白榴石的制备及其对牙科玻璃陶瓷强度的影响

采用传统的固相法合成白榴石晶体,研究了化工原料、钾长石及制备方式对合成白榴石晶体的影响,以及白榴石含量对玻璃陶瓷强度的影响.结果显示:采用化工原料合成并压制成型所得到的白榴石晶体最好;当白榴石含量不超过50%时,增加白榴石含量可明显提高玻璃陶瓷的强度;玻璃陶瓷的显微结构表明添加的白榴石可均匀分布于玻璃陶瓷的玻璃相中.     

玻璃陶瓷抛光砖的研制

以成型烧结晶化工艺制备了玻璃陶瓷抛光砖样品,主晶相为硅灰石,结构均一,物化性能优异,美观大方,工艺简单易行,技术成熟度高。成型烧结法制造玻璃陶瓷抛光砖是尾矿利用的最佳途径,也是高档建筑装饰材料的优势产品之一。     

生物凝胶玻璃陶瓷的体内外生物学性能研究

采用溶胶凝胶自蔓延法制备生物凝胶玻璃粉,采用冷等静压法压制成圆片状和圆柱状,对经过烧结处理的两种生物凝胶玻璃陶瓷样品在体外、体内环境中的生物学行为进行了研究.试验结果表明:两试样均具有很好的体外生物活性和体内组织相容性,其中,硅含量较低的试样的体外生物活性优于硅含量较高的试样;而硅含量较高的试样的组织相容性较好且具有一定的骨诱导能力.试验证明:体外试验与体内试验的结果具有一定相关性,但对体内植入试验只起到一定的指导性所用.     

磁性生物活性玻璃陶瓷的制备研究进展

磁性生物玻璃陶瓷主要指将具有磁性的元素,如铁等引入到生物玻璃陶瓷中,制备出结构和性质类似于人体组织的生物材料,其独特的功能使之成为近来新材料研究的热点.介绍了较为常见的几种磁性生物玻璃陶瓷的制备方法,如熔融煅烧法、溶胶-凝胶法、共沉淀法、双相复合法等,并对它们的特点进行了分析.     

纤维增强玻璃和陶瓷复合材料

玻璃和陶瓷复合材料都是高强度和抗脆性断裂的材料,同属高性能的新型陶瓷。生产这种材料有许多方法,其中包括往玻璃和陶瓷中掺耐火纤维、晶须和颗粒。本文要讨论的是这种材料的开发,主要谈连续纤维掺入玻璃和陶瓷材料的问题。     

孔径可控羟基磷灰石复相陶瓷中玻璃相的作用

采用颗粒直径尺寸可控的聚甲基丙烯酸甲酯作为造孔剂，以自行熔制所得的生物玻璃作为玻璃相，通过添加和调节玻璃相的用量和烧结温度制备了多孔羟基磷灰石瓷。采用电子探针对所制备的样品进行了分析，添加玻璃相明显地修复了烧结体的显微结构，减少了裂纹的尺寸，适量添加能提高多孔羟基磷灰石瓷的抗折强度。     

不同粉体粒度对二硅酸锂玻璃陶瓷热压铸前后微观结构和性能的影响

分析了不同粒度对Li2O-SiO2-K2O-Al2O3-ZrO2-P2O5系新型齿科二硅酸锂玻璃陶瓷在热压铸前后微观结构和性能的影响。分别用差热分析(DTA)、扫描电镜(SEM)和X射线衍射(XRD)分析了玻璃陶瓷的晶化温度、微观结构和物相组成。根据ISO6872标准测试材料的弯曲强度。结果显示,不同粉体粒度的玻璃陶瓷间微观形貌有明显差异;不同的粉体粒度和热压铸工艺对玻璃陶瓷的晶相组成无显著影响;不同粉体粒度的玻璃陶瓷在热压铸前后强度均有差异,热压铸后,各组弯曲强度显著提高,但是粒度的变化和强度之间无明确的相关性。结果表明,不同粒度对实验玻璃陶瓷的晶化行为和性能都有显著影响。     

生物微晶玻璃研究的现状与展望

综述了近年来国内外研究生物微晶玻璃的种类、性能和应用,以及生物微晶玻璃的发展趋势。     

热压铸法制备偏铝酸锂陶瓷薄壁管的研究

以固相反应法合成出的LiAlO2细粉作为原料,采用改进的热压铸活塞法压制出薄壁管生坯,并对脱蜡后的素坯进行微波烧结与常规烧结两种不同工艺试验的比较,从产氚机理、粉体煅烧温度、颗粒尺寸、表面活性剂种类和烧结工艺等方面展开了较为系统的研究.实验结果表明,微波烧结不仅可以有效地降低烧结温度和缩短保温时间,使晶粒细化均匀,还能提高样品的抗压强度,非常有利于提高氚固体增殖剂的最终产氚性能.     

Studies on Bi-Sr-Ca-Cu-O glasses and superconducting glass ceramics

Bi-Sr-Ca-Cu-O glasses and glass ceramics of various compositions were synthesised. The glass transition temperature varies from 396 to 422°C depending on the glass composition. The bulk glass ceramics of 4334, 4336, 2223 and 4246 compositions show superconductivity when the corresponding glass samples were heat-treated in air at 820°C for 3, 9, 12 and 24 h respectively. X-ray diffraction studies show that the superconducting phase present in all these compositions is Bi₂Sr₂Ca₁Cu₂O _x . The 4334 glass ceramic is almost a single-phase material with a preferred orientation such that thec axis is normal to the sample surface. The 2223 glass ceramic has a higherT _c (onset) than the other three compositions indicating the presence of highT _c phase (110K) also. ESR studies on the glass samples indicate the existence of Cu²⁺. The effect of heat treatment on ESR shows that the intensity of resonance decreases with increase in heat-treatment duration. This effect is more pronounced for the 4334 and 2223 compositions. The advantages of synthesizing superconducting materials by glass route are discussed in view of practical applications.     

玻璃与陶瓷高温超导体制取工艺的进展

简略介绍以玻璃与陶瓷为基体的高温超导材料的各种制取工艺。     

Studies on synthesis of calcium ferrite-based bio glass ceramics

The possibility of synthesizing a Ca-ferrite based biocompatible glass ceramic has been explored in the following two glass compositions: (i) 28Na₂O-8CaO-3P₂O₅-llFe₂O₃-50SiO₂, and (ii) 25Na₂O-8CaO-3P₂O₅-20Fe₂O₃-41SiO₂-3B₂O₃ (in weight ratio). The effect of simulated body fluid on the different glasses and glass ceramics was also investigated. While there is no direct evidence for apatite formation, the weight losses recorded and formation of a Si-rich layer at the surface appears to be an indication of onset of apatite formation. The rate of apatite formation is presumably retarded due to the presence of Al³⁺ (picked up from AL₂O₃ crucible). Ferromagnetic resonance experiments at 9.03 GHz demonstrate that these glass ceramics can possibly be used for microwave hyperthermia.     

以钙云母为主相的可切削微晶玻璃的显微结构和性能

研究根据提高云母层结合强度的构想,研制以钙云母为主相可切削微晶玻璃,以钙云母和氧化锆为主相的微晶玻璃,具有棒状,长径比大,相互交错的晶粒,强度184MPa,断裂韧性2.17MPa.m^1/2,比目前临床用VITA提高了一倍,切削性能优良,材料的断裂和加工断口主要是云母层间的解理断裂和准解理断裂,故切削面光滑,易于保证加工的精度。同时说明提高云母层间结合强度是此类材料增强的本质所在。     

可降解生物活性玻璃丝贯穿骨水泥的制备和性能研究

以硼硅酸盐玻璃丝作为增强材料,对具有较高孔隙率的骨水泥进行补强,利用SEM对骨水泥的显微结构进行了观察和分析,并对骨水泥的力学强度进行了测试。结果表明硼酸盐玻璃降解有助于环境中HAP的生成,30d后玻璃丝与骨水泥界面良好键合形成统一体,并且30d中骨水泥力学强度处于稳步增长态势。     

Structure and luminescence properties of Eu/Tb codoped oxyfluoride glass ceramics containing Sr2GdF7 nanocrystals

Eu/Tb codoped transparent oxyfluoride borosilicate glass ceramics containing Sr₂GdF₇ nanocrystals were fabricated under a reductive atmosphere and the conversion of Eu³⁺ ions to Eu²⁺ ions was observed. The Sr₂GdF₇ nanocrystals with an average size of 32 nm were homogeneously precipitated in the oxyfluoride borosilicate glass matrix, which could be evidenced by X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy-dispersive X-ray (EDX) spectroscopy. The enhancement of photoluminescence emission intensity, reduction of the relative emission intensities between ⁵D₀ → ⁷F₂ and ⁵D₀ → ⁷F₁, and long fluorescence lifetimes of Eu²⁺, Eu³⁺, and Tb³⁺ ions revealed that more rare earth ions were partitioned into the low phonon energy environment Sr₂GdF₇ nanocrystals. Under ultraviolet excitation, pure and bright white light emission was obtained in the oxyfluoride borosilicate glass ceramic, which may be a potential blue, green and red-emitting phosphor for white LEDs.     

退火工艺对SiO2-Al2 O3-MgO-F系玻璃陶瓷分相和析晶的影响

以SiO2、Al2O3、MgO和AlF3为主要原料,采用高温熔融法,在一定温度下将原料熔化,然后将熔体浇铸到预热的模具中,经不同退火工艺得到基础玻璃。将此玻璃快速加热到析晶温度,进行相同的析晶处理,得到玻璃陶瓷样品。应用TEM、SEM和XRD等技术,系统研究了退火工艺对SiO2-Al2O3-MgO-F系玻璃陶瓷分相和析晶的影响。结果表明：随着退火温度的提高,玻璃的结构逐渐得到松弛,促进了Mg^2 和F^-离子的扩散,玻璃内分相程度逐渐增大,其分相形貌由液滴状→连通状→团簇状过渡;玻璃的分相程度对高温析晶时晶体的析出形态也有一定影响,与低温退火的玻璃相比较,高温退火时析出的云母晶体更加均匀;随着退火时间的延长,析出的晶体变得越来越细小,晶体间的交错度和晶体的均匀程度逐渐增大。     

Preparation and characterization of magnesium-aluminium-silicate glass ceramics

Synthesis of machinable quality magnesium aluminium silicate (MgO-Al₂O₃-SiO₂) for fabrication of insulators/spacers usable in high voltage applications under high vacuum conditions has been carried out following two different routes i.e. (i) sintering route, and (ii) glass route. A three-stage heating schedule involving calcination, nucleation and crystallization, has been evolved for the preparation of magnesium aluminium silicate (MAS) glass ceramic with MgF₂ as a nucleating agent. The effect of sintering temperature on the density of compacted material was studied. Microstructure and machinability of samples obtained from both routes were investigated. They were also characterized for microhardness. Initial studies on material obtained by glass route reveal that these samples are superior to those obtained from sintered route in respect of their high voltage breakdown strength and outgassing behaviour. Outgassing rate of 10⁻⁹ Torr l·s⁻¹ cm⁻² and breakdown strength of 160 kV/cm were obtained. Different types of spacers, lugs, nuts and bolts have been prepared by direct machining of the indigenously developed glass ceramic.     

Long term soft tissue response to metals,ceramics and composites—a comparative histopathological evaluation

Soft tissue reaction to metals, ceramics and composites was investigated over a long period. Titanium, nitrided titanium, ruby, sapphire and carbon-carbon composite materials were used. Histological response was uniform for all materials despite their differing chemical and physical properties.     

Sol-gel preparation of silica glass

This paper is a preliminary report on the preparation of silica glass containing very low amount of hydroxyl by the sol-gel processing technique. Gels were prepared from optimized amounts of tetraethyl orthosilicate, fumed silica and water. Acids and bases in small quantities were added for catalysing hydrolysis and adjusting the pH. Dried gels were heated up to 1400°C in various atmospheres to obtain transparent silica glass of the required density and very low (<5 ppm) hydroxyl content.