高含量氧化铝陶瓷的掺杂-低温液相烧结

针对常规烧结制备高含量氧化铝陶瓷均存在烧成温度高的缺点,提出了以掺杂、低温液相烧结结合的方法制备高含量氧化铝陶瓷的方法,并研究了以该方法制备的95瓷微观结构与吸水率、弯曲强度。研究结果表明,掺杂-低温液相烧结的方法可在相同烧成温度下制备出比离子掺杂、低温液相烧结更致密的95瓷,且吸水率小,弯曲强度高于相同温度下采用掺杂和低温液相烧结制备的95瓷。     

“80瓷”球磨坛的研制

采用８０瓷为配方,解决了高铝瓷泥浆注浆难及烧成变形的问题,且在１３９０℃－１４２０℃低温烧成。     

低温烧成含磷酸盐高铝瓷的研究

本文对含磷酸盐高铝瓷的低温烧成进行实用性研究,从其原来的烧结温度1600℃以上降至1380—1420℃,对节能和一般厂家也能生产具有重要的实际意义,同时,指出了添加剂的作用机理。     

“80瓷”球磨坛的研制

采用８０瓷为配方，解决了高铝瓷泥浆注浆难成烧成变形的问题，且在１３９０℃－１４２０℃低温烧成。     

TiO_2对高铝瓷烧结性质的影响

本文研究了TiO_2对高铝瓷烧结性质的影响,发现添加适量TiO_2有助于高铝瓷的烧结。影响高铝瓷烧结性质的因素是气孔,裂纹和粗大晶粒。     

BaTiO3系低温烧成高介X7R电容器瓷料

介绍了BaTiO3 系低温烧成高介X7R瓷料。采用了由BaTiO3 与Nd2O3 合成的主基材料 ,添加Bi2O3 ·2TiO2 陶瓷烧结助熔剂和硼硅铅低熔玻璃 ,可适于在低于1100℃下烧成 ,且介电常数大于3200 ,对影响瓷料的各种因素进行分析研究     

高铝瓷的低温烧成

研究了平均粒径为０．３微米的氧化铝微粉对高铝瓷烧结与性能的影响。随着氧化铝原料中微粉的增多,烧结温度不断下降,但是,烧成后瓷体性质变差,性质指标的分散性增大。微粉质量占氧化铝原料在百之三十时,烧结温度可下降７０～８０℃。并保持较高的性质指标。     

高铝瓷的低温烧成

研究了平均粒径为0．3微米的氧化铝微粉对高铝瓷烧结与性能的影响。随着氧化铝原料中微粉的增多,烧结温度不断下降,但是,烧成后瓷体性质变差,性质指标的分散性增大,微粉质量占氧化铝原料在百分之三十时,烧结温度可下降70－80℃,并保持较高的性质指标。     

95Al2O3瓷烧成制度的研究

通过利用影像式烧结点仪对９５Ａｌ２Ｏ３瓷的烧成制度进行了初步研究，探讨了９５Ａｌ２Ｏ３瓷在烧结过程中的收缩变化情况及不同的烧成制度对９５Ａｌ２Ｏ３瓷显微结构的影响。研究发现，采用低温阶段快速升温、中温阶段缓慢升温、高温阶段快速升温和短时间保温的烧成制度有利于制度９５Ａｌ２Ｏ３的瓷的致密度，改善其显微结构。     

BaTiO_3——玻璃粉系瓷料低温烧结机理探讨

一、降低瓷料烧结温度的基本途径目前我国采用的铌镁铅(简称PMN)系瓷料,介电常数虽高,但成本高、对环境污染严重。我们所研制的低温烧结、Ag为电极的BaTiO_3基独石电容器瓷料,成本低、对环境污染小、性能较好而且可以大幅度降低能耗(初步估算,910℃烧成的瓷料,其     

铝矾土-伊利石-高岭土体系陶瓷材料制备工艺的研究

以生铝矾土、高岭土和伊利石为主要原料,采用传统陶瓷工艺方法,制备了铝矾土-伊利石-高岭土体系陶瓷材料。以Al2O3质量分数在60～65%范围的坯料为研究对象,研究了原料配比和坯料细度等因素与试样的烧成温度及抗弯强度的关系。利用XRD、SEM等分析手段对材料的物相组成和显微结构进行了表征。结果表明:铝矾土-伊利石-高岭土体系陶瓷材料,在1320～1360℃烧结范围内能够制备抗弯强度110～140MPa的高强度陶瓷材料;提高铝矾土的含量和原料的细度均有利于强度的提高;添加适量的滑石有助于强度的提高以及烧结温度的降低;在原料配比相同的条件下,烧结范围下限附近烧成的试样强度较高。     

Evolution of the microstructure and mechanical properties of stereolithography formed alumina cores sintered in vacuum

Stereolithography (SL) was used to form alumina ceramic cores. The effect of sintering temperature on the microstructure and mechanical properties of the alumina ceramics are investigated, which were sintered in vacuum. The results indicate that, as the sintering temperature increased the particle size of alumina slightly increased, and the interlayer spacing first decreased and then increased. The open porosity of alumina ceramics significantly decreased as the sintering temperature in vacuum increased. The flexural strength and hardness increased as the sintering temperature increased. When sintered at 1150 °C, the flexural strength was found to be 33.7 MPa, the shrinkage was 2.3 %, 2.4 %, and 5.3 % in the X, Y, and Z directions, respectively, and the open porosity was 37.9 %. These results are similar to those found from sintering at 1280 °C in air.     

稀土La2O3添加对氧化铝多孔陶瓷性能的影响

以煅烧α-Al2O3为原料,稀土氧化镧(La2O3)为添加剂,羧甲基纤维素为成型粘结剂,通过混料、困料、研磨、模压成型、高温烧结等工序制备了氧化铝多孔陶瓷,研究了烧结温度及La2O3添加量对氧化铝多孔陶瓷的线收缩率、体积密度、孔隙率、抗折强度和微观形貌的影响。结果表明:在相同烧结温度下,随稀土添加量的增加,多孔陶瓷的体积密度、线收缩率与抗折强度均降低,而孔隙率则逐渐增加。微观形貌与X衍射分析表明,稀土La2O3的加入,抑制了氧化铝颗粒间的烧结,并在高温下与氧化铝反应生成了片状晶体LaAl11O18,片状晶LaAl11O18阻碍了氧化铝晶粒的长大,进而抑制了坯体的收缩,最终使得氧化铝多孔陶瓷具有较高的孔隙率。     

高铝瓷微观结构与配方工艺关系研究

通过配方调整与工艺改变,获得两种明显不同的高铝陶瓷材料微观结构,测试比较了材料的性能,分析了材料微观结构与配方、工艺之关系。实验表明:引入添加剂或合理控制烧成制度均可改善材料微观结构,达到提高高铝材料性能的目的。     

La2O3对镁铝尖晶石透明陶瓷致密化及其性能的影响

镁铝尖晶石透明陶瓷兼具了良好的光学和力学性能,在军、民两用领域有着广泛的实际和潜在应用前景。由于其致密化速率低,在烧结过程中往往需要引入烧结助剂。稀土倍半氧化物熔点高,高温不易挥发,近些年被证实可以促进镁铝尖晶石陶瓷的致密化,但其促烧机理尚不明确。本文以高纯商业化镁铝尖晶石粉体为原料,La₂O₃为烧结助剂,采用无压预烧结合热等静压烧结,制备镁铝尖晶石透明陶瓷,通过XRD、SEM、紫外-可见分光光度计、万能试验机等测试手段对其致密化过程及其力学和光学性能进行表征和分析,研究了La₂O₃对镁铝尖晶石透明陶瓷致密化过程的影响规律和作用机制。结果表明,La₂O₃通过与尖晶石反应或固溶产生晶格畸变,增加缺陷浓度,从而起到促进致密化的作用,一定程度上降低了预烧温度和热等静压温度。对于190 MPa、1 500 ℃热等静压烧结3 h的样品,La₂O₃掺杂可以显著提高紫外区域的透过率;同时,La偏析到晶粒表面,抑制了尖晶石晶粒的生长,从而提高了样品的力学强度。掺杂0.05%(质量分数)La₂O₃样品较未掺的样品,400 nm处透过率从63%提高到81%,弯曲强度从263.7 MPa提高至319.0 MPa,断裂韧性从1.69 MPa·m^1/2提高至1.82 MPa·m^1/2。     

添加剂对高铝瓷烧结性质和力学性能的影响

研究滑石、TiO2添加剂对以CaO-Al2O3-SiO2系为基础的高铝瓷的烧结特性和力学性能的影响。研究发现：在高铝瓷中添加剂的作用机理不同于它们在纯氧化铝烧结中的,添加剂的作用大小取决于它们的表面张力。烧结中的粗大气孔、裂纹、粗大晶粒、玻璃相等形成了瓷体的断裂源,降低了强度。     

稀土Pr_6O_(11)及其氢氧化物对高铝瓷耐磨性能的影响

实验以工业氧化铝为原料,设计了3组实验,研究了不掺入稀土、掺入稀土Pr6O11、掺入稀土Pr(OH)3对高铝瓷烧结性能的影响。通过对比烧结温度、耐磨性能发现,掺入稀土Pr(OH)3的比掺入氧化物能够获得更优异的性能。     

Transient liquid phase sintering of high-purity mullite for high-temperature structural ceramics

High-purity mullite ceramics, promising engineering ceramics for high-temperature applications, were fabricated using transient liquid phase sintering to improve their high-temperature mechanical properties. Small amounts of ultrafine alumina or silica powders were uniformly mixed with the mullite precursor depending on the silica-alumina ratio of the resulting ceramics to allow for the formation of a transient liquid phase during sintering, thus, enhancing densification at the early stage of sintering and mullite formation by the reaction between additional alumina and the residual glassy phase (mullitization) at the final stage of sintering. The addition of alumina powder to the silica-rich mullite precursor resulted in a reaction between the glassy silica and alumina phases during sintering, thereby forming a mullite phase without inhibiting densification. The addition of fine silica powder to the mullite single-phase precursor led to densification with an abnormal grain growth of mullite, whereas some of the added silica remained as a glassy phase after sintering. The resulting mullite ceramics prepared using different powder compositions showed different sintering behaviors, depending on the amount of alumina added. Upon selecting an optimum process and the amount of alumina to be added, the pure mullite ceramics obtained via transient liquid phase sintering exhibited high density (approximately 99%) and excellent high-temperature flexural strength (approximately 320 MPa) at 1500 °C in air. These results clearly demonstrate that pure mullite ceramics fabricated via transient liquid phase sintering with compositions close to those of stoichiometric mullite could be a promising process for the fabrication of high-temperature structural ceramics used in an ambient atmosphere. The transient liquid phase sintering process proposed in this study could be a powerful processing tool that allows for the preparation of superior high-temperature structural ceramics used in the ambient processing atmosphere.     

Lightweight and thermally insulating aluminum borate nanofibrous porous ceramics

Aluminum borate porous ceramics are excellent candidates for high-temperature insulation applications. Current research on aluminum borate-based porous ceramics mainly focuses on porous ceramics made up of aluminum borate whiskers, whose low aspect ratio leads to a relatively dense porous structure; this results in porous ceramics with low porosity and relatively high thermal conductivity. In this study, we report the manufacturing of aluminum borate nanofibrous porous ceramics by an agar-based gel casting method using electrospun nanofibers with a high aspect ratio as the three-dimensional skeleton structure. We explored the effect of the alumina/boron oxide molar ratio on the microscopic morphology and crystal phase composition of the aluminum borate nanofibers and that of the sintering temperature on the micro and macro properties of porous ceramics based on the nanofibers. The results showed that aluminum borate nanofibers with an alumina/boron oxide molar ratio of 7:2 had the densest microscopic morphology, and the corresponding porous ceramics exhibited a higher porosity (91%) and lower thermal conductivity (0.11 W m^?1 K^?1) after sintering at 1200 °C than aluminum borate porous ceramics with aluminum borate whiskers as the skeleton. The successful synthesis of aluminum borate nanofibrous porous ceramics provides new insights into the development of high-temperature insulators.