Ioan Gabriel Sandu

Influence of archaeological environment factors in alteration processes of copper alloy artifacts

The article presents the experimental results obtained by combining noninvasive techniques (OM, SEM/EDX, XRF) to analyze three artifacts made of copper alloys discovered in a inhumation tomb (2) and in the soil profile (1) in archaeological sites from Neamt County Romania. To uncover the mechanism of alteration thereof during their longtime underground stay in specific chemical conditions and under the influence of other pedological factors, the corrosion products must be identified. The excess of the chloride ion, from burial site, disturbs the Liesegang effect, transforming the bulk in a stratified sponge structure with chlorapatite and hydroxyapatite. Some of the compounds from primary and secondary patina can be found on the surface of the bulk, as color stains. The presence of alloy components (Cu, Sn, Pb, Zn, Fe, etc.) and of the underground contamination components, allowed us to establish the origin of the ore, the manufacture technology and we identified other materials which affected the artifacts after abandonment. Microsc. Res. Tech., 2012.

Establishing the archaeo‐metallurgic ornamentation process of an axe from the bronze age by OM, SEM‐EDX, and Micro‐FTIR

Our article presents the results of the analyses we performed by corroborating the Optical Microscopy, Scanning Electron Microscopy, Energy Dispersive Xray Analysis and micro Fourier Transformed InfraRed Analysis techniques to identify the archaeo‐metallurgic casting and ornamentation procedure of a decorated disk‐butted axe, which was discovered recently east of the Carpathian mountains, in the Moldavian Plateau. There are few known axes of that type found (A1, according to the usual typologies), as they are specific to the Middle Bronze Age period west of the Carpathians—the Wietenberg, Suciu de Sus, and Otomani‐Füzesabony cultures. The experimental data on the item under study revealed the fact that after casting it in molds made from porous silicone‐based stone, the object was coated with a thin layer, by immersing it in a lightly fusible tin alloy, whose main alloy component was copper and arsenic and iron as secondary components. After refining the shiny white layer, they applied a beautiful decoration pattern made by incision and engraving. This battle axe was an indication of higher status, such items usually being owned by community leaders. This important fact proves that the ancient metallurgic craftsmen were able to elaborate and manufacture various alloys from which they made beautiful objects and it also offers a new insight into the social and symbolic function of certain antique bronze items. Microsc. Res. Tech. 77:918–927, 2014.

Chemical Deposition of Thin Layers on Reinforcing Steel

This paper presents the results of experimental research on the influence of using microcrystalline phosphating process on the OB37 steel used in construction. For this purpose, the samples were immersed in phosphate solution and the structures were characterized using SEM microscope. The results show that the obtained structures, are influenced by pH and immersion time and show a good surface compactity and roughness, which means that the obtained layer on the OB37 reinforcement improves corrosion resistance and adhesion of these reinforcements in the reinforced concrete.

Influence of Process Parameters on the Properties of TiO2 Films Deposited by a D.C. Magnetron Sputtering System on Glass Support

In this paper it has been deposited films of titanium oxide (TiO2), on a support of glass, by a D.C. magnetron sputtering system, by varying the working pressure (p = 2∙10-3 - 6.5∙10-3mbar) of the substrate temperature on three levels. The obtained layers were investigated and characterized by optical microscopy, Scanning Electron Microscopy SEM, X-ray diffraction and Atomic Force Microscopy. It was observed that, by modifying technological parameters of the process (working pressure and substrate temperature) it is changing the initial orientation of the compounds ((100) turns into (101) or (002)). The AFM analysis has allowed the observation of the fact that the average roughness of deposited films, expressed as RMS, has increased over 98% at the increasing of sputtering pressure from 2 10-3mbar to 6.5 10-3mbar. SEM analysis showed that the density of the deposit increases with substrate temperature. The granulation of the films obtained, presents an increasing trend with the variation of process parameters.

New Concrete with Recycled Aggregates from Leftover Concrete

We live in an era where people should be more aware of pollution and its consequences. The present paper reveals a way protecting the environment while producing high quality concrete. What make this type of concrete environmentally friendly are the recycled aggregates in the concrete composition amongst with eliminating the ecological impact by saving large amounts of natural aggregates resources. Recycling concrete comes with many other advantages that lead to waste reduction, economy in waste transportation and storage taxes, which are becoming increasingly expensive. This research is based on mix design and experimental tests carried out on C20/25 strength class concrete with uncontaminated leftover concrete aggregates (LCAgg). It reveals favorable results in order to militate for recycled concrete aggregate uses in regular concrete strength classes respectively for common structural elements, mainly for slabs. River sand (0/4 mm) and coarse aggregates (4/8 mm and 8/16 mm): natural sources or recycled concrete type-alternatively used in several mixes-were utilized in concrete mixes.

Enhancing Properties of Reinforcing Steel by Chemical Phosphatation

This paper presents the first results of complex study concerning the protection of reinforcing steel used in concrete structures from civil and industrial buildings. The obtained coatings have multiple purpose, increasing the corrosion resistance but also the adherence with the concrete, improving the overall performance of concrete and its durability.

Study on Al-Si Alloys Properties Enhancement

The paper presents a study about aluminum alloy, allied with Si, Cu, Mn, Mg. The Al-Si-Cu-Mg alloys for foundry are used for parts strongly required and which work at high temperatures, due to their good wear resistance. The industrial Al-Cu alloys contain 12 % cooper, are hipo-eutectic and may be for foundry or deformable. By alloying with magnesium, the Al-Cu alloys become with remarkable properties of resistance and plastic deformation processing. The improvement of mechanical characteristics for Al-Si alloys is realized with metals which forms the intermediate phases with silicon or aluminum, with variable solubility in solid state and which permits the structural hardening by heat treatments (quenching and ageing). From the analysis of dilatogramms, grouped for each sample, with the specific initial length, subjected to successive heating, from ambiance temperature up to 500°C, it is found that, with the appearance of ageing phenomena, on the samples aren’t significant modifications for elongation (few microns), only different may be the form of elongation-temperature curve. This analysis permits the determination of experimental data, regarding the behavior of Al-Si alloy subjected to heat treatments and repeated warming. Therefore, the Al-Si-Cu-Mg alloys, for foundry, are used for manufacture the parts strong required and which work at high temperatures, like pistons for engines with internal burn, parts for machines and reinforcements construction, due to their high usage resistance.

SURVEY ON BEHAVIOUR OF INTERVENTIONS FOR PROBOTA MONASTERY INDOOR FRESCOES CONSERVATION UNDER ENVIRONMENTAL FACTORS INFLUENCE. III. CORRELATIONS BETWEEN THERMAL, HYGROSCOPIC AND SONIC PARAMETERS

The paper deals with the correlations between thermal, hygroscopic and sonic parameters modifications of the components from the preparation layers of the indoor frescoes, after two years from the restoration of the Church of Probota Monastery (Romania), more precisely the old layers of arriccio and intonaco, that were subject to the interventions of consolidation, stabilization and structural reintegration.