玻璃渗透氧化锆全陶瓷牙科材料的制备和表征

开发了一种适合渗透多孔四方相氧化锆的玻璃,并通过玻璃渗透工艺制备了氧化锆-玻璃全陶瓷牙科材料. 研究表明,该渗透玻璃在渗透温度下(1100~1200℃)具有合适的粘度、良好的渗透性和化学相容性,且热膨胀系数与氧化锆匹配;熔融态玻璃通过毛细管作用力填充预烧后的多孔四方相氧化锆坯体的孔隙,形成氧化锆和玻璃相互交融的致密的三维网络结构,渗透过程中没有发生氧化锆从四方相到单斜相的转变. 该氧化锆-玻璃复合材料的弯曲强度和断裂韧性分别为400 MPa和5.5 MPa×m1/2,较氧化玻璃复合材料分别提高了32%和41%.     

莫来石-尖晶石-氧化锆复合材料的合成及特征

利用非传统的方法合成氧化锆-莫来石-尖晶石基复合材料。锆英石粉、活性氧化铝和轻烧氧化镁被用来制备先质材料。压实粉末混合物在不同温度下烧制(大约在1440℃、1550℃和1600℃),烧坯获得很高的密度。它们的压缩强度随氧化锆含量和烧结温度的增加而增强,同时发现气孔率作为批料成分的一项函数发生变化。这些性能与烧坯的显微结构和相分布有关。     

粉煤灰堇青石玻璃陶瓷的抗热震性能

粉煤灰堇青石玻璃陶瓷采用处理后的武汉阳逻电厂粉煤灰为主要原料合成.X射线粉晶衍射(XRD)分析样品的主晶相为堇青石,次晶相为尖晶石.图像分析显示堇青石含量达到84.12％.电子背散射图像显示尖晶石和玻璃相均匀弥散分布在堇青石基体中,气孔分布较均匀.粉煤灰堇青石玻璃陶瓷的热膨胀系数α1为2.80×10-6B/℃(1000℃).样品经过在1200℃到室温(空气)的范围分段淬火(温度间隔为200℃)后,材料的弹性模量不但没有下降,反而略有上升,表明材料抗热震能力△T≈1 200℃.     

ZrO2-Al2TiO5复相材料的抗热冲击性能

以不同粒径的部分稳定ZrO2 (partially stabilized zirconia,PSZ)粉体为原料,采用共沉淀法包覆Al2TiO5纳米颗粒层,经高温烧结制备了高强度低膨胀的ZrO2-Al2TiO5复相材料.研究了原料粒径、Al2TiO5含量、烧成温度对复相材料的烧结性能、相组成、显微结构以及抗热冲击性能的影响.结果表明:随烧成温度的提高,PSZ各粒径样品的显气孔率呈逐步减小的规律,抗折强度呈逐步增大的趋势.随样品中纳米Al2TiO5含量的增加,单斜氧化锆到四方氧化锆的相变温度不断降低.在1 500℃烧结的、Al2TiO5含量为5%(质量分数,下同)、ZrO2(平均粒径为0.8μm)的样品,其显气孔率最小,为6.29%;抗折强度最大,为53.14MPa;室温到1100℃急冷急热冲击20次后,样品仍保持完整,仅在表面出现轻微剥落,抗热震性能明显高于其他样品.     

粉煤灰为原料的堇青石多孔陶瓷的烧结过程研究

以粉煤灰和碱式碳酸镁为主要原料,在高于1150℃温度下合成α-堇青石。优化的条件下,材料的弯曲强度高达65 MPa,虽然本身是多孔材料,但是其强度仅略低于工程陶瓷的致密化堇青石的强度标准(70 MPa),远远高于作为低密度堇青石的强度(13 MPa),热膨胀系数仅为4.21×10-6℃,可以满足苛刻的高温环境下的高强度应用。     

ZrO2-AlN复相材料的制备与性能研究

试样以部分稳定氧化锆（PSZ）和金属Al粉为原料。在N5气氛下经1600℃×4h烧结可制备出以AIN为结合相的ZrO2-AlN复相材料（ZAN）。试验研究了金属Al的氮化反应过程。以及金属Al的加入量对复相材料性能的影响。结果显示：Al粉反应生成AIN的全过程,主要由界面反应和内扩散反应交替完成．且整个反应过程应为扩散机制控制。随金属Al粉引入量的增加、ZAN试样的热膨胀系数减小,抗折强度增大,抗热震性及抗氧化性提高。ZAN-3试样的综合性能优良,其常温抗折强度为73．61MPa,热膨胀系数为6．06×10^-6/℃。室温～1100℃水冷残余抗折强度为4．64MPa。     

不同成分对白榴石合成及性能的影响

采用熔体冷却析晶法制备了白榴石。利用X射线衍射分析、扫描电镜、热膨胀系数测试、抗折强度测试研究了不同的成分及析晶温度对白榴石析晶、热膨胀系数及其对牙科材料增强作用的影响。结果表明,当化学成分接近白榴石理论含量,Al2O3微过量,析晶温度为1100℃时,样品的析晶能力最好,热膨胀系数最高为20.13×10-6℃-1(20~500℃)。并且,白榴石掺杂可以有效提高牙科玻璃陶瓷的抗折强度和热膨胀系数,当掺杂量为50%时,材料的抗折强度提高到127.43 MPa,热膨胀系数提高到15.72×10-6℃-1。     

烧结法制备Al2TiO5材料

以α-Al2O3、钛白粉为主要原料,加入氧化镁、氧化硅、氧化锆稳定剂,采用固相烧结法,于1 500℃/2 h制备了Al2TiO5材料.进行了XRD分析、热膨胀系数测定、循环加热(冷却)5次的综合热分析测试以及激光粒度分析.研究表明,制备材料的主晶相为Al2TiO5,1300℃平均热膨胀系数为3.709 × 10-6/℃,在500～1300℃使用温度区间稳定.经过研磨制备了粒径≤10μm的Al2TiO5粉料.     

碳包纳米氧化锆粉体的制备及其晶型转变

采用溶剂共混法将氢氧化锆沉淀与液态酚醛树脂混合,制备成树脂-氢氧化锆复合体系,在埋碳气氛经500～1 000℃热处理、研磨,得到碳-氧化锆纳米复合粉体.用热重-差示扫描量热仪、X射线衍射仪、场发射扫描电子显微镜及高分辨透射电子显微镜对样品进行了表征.结果表明;在复合粉体中,一部分碳进入氧化锆晶格中使高温四方相氧化锆在室温稳定存在;另一部分游离于氧化锆周围的碳起空间位阻作用,有效地抑制了复合粉中氧化锆颗粒在烧结过程中的晶粒长大;在空气中700℃氧化除去复合粉中的碳后,氧化锆的粒径仅为20～50nm,但由氢氧化锆分解形成的氧化锆容易成团聚状态,一次粒径可达50～100 nm.     

钙掺杂对铬酸镧热膨胀系数的影响

利用固相法合成的铬酸镧粉制备铬酸镧样品。研究了钙掺杂量对铬酸镧样品热膨胀系数的影响。结果表明：当钙掺杂铬酸镧时,Ca^2＋于A位取代La^3＋,引起A位离子半径减小,晶胞参数发生变化,同时Cr^3＋变价形成Cr^4＋,引起了O^2--O^2-和Cr^3＋-O^2-键长、键角和键能相应改变,从而对铬酸镧样品的热膨胀系数和相变温度造成影响;从室温到1000℃,铬酸镧的热膨胀系数随钙掺杂量增加而增大,由正交结构向菱形结构转变的相变温度随钙掺杂量增加呈线性提高。     

热膨胀法判定建窑黑瓷烧成温度的应用研究

以热膨胀仪判定建窑黑瓷烧成温度的研究为例,综合运用多种测试方法对建窑黑瓷标本进行了系统研究,探讨如何从建窑黑瓷胎体重烧热膨胀曲线中筛选有效转折点的问题及其转折点的形成原因。研究表明:(1)建窑黑瓷胎体重烧热膨胀曲线上有三个转折点,分别为收缩转折点、膨胀转折点和急剧收缩点。其中第一个收缩转折点是判定其古代烧成温度的关键点。(2)建窑黑瓷胎体重烧热膨胀曲线上膨胀转折点和急剧收缩点的形成皆与其胎体中大量Fe_2O_3在高温下发生分解反应有关。该研究不仅为热膨胀仪测定建窑黑瓷烧成温度的应用研究提供判定依据,也将为科学认识古陶瓷胎体重烧热膨胀曲线上多个转折点的形成机理提供数据支持。     

Effect of Crystalline Leucite on Porcelain Bonding on Titanium

The effect of elimination of crystalline leucite on porcelain bonding to Ti was studied. The thermal expansion coefficient of low-fusing dental porcelain was decreased by eliminating the crystalline leucite phase. As a result, minimal thermal mismatch and better bonding between Ti and porcelain were obtained.     

大红釉性能的测试和研究

采用高温型硫硒化镉包裹色料^[1]成功地开发出了性能优良，呈色鲜艳且高温稳定的大红釉艺术瓷系列；采用色度色差仪和图像分析仪对瓷釉的颜色和表面形貌进行了观察和测定；采用热膨胀仪测定了瓷釉的热膨胀系数；采用观察显微镜测定了釉层的厚度。结果表明，大红釉的性能优良，呈色鲜艳。     

金属基烤瓷牙冠残余应力产生的原因与控制方法

详细分析了金属基烤瓷牙冠残余应力产生的原因，认为金属与烤瓷热膨胀系数不匹配，制备工艺不合理以及金属与烤瓷结合欠佳等是产生残余应力和导致烤瓷破坏的主要原因，并对如何控制残余应力，关少烤瓷开裂和肃落进行了论述。     

Quantitative X-ray Diffraction Determination of Leucite Thermal instability in Dental Porcelain

Alterations in the leucite content of dental porcelain during thermal treatments required for fabrication of dental restorations produce proportional changes in the thermal expansion coefficient. Such thermal expansion changes can create a thermal expansion mismatch with the metal to which it is fused and can result in the fracture of the porcelain during fabrication. The purpose of this study was to determine whether changes in the leucite content of a dental porcelain resulting from thermal treatments could be detected via quantitative X-ray diffraction. The thermal treatments investigated were isothermal soaks for 0, 4, 8, and 16 min at 500° and 750°C, or multiple firings of 1, 2, 4, 8, and 16 times. Quantitative X-ray diffraction was performed on the heat-treated porcelain specimens, and the data were subjected to linear regression analysis. A significant negative correlation ( r =−0.92, p < 0.001) was found between leucite volume fraction and the number of firings. A significant positive correlation ( r = 0.88, p < 0.001) was obtained between leucite volume fraction and duration of heat soak at 750°C. No relationship was found ( r = 0.40, p = 0.127) between the leucite content and the duration of the heat soak at 500°C. Such leucite variations could be responsible for changes in porcelain—metal thermal compatibility.     

Delayed curvature and residual stresses in porcelain tiles

Most industrial porcelain tiles suffer changes in their curvature after firing: such process is known as delayed curvature. One of the hypotheses used to explain this phenomenon is based on the relaxation of residual stresses by creep. In this study two types of industrial glazed porcelain tiles have been studied. One of them displayed delayed curvature after firing, whereas the other one presented a stable curvature. The main objective was to determine if the delayed curvatures were caused by the residual stresses generated during rapid industrial cooling. Both types of existing residual stresses (thermal stresses, caused by thermal gradients inside the tile during cooling, and body–glaze fit stresses, due to the thermal expansion mismatch between body and glaze) were measured, as well as related samples properties (elastic modulus, creep behaviour, thermal expansion). The results demonstrated that the residual stresses are not the main cause of the delayed curvature phenomenon.     

添加线胀材料对瓷器坯体抗热震性的影响

以锂辉石、堇青石、钛酸铝三种线胀系数较低的材料作为添加剂,单独或复合加入到普通瓷器坯料中,研究了加入不同比例的上述材料来降低陶瓷坯料线胀系数、提高产品抗热震性的可行性。     

纳米二氧化锆增强丁腈橡胶力学性能的分子动力学模拟

采用分子动力学模拟的方法建立了纳米二氧化锆增强丁腈橡胶（NBR）复合材料的分子模型,对比分析了外部填充、原位填充以及原位填充且经过偶联化处理三种形态的二氧化锆对NBR力学性能的增强效果,从原子层面探讨了定子橡胶力学性能的内在增强机制。结果表明,相比于纯NBR,三种形态二氧化锆的引入均显著改善了NBR的力学性能。原位填充纳米二氧化锆的表面羟基与NBR形成氢键型偶极相互作用,表面活性偶联剂双-（3-三乙氧基硅烷丙基）四硫化物的加入进一步提供了与橡胶基质之间的化学桥接,从而大大提升了NBR基质的力学性能。与纯NBR体系相比,原位填充且经过偶联化处理的二氧化锆增强NBR的力学性能表现最佳,复合体系的杨氏模量、体积模量和剪切模量均提升得最多。通过界面结合能、非键合能、均方位移和扩散系数的计算,验证了纳米二氧化锆的添加改善了定子橡胶力学性能的结论。     

Influence of corundum content on integrity of porcelain after long-term exposure to thermo-mechanical fatigue environments

Ceramic insulators experience thermo-mechanical fatigue and deterioration when exposed to outdoor environments. Therefore, the constituent porcelain materials must have excellent durability. In this study, the effect of the corundum content on the microstructure of porcelain was analyzed, and its thermal and mechanical properties were determined. As the corundum content increased, the coefficient of thermal expansion decreased, which mitigated the thermal stress. In addition, the role of corundum particles in reducing the residual stress and cracks generated during the sintering process was analyzed. Tensile tests on real-field insulators confirmed that excellent integrity was maintained with an increase in the corundum content.     

Reusing sanitaryware waste products in glazed porcelain tile production

Reusing the waste products generated in ceramic manufacturing is an environmentally responsible and sustainable approach. This study aims to protect natural resources, minimise raw material costs and manage waste-generated pollution by reusing the vitrified sanitaryware waste (VSW) products from Canakkale Kalebodur Seramik San. A. S. Six sample formulations were prepared under industrial conditions and compared with a standard tile body. The results indicated that using VSW in place of feldspar results in an increased firing shrinkage and decreased bending strength, whereas using VSW in place of pegmatite results in an increased bending strength and reduced thermal expansion coefficients. The reduction in the thermal expansion coefficients is an important finding that aids in meeting the dimensional and deformation requirements of porcelain tiles and also results in a slight lightening of the tile colour. This study shows that the fired VSW products can be used in glazed porcelain tile production as a sustainable and technologically, economically and environmentally suitable approach.