THE CONTROL OF GLAZE-FIT BY MEANS OF TENSILE TEST SPECIMENS1

The selection of a suitable glaze for a particular body by usual inspection of a field of glaze trials is not sufficiently precise, and gives no indication of slow crazing tendencies. A new method of selecting glazes depends on the effect of a glaze on the strength of a porcelain tensile test specimen. The best fitting glazes increase the strength while poorer ones decrease it. Glazes which craze weaken the specimens very markedly. Results obtained with various glazes on one fire porcelain are given.     

Characterization of transparent glaze for single-crystalline anorthite porcelain

The objective of this work was to design a transparent glaze for matching single-crystalline anorthite porcelain. Excessive amounts of quartz were used in glaze to improve surface hardness. Technological properties including hardness and thermal shock resistance were investigated. X-ray diffraction (XRD) and scanning electron microscopy (SEM) studies were also carried out to analyze the microstructure. The phases found in glaze were aluminosilicate glass, quartz and cristobalite crystals. The Vickers hardness of the transparent glaze was about 2.48 GPa, which was much higher than that of commercial soft glaze and was close to hard porcelain glaze due to forming dispersed crystal particles (quartz and cristobalite) in the glass matrix. Moreover, the thermal expansion coefficient of the glaze was slightly lower than that of porcelain body which was easy to produce compressive stress in glaze surface to increase the strength of porcelain. And no cracks were observed on glaze surface after heat exchange three times from 220 °C to 25 °C, presenting excellent thermal shock resistance.     

THE FIELD OF PORCELAIN GLAZES MATURING BETWEEN CONES 17 AND 201

Field Covered .—A typical porcelain glaze formula: was used. The RO was held constant, the Al₂O₃ was varied between 0.8 and 1.6 equivalents, and the SiO₂ between 6 and 16 equivalents. Firing Test.— the galzes were applied to green porcelain dises and fired to cone 173/4 down, and cones, 18, 19, and 20 down in commercial kilns. Representation of Results.—The glazes are plotted according to batch weights and empirical formula. The diagrams show the location of the best glazes at each temperature better than would statements of limits. Best Compositions.—Under conditions similar to those used, the best glazes for temperatures between cones 17 and 20 have the following range of composition:      

汝官瓷和钧官瓷的主成分鉴别

为了解多种釉色汝官瓷和钧官瓷的原料来源、成分和分类关系,正确鉴别两窑瓷器,选取汝官瓷样品34个、钧官瓷样品50个,由质子激发X射线荧光分析测定了样品的化学组分.将所有样品的7种主成分数据进行统计分析,得到以下分析结果:汝官瓷胎的Al2O3平均含量明显高于钧官瓷胎的,而CaO,TiO2的平均含量比钧官瓷胎的略高;汝官瓷胎的SiO2,Fe2O3,K2O平均含量明显低于钧官瓷胎的,而MnO平均含量比钧官瓷胎的稍低.汝官瓷釉的Al2O3,CaO平均含量明显高于钧官瓷釉的,而K2O,MnO的平均含量比钧官瓷釉的略高;汝官瓷釉的SiO2平均含量明显低于钧官瓷釉的,而TiO2,Fe2O3平均含量比钧官瓷釉的稍低,即汝官瓷釉和钧官瓷釉的主成分平均值是不相同的.模糊聚类分析表明:多数汝官瓷胎、钧官瓷胎样品的原料产地和成分接近但有所不同,汝官瓷釉和钧官瓷釉的原料产地和配方则明显不同.从主量化学组成上可以较好的区分汝官瓷釉和钧官瓷釉样品.     

清凉寺窑汝瓷和张公巷窑青瓷釉的起源关系

为了探讨宝丰清凉寺窑汝瓷与汝州张公巷窑青瓷釉之间的关系,选取清凉寺窑汝官瓷釉样品31个,汝民瓷釉样品4个和张公巷窑青瓷釉样品32个,用中子活化分析(neutron activation analysis,NAA)测定每个样品中的24种元素的含量,并将NAA数据进行主成分分析及等级聚类分析.结果表明:常见着色元素Fe和Co汝官瓷釉的含量显著高于张公巷窑青瓷釉样品;汝官瓷釉料配方比较稳定,原料来源集中;汝民瓷釉料产地分散,且与汝官瓷釉料配方明显不同;张公巷窑青瓷釉料比较分散,但大部分样品与汝官瓷关系较近.由此,可以推断清凉寺窑与张公巷窑之间存在一定的联系.     

PARTICLE-SIZE DISTRIBUTION OF GLAZES*

The particle-size distributions of experimental and commercial stains and glazes and glaze materials were determined by using the Andreasen pipette method. The variation in particle size of two porcelain glazes, raw and fritted, was correlated with the glaze working properties and certain physical properties of the glaze film, such as fluidity, microtexture, scratch-hardness, and glaze stress. The relation of grinding efficiency to length of milling time and different ball size was studied for these two glazes and also for a stain, and the color imparted by the stain at different grain sizes was noted.     

A novel low-clay translucent whiteware based on anorthite

This study was carried out to characterize the properties of a novel low-clay translucent whiteware suitable for daily use. The low-clay whiteware is produced from coarsely and finely milled prefired materials of the same composition plus a small amount of clay. It consists of anorthite (CaO·Al₂O₃·2SiO₂) and mullite (3Al₂O₃·2SiO₂) crystalline phases and a glassy phase with high crystalline to glassy phase ratio. The development of needle shaped long mullite crystals that were forming three dimensional interlocking network had significant effect on the elimination of pyroplastic deformation during glaze firing. Typical flexural strength and fracture toughness values were ∼110 MPa and ∼1.85 MPam^1/2, respectively. The low-clay whiteware had relatively low (4.6 × 10⁻⁶/°C) thermal expansion coefficient which made possible to glaze the whiteware with a typical hard porcelain glaze. A continuous interface layer was produced between the whiteware and the glaze and no crack was present through layer because of expansion mismatch.     

EARTHENWARE BODIES AND GLAZES1

Effect of body composition on crazing .—-Six bodies of each of 2 standard clay compositions were prepared with variable clay and flint content and after biscuiting at cone 8 were glazed with 21 earthenware glazes and glost fired at cones 4 and 6. The results indicated that the variability of the silica content of clays would not be great enough to produce crazing in a well-balanced glaze. Effect of proportion and composition of frit .—-A standard whiteware glaze was compounded in 6 different ways and several other glazes in 2 ways. It was found that the method of compounding had no effect on crazing but it affected the gloss and fusibility. Increase in the percentage of material fritted increased the gloss and fusibility. With the same percentage of frit the best glost and highest fusibility were obtained when the flint and part of the clay were included in the frit. Effect of some variations in glaze composition .—-Substitution of CaO by Na₂O, pound for pound, as well as direct addition of Na₂O, increased crazing, improved gloss and increased the fusibility. Direct addition of feldspar increased crazing slightly and diminished gloss, but did not noticeably affect the fusibility. Substitution of 1½1/2 parts of feldspar for one part of flint to maintain the same fusibility increased crazing and diminished gloss. Direct addition of CaO improved gloss, increased fusibility and slightly reduced crazing.     

Potential fingerprints for the usage of botanic ash in the glaze recipes of the Jizhou tea bowl

A glaze slip made from a mixture of porcelain clay and flux was melted at high temperatures to form an amorphous glaze layer on a ceramic body. All information about the raw materials and recipes of the glaze was lost in this process, leading to difficulties in the reconstruction of the ceramic-making process performed in ancient China. Herein, the refiring experiment was performed and the thermal dilatometer (DIL), X-ray diffractometer (XRD), X-ray fluorescence (XRF) and field emission scanning electron microscope (SEM) were utilized to investigate the crystallization behavior in the glazes of an underfired Jizhou tea bowl. The results showed that diopside, fluorapatite, and anorthite crystallized from the heterogeneous glaze slip, induced by the inhomogeneity of the raw materials and the incomplete mixing process, during the firing process in the glazes of the Jizhou tea bowl. All these crystals melted with increasing temperature, indicating the importance of the underfired samples in reconstructing the ancient ceramic-making technique. Diopside and fluorapatite could be potential fingerprints to identify the usage of botanic ash in the glaze recipes.     

Anorthite-based transparent glass-ceramic glaze for ceramic tiles: Preparation and crystallization mechanism

A series of high hardness anorthite-based transparent glass-ceramic glaze was successfully developed for ceramic tiles. These glazes were prepared by mixing a high-calcium frit (denoted as HCa) that can crystallize anorthite with other fluxes. The effect of HCa content on the crystalline phase, microstructure and properties of the glaze was studied. In addition, the phase transformation, microstructure evolution and crystallization kinetics of anorthite from frit glaze were investigated in detail. The results revealed that when the HCa content was 45–55 wt%, the glazes had excellent transparency with a hardness of 6.4–7.3 GPa, which was higher than conventional glazes. The XRD and SEM tests showed the crystallization of single-phase lamellar-shaped anorthite crystals up to 20–40 μm in length. Anorthite was found to crystallize directly from the frit glaze at 850 °C. The laminated anorthite was composed of thinner lamellae, and cracks were observed inside the large crystals. The activation energy of anorthite crystallization was about 420 kJ/mol, and the Avrami index (n) was 2.03?2.36. The n value indicates that the crystal is grown in two dimensions, which explains the formation of lamellar-shaped anorthite in SEM.     

A GRAPHICAL REPRESENTATION OF THE MOLECULAR FORMULAS OF CERAMIC GLAZES1

A chart representing average glaze composition, including lead, fritted, Bristol, and porcelain glazes, as plotted against temperature is presented as a means for teaching glaze compositions and for getting a broad view of the constituents of glazes and their variation with temperature. The chart covers the range from cones 015 to 18.     

Firing process and colouring mechanism of black glaze and brown glaze porcelains from the Yuan and Ming dynasties from the Qingliang Temple kiln in Baofeng,Henan, China

Black glaze and brown glaze porcelains were an important part of ancient Chinese iron-based high temperature glazes. The excavation of black glaze and brown glaze porcelains from the Yuan and Ming dynasties at the Qingliang Temple kiln site in Baofeng, Henan, China, in 2014, enriched the firing history of this kiln site and history of Chinese ceramics. In this study, black glaze and brown glaze porcelain samples from the Qingliang Temple kiln site from the Yuan and Ming dynasties were selected and analysed via optical microscopy, laser Raman spectroscopy, focused ion beam scanning electron microscopy combined with EDS and energy dispersive X-ray fluorescence to determine their microscopic morphology, microzone composition, microstructure and chemical composition. Moreover, the main wavelength range of the brown glaze porcelain samples were measured by UV–Vis–NIR spectrophotometer systems. The main conclusions of this study are as follows. The brown glaze porcelain from the Yuan and Ming dynasties at the Qingliang Temple kiln site has two different colour layers, with the surface is brown and the bottom is black. The presence of a glass phase and α-Fe₂O₃ phase in the black glaze porcelain samples, and a rare ε-Fe₂O₃ phase in the brown glaze porcelain samples. The brown colour was a result of ε-Fe₂O₃ precipitation, whilst the black base layer also enhanced the brown-colouring effect. Different glaze formulations were used for brown glazed porcelain, some of which were similar to those used for black glaze porcelain and derived from the transformation of black glaze porcelain through different firing atmospheres and cooling rates. Although the formula of the brown glaze porcelain samples exhibited differences, the main wavelength difference was not large, was within the 645–682 nm range and belonged to the visible red region.     

The thermal and microstructural behavior of a R2O–RO–(ZnO)–Al2O3–(TiO2)–SiO2 based macro-crystalline raw glaze system

Macro-crystalline glazes containing significantly large crystals visible to the naked eye are a type of artistic glaze with a decorative and esthetic performance. The use of raw glaze compositions is a cost effective alternative for these types of crystal glazes. In the present study, R₂O–RO–(ZnO)–Al₂O₃–(TiO₂)–SiO₂-based raw glaze system was studied to produce macro-crystalline glazes for Limoges porcelain bodies. The influence of the addition of TiO₂ as a nucleating agent or major phase was evaluated in zinc-based glazes as well as ZnO-free ones. Designed glaze compositions were fired according to a special heat treatment cycle and characterized in terms of thermal and microstructural behavior using a digital microscope, differential thermal analyses, hot stage microscopy, X-ray diffraction, a scanning electron microscope, and energy-dispersive X-ray spectroscopy.     

Colouring mechanism and firing process of celadon from the Xiangzhou kiln in Anyang,China, from the 5th-7th century

The Xiangzhou kiln was the largest celadon kiln site in northern China from the Northern and Southern Dynasties to the Sui Dynasty (5th-7th centuries). In order to investigate the colouring mechanisms and firing process of two types of celadon (yellow-green and earthen-yellow glazes) from the Xiangzhou kiln, samples were tested and analysed using OM, ED-XRF, TD, SEM-EDS, LRS, XPS and UV-Vis-NIR. The study results show that most of the samples in the two enamels have different formulations. The celadon glaze of the Xiangzhou kiln contains a small amount of quartz, anorthite and other crystals. The yellow-green glaze is fired in a reducing atmosphere and the earthy yellow glaze is fired in an oxidising atmosphere. The colouring mechanism of the Xiangzhou kiln celadon is mainly dominated by the chemical colouring of ionic colouring and aided by structural colouring caused by the microstructure (bubbles, various crystals, fractal structures, etc.).     

THE EFFECT OF HEAT-TREATMENT AND COMPOSITION OF SEMI-PORCELAIN BODIES ON CRAZING

Limits of Investigation.—The investigation was confined to practical semi-porcelain bodies and glazes, therefore, the results may be applicable only to this branch of the whitewares industry. Effect of Thickness of Glaze.—The thicker the glaze the greater the tendency to craze. The glaze on several pieces of dinner ware may appear to the eye to be of uniform thickness, but still have sufficient variation in thickness as to show difference in crazing behavior. It being impossible to obtain a uniform thickness of glaze by hand dipping there is a need for a mechanical dipper. An improved type of biscuit kiln which will produce ware with a uniform absorption is another need. Effect of Glaze Composition.—When sufficient change was made in the composition of a typical semi-porcelain glaze to cause a marked decrease in its crazing tendency, it was at the expense of other desirable properties. Effect of Body Composition.—The addition of 10.0% to 20.0% of “Hercules” clay to a general ware body greatly decreased its tendency to craze. No other change in body composition was found feasible, for when the change was sufficient to cause a decrease in the crazing it was at the sacrifice of other essential properties. Effect of Variation in Absorption.—Contrary to the general opinion among potters, the tendency to craze was not increased by every increase in absorption. An absorption of about 7.0% to 12.0% showed the most resistance to crazing. Effect of the Time-temperature of the Gloss Burn.—Tendency to craze is decreased by increasing the maturing time-temperature portion of the gloss burn.     

Preparation and characterization of glazes from combinations of different industrial wastes

The work reported here involves the preparation and characterization of ceramic glazes made from combinations of different industrial wastes. The wastes were float glass, granite and lime shale (a raw material waste from the oil shale industry in São Mateus do Sul, state of Paraná, Brazil), which were used to replace natural raw materials in a proportion of up to 50% in weight. The compositions were formulated using the Seger method and prepared by conventional ceramic processing. The stabilized suspensions were applied in commercial wall tile and porcelain stoneware tile, which were sintered at temperatures of 1080 °C and 1150 °C, respectively, using two different heating cycle. Three compositions were developed, two of which yielded opaque glazes and one a transparent glaze. Linear thermal expansion coefficients (α) of 80.10^?7 °C^?1 to 100.10^?7 °C^?1, and glaze softening temperatures of 600–700 °C were characterized by dilatometric analysis. The glaze compositions showed chemical resistance against acid and alkaline attack after 96 h, showing a mass loss of less than 0.1% in weight. The surface hardness of the glazes determined by the Mohs scale, Vickers microhardness and abrasion resistance (PEI indices) were between 6–7, 3–3.7 GPa and 3–4, respectively. These properties are compatible with those of commercial glazes for wall tiles and porcelain stoneware ceramics.     

论当代高温色釉瓷绘作品情景交融意蕴美形象特征

当代高温色釉瓷画的意蕴美是以形象的或感性的方式显现出来,高温色釉经过火的神炼,具有＂入窑一色,出窑万色＂的这一神气现象,加上它可以与其他陶瓷装饰形式相结合,如粉彩、新彩、古彩、五彩、刻划花等,从而从形式上产生了别有韵味的意蕴美特点。陶瓷艺术作品不象其他艺术作品在创作的过程中就能看到效果,它必须经过火的神炼后才能知道创作画面的形式美感,这就包含着许多＂意义未定性＂和＂意义空白性＂。艺术家在进行创作前,一定要对材质有充分的实践活动和对材质掌握的实际能力,而这种实践活动和实际能力也只是对材质的基本理解和基本把握,但釉在高温窑的变化,会受到窑位、窑的气氛和釉的厚薄等因素的影响,产生不同的艺术效果。因此,就会产生高温色釉瓷画意蕴美的＂意义未定性＂和＂意义空白性＂。同时,不同文化背景、不同生活经历等的艺术家做同一形式的作品也会产生不同的效果,所以高温色釉瓷绘作品的意蕴美也会产生多样性。     

Chemical and microstructural comparison of the export porcelain from five different kilns excavated from Nanhai I shipwreck

Nanhai I shipwreck, a fully loaded merchant ship of the Southern Song Dynasty, once heading for the Southeast Asia, represents the prosperous international ceramic trades during that time. Recent excavation provides us with the great opportunity to investigate the export porcelain on this ship. Black Porcelain and green porcelain of Cizao kiln, white porcelain of Dehua kiln, bluish white porcelain of Jingdezhen kiln, celadon of Longquan kiln, and white porcelain of Minqing Yi kiln were analyzed chemically and morphologically by polarizing microscopy, energy dispersive X-ray fluorescence spectroscopy and scanning electron microscopy with energy dispersive spectroscopy. The chemical and microstructural features of each kind of porcelain, evidently different from each other, are discussed in detail in this paper. Among them, the Dehua white porcelain and the Jingdezhen bluish white porcelain may represent the best manufacture techniques for their purest glazes and bodies. Also, anorthite crystals are common in the calcium glazes of the Longquan celadon and the Jingdezhen bluish white porcelain. The most interesting structure among the samples observed is the structure of crystals and MgFe rich phase separation in the black glaze of Cizao porcelain, which is also different from other black glazes studied in previous research.     

浅论陶瓷铜红釉色的自然美

陶瓷铜红釉是我国著名的色釉之一，以自身的特殊语言来表现其风彩神韵－－自然美，有自己的美学追求。它的自然美依赖于原材料，工艺流程，窑火及陶瓷艺术家的运用与创新。本文从工艺条件的作用，火的艺术，自然美的艺术表现形式三大主要因素及特点出发，通过大量的例证论述陶瓷铜红釉色的自然美。     

Utilization of seashells in matte glaze preparation

In this study, the investigation of the optical properties and microstructural development of matte glaze compositions prepared with the addition of seashells was aimed. The seashells obtained from Black Sea beaches of Samsun, Turkey were characterized using XRF, XRD, FTIR, TG-DTA techniques, and heating microscope. The calcite-aragonite polymorphic transition was provided by heat treatment of seashell powders at 700°C for 1 hour and then, aragonite-based seashell powders were incorporated to matte glaze compositions up to 30 wt%. Firstly, four different types of fired body specimens (red clay, chamotte, white, and porcelain) were produced at 800ºC for 7 hour. Secondly, the prepared glazes were applied on surface of all fired bodies and then, all bodies were sintered at 1100ºC for 8 hour. Finally, coloring parameters and microstructural features of seashell added glazes were determined. The addition of seashells to glaze composition by 10 and 20 wt% resulted in higher transparency. The matte glaze was formed with increment of seashell content to 30 wt%. The more reduced fluidity of the glaze caused nonhomogenous matte appearance. As a result, it is possible to produce transparent glazes in eco-friendly and cost-effective way by addition of seashells into glaze composition in 20 wt%.