Search

A study of the influence of the SiCp proportion of four aluminium metal composites (A380/SiC/10p, A380/SiC/20p, A360/SiC/10p y A360/ SiC/20p) on 80%HR at 25 and 50ºC, simulated under climatic chamber. The matrix of A360/SiC/xxp composites is virtually free of Cu while the A380/SiC/xxp matrix contains 1.39-1.44wt%Ni and 3.13-3.45wt%Cu. The kinetics of the corrosion process were studied on the basis of gravimetric tests. The nature of corrosion products was studied as a function of the reinforcement proportion, matrix concentration and test conditions. At the humidity environment tested, both the material corrosion resistance and the stability of the passive layer were high. The damage was low and increased with temperature, SiCp proportion and Cu matrix composition.Se estudia la influencia de la proporción de SiC en la resistencia a la corrosión de los materiales compuestos de matriz de aluminio A380/ SiC/10p, A380/SiC/20p, A360/SiC/10p y A360/SiC/20p, cuando operan en un ambiente con 80% HR a 25º y 50ºC, que ha sido simulado mediante cámara climática. La matriz del material A360/SiC/xxp no contiene Cu, mientras que el material A380/SiC/xxp contiene entre el 1,39-1,44% de Ni y 3,13-3,45 de Cu. Se ha llevado a cabo un estudio cinético mediante medidas gravimétricas. Se ha estudiado la naturaleza de los productos de corrosión en función de la proporción de refuerzo, de la composición de la matriz y de las condiciones de exposición al medio agresivo. Para la humedad ensayada, la resistencia a la corrosión de estos materiales es elevada y el grado de protección de la capa pasiva es alto. El grado de daño, aunque es pequeño aumenta con la temperatura y es función tanto de la composición de la matriz como del porcentaje de refuerzo.

• The TEOS-GPTMS system is a promising approach to produce barrier-bioactive coatings. • The barrier sol-gel coating reduced the corrosion rate of Elektron 21 alloy in SBF. • The bioactive coating increased the superficial reactivity of the metallic substrate. • Ca/Mg doping of coatings led to the formation of calcium phosphates in SBF. The present study aims to develop multilayer barrier-bioactive hybrid sol-gel coatings from a mixture of the silane precursors tetraethylorthosilicate (TEOS) and glycidoxypropyltriethoxysilane (GPTMS) deposited on the Elektron 21 magnesium alloy. The purpose of the inner layer (barrier coating) was to provide corrosion protection to the magnesium alloy, whereas the outer layer (bioactive coating) was doped with different Ca and Mg contents to produce a bioactive material. The coatings were characterised using scanning electron microscopy (SEM) and their corrosion behaviour was evaluated by anodic polarisation and electrochemical impedance spectroscopy after immersion in simulated body fluid (SBF) at 37 ± 0.5 °C. The experimental results showed that the multilayer coatings increased the corrosion resistance of the alloy up to three orders of magnitude during immersion in SBF solution. On the other hand, the presence of Ca and Mg in the bioactive coating promoted the growth of apatite-like phases. However, an increment of salt content favoured the formation of porous coatings, which allowed the access of the electrolyte to the substrate leading to their rapid deterioration. Despite the latter, this research endorses the premise that the TEOS-GPTMS hybrid system represents a promising alternative to produce bifunctional barrier-bioactive coatings. [ABSTRACT FROM AUTHOR]

This paper reports an investigation of microstructural characteristics in electroless Ni-3·9W-13·4P (wt.%) coating by laser nanocrystallisation using a quantitative X-ray diffraction (XRD) method and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX). The corrosion resistance of the coatings before and after laser treatment has been evaluated in 0·5 M H2SO4 solution by potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS) techniques. The results show that the laser treatment improves the corrosion resistance of the coatings. The corrosion mechanism has been studied and correlated to the microstructural characteristics including volume fraction of INi3P/ Itotal, microstrain, and the crystallite size of the Ni and Ni3P phases. [ABSTRACT FROM AUTHOR]

An investigation has been undertaken of the influence of the mixed nanocrystalline and amorphous microstructure on the corrosion behaviour of electroless Ni-5·5W-6·5P (wt-%) deposits on steel substrates. The effects of annealing temperature on microstructure evolution were investigated. The corrosion behaviour of the deposits was evaluated by potentiodynamic polarisation in 0·5M H2SO4 solution and EIS measurements in 3·5%NaCl solution. Relationships between the microstructure and corrosion mechanisms of the as plated and the annealed deposits were considered by reference to microstructural information, including degree of crystallisation, grain sizes of both nickel and Ni3P phases, porosity development, microstrains and residual stresses. [ABSTRACT FROM AUTHOR]

Abstract: Surface modification by excimer laser surface melting (LSM) has been performed with the aim to improve the corrosion resistance of the AA2050-T8 alloy. LSM produced melted surfaces, largely free of precipitates, with both microstructure and corrosion behaviour depending upon the number of laser pulses employed. Increased number of laser pulses resulted in thicker melted layers, but also in greater trapped porosity and formation of micro-cracks at the overlapping area. Nevertheless, the LSM-treated specimens exhibited enhanced corrosion resistance compared to the untreated alloy, which was associated with the formation of a relatively uniform melted layer and a diminished presence of precipitates. [Copyright &y& Elsevier]

Abstract: This paper presents an investigation of amorphous electroless Ni–W–P coatings on mild steel substrate treated by a high-power diode laser. Effects of the laser operating parameters on microstructures, in terms of porosity formation, crystallisation, phase transformation, grain growth, microstrain and residual stress, were investigated using SEM/EDX and quantitative XRD technique. Corrosion behaviors of the coatings before and after laser treatments were evaluated by anodic polarisation in 0.5M H2SO4 solution and immersion test in 10wt.% HCl solution. The results showed that the laser treatment produced nanocrystallined Ni phase and Ni3P precipitation with remaining amorphous structure. Corrosion performance of the coatings was significantly improved by the laser treatment. Further, corrosion mechanisms of the as-plated and laser-treated coatings were discussed in the consideration of porosity, integrated intensity ratios of individual phases, grain sizes of both Ni and Ni3P phases, microstrain and residual stress. [Copyright &y& Elsevier]

The influence of Cu and Sn additions on the corrosion resistance of AISI 316 stainless steels has been evaluated in various acid media (boiling 50 wt-%H3PO4, boiling 65 wt-%HNO3, 3 wt-%HCl at 25°C and 30 wt-%H2SO4 at 50°C). A kinetic study of the corrosion process was carried out using gravimetric tests. The nature of the corrosion products was analysed by SEM, X-ray mapping and X-ray photoelectron spectroscopy both before and after accelerated corrosion tests. The steels displayed high chemical resistance to the nitric, hydrochloric and phosphoric acid media. An increase in Cu and Sn concentration did not significantly affect the corrosion resistance in boiling 50 wt-% phosphoric acid, boiling 65 wt-% nitric acid or 3 wt-% hydrochloric acid. The behaviour of AISI 316 in sulphuric acid solution was greatly improved by increasing the Cu concentration, whether alone or in combination with Sn. The effect of Sn addition in decreasing the corrosion rate was minor in comparison with that of Cu. [ABSTRACT FROM AUTHOR]

A study has been carried out into the influence of the proportion of SiCp and the matrix composition of four aluminium metal matrix composites (A360/SiC/10p, A360/SiC/20p, A380/SiC/10p and A380/SiC/20p) on their salt fog corrosion behaviour. The matrix of the A360/SiC/xxp composites is virtually free of Ni and Cu while the A380/SiC/xxp matrix contains 1.39 - 1.44 wt-%Ni and 3.13 - 3.45 wt-%Cu. The kinetics of the corrosion process were studied using gravimetric tests. The nature of corrosion products was analysed by SEM and low angle XRD before and after accelerated testing to determine the influence of microstructural changes on corrosion behaviour during exposure to the corrosive environment. The extent of the corrosion damage to the Al/SiC composites depended on the concentration of nucleation sites and the matrix composition. One of these nucleation sites is in the interface region between the matrix and the particles. The corrosion process was influenced more by the concentration of alloy elements in the matrix than by the proportion of SiCp reinforcement. [ABSTRACT FROM AUTHOR]

Abstract: Damage caused to objects of cultural heritage is one of the most serious detrimental effects of air pollutants. Within the 6th Framework Programme of the EU, the CULT-STRAT project is an inter-agency, multi-disciplinary project that has integrated research and monitoring information to provide answers to policy and management questions, which relate the effects of air pollutants on heritage and the management options available to mitigate them. The overall aim of the project has been to assess and predict the effects of different pollutants on materials and objects of cultural heritage in a multipollutant scenario and to identify indicators and thresholds levels of pollutants. These have been used for development of management strategies for sustainable maintenance and preventive conservation of European Cultural Heritage and air quality policy from continental to local scale. The present paper reports one of the studies carried out in the CULT-STRAT project at city level and focused on the town of Madrid (Spain). Different maps are shown for the present and possible future scenarios (2010 and 2020): inventory of stock of cultural heritage for each selected material, concentration of selected pollutants (SO2, NO2, O3 and PM10), corrosion (cast bronze) and recession (Portland limestone), exceedance of tolerable degradation thresholds for each material and corrosion-cultural heritage overlapped maps. [Copyright &y& Elsevier]

Abstract: The work addresses the influence of Mn and Mo additions on corrosion resistance of AISI 304 and 316 stainless steels in 30wt.% H2SO4 at 25 and 50°C. Corrosion mechanism was determined by gravimetric tests, DC polarization measurements and electrochemical impedance spectroscopy (EIS). The morphology and nature of the reaction products formed on the material surface were analysed by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). Reduction of temperature from 50 to 25°C drastically decreased the corrosion rate of AISI 304 and 316 stainless steels in sulphuric acid solution. Mn additions did not affect significantly the general corrosion resistance due to its low ability to form insoluble compounds in acid medium. Meanwhile, the formation of molybdenum insoluble oxides enhanced the corrosion performance. [Copyright &y& Elsevier]

Abstract: The work addresses the influence of cementation and electrodeposition of copper coatings on the corrosion resistance of AISI 304 stainless steel immersed in 30wt.% H2SO4 at temperatures of 25 and 50°C. Corrosion process was evaluated by gravimetric tests, DC measurements and electrochemical impedance spectroscopy (EIS). The specimen surfaces were analysed by scanning electron microscopy, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction. The corrosion performance of AISI 304 stainless steel in sulphuric acid solution was greatly improved by copper coatings. The amount of copper deposited by the cementation process was sufficient to protect the stainless steel of corrosion. A greater amount of copper obtained by electrodeposition treatments does not supply further improvement in the corrosion behaviour. The improved corrosion resistance is related to copper dissolution at the initial stages of immersion tests and the presence of Cu2+ in the solution, which makes the medium more oxidizing, increasing the stability of the passive layer. In addition, the presence of copper at the surface reduces the overpotential of cathodic reaction, enabling the transition from an active region to the passive one. [Copyright &y& Elsevier]

Abstract: The influence of silicon carbide particles (SiCp) proportion and matrix composition of aluminium metal matrix composites (A3xx.x/SiCp) modified by lanthanum-based conversion or electrolysis coating was evaluated in 3.5wt% NaCl aerated solution. The intermetallic compounds were preferentially covered by lanthanum-based conversion coatings obtained by immersion in 50°C solution of La(III) salt, and the intermetallic compounds, SiCp and aluminium matrix were covered by lanthanum electrolysis treatment. The corrosion process was studied on the basis of gravimetric tests and electrochemical impedance spectroscopy (EIS) during immersion in 3.5wt% NaCl aerated solution. The composition of both La coating and corrosion products was analyzed before and after accelerated testing, by scanning electron microscopy (SEM), atomic force microscopy (AFM), low-angle X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) to determine the influence of surface microstructural changes on corrosion behaviour during exposure to the corrosive environment. The corrosion process was more influenced by the concentration of alloy elements in the matrix than by the proportion of SiCp reinforcement. Both lanthanum treated surfaces presented better behaviour to chloride solution corrosion than original composite surfaces without treatment; however, electrolysis afforded a higher degree of protection than the conversion treatment because the coating was more extensive. [Copyright &y& Elsevier]

Abstract: This paper addresses the influence of Cu and Sn addition on the corrosion resistance of AISI 304 and 316 stainless steels in 30wt% H2SO4 at 25 and 50°C. The corrosion process was evaluated by gravimetric tests, DC measurements and electrochemical impedance spectroscopy (EIS). The corrosion products were analysed by SEM, X-ray mapping and XPS before and after accelerated tests. The behaviour of both AISI 304 and 316 stainless steels in sulphuric acid solution was greatly improved by increasing Cu concentration and the synergic effect of Cu and Sn. Addition of Sn increased corrosion resistance, but less than addition of copper. [Copyright &y& Elsevier]

Abstract: The influence of the SiCp proportion and the matrix concentration of four aluminium metal matrix composites (A360/SiC/10p, A360/SiC/20p, A380/SiC/10p, A380/SiC/20p) modified by lanthanum-based conversion or electrolysis coating was evaluated in neutral salt fog according to ASTM B 117. Lanthanum-based conversion coatings were obtained by immersion in 50°C solution of La(III) salt and lanthanum electrolysis treatments were performed in ethylene glycol mono-butyl ether solution. These treatments preferentially covered cathodic areas such as intermetallic compounds, Si eutectic and SiCp. The kinetic of the corrosion process was studied on the basis of gravimetric tests. Both coating microstructure and nature of corrosion products were analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-ray analysis (EDS) and low angle X-ray diffraction (XRD) before and after accelerated testing to determine the influence of microstructural changes on corrosion behaviour during exposure to the corrosive environment. The corrosion process was more influenced by the concentration of alloy elements in the matrix than by the proportion of SiCp reinforcement. Both conversion and electrolysis surface treatments improved the behaviour to salt fog corrosion in comparison with original composites without treatment. Additionally, electrolysis provided a higher degree of protection than the conversion treatment because the coating was more extensive. [Copyright &y& Elsevier]

Trichinellosis is a major foodborne zoonotic disease responsible for 41 human cases, according to the European Union One Health Zoonoses Report. In southern Spain, a quality management system (QMS) was applied to satellite laboratories (SLs) that conduct meat inspections of Trichinella spp. ensuring excellence practices. This study aimed to determine how eventual deviations from standard procedures may influence risk levels using Canonical Discriminant Analysis (CDA). Data were collected during slaughterhouses and game handling establishments' official audits in 18 SLs located in the provinces of Cordoba and Seville during a 6-year period. Technical requirement deviations regarding technique and trial information, such as performing tests or calculations incorrectly or not following technical procedures, significantly increased risk level differences. Imminent risk levels were detected if the above-mentioned deviations arose. Quality assurance compromising deviations were responsible for 1150 times risk level differences, suggesting finding such may be critical for risk determination. A lack of significant influence of records and documents compromising deviations (incomplete forms or missing-erroneous or illegible data) was found. These results strengthen Trichinella spp. control strategies by pinpointing crucial aspects within QMS that require improvement, particularly in addressing deviations related to technique, trial information, and quality assurance procedures to mitigate associated risks effectively.

Trichinellosis is a parasitic foodborne zoonotic disease transmitted by ingestion of raw or undercooked meat containing the first larval stage (L1) of the nematode. To ensure the quality and safety of food intended for human consumption, meat inspection for detection of Trichinella spp. larvae is a mandatory procedure according to EU regulations. The implementation of quality assurance practices in laboratories that are responsible for Trichinella spp. detection is essential given that the detection of this parasite is still a pivotal threat to public health, and it is included in list A of Annex I, Directive 2003/99/EC, which determines the agents to be monitored on a mandatory basis. A Quality Management System (QMS) was applied to slaughterhouses and game handling establishments conducting Trichinella spp. testing without official accreditation but under the supervision of the relevant authority. This study aims to retrospectively analyze the outcomes of implementing the QMS in slaughterhouses and game handling establishments involved in Trichinella testing in southern Spain. Canonical discriminant analyses (CDAs) were performed to design a tool enabling the classification of SLs while determining whether linear combinations of measures of quality-assurance-related traits describe within- and between-SL clustering patterns. The participation of two or more auditors improves the homogeneity of the results deriving from audits. However, when training expertise ensures that such levels of inter-/intralaboratory homogeneity are reached, auditors can perform single audits and act as potential trainers for other auditors. Additionally, technical procedure issues were the primary risk factors identified during audits, which suggests that they should be considered a critical control point within the QMS.

In this study, the possible influence of the food matrix and the interfering population of microorganisms on the detection and count of Listeria monocytogenes in three common foods of the Spanish diet (Spanish omelette, fresh cheese and vegetable salad) was determined. Four groups were assayed: one control, two groups with interfering microorganisms ( Salmonella Enteritidis, Staphylococcus aureus and Proteus mirabilis ) with different levels of L. monocytogenes and a final group only contaminated with L. monocytogenes . The samples were analyzed with the normalized method (UNE-EN ISO 11290:2018) and with an alternative technique (VIDAS). The results show that the presence of interfering microorganisms did not seem to interfere with the determination of L. monocytogenes . Furthermore, the type of food did not seem to influence the determination of L. monocytogenes , but the culture media used showed differences. In fact, regardless of the type of food, the ALOA medium showed higher sensitivity than the other media, with higher recovery in 100% of samples (only for the Spanish omelette in Group B was the result the same as that for PALCAM, -8.11 log cfu/g). The results obtained using the VIDAS were not influenced by any of the factors or conditions used and show 100% efficiency.