română VASILICA DIMA, MIHAI EFTIMIE, ADRIAN VOLCEANOV, MARIA IONESCU
Abstract
Present paper deals with some experimental results obtained for fabrication of ceramic glazes from basaltic fibers waste and mixed with processed E-glass fibers waste, as well.
The use of basaltic fiber waste and of E-glass fiber waste in frits and glazes, taking advantage of oxide composition, energy content of glass and ecological effects, as well, may represent an efficient and effective solution from technical and economical point of view.
Keywords
vitreous glazes, basaltic fibers waste
DOREL RADU, RĂZVAN STATE
Abstract
In the field of advanced ceramics, the obtaining of some high strength ceramic materials is, nowadays, of interest for a series of practical applications. Their properties are highly correlated with their chemical composition and their processing methods.
In this article we try to highlight the main types of ceramic materials which are of interest for the targeted field. The mechanical and thermal properties of the ceramic compounds are determined by the electronic structure of their atoms and by their high degree of covalent chemical bonds.
Based on information from literature and from some own preliminary result, we have highlighted, for the Al2O3 ceramics, the interdependence between the main mechanical properties and their Al2O3 content.
Keywords
structural ceramics, correlation between properties and composition, ceramics with high mechanical strenght
CORNELIA PĂCURARIU, RADU LAZĂU, IOAN LAZĂU
Abstract
Decorative aventurine glazes with Fe2O3 content have been synthesized. The crystallization of hematite in the synthesized glazes has been studied in non-isothermal conditions using DTA technique. The apparent activation energies of the crystallization processes were calculated using the Kissinger method. The influence of CaF2 and LiF addition on the activation energy of the crystallization process has also been investigated. The hematite presence in the samples has been confirmed by XRD analysis. The prepared glazes ensure a strong decorative effect and are suitable for faience and terracotta products.
Keywords
crystallization kinetics, aventurine glaze, thermal analysis, ceramics
ANAMARIA MIHĂILĂ, MARCEL BENEA
Abstract
Cârţa Cistercian Monastery was first attested at the beginning of the XIIIth century and is considered to be the first early gothic monument in Transylvania. It is located on the left side of the river Olt, between Sibiu and Făgăraş cities. The raw materials used at the construction of the monument are Miocene sandstones - litharenites with carbonate cement and bioclasts. The study focuses on the western portal of the monastery and the geminate window from the former chapter hall, on which we performed the mapping of the sandstone blocks. The paper presents the petrographic characteristics of the sandstones after detailed study on the polarised microscope: sorting degree, medium grain size and mineralogical composition, the latter one correlated also with XRD-analysis
Keywords
Building stones, Cârţa Cistercian Monastery, Sandstones, Miocene (Sarmatian).
BOGDAN ALEXANDRU SAVA, LUCICA BOROICA, MIHAI SAVA, MIHAI ELIŞA
Abstract
The present work investigates vitreous fertilizers for agricultural purposes. The studied compositions belong to K2O – MgO – P2O5 ternary system. The samples were investigated by IR and Raman spectroscopy, showing vibrations specific to P-O-P, PO32-, PO2 and P = O bonds. In the case of AG.5 sample, IR peaks are shifted, indicating that nitrogen replaces oxygen in a great extent that modifies the vitreous phosphate network. XRD plots revealed specific shapes for glassy state both for un-nitrided and nitrided samples. SEM investigations on powders show more homogeneous darker phases in the case of AG 5 sample comparatively to AG 2 series.
Keywords
phosphate glass, fertilizers, XRD, IR and Raman spectroscopy, SEM