对多孔莫来石陶瓷性能的影响.该方法简便易行,可控性强.通过该方法可制得气孔率高达85.4;,抗压强度为(3.69±0.86) MPa,低介电常数为1.70的多孔莫来石陶瓷,有望应用于透波材料领域.     

Study of color and structural changes in silver painted medieval glasses

Silver was introduced into medieval glass by an ancient painting process using different clay minerals (ochre, illitic, montmorillonitic, and kaolinitic clays). The colorimetric properties, studied by UV-Vis spectroscopy, were dependent on the clay mineral as a result of different concentration of Ag ions diffused into the glass surface. TEM results showed the well known formation of silver nanoclusters which give the yellow coloration of the glass. The obtained results showed that clay properties such as specific surface area, pore volume and iron concentration (Fe₂O₃), are important factors that affect the yellow coloration. It is also observed that Fe₂O₃ acts as an oxidant agent for silver atoms providing the Ag₂O formation. This oxide cannot diffuse into the glass structure and avoid the ion-exchanged process. After Ag ion diffusion some structural changes occur in the glass as it has been shown by Raman spectroscopy. It is observed that the diffusion process leads to depolymerization of the glass network as it is determined by analyzing the Qⁿ components of Raman spectra. Two Raman bands at 148 and 244 cm⁻¹ assigned to Ag-O bonds can be associated to the presence of Ag₂O on the glass painted surface.     

Archaeometrical analyses of glass cakes and vitreous mosaic tesserae from Messina (Sicily,Italy)

We report the results of a study performed on several glass samples recovered after the destruction caused in Messina by the earthquake of 1908, and stored in the ‘Fiore’ deposit of the Regional Museum of Messina (Italy). The samples, still lacking a reliable classification, are glass cakes, some spare mosaic tesserae, and fragments of a well-dated mosaic (Mosaico dell’Angelo, XIII–XIV century A.D.). EPMA, SEM-EDS, XRPD and XAS were employed to provide a detailed chemical, mineralogical and spectroscopic characterization of the samples. The chemical analyses of major elements show high levels of K₂O and MgO, as a result of the prevalent use of plant ashes as flux. The cakes are characterized by a large dispersion of Si, Al and Ca contents, suggesting the use of different starting raw materials. The most common crystalline phases used as opacifiers and colorants are quartz and wollastonite. Crystalline aggregates of SnO₂ are present in the gray cakes, whereas PbSnO₃ crystals are found in two green mosaic tesserae. All the red samples contain small clusters of metallic copper. On the basis of the chemical composition, it is possible to confirm that most of the samples were produced in the XIII–XIV century, while no specific conclusions were reached on the possible use of the glass cakes as raw glass materials for the production of the investigated mosaic tesserae.     

陶瓷纤维/莫来石晶须原位增强堇青石-莫来石轻质隔热材料

以蓝晶石、粘土、氧化镁粉为原料,以淀粉为造孔剂和固化剂,引入适量的硅酸铝陶瓷纤维或多晶莫来石纤维和AlF3,通过莫来石晶须在陶瓷纤维表面的原位形成,制备了具有陶瓷纤维/莫来石晶须互锁结构的堇青石-莫来石轻质隔热材料.研究了陶瓷纤维在AlF3的作用下对材料显微结构观察、常温力学性能和导热系数的影响.研究表明:在AlF3的作用下,莫来石晶须在硅酸铝纤维表面垂直生长,部分穿插在发育良好的堇青石晶粒中;这种具有陶瓷纤维/莫来石晶须互锁结构的的陶瓷材料,其力学性能得以提高并降低了材料的导热系数.     

商洛钒尾矿烧制轻质高强陶粒的研究

采用80wt;商洛钒尾矿为主要原料,加入钾长石、粘土为辅助原料,以SiC为发泡剂,制备性能优异的轻质高强陶瓷颗粒.采用单因素变量分析法研究钒尾矿含量、SiC添加量、烧成温度和保温时间对陶粒结构及性能的影响.研究结果表明:随着发泡剂SiC含量的增加、烧成温度的提高和保温时间的延长,陶粒的堆积密度和筒压强度均降低,吸水率均升高.最终加入2wt;SiC为发泡剂,在1125℃下保温30min制得堆积密度631kg/m3,筒压强度9.1MPa,吸水率3.1;的轻质高强陶瓷颗粒.     

Investigations on glass-to-mold sticking in the hot forming process

The sticking behavior of various mold materials and coatings for hot glass melt forming processes, like, e.g. glass container manufacturing, was investigated using a new testing procedure. The mold material specimens under test were subjected to frequent contact with hot viscous glass gobs in a pressing process with presetting well defined non-isothermal pressing parameters to simulate industrial working conditions. Three different glass compositions were used in this investigation, soda-lime silicate glass, lead crystal glass, and borosilicate glass. The sticking characteristics of the tested mold materials and coatings were described by two quantities, a ‘lower’ and an ‘upper’ sticking temperature, which are specific for each mold material and type of glass in the non-isothermal pressing process. The ‘lower’ sticking temperatures of uncoated mold materials were found to depend monotonically on the thermal effusivity (heat penetration coefficient) of the bulk mold materials. All of the coating materials applied to various substrate mold materials were found to reduce the ‘lower’ sticking temperature as compared to the uncoated materials. Most of the coating materials were found to reduce also the ‘upper’ sticking temperature.     

Condensation of aluminosilicate gels—model system for geopolymer binders

The reaction of geopolymer binders can be subdivided into two more or less parallel reactions, (1) the dissolution of reactable silicate and aluminate monomers from the reactive solid material and (2) the condensation to an aluminosilicate gel. Due to the wide range of possible raw materials, the question arises whether the Si/Al ratio of the hardened aluminosilicate network is predominated by the Si/Al ratio of the raw materials, or a gel with preferred Si/Al ratio wants to condense. Therefore, aluminosilicate gels were synthesized with pure alkali silicate and alkali aluminate solutions. Two measurement series were started to investigate the influence of hydroxide concentration as well as the influence of Si/Al in the model system. The gels were characterized by chemical analysis, FT-IR spectroscopy, X-ray diffraction as well as ²⁹Si and ²⁷Al MAS NMR spectroscopy.     

低品位非金属矿制备多孔陶瓷及其吸音性能研究

以岩浆土、凝灰岩和玻璃粉为主要原料,以碳化硅和稻草粉分别为发泡剂和造孔剂制备多孔吸音陶瓷.结合原料热分析结果,运用单因素研究法考查了烧结温度、保温时间、造孔剂用量、发泡剂用量、样品厚度及显气孔率和孔径对多孔陶瓷材料吸音性能的影响.采用XRD和超景深显微技术对材料的晶相结构和形貌进行表征.结果表明,在烧结温度1150℃、保温时间50 min、发泡剂和造孔剂用量分别为原料质量的1.4;和6;、样品厚度30 mm时制备的材料性能最优,即在200~4000 Hz下材料平均吸音系数为0.34;此外,随着样品厚度的增加,第一吸收峰频率由高频向低频方向移动.     

The study on the phosphate glass melted by microwave irradiation

In this study, NH₄H₂PO₄, Li₂CO₃, and Ca(OH)₂ raw materials were mixed with and without adding water or pressing pressure. The three types of mixture (i.e., raw mixtures, waterish mixtures, and dense mixtures) were then subjected to microwave irradiation. The samples were characterized by various methods of analysis method. With adding water, the particles changed from irregularity into aggregation. Simultaneously, the existence of H₃PO₄ and increase in hydroxyl group of waterish mixtures is due to the decomposition of NH₄H₂PO₄, which could promote microwave absorption. In addition, dense mixtures could change into glass after microwave irradiation with increasing pressing pressure. The connection between mixtures with and without adding water or pressing pressure and degree of microwave absorption, and how they are influenced on glass formation is discussed.     

烧成工艺制度对钒尾矿基泡沫陶瓷性能的影响

采用商洛钒尾矿、钾长石和粘土为原料制备泡沫陶瓷,在确定原料配方的基础上,研究烧结温度、升温速率和保温时间对泡沫陶瓷体积密度和抗压强度的影响,确定最优烧成工艺参数,制得质量轻、强度高、导热系数低的高性能泡沫陶瓷材料.结果表明:8℃/min从室温至1000℃,再以3℃/min的升温速度烧至1135 ℃保温30 min,在此烧成工艺条件下制备的泡沫陶瓷试样的体积密度为420 kg/m3,抗压强度为3.1 MPa,导热系数为0.09 W/(m· K).