CLASSIFICATION OF ARTISTIC GLAZED CERAMICS OF DERBENT OF THE END VIII-X CENTURIES. (on the example of materials from excavations XXVII and XXXIII)

The article is devoted to the classification analysis of the glazed ceramics of Derbent, originating from the materials of archaeological excavations (excavations XXVII and XXXIII), carried out in 2014-2015. in the city. The chronological framework of the study was presumably determined by the end of the VIII-X centuries. The relevance of the topic is characterized by the importance of studying the glazed ceramics of Derbent as a source of a large set of information (historical, cultural and socio-economic interactions of Derbent with a wide range of countries of the Near and Far Abroad).Typology of glazed ceramics in Derbent at the end of the 8th-10th centuries is considered in the article on the basis of modern methodological developments based on three main approaches to the study of any ceramics: the study of technology together with the morphology and decor of the dishes. All investigated ceramics, consisting of fragments of rims, bodies, bases and handles of vessels, are included in one large Section - Household ceramics. This section includes three sections, which are based on the analysis of the clay color of the shard (red clay, brown clay, beige clay ceramics), which determines the technology for the production of dishes. Based on the presence or absence of engobe on ceramics, two subsections are allocated in each department. The next division is the groups that are formed according to the degree of transparency of the opaque glaze. There are three of them: ceramics with transparent, translucent, opaque (dull) glaze. Within some groups, four subgroups are additionally distinguished, determined by the color of the glaze. According to the peculiarities of the additional decor, the types (overglaze, underglaze ornament) and subtypes (painting, engraving, combination of painting with engraving, relief ornament) of ceramics are distinguished. Thus, the characteristics of the glazed ceramics of Derbent from these excavations include: Section, department, sub-department, group, subgroup, type, subtype.

Mechanical Properties of Nano-Crystalline Glaze for Wall Tiles Prepared by Controlling TiO2 Nucleating Agents

In this paper, TiO2 is substituted as a nucleating agent in opaque glaze to produce nano-crystalline glaze with high hardness. The crystallization mechanism of glaze was calculated by non-isothermal thermal analysis by Differential Thermal Analysis (DTA), and the glaze was heat treated at the crystallization temperature (Tp). In the case of glaze (88G20T), in which TiO2 was substituted by 20 wt% showed surface crystallization behaviors because the Avrami constant (n) was 1.18 and the activation energy (E) values were 747.0 kJ/mol at the crystallization temperature (Tp2). The microstructure of the glazes without heat-treatment showed that phase separation transferred from spinodal to nucleation-growth as TiO2 substitution increased. The size of droplets was nano-sized, below 100 nm. The glazes heated at the crystallization temperature (Tp) and crystal size of several hundred nm to several μm was observed. The surface hardness of the crystalline glaze showed a high hardness of 6.74 GPa and the degree of crystallization was 47.5% at 80G20T after heat treatment at Tp2 (1207 °C).

Non-Emulsifiers Multi-Liquid-Crystallized-Phase Opalescence Glaze

A multiphase opaque glaze with opalescent color was prepared in a basic composition glaze system with some phase separation agent. Effects of the B2O3/P2O5 ratio on the opacifying power and microstructure of the glaze, and opalescent mechanism were studied with scanning electron microscope (SEM), X-ray diffraction (XRD) and colorimeter. The results indicate that the droplets of the liquid phase separation and the crystals precipitated out in the glaze enhance the refraction and the scattering to light, resulting in glaze opacifying. With the mol ratio of B2O3/P2O5 as 1:2 in the selected composition and fired at 1200oC, the glaze possessed the highest whiteness. It is testified that a function transformation existed in glaze, which results in a multiphase coexistence, together with the size, content, contribution of the droplets and crystals have great influence not only on the opacity and the whiteness, but also on the bright and jade likeness of the glaze. The mathematical relation of opacity intensity and the characteristics of the particles in the glaze were also established based on the related analysis.