Experimental Study of Typical Defects in Traditional Ceramic Products Caused by Deformations and State of Tension Occurring During Industrial Thermal Cycle

Deformations of traditional ceramic materials during and after firing may depend on several factors and are in general too complex to be studied theoretically. If the products are made up of a single material, such deformations are mainly due to pyroplastic phenomena. In the case of glazed materials, two further factors must be considered: the state of tension established between glaze and body, and their differences in behaviour during sintering. A novel optical technique is described to measure the state of tension of ceramic glazed bodies and applied to the study of delayed crazing and pyroplastic deformation of the body. In addition, this article outlines how can ceramists avail themselves of new optical equipment in order to design high quality products and avoid ordinary defects. Combining dilatometric tests and bending analysis, a full study of residual stresses on glazed ceramic can be performed, therefore this is how planarity problems can be solved. Furthermore the Optical Fleximeter is able to get information about viscosity changing during firing process in traditional sintered ceramic bodies, like stone-ware or porcelain-ware: the viscous flow occurring during the sintering process, where the driving force is mainly given by the surface tension of the liquid glassy phase, and the speed of the process is controlled by the viscosity of the glassy phase. This kind of analysis is crucial for the complete comprehension of pyroplastic behaviour. As a fundamental result, the bending and expansion curves obtained experimentally with optical techniques proved to be a valid help for the study of the deformations and state of tension in glazed ceramic materials

Anion exchange selectivity of surfactant modified clinoptilolite-rich tuff for environmental remediation

Lately, the functionalization of industrial minerals with high technological properties, such as natural zeolites, is shaping as a promising approach in environmental sphere. In fact, under the specific conditions, the surface functionalization via adsorption of cationic surfactants reverses the surface charge of the mineral, enabling zeolites to simultaneously interact either with organic contaminants or inorganic anions. This aspect allows zeolites to be used in the remediation of contaminated fluids.The present research shed new light on some still not fully understood aspects concerning exchange kinetics such as anion-exchange mechanisms and selectivity of surface modified minerals. For this purpose the mineralogical characterization and the surface properties evaluation (X Ray Powder Diffraction, chemical analysis, thermal analysis, ECEC and AEC) of a clinoptilolite-rich tuff were performed, and the anion exchange isotherms of the sample, modified with hexadecyltrimethylammonium chloride or bromide (HDTMA-Cl/-Br), were determined. Ion-exchange equilibrium data of uni-uni valent reaction were obtained by solutions containing Br-, Cl-, NO3 - or ClO4 -. Liquid phase was analysed via high performance liquid chromatography. Thermodynamic quantities (Ka and δG0) were determined and compared with the Hofmeister series.The value of the ECEC, calculated in batch conditions, was about 137. mmol/kg, in good agreement with that evaluated in dynamic conditions, while the AEC data were different for the SMNZ-Br and -Cl samples, amounting to 137 and 106. mmol/kg, respectively, thus indicating a different compactness of the bilayer formed in the two cases. Moreover, the anion isotherm results and the mathematical evaluation of the thermodynamic parameters, demonstrated the good affinity of SMNZ-Br towards chloride, nitrate and perchlorate, and of SMNZ-Cl for nitrate and perchlorate, also endorsing the possibility of using the same thermodynamic approach developed to describe cation exchange selectivity in zeolites. Finally, it was also verified that the zeolite modified with HDTMA-Cl is able to better exploit its anion exchange capacity compared to the same zeolite modified with HDTMA-Br

Unicuique suum tribuere: The latent geological influence on "Fiano di Avellino DOCG" terroir. Case study

Campania Region hosts prestigious terroirs, the most famous interesting the Irpinia area. Actually, Lapio district (Avellino province) represents a reliable example of the relationship between wine production and territory development. The present study reports the geological and mineropedological features of the selected territory and aims at appraising the typicalness of a prestigious wine production, the Fiano di Avellino DOCG by spreading the results of such an interdisciplinary study

Production technology of mortar-based building materials from the Arch of Trajan and the Roman Theatre in Benevento, Italy

This research deals with the archaeometric study of mortars of two outstanding examples of Roman architecture in Benevento (southern Italy): The Roman Theatre and the Arch of Trajan. Mortars were analysed by means of a multi-analytical approach (i.e., polarized light microscopy, thermal analyses, infrared spectroscopy, scanning electron microscopy and energy-dispersed spectrometry) according to existing recommendations. Two different types of recipes were identified for the mortars of the Roman Theatre: a lime-based pozzolanic mortar and a hydraulic one, the hydraulicity of which, in both recipes, was due to the occurrence of natural pozzolanic admixture in air-hardening lime. As far as the Arch of Trajan is concerned, the investigated mortars are highly hydraulic as a consequence of the concomitant effect of a pozzolana-based aggregate and of a binder deriving from a marly-limestone-like stone. Although having the same function, the two different recipes identified for the bedding mortars of the Roman Theatre are clearly referred to different building phases of the monument associated to two out of the three documented construction phases