Surface analysis of localized corrosion of austenitic 316L and duplex 2205 stainless steels in simulated body solutions

We report on cyclic voltammetry and in situ electrochemical atomic force microscopy (EC-AFM) studies of localized corrosion of duplex 2205 stainless steel (DSS 2205) and austenitic stainless steel of the type AISI 316L in two model solutions, including artificial saliva (AS) and a simulated physiological solution known as – Hank's solution (PS). The AFM topography analysis illustrated the higher corrosion resistance of DSS 2205 steel for the chosen range of electrochemical potentials that were applied to the steel surface in both solutions. In contrast, pitting corrosion was observed at the surface of AISI 316L steel, with the pits becoming more evident, larger and deeper, when the sample was electrochemically treated in the PS. On both surfaces the growth of corrosion products formed during the oxidation process was observed. As a result, depending on the sample's metallurgical structure, different types of oxides covered the surface close to the breakdown potential. We distinguished between the square-like type of oxides on the surface of the DSS 2205, and the AISI 316L with its ellipse-like oxide deposits. The X-ray photoelectron spectroscopy (XPS) revealed the chemical composition of the deposition products, which consisted of two main elements, Fe and Cr. However, the oxides of the alloying elements Ni and Mo were negligible compared to the bulk

CLINICAL CHARACTERISTICS AND COMORBIDITY OF PEDIATRIC TRICHOTILLOMANIA: THE STUDY OF 38 CASES IN CROATIA

Background: The main goal of this study was to analyse and show clinical characteristics and psychiatric comorbidity in 38 participants aged between 10 and 17 with DSM-IV diagnoses of Trichotillomania (TTM) that we were treating at Children\u27s Hospital Zagreb from 2008 to 2017. Subjects and methods: We analyzed the data obtained from semi-structured interviews by the criteria of DSM-IV, Youth Self Report (YSR) (Achenbach & Rescorla 2001) and survey that we created. Results: From 38 participants 21 were girls. The activities during which the participants state that they mostly pull hairs are as follows: doing homework and learning, working on PC, in the toilet, watching TV etc. The most common sites on the body from which participants pulled hair were scalp and among nonscalp sites eyebrows and eyelashes. We found nail biting in more than a half of participants. In 22 participants one or more comorbid disorder has been found, of which ADHD (n=6) and tics (n=5) are most co-occurring disorders. The internalized and externalized problems were nearly evenly represented. Trichophagia was reported by two participants. The results indicate that more than two thirds of participants isolate themselves during hair pulling and half of them try to hide consequences. Median time from the first occurrence of the symptoms to the first visit to a child psychiatrist caused by TTM problem was 9 months (min 5; max 24) what we consider a very long period of time that increased the probability of complications. Conclusions: Knowledge about this disorder and cooperation among pediatric experts is extremely important for recognizing it at an early stage and starting the treatment especially considering habit-forming mechanism, the burden of an emotional distress and frequent comorbidity. Further research is needed

Influence of oil viscosity on the tribological behavior of a laser-textured Ti6Al4V alloy

Laser texturing with a dimple pattern was applied to modify a Ti6Al4V alloy at the micro level, aiming to improve its friction and wear resistance in combination with oil lubrication to optimize the performance in demanding industrial environments. The tribological analysis was performed on four different dimple-textured surfaces with varying dimple size and dimple-to-dimple distance and under lubrication with three different oils, i.e., T9, VG46, and VG100, to reflect the oil viscosity’s influence on the friction/wear of the laser-textured Ti6Al4V alloy. The results show that the surfaces with the highest texture density showed the most significant COF reduction of around 10% in a low-viscosity oil (T9). However, in high-viscosity oils (VG46 and VG100), the influence of the laser texturing on the COF was less pronounced. A wear analysis revealed that the laser texturing intensified the abrasive wear, especially on surfaces with a higher texture density. For low-texturing-density surfaces, less wear was observed for low- and medium-viscosity oils (T9 and VG46). For medium-to-high-texturing densities, the high-viscosity oil (VG100) provided the best contact conditions and wear results. Overall, reduced wear, even below the non-texturing case, was observed for sample 50–200 in VG100 lubrication, indicating the combined effect of oil reservoirs and increased oil-film thickness within the dimples due to the high viscosity

THE CORROSION BEHAVIOUR OF FERRITIC STAINLESS STEELS IN ALKALINE SOLUTIONS KOROZIJSKO VEDENJE FERITNIH NERJAVNIH JEKEL V ALKALNIH RAZTOPINAH

The corrosion resistances of X6Cr17 and X2CrTi17 ferritic stainless steels and cold-rolled, low-carbon steel, as well as circular and transversal welds of X6Cr17 ferritic stainless steel, were investigated in a non-phosphate detergent with a solution pH of 10.5 and at a temperature of 60°C. The second investigated solution contained the non-phosphate detergent and sodium perborate tetrahydrate at pH 11 and was at a temperature of 90°C. The potentiodynamic measurements showed that the corrosion resistance decreased from X2CrTi17 and X6Cr17 to the welded specimens and the cold-rolled, low-carbon steel in non-phosphate detergent at the lower temperature. At the elevated temperature and with the addition of sodium perborate tetrahydrate the corrosion stability of all the investigated materials decreased significantly. Keywords: ferritic stainless steel, potentiodynamic, alkaline solution, corrosion Preu~evali smo korozijsko odpornost vzorcev X6Cr17, X2CrTi17 feritnih nerjavnih jekel, hladno valjanega malooglji~nega jekla in kro`nega ter pre~nega zvara X6Cr17 feritnega nerjavnega jekla v raztopini nefosfatnega detergenta pri pH 10,5 in temperaturi 60°C. Druga preiskovana raztopina je vsebovala nefosfatni detergent in natrijev perborat tetrahidrat pri pH 11 in temperaturi 90°C. Rezultati potenciodinamskih meritev so pokazali, da sta korozijsko najbolj obstojna materiala X2CrTi17 in X6Cr17, manj pa obe vrsti zvarov in hladno valjano malooglji~no jeklo. Pri povi{ani temperaturi in z dodatkom natrijevega perborata tetrahidrata se je korozijska odpornost vseh petih vzorcev izrazito zmanj{ala

Short- and long-term wettability evolution and corrosion resistance of uncoated and polymer-coated laser-textured steel surface

We present the results of one year observation of wetting and corrosion properties of nanosecond fiber laser-textured stainless steel, uncoated and coated with epoxy or FAS (fluoroalkylsilane)-TiO$_2$/epoxy. A comparative study was performed on samples kept under ambient conditions and in reduced air pressure and humidity. The results show the ability to induce wettability conversion from initially superhydrophilic to final superhydrophobic state either indirectly by ageing the uncoated laser-textured surface or directly by application of FAS-TiO$_2$/epoxy coating. The storage conditions significantly influenced the wettability development of uncoated laser-textured steel, i.e., the process of ageing was slowed down in reduced air pressure and humidity. Detailed surface chemical analysis revealed that adsorption of the organic matters from the surrounding media influences the wettability conversion and ageing. However, the ageing of the coated surfaces was not affected by the storage conditions. Corrosion stability of uncoated laser-textured surfaces was enhanced over time due to the wettability transition, depending on their morphology. Coatings represent a superior barrier over the texture and wettability with the stable long-term surface protection against aggressive media

Current trends on mechanical, corrosion resistance, and antibacterial properties of metallic materials : editorial

The scope of the Special Issue entitled “Mechanical, Corrosion Resistance, and Antibacterial Properties of Metallic Materials” includes research regarding the latest developments in materials’ mechanical properties and characterization, pure/applied corrosion phenomena, and advanced understanding of bacterial adhesion and the induced antibacterial properties of metallic materials [...