Crystalline Glazes Research Articles

Impact of Zinc Oxide on the Structure and Surface Properties of Magnesium–Potassium Glass–Crystalline Glazes

Impact of Zinc Oxide on the Structure and Surface Properties of Magnesium–Potassium Glass–Crystalline Glazes

The Novel Crystalline Glaze for Decoration of Ceramic Pottery

The ceramic glaze is a glass layer with an amorphous structure. Crystalline glazes are special glazes used to decorate ceramic products. It is based on the research results, the authors proposed a novel crystalline glaze from titanium frit (denoted by FV090/540) for pottery and ceramics with the heating temperature at 1200°C. The heating temperature for the crystallization of glaze was determined by differential thermal analysis (DTA). This study aimed to synthesis willemite crystals (Zn2SiO4) in pottery and ceramics. These crystals were detected and identified using X–ray diffraction (XRD), optical microscope (OM), and scanning electron microscope (SEM). The chemical composition of the samples was analyzed by X-ray fluorescence (XRF). From the results of experiments, the authors carried out decorating on industrial ceramic pottery products using this novel crystalline glaze and adjusted the required technological parameters.

EFFECT OF DIFFERENT METAL OXIDES ON VICKERS HARDNESS OF THE FRIT BASED CRYSTALLINE GLAZES

Frit based glaze is a thin glassy surface coating which gives technical and aesthetic value to the ceramic product after firing. Crystalline glazes are one of the most important type of artistic glazes formed through a controlled crystallization of glass during a special heat treatment. Crystals are visible to the naked eye and the product can have only a few single crystals on the surface or the entire surface can be coated with crystals. The preferred clay substrate for crystalline glazes is porcelain and in some cases may be used for the macrocrystallines. Usage of these types of glazes as porcelain tile coatings is an alternative choice for relevant ceramic industry and these glazes strongly enhance the visual quality of the final products. When designing crystalline glazes for porcelain tiles; besides the chemical composition, mechanical properties such as hardness is also an important factor. Within the scope of experimental studies, frit based crystalline glazes which consist of different nucleating agents such as MnO, Fe 2 O 3 , NiO, CoO, CuO and Cr 2 O 3 were applied on the raw porcelain bodies and then subjected to a special heat treatment cycle. The aim of this study was to investigate the effect of different metal oxides on crystallization capacity of newly developed fritted glaze compositions and Vickers hardness of the final products. Micro hardness of the glazes was measured with Vickers hardness test method. Characterization of crystalline glazes was done by x-ray diffraction (XRD) technique.

Reduction of maturation point in crystalline glaze through frit addition

This study aims to systematically investigate the effect of frit addition into crystalline glaze on the maturation point decrease. The samples were based on a general formula: (x)[Frit] + (1 − x)[Base glaze]; x = 0, 0.2, 0.4, 0.6, 0.8, and 1.0 (by weight fraction). In depth, melting behavior coupled with microstructural alterations was examined by various characterization techniques to gain sufficient technical knowledge and bring about the science behind crystalline glazes. Between 1125 and 1200 °C, crystallographic changes took place, resulting in an amorphous or non-crystalline structure as evident by a small XRD halo in the 20–35° 2θ range which is typical for silicate glass structure as further confirmed by infrared spectroscopy. Raman broad peaks could be deconvoluted to extract information on the mean number of non-bridging oxygen. Increasing frit amount resulted in an increase in the degree of non-oxygen bridging which could be associated with the pivotal role of the frit as a network modifier in the glass structure. The non-fritted glaze started to sinter at approximately 1091 °C and finally reached its half-sphere point at 1200 °C. Increasing the frit to 20 wt % resulted in a drastic decrease in the sintering point down to 994 °C with a half-sphere point lying in the 1175 °C range. If considering the half-sphere point as a crude estimation of the onset of maturation, adding frit by 20 wt % could effectively lower the melting point by 25 °C whereas a higher amount of frit (40 wt %) suggested the glaze to be matured at as low as 1005 °C. Although the lowest maturation starting point could be lowered to 900 °C for the sample with 100 wt % frit amount, such composition might not be appropriate for the current study on crystalline glaze as the fraction of ZnO to the total glaze body might not be sufficient enough for crystallization of willemite (Zn2SiO4) phase.

Crystallization Behaviour of Willemite Crystalline Glazes in Presence of NiO, TiO2 and Fe2O3

Crystalline glazes based on the willemite crystals (Zn2SiO4) were prepared in presence of nickel oxide, titanium oxide and iron oxide by two step heating process, i.e. glaze firing at 1200°C and crystallization above differential thermal analysis crystallization peak temperature. The mechanism of crystallization of the glazes was determined. The result showed that titanium and iron oxides induced a bulk crystallization mechanism in the glaze while in the presence of nickel oxide crystallization of willemite was initiated from the surface layer. Willemite got crystallized randomly as spherulites in the nickel bearing glazes when it was applied on a horizontal substrate. However, it was crystallized as grape-like clusters in the vertical surfaces.

Effect of Concentration of Iron Oxide on Crystallization Behavior in Leadless Iron Oxide Crystalline Glaze

The objectives of this study were to prepare leadless crystalline glazes from iron oxide by using low temperature firing (1,100°C) and to study the effect of concentration of iron oxide on the phase composition of the glaze raw materials on phase transformation in leadless iron oxide crystalline glaze. The crystalline phases were investigated by using the DTA, X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The composition of the glaze raw materials compose of nepheline syenite, colemanite, pottery stone, bentonite, ZnO, Li2CO3, SiOSubscript text2 and 10, 15 and 20%(w/w) iron oxide (Fe2O3). The glaze raw materials were ground for homogeneous mixtures by ball milling for 24h. The average particle size of the mixture was 3.86 µm. The glaze bodies were carried to firing at 1,100°C at the heating rate of 2°C/min and soaking for 0.5h. Then, the glaze bodies were cooled at the cooling rate of 1°C/min and maintained at 1,080°C for 3h and then maintained at 980°C for 1h, respectively. From the experiment results, it was found that the crystallization temperatures (Tc) of franklinite (ZnFe2O4) and anorthite (CaAl2Si2O8) depend on the concentration of iron oxide content.

Floor tile glass-ceramic glaze for improvement of the resistance to surface abrasion

The results of research aimed at the study on frits and glass-ceramic glazes for floor tiles, based on compositions located in the primary field of cordierite crystallization within the system MgO-Al2O3-SiO2, have been presented.The results comprise investigations on the frits crystallization abilities, stability of the crystallizing phase under conditions of single-stage a fast firing cycle (time below 60 minutes) depending on their chemical composition and the influence of the nucleation agents. The influence of the nucleating agents namely TiO2, ZrO2, V2O5 on phase composition of obtained crystalline glazes, mechanical parameters and microstructure, has been examined.The strength tests proved increased mechanical resistance of crystalline glazes. Obtained glazes are characterized by high microhardness in range 6∼8 GPa, as well as the increased wear resistance measured by the loss of weight below 100 mg / 55 cm2 (PN-EN ISO 10545-7). Significant increase of these parameters as compared with non-crystalline glazes, where micro-hardness values range between 5∼6 GPa and the wear resistance values range from 120 to 200 mg, has been proved.Starting glasses (frits) and glazes of the ternary system MgO-SiO2-Al2O3, were examined with use of DTA, XRD and SEM methods.

Coloration Mechanism of Hard Oxidizing Fire Iron Red Glaze (Part 1)-The Relation among Coloration, Glaze Composition and Formed Crystals-

The purpose of the present experiments is to consider the relations between coloration and crystalline phases of lime-glaze, dolomite-glaze and lime-barium-glaze containing 15 mass% ferric oxide and 15 mass% phosphate. The result of the experiments showed that red color under hard oxidizing fire only appeared in the glaze with MgO, Fe2O3 and P2O5. As a result of X-ray diffractometry, the colour of red was exposed by magnesioferrite-crystal. However, magnesioferrite-crystal can exist as whitlockite-type crystals. The hard oxidizing fire iron red glaze is one of the crystalline glazes which is colorized by magnesioferrite during cooling process from firing. In addition, magnesioferrite crystal formation is closely related to the presence of whitlockite-type crystals.

Microscopy and microanalysis of crystalline glazes.

Crystalline glazes on ceramic plates produced commercially in the UK and on ceramic pots produced commercially in Taiwan and Spain have been examined by X-ray diffraction, conventional and polarized light microscopy, and scanning electron microscopy in order to identify the crystalline phases present in the glazes and to ascertain through X-ray microanalysis the partitioning behaviour of the transition metal ions used to colour the glazes and the crystals within them. In each case examined, the macroscopic two-dimensional spherulites within the glazes clearly seen by the naked eye were found to consist of large numbers of radially orientated acicular crystals each 5 micro m or less in width embedded within the silica-rich glaze. Energy dispersive X-ray microanalysis and X-ray diffraction of these crystals identified these crystals as willemite, alpha-Zn2SiO4. The strong [001] texture of these crystals within the glaze evident from the X-ray diffraction patterns was consistent with polarized light microscopy observations of the willemite crystals. In addition to willemite, small iron-doped gahnite (ZnAl2O4) crystals were found in a honey-coloured crystalline glaze and acicular rutile (TiO2) crystals were found in the Portmeirion Pottery plates examined. Transition metal ions with a preference for tetrahedral coordination were observed to substitute for Zn2+ ions in willemite and to partition preferentially to the willemite crystals, whereas ions preferring octahedral coordination preferred to remain in the glaze.

Experiments with Decorative Glazes

Some experimental research was undertaken with the aim of producing decorative glazes on vitreous china. Glaze formula, application and firing schedule were combined in a variety of ways for the glazes achieved, from the common coloured glazes to the unusual crystalline glazes (including matt, micro and macro crystalline glazes), as well as glazes whose decorative effects are due to an intentional glaze fault (e.g. crackle glaze, snakeskin glaze). Combining the art and technique of ceramics, the aesthetic qualities of these glaze types destine them to be used for the production of special ceramic objects, true to the notion that ...industry without art is brutality.

Development of Mica Glass‐Ceramic Glazes

The effect of iron content on crystallization of a mica glaze as coating for fast firing stoneware substrates has been investigated. Measurements by differential thermal analysis (DTA) combined with X‐ray diffraction (XRD) and scanning electron microscopy (SEM) have shown the development of preferential crystal orientation in the mica glass‐ceramic glaze. By comparison with amorphous and partly crystalline glazes, an enhancement of the mechanical properties of coatings with aligned and interlocked crystals of mica has been observed.

Decorative Zinc-Containing Crystalline Glazes for Ornamental Ceramics (A Review)

Published data on compositions and properties of zinc-containing crystalline glazes for ornamental ceramics are summarized. Current concepts of the mechanism of crystallization and spherulite formation in a glaze coating are discussed, The possibility of controlling the crystallization process and decorative properties of glazes by varying firing conditions and parameters is demonstrated. Examples of production of tinted crystalline glazes are described.

Production of iron-containing crystalline glazes

Results of production of crystalline glaze with a decorative aventurine effect are given. Synthesis of glaze was performed based on frit containing Na2O, B2O3, and SiO2 using the simplex-lattice method of experiment design. It is established that the aventurine effect is caused by hematite crystals.

Types and compositions of crystalline glazes

The data on synthesis and research of various crystalline glazes published in the literature are summarized. The types and compositions of glazes, as well as their structural specifics, firing conditions, and areas of application are described. The effect of the phase composition on the decorative properties of crystalline glazes is shown.

Modification and Characterization of Crystalline Glazes

Modification and Characterization of Crystalline Glazes

THE CONTROL OF CRYSTALLINE GLAZES*

AbstractIn this investigation there is carried out the carefully controlled heat treatment of a single crystalline glaze in which both the crystallizing and growth velocity were determined for the four types of crystal produced. It was found possible to produce crystals at any desired location by seeding; their size could be controlled by the growing time and their shape by the growing temperature. Commercial production of crystalline glazes is possible if close temperature control is maintained.

PERMANENT EXHIBIT AT SOCIETY'S EXECUTIVE OFFICES CRYSTALLINE GLAZES CONE 11 PORCELAIN

Journal of the American Ceramic SocietyVolume 10, Issue 1 p. 33-33 PERMANENT EXHIBIT AT SOCIETY'S EXECUTIVE OFFICES CRYSTALLINE GLAZES CONE 11 PORCELAIN First published: January 1927 https://doi.org/10.1111/j.1151-2916.1927.tb17976.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume10, Issue1January 1927Pages 33-33 RelatedInformation