The present study aims to explain the corrosion and the tribocorrosion performance in simulated conditions of the human body by the level of stress, adhesion of coating to substrate, roughness, and hardness. The coatings were synthesized by the cathodic arc evaporation method on 316L stainless steel substrates to be used for load bearing implants. Structure, elemental, and phase compositions were studied by means of energy dispersive spectrometry and X-ray diffraction, respectively. The grain size and strain of the coatings were determined by the Williamson–Hall plot method. Tests on hardness, adhesion, roughness, and electrochemical behavior in 0.9% NaCl solution at 37 ± 0.5 °C were carried out. Tribocorrosion performances, evaluated by measuring the friction coefficient and wear rate, were conducted in 0.9% NaCl solution using the pin on disc method at 37 ± 0.5 °C. TiC and ZrC exhibited a (111) preferred orientation, while TiNbC had a (200) orientation and the smallest crystallite size (8.1 nm). TiC was rougher than ZrC and TiNbC; the lowest roughness was found for TiNbC coatings. The highest hardness and adhesion values were found for TiNbC, followed by TiC and the ZrC. All coatings improved the corrosion resistance of 316L steels, but TiNbC showed the best corrosion behavior. TiNbC had the lowest friction coefficient (1.6) and wear rate (0.99 × 10−5 mm3·N−1∙m−1) values, indicating the best tribocorrosive performance in 0.9% NaCl at 37 ± 0.5 °C.
The paper presents the expertise of authenticating a painting by Nicolae Grigorescu through the involvement of multi-analytical techniques, in order to identify and evaluate some archaeometric and chemometric characteristics of the pictorial materials and of the support, used in determining the age. The painting is made with oil colors on pressed cardboard, with preparation based on chalk powder and animal glue. The painting presents two elements as being counterfeit, which have attracted suspicions, namely the signature of the author (presenting a semi-transparent covering veil), and, on the back, a writing of dating, performed by a very controversial art historian. The investigation was carried out by direct analysis with magnification devices, in reflected UV (ultraviolet), VIS (visible), and NIR (near- infrared) light, and by OM, SEM-EDX, and μ-FTIR. The results showed that the painting is authentic and belongs to Nicolae Grigorescu, and the dating established previously by Amelia Pavel through the writing on the back is certain.
The response of the human body to implanted biomaterials involves several complex reactions. The potential success of implantation depends on the knowledge of the interaction between the biomaterials and the corrosive environment prior to the implantation. Thus, in the present study, the in vitro corrosion behavior of biocompatible carbonitride-based coatings are discussed, based on microstructure, mechanical properties, roughness and morphology. TiCN and TiSiCN coatings were prepared by the cathodic arc deposition method and were analyzed as a possible solution for load bearing implants. It was found that both coatings have an almost stoichiometric structure, being solid solutions, which consist of a mixture of TiC and TiN, with a face-centered cubic (FCC) structure. The crystallite size decreased with the addition of Si into the TiCN matrix: the crystallite size of TiCN was 16.4 nm, while TiSiCN was 14.6 nm. The addition of Si into TiCN resulted in smaller Ra roughness values, indicating a beneficial effect of Si. All investigated surfaces have positive skewness, being adequate for the load bearing implants, which work in a corrosive environment. The hardness of the TiCN coating was 36.6 ± 2.9 GPa and was significantly increased to 47.4 ± 1 GPa when small amounts of Si were added into the TiCN layer structure. A sharp increase in resistance to plastic deformation (H3/E2 ratio) from 0.63 to 1.1 was found after the addition of Si into the TiCN matrix. The most electropositive value of corrosion potential was found for the TiSiCN coating (−14 mV), as well as the smallest value of corrosion current density (49.6 nA cm2), indicating good corrosion resistance in 90% DMEM + 10% FBS, at 37 ± 0.5 °C.
15 September 2023 in International Journal of Conservation Science
Our research was conducted on a copper disc-butted axe, with a surface decoration made of a tin-based alloy, which was found east of the Carpathian Mountains in the Moldavian Plateau. This unique piece is thought to belong to the Middle Bronze Age in the Western Carpathians—Wietenberg, Suciu de Sus and Otomani–Füzesabony cultures. In order to evaluate the application process and the origin of the ores used, the surface and volume phase variation of the concentration of the metal components of the basic alloy (copper) and of the ornament was analysed using optical microscopy (OM), stereomicroscopy (SM) and SEM-EDX. The archaeometric features, formed both during its use and during its lying in the archaeological site, were identified and later used in archaeometallurgical evaluations and in determining the preservation condition of the two components (axe and ornament) on the surface, interface and in stratigraphic section. Experimental data revealed that, after its casting in porous silicon stone moulds, the object was coated with a thin film by immersion in an easily fusible tin alloy, which included copper as the major alloying component and arsenic and iron as minor components. After finishing the shiny white coat, a beautiful decoration was applied by incision and engraving. Used as a battle axe, it also had a rank function, as it belonged to the community leaders. The data prove the ability of ancient craftsmen to design and process copper alloys to obtain authentic extremely beautiful artefacts, which provide new possibilities to reveal the social and symbolic function of certain ancient bronze objects.
The paper presents the results of ample investigations performed on industrial and traditional ceramics of fired clay used in processes of water potabilization in the last stage of filtration, after that of active charcoal. Using the data obtained through the scanning electron microscope coupled with energy dispersive X-ray analysis (SEM-EDX) and pH analyses, on the basis of the atomic composition and free concentration of hydronium ions, the normal caustic (Si/Al) and summative [(Si+Ti+FeIII+Cl)/(Al+Ca+Mg+Na+K)] modules were assessed, which were correlated with the free acidity and, respectively, the capacity of absorption and ionic exchange of the Fe3+ and Al3+ ions. The study allowed the selection, on the basis of the caustic module, of the ceramics with high capacity for ionic exchange.