烧成制度对锆铁红颜料合成的影响

以实验为依据,探讨烧成温度、升温速度、保温时间、烧成气氛等烧成工艺条件对锆铁红颜料合成的影响,依此得出确定颜料烧成制度的基本原则。     

陶瓷制品烧成周期的调节范围与节能

陶瓷制品烧成周期有一合适的调节范围，其上下限随制品类、壁厚及升温曲线的不同而变化。若烧成周期小于调节范围下限，器壁内外温差将随烧成周期的减小而急剧增加，引起器壁内部应力的突变，造成烧成缺陷；若烧成周期大于调节范围上限，器壁内外温差几乎不再随烧成周期的增加而减小，靠延长烧成周期减少烧成缺陷将得不偿失。     

日用陶瓷烧成能耗状况与节能分析

介绍了我国日用陶瓷烧成能耗的状况,在窑型、装烧方式、烧成工艺、窑炉余热利用等方面对日用陶瓷烧成能耗进行了分析,指出了日用陶瓷烧成节能途径。     

关于陶艺烧成工艺的探索

1国内外烧成工艺探索目前状况之比较 国际上，许多陶艺家都在致力于对各种烧成方式的探索性探究，以追求作品的特色和个性。他们多结合现代化的技术手段，改良传统烧成工艺，探索新的烧成工艺，发展为现代熏烧、坑烧、乐烧、盐烧、柴烧等烧成方法，同时，在每种烧成方法中，创造性地衍生出具有个人特色的烧成工艺手段，由这些工艺手段完成的作品甚至成为他们本人创作风格的代表。个性化和多元化是烧成工艺在当代陶艺创作中的发展和应用方面突出的特征。     

降低长石釉烧成温度关键技术的研究

笔者研究了降低长石釉烧成温度的配方与工艺制度等。研究表明,通过调整氧化锌、碳酸钡、钟乳石以及锂辉石的配比,来降低长石釉的烧成温度(从原来的1 285℃降低到1 120℃)。较大地降低了长石釉的烧成温度,从而降低了烧成能耗,节约了燃料;并且增强长石釉的白度、亮度、透明度以及热震稳定性等各项理化指标;从根本上改善了长石釉从高温烧成到中温烧成的烧成制度。     

陶瓷创意烧成在当代陶艺创作中的应用

在当代陶艺创作中烧成方式可谓是起到关键性的作用,这种烧成方式相对于以往传统的烧成方式还是有较大的区别意义,我们称之为“陶瓷创意烧成”。其类别包括乐烧、坑烧、熏烧等烧成方式,这些创意的烧成方式不仅是在泥坯、烟火相互作用下所产生的视觉效果,而且还给予了烧制者无限的意外收获,这对我们在当代陶艺创作中提供了更多的偶然性。陶瓷创意烧成方式不局限于单一的,它是多元化的存在,这也是值得陶艺家去探索的一种多变烧成方式。     

明焰快速烧成窑在日用精陶生产上的应用

本文阐述明焰快速烧成机理和明焰快速烧成辊道窑在日用精陶生产上采用的烧成新工艺、新技术。     

卫生陶瓷的低温快速烧成

建筑卫生陶瓷工业是耗能行业之一。为了节约能源,保护环境,提高效率和增加效益,采用低温快速烧成是必要的。实践经验表明,在卫生陶瓷生产成本中,烧成燃料占成本高达25%;当烧成温度达到1000℃以上时,各种热传导方式同时起作用,散热增强,烧成温度每提高30～50℃,烧成单位制品的燃耗就可能提高1%～5%,烧成时间缩短1h,烧成单位制品的能耗则可能降低5%以上。现在,我国卫生陶瓷生产广泛应用现代隧道窑、梭式窑和辊道窑烧成,烧成单位制品能耗达到1100～1400Kcal/kg制品,烧成温度达到1170～1210℃,烧成周期达到9～12h的先进水平。但是,与世界先进国…     

晶体缺位理论在陶瓷工艺中应用

在陶瓷烧成时，晶体结构中产生的阳离子缺位和阴离子缺位，给予质量扩散传递有决定性影响，从而最终影响陶瓷烧成，包括在烧成过程中晶型转变，晶体生长，烧成温度，烧成速度，气孔率等等，该文在生产实际出发，将讨论缺位对氧化物陶瓷烧成过程中晶型转变，晶体生长，烧成温度，烧成速度及气孔率的影响。     

锂瓷石中温日用瓷的研制

采用江西宜丰锂瓷石取代部分其它陶瓷原料,研制出了烧成、工艺性能良好的日用瓷.该课题不仅降低了烧成温度,而且缩短了烧成时间,拓宽了烧成范围,对日用瓷行业节能降耗具有重要意义.     

Structure, energy, and structural transformations of graphene grain boundaries from atomistic simulations

Domain/grain boundaries are often introduced into graphene during chemical vapor deposition growth processes. Here, we performed a series of hybrid molecular dynamics simulations to study the structures, energies, and structural transformations of symmetric tilt grain boundaries of graphene. The grain boundary comprises an array of edge dislocations, with the dislocation density increasing upon increasing the grain boundary misorientation angle. The dislocation in the zigzag-oriented grain boundary contains an edge-sharing pentagon/heptagon defect, whereas the dislocation in the armchair-oriented grain boundary contains two paired pentagon/heptagon defects. In some grain boundaries, out-of-plane buckling exists due to the presence of dislocations. In the transition region (the region between the zigzag- and armchair-oriented grain boundaries), the grain boundary structures feature complex mixtures of both zigzag and armchair grain boundaries. We also discuss the grain boundary transformations and migrations that occur upon adding or removing carbon atoms at the grain boundaries for all of our investigated types of grain boundaries.     

Influence of grain boundary and grain size on the mechanical properties of polycrystalline ceramics: Grain-scale simulations

The Orowan-Petch relation is a famous model to describe the strength of polycrystalline ceramics covering a wide range of grain sizes. However, it becomes difficult to explain the strength trend when the grain size decreases to the sub-microscale or nanoscale. This is because some microstructural parameters (such as grain size, grain boundary fracture energy, and grain boundary defects) vary with different processing technologies, and their coupling effects on mechanical properties are still unclear. In this study, a finite element method (FEM) was applied to investigate the dependence of mechanical properties, such as strength and damage resistance, on the abovementioned microstructural parameters on example of alumina. The numerical results show that the grain boundary energy is weakly coupled with the grain size and grain boundary defects. The grain size and grain boundary are intercoupling, which affects mechanical properties. The mechanical properties could be improved by increasing the grain boundary fracture energy and decreasing the grain size and the grain boundary defect density.     

不定形耐火材料颗粒级配的优化

针对生产实际情况 ,结合紧密堆积理论 ,建立了在给定的条件下如何选取最优配比的优化模型 ,并求解最优配比。通过将所配出坯料的粒度分布和按照经验配比给出的坯料的粒度分布与紧密堆积时 (Dinger-Funk方程 )的粒度分布进行比较 ,说明按最优配比配出的坯料 ,其粒度分布与紧密堆积时的粒度分布接近程度较好     

Analysis of abnormal grain growth behavior during hot-press sintering of boron carbide

Dense boron carbide bearings with a central through hole were fabricated by hot-press sintering. When the sintering temperature was above the critical grain growth temperature, an increase in the applied pressure at 2100 °C caused a distinct abnormal grain size region. Two grain growth mechanisms were explored; normal grain growth (NGG) is controlled by a grain boundary diffusion mechanism whereas the abnormal grain growth (AGG) pattern abides by the ‘Bose–Einstein’ grain growth law.     

Effects of Nb Doping and Segregation on the Grain Boundary Plane Distribution in TiO2

Orientation imaging microscopy has been used to investigate the effects of Nb doping on the grain boundary plane distributions in TiO₂ (rutile). By comparing the grain boundary plane distribution of the undoped material with theoretical estimates of grain boundary energy anisotropy of pure rutile, it is possible to show that the frequency of grain boundary planes is inversely correlated with grain boundary energy. In the case of Nb-doped material, this inverse correlation can also be demonstrated by a comparison of grain boundary plane frequency with measurements of surface energy anisotropy. In addition, by comparing the grain boundary plane distribution of doped and undoped materials with previous measurements of Nb grain boundary segregation in TiO₂ as a function of grain boundary plane orientation, it is possible to explain the changes in grain boundary plane distribution which result from doping.     

Role of Grain Size in Strength Variability of Alumina

Relationships between grain size and strength variability in alumina were investigated. Results are presented for an Ultra-high-purity alumina with a narrow grain size distribution and an equiaxed grain morphology at three grain sizes ranging from 5 to 27 μ.m. Vickers indentations are used to introduce controlled flaws into the specimens. It is found that increasing the grain size leads to enhanced flaw tolerance owing to a rising R -curve. However, contrary to recent theoretical predictions, no reduction in strength variability is found with increasing grain size. It is proposed that increasing variability in local fracture toughness with grain size offsets any improvement in reliability. This suggests that an upper bound to the reliability of grain bridging materials may exist.     

Thermal conductivity of pressed powder compacts: tin oxide and alumina

Three aspects, which significantly reduce heat transfer through a polycrystalline material, are considered in this paper: porosity, grain boundary thermal resistance and the state of the grain–grain contacts. Tin oxide and alumina were chosen as model systems. Tin oxide, without a sintering additive, does not densify during thermal treatment but grain growth is not inhibited and consequently the microstructure can be varied. In alumina, variation of the thermal treatment conditions varies both grain size and porosity. Thermal conductivity measurements, using the laser-flash technique, reveal that the thermal resistance of a pressed powder compact is almost independent of temperature and at least a factor of 2.5 greater than a consolidated material with similar pore volume fraction and grain size. The reduced contact area of the grain–grain interfaces in the green body can explain this as demonstrated by numerical simulation. We also show that larger grain size increases the thermal conductivity of the porous ceramic.     

Microstructural Mechanics Model of Anisotropic-Thermal-Expansion-Induced Microcracking

Thermal-expansion-induced microcracking in single-phase ceramics has been simulated using a simple mechanics model based upon a regular lattice of brittle, elastic springs. Microcracks preferentially form at grain boundaries and propagate either into the bulk or along grain boundaries, depending on the toughness of the boundaries relative to the grain interiors. The present results show that anisotropic-thermal-expansion-induced microcracking can be more severe for either large or small grain size samples depending on the damage measure employed. At very small misfit strains, the large grain microstructure develops microcracks before the small grain microstructure. However, over most of the misfit strain regime examined, the total length/area of all cracks in a sample is larger when the grain size is small. This is manifested in a larger decrement of the elastic modulus in small grain size samples as compared with large grain size samples at the same misfit (Δ T ). However, large grain sizes are more detrimental with regard to fracture properties. This is because the fracture stress scales as inversely with the crack length and large grain samples exhibit larger microcracks than small grain samples. Unlike in the unconstrained samples, when a sample is constrained during a temperature excursion, the stress created by the overall thermal expansion can directly lead to fracture of the entire sample.     

Poling behaviour at the grain boundaries of ferroelectric PZT thin films investigated by electric scanning force microscopy

The poling behaviour of PZT(53/47) films was investigated separately at the grain boundaries and inside the grain volumes by ESFM. The films were prepared by sol-gel processing on Pt-metallized polycrystalline Al₂O₃, substrates and consisted of columnar grains with mean diameter of 220 nm. It was found that the polarization was decreased at simple grain boundaries in a border zone of 20 nm to 40 nm width, with up to 42% related to the grain volumes. At triple points, the polarization was decreased by the same amount in a border zone of 40 nm to 80 nm width with respect to the grain volumes. An asymmetric poling behaviour of the saturation polarization was found at the grain boundaries. The switchable polarization of the grain boundaries was determined to be 74% of that of the grain volumes. The coercive field was clearly increased at the grain boundaries.