română CRISTINA STANCU
Abstract
The aim of this paper is to present the importance of the laboratories participation in the interlaboratory comparison (ILC) scheme, using the case study called Interlaboratory Test for adhesive for ceramic tiles. At present, the ILC scheme organized by CEPROCIM is the only one addressed to the laboratories for testing adhesives for ceramic tiles.
The paper aims to present, by using several case studies, the influence of continuous participation at the ILC scheme on the performance improvement of the participants, affecting also the coefficient of variation, as well as the influence brought by the joining of new participants. The case studies represent both accredited laboratories according to EN ISO/IEC 17025 and non-accredited laboratories whose performance (z-score) were assessed during their participation of the all 12 editions of the Interlaboratory Test for adhesive for ceramic tiles.
Keywords
Interlaboratory comparison scheme, adhesive for ceramic tiles, initial adhesion strength, tensile adhesion strength after water immersion, open-time, z-score
GHEORGHE DOBRA, SORIN ILIEV, LUCIAN COTEȚ, ALINA BOIANGIU, ILEANA MOHANU, NICOLETA FLORENTINA CÎRSTEA
Abstract
In this paper the possibility of obtaining porous ceramics by using of two commercial sorts of aluminum hydroxide with different fineness (from Vimetco Alum SA Tulcea Romania) was investigated. Proposed method for obtaining a such ceramics is based on a very low-pressing (30kN) of powder mixtures, followed by a thermal treatment at 1550oC. The effect of aluminum hydroxide finesses on the apparent porosity and density, compressive strength and thermal expansion coefficient of the ceramics obtained was investigated. Also, the mineralogical and microstructural characteristics were evaluated by XRD and SEM analyses. The results showed that both samples of aluminum hydroxide led to improve of porosity, density and mechanical strengths properties compared to standard ceramics prepared with calcined alumina. The use of the coarser powder (below 45µm) in the proportion of 25% leads to the obtaining of ceramics with physical-mechanical characteristics close to those of ceramics made with finer powder (less than 10µm) in a proportion of 25-50%, with beneficial effect on production costs. The properties of porous ceramics had suggested that they may be used in filtering applications.
Keywords
aluminum hydroxide, porous ceramics, microstructure, physical and mechanical characterization
ALINA IULIA DUMITRU, GEORGETA VELCIU, DELIA PATROI JANA PINTEA, TUDOR-GABRIEL DUMITRU, ILDIKO PETER
Abstract
The influence of dopants, such as Y3+, Sm3+ and Bi3+ and poling conditions on the piezo - electrical properties of (Pb0.91Me0.06)(Ti0.98Mn0.02)O3 compositions have been investigated. The compositions have been obtained at high sintering temperature (1190°C and 1240°C) by solid state reaction methode. In the present research paper the effect of sintering temperature on some properties, in particular on the physical characteristics, on the structural and microstructural features and on the dielectric and piezo-electric properties of the bulk materials have been considered and investigated.
From the studies carried out, it comes out that the type of dopant has an effect on the structure and microstructure, as well as on the dielectric and piezoelectric properties. The structure has been identification by X-ray measurements and the crystallite size has been monitored by SEM analyses. At room temperature, all the sintered samples show a tetragonal perovskite structure. Piezoelectric parameters (kp) determinations have been performed using resonance - antiresonance methods. The obtained results indicate that the sintered compositions (doped PT) can be used in obtaining active elements as well as targets for deposition.
The obtained results indicate that the sintered compositions (doped PT) can be used in obtaining active elements as well as targets for deposition.
Keywords
doped PZT, dielectric and piezoelectric properties, ferroelectric properties
CORNELIA-FLORENTINA DOBRESCU, RAMONA PINȚOI
Abstract
The paper aims to analyze the potential use of glass waste for the production of construction materials and the improvement of clayey soils. Experimental applications based on the integration of recycled products as binders have shown that glass waste contributes positively to the micro-structural properties of the mixture through an obvious improvement in mechanical performance. Within the paper, an experimental program is structured which represents a preliminary stage for small-scale modeling applied in the design of structures and eco-sustainable elements useful in construction works. The obtained results confirmed the efficiency of using recycled glass as a construction material in engineering applications. The advantages of using glass waste in the manufacture of construction elements consist in the durability of the material, the improved abrasion resistance of concrete, the improved rheological properties of fresh concrete, without using superplasticizers in the mixtures.
Keywords
stability, performance, improvement, alternative materials, clayey soils, waste glass