Weldability of spheroidal graphite ductile cast iron using Ni / Ni-Fe electrodes

[ES] Se establece la soldabilidad de funciones dúctiles de grafito según las características mecánicas alcanzadas, utilizando un electrodo puro de Ni mientras se compara con uno más económico de Ni-Fe. Diferentes tratamientos térmicos son propuestos y analizados. El electrodo de Ni puro mostró difusión de grafito desde el material original al cordón de soldadura, dando como resultado una fase homogénea que mejoró la soldabilidad y redujo la fragilidad. Un pre tratamiento a 350 °C y un recocido a 850 °C incrementaron la ductilidad y mejoró la soldabilidad.[EN] Weldability of spheroidal graphite ductile cast iron was established using a cheap Ni-Fe and a high purity Ni electrode. A preheating treatment at 350 °C and an annealing treatment at 850 °C were carried out to improve mechanical properties of welded pieces. The pure Ni electrode showed graphite diffusion in the bead with a uniform distribution of phases, improving weldability and decreasing fragility. Preheating and annealing treatments increased ductility and improved weldability.Pascual Guillamón, M.; Ferrer Giménez, C.; Rayón Encinas, E. (2009). Weldability of spheroidal graphite ductile cast iron using Ni / Ni-Fe electrodes. Revista de Metalurgia. 45(5):334-338. doi:10.3989/revmetalm.0814S33433845

Microstructure, mechanical, and thermogravimetric characterization of cellulosic by-products obtained from biomass seeds

The microstructural, thermal, and nanomechanical characterization of biomass by-products coming from the food industry were studied. Scanning electron microscopy showed a microstructure formed by polygonal grains. The thermal behavior of seeds, evaluated by thermogravimetric analysis, revealed three main components (hemicellulose, cellulose, and lignin). Walnut shell showed the highest thermal stability and also the highest amount of lignin. The nanomechanical aspects were evaluated by nanoindentation. Samples with higher amount of cellulose presented minor modulus values. In accordance with the thermal stability, the highest modulus and hardness were observed in walnut. These by-products could be useful as reinforcement materials for biodegradable plastic industry.This work has been supported by the Spanish Ministry of Science and Innovation (MAT2011-28468-C02-02) and the Autonomous Government of Valencia (Spain) through the research program Geronimo Forteza (62/2010, 9 de Junio DOCV no 6291). M.P. Arrieta is granted by Santiago Grisolia program (GRISOLIA/2011/007).Rayón Encinas, E.; Ferrándiz Bou, S.; Rico Beneito, MI.; López Martínez, J.; Arrieta, MP. (2015). Microstructure, mechanical, and thermogravimetric characterization of cellulosic by-products obtained from biomass seeds. International Journal of Food Properties. 18(6):1211-1222. https://doi.org/10.1080/10942912.2014.884578S1211122218

Enhancing the Thermal Stability of Polypropylene by Blending with Low Amounts of Natural Antioxidants

"This is the peer reviewed version of the following article: Hernández-Fernández, Joaquín, Emilio Rayón, Juan López, and Marina P. Arrieta. 2019. Enhancing the Thermal Stability of Polypropylene by Blending with Low Amounts of Natural Antioxidants. Macromolecular Materials and Engineering 304 (11). Wiley: 1900379. doi:10.1002/mame.201900379, which has been published in final form at https://doi.org/10.1002/mame.201900379. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving."[EN] Natural antioxidants are added in very low amounts to protect a polypropylene (PP) matrix against thermo-oxidative degradation during processing. Thus, PP is melt-blended with caffeic, chlorogenic, trans-ferrulic, and p-coumaric acids, and also with flavone and 3-hydroxyflavone at 0.1 wt% with respect to the PP matrix. Neat PP and PP blended with three traditional antioxidants are prepared for comparison. A complete structural, thermal, and mechanical characterization is conducted. Ferrulic acid and particularly caffeic acid increases the thermal stability, showing also the highest activation energy. The structural changes of PP-based films due to the polymer thermal degradation at high temperature (i.e., 400 degrees C) followed by FTIR reveal that antioxidants effectively delay the thermal degradation process. The wettability and the mechanical performance are also studied to get information regarding the industrial application of such films. While caffeic acid provides a more flexible material, ferrulic acid provides higher water resistance. Finally, AFM-QNM shows that PP with caffeic acid has the highest miscibility.This work was supported by the Spanish Ministry of Economy and Competitiveness (MINECO), PROMADEPCOL (MAT2017-84909-C2-2-R). M.P.A. thanks MINECO for Juan de la Cierva-incorporación postdoctoral contract (FJCI-2017-33536).Hernández-Fernández, J.; Rayón, E.; López-Martínez, J.; Arrieta, MP. (2019). Enhancing the Thermal Stability of Polypropylene by Blending with Low Amounts of Natural Antioxidants. Macromolecular Materials and Engineering. 304(11):1-13. https://doi.org/10.1002/mame.201900379S1133041

Tribological study of FeCuCrgraphite alloy and cast iron railway brake shoes

[EN] A new class of materials is being installed in railway brake blocks to substitute classic cast iron in order to reduce the rolling noise produced by the roughness of the tread-wheel surface. The tribological properties of cast iron and Fe-Cu-Cr-graphite sintered alloy brake shoes were analyzed. Kinetic friction coefficient (mu) and wear were monitored by means of a pin-on-disc technique. The sintered alloy brake showed an increase in mu at higher braking velocities while the cast iron brake exhibited a decrease in mu. Wear was greater on the sintered alloy, explained by its low shear strength which decreased due to its low thermal conductivity. The roughness produced by the sintered brake shoes in wheel-tread surface was 10 times lower than that produced by cast iron. (c) 2009 Elsevier B.V. All rights reserved.Ferrer Giménez, C.; Pascual Guillamón, M.; Busquets Mataix, DJ.; Rayón, E. (2010). Tribological study of FeCuCrgraphite alloy and cast iron railway brake shoes. Wear. 268(5):784-789. doi:10.1016/j.wear.2009.12.014S784789268

Microstructure and indentation mechanical properties of YSZ nanostructured coatings obtained by suspension plasma spraying

[EN] A commercial nanosuspension of yttria-stabilised zirconia (YSZ) was successfully deposited on austenitic stainless steel substrate by suspension plasma spraying technique (SPS). A SG-100 torch with internal radial injection was used for the spraying. The pneumatic system transported the feed suspension from the containers to the plasma torch. In order to study the effect of the spraying parameters, a factorial model was used to design the experiments, changing both spraying translation speed and suspension flow rate. The coating microstructure was characterised by FEG-SEM. All coatings displayed a two-zone microstructure formed by nanometre-sized particles surrounded by fully molten areas. Moreover, crystalline phases were determined by XRD and Raman spectroscopy. Mechanical properties were also determined using nanoindentation technique. Nanoindentation tests showed a bimodal distribution of the mechanical properties (hardness and Young's modulus) which is related to the two zones (molten and partially molten) present in the coatings. (C) 2012 Elsevier B.V. All rights reserved.This work has been supported by the Spanish Ministry of Science and Innovation (project MAT2009-14144-C03) and the Research Promotion Plan of the Universitat Jaume I, action 2.1 (ref. E-2011-05) and action 3.1 (ref. PREDOC/2009/10). The authors are grateful to Leszek Łatka for his help in plasma spray experiments.Carpio, P.; Rayón Encinas, E.; Pawlowski, L.; Cattini, A.; Benavente Martínez, R.; Bannier, E.; Salvador Moya, MD.... (2013). Microstructure and indentation mechanical properties of YSZ nanostructured coatings obtained by suspension plasma spraying. Surface and Coatings Technology. 220:237-243. https://doi.org/10.1016/j.surfcoat.2012.09.047S23724322

Enhancing the mechanical features of clay surfaces by the absorption of nano-SiO2 particles in aqueous media. Case of study on Bronze Age clay objects

[EN] Nanoparticles are known to be able to enhance the performance of low dense materials, achieving the small intergranular spaces to further interact with the matrix. In this work, a consolidation treatment of an ancient clay material is reported. It is based on the use of silica nanoparticles dispersed in an aqueous medium as a more sustainable approach than those currently used in the conservation field. The effective consolidation has been determined by ensuring an appropriate mechanical surface resistance using the nanoindentation technique as non-destructive measurements. Moreover, the ability of SiO(2 )nanoparticles to fill the microstructure is studied by scanning electron microscopy. As a case report, several low-strength clay fragments dated from the Bronze Age were surface treated with a commercial aqueous suspension of SiO2 nanoparticles that were analyzed by transmission electron microscopy (TEM) displaying dimensions of about 20 nm in diameter. Field Emission Electron Microscopy (FESEM) revealed that nanoparticles filled the inter-granular spaces of the clay, leading to a nanostructured material. The nanoindentation results showed an increase in surface resistance against scratching. Meanwhile, the nanohardness and elastic modulus increased 10 times (from 15 to 150 MPa) and 8 times (from 1 to 8 GPa), respectively due to the nano-SiO2 treatment, confirming the consolidation effect of the nanoparticles.Authors acknowledge the financial support of Spanish Ministry of Economy and Competitiveness, MAT2014-59242-C2-1-R. Authors also acknowledge the support of Helena Bonet, Director of the Prehistory Museum of Valencia and Ma Jesus de Pedro, conservator of this Museum, and to the Photographic Archive Department. M.P. Arrieta wishes to thank the financial support of MINECO for a Juan de la Cierva (FJCI-2014-20630) contract.Rayón, E.; Arrieta, MP.; Pasies -Oviedo, T.; López-Martínez, J.; Jorda Moret, JL. (2018). Enhancing the mechanical features of clay surfaces by the absorption of nano-SiO2 particles in aqueous media. Case of study on Bronze Age clay objects. Cement and Concrete Composites. 93:107-117. https://doi.org/10.1016/j.cemconcomp.2018.07.005S1071179

A study of the influence of TiO2 addition in Al2O3 coatings sprayed by suspension plasma spray

In this work, five different concentrations of a mixture of TiO2/Al2O3 nanopowders in an alcoholic suspension at 10wt.% solid content were sprayed by Suspension Plasma Spraying on steel discs. The influence of the presence of TiO2 at 0, 13, 40 and 75wt.% in Al2O3 was analysed by studying the properties of the sprayed coatings. Microscopy analysis of the projected coatings revealed a homogeneously distributed microstructure, where the densification of the coating increases with TiO2 content, while the original nanostructure is maintained. A nanoindentation study revealed an increment of nanohardness and elastic modulus due to the densifying effect of TiO2. The addition of significant amounts of TiO2 has been revealed as necessary in order to favour the fusion of Al2O3 in the SPS process

Effect of the initial particle size distribution on the properties of suspension plasma sprayed Al2O3-TiO2 coatings

“NOTICE: this is the author’s version of a work that was accepted for publication in Surface & Coatings Technology. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Surface & Coatings Technology, [268 (2015) 209-215] DOI 10.1016/j.surfcoat.2014.12.010¨Al2O3-TiO2 coatings have been deposited by atmospheric plasma spraying from agglomerated, nanostructured powders showing better properties than those of their conventional (microstructured) counterparts. These nanostructured coatings can be also obtained by suspension plasma spraying however the research on suspension plasma sprayed Al2O3-TiO2 is still scarce. Consequently, it is crucial to study the effect of the suspension characteristics on the coating properties and to optimize the deposition process. In this work, Al2O3-13 wt.% TiO2 tribological coatings were successfully deposited by suspension plasma spraying from three different feedstocks: a nanometric suspension and two bimodal suspensions with different solid contents made up of titania nanoparticles and alumina submicron-sized particles. The coating microstructure and phase composition were characterized using scanning electron microscopy and X-ray diffraction analysis. Moreover, nanoindentation technique was used to determine the nanomechanical properties of coatings. The influence of the feed suspension characteristics on the final coating quality was analyzed. Findings showed that similar microstructures and phases were developed after depositing the different feedstocks. In addition suspension feedstock made up of nanoparticles resulted in a coating with better mechanical properties. However the use of submicron-sized particles in the suspension feedstocks gives rise to some technical and economic advantages in the process which should be taken into account when a suspension plasma spraying process is to be setup. (C) 2014 Elsevier B.V. All rights reserved.This work has been supported by the Spanish Ministry of Science and Innovation (project MAT2012-38364-C03) and it has been co-funded by ERDF (European Regional Development Funds).Vicent, M.; Bannier, E.; Carpio, P.; Rayón Encinas, E.; Benavente Martínez, R.; Salvador Moya, MD.; Sánchez, E. (2015). Effect of the initial particle size distribution on the properties of suspension plasma sprayed Al2O3-TiO2 coatings. Surface and Coatings Technology. 268:209-215. https://doi.org/10.1016/j.surfcoat.2014.12.010S20921526

Effect of TiO2 addition on the microstructure and nanomechanical properties of Al2O3 Suspension Plasma Sprayed coatings

Alumina–titania coatings are widely used in industry for wear, abrasion or corrosion protection components. Such layers are commonly deposited by atmospheric plasma spraying (APS) using powder as feedstock. In this study, both Al2O3 and Al2O3–13 wt% TiO2 coatings were deposited on austenitic stainless steel coupons by suspension plasma spraying (SPS). Two commercial suspensions of nanosized Al2O3 and TiO2 particles were used as starting materials. The coatings microstructure and phase composition were fully characterised using FEG-SEM and XRD techniques. Nanoindentation technique was used to determine the coatings hardness and elastic modulus properties. Results have shown that the addition of titania to alumina SPS coatings causes different crystalline phases and a higher powder melting rate is reached. The higher melted material achieved, when titania is added leads to higher hardness and elastic modulus when the same spraying parameters are use

Microstructure and photocatalytic activity of suspension plasma sprayed TiO2 coatings on steel and glass substrates

In this study, TiO 2 coatings were deposited by suspension plasma spraying (SPS) from a commercial TiO 2 nanoparticle suspension on two different substrates: a standard stainless steel and a Pyrex glass. Coatings were sprayed on both substrates with an F4-MB monocathode torch; a Triplex Pro tricathode torch was also used to spray coatings just on the stainless steel substrates. Spraying distance and cooling were varied.The anatase content in the coatings, determined by XRD, ranged from 32 to 72 wt% A significant amount of anatase to rutile transformation was found to occur during cooling. Examination of the microstructure revealed that the coating microstructure was bimodal, involving a non-molten region consisting mainly of anatase nanoparticle agglomerates and a molten region. The glass substrate coatings displayed a segregated phase distribution, particularly when the surface to be coated was cooled. Photocatalytic activity was determined by a methylene blue test.The experimental data fitted well to a first-order kinetic. All the coatings exhibited high photocatalytic activity in comparison with that of a commercial sol-gel coating. However, unlike much of the previous research, photocatalytic activity did not correlate with the anatase content determined by XRD. © 2011 Elsevier B.V.This work has been supported by the Spanish Ministry of Science and Education (MAT2009-14144-C03-01), by the Spanish Ministry of Science and Innovation (PID-600200-2009-5) and by the European Commission in the frame of the Interreg IV B Sudoe programme (Eliare: SOE1/P1/F169).Bannier, E.; Darut, G.; Sánchez, E.; Denoirjean, A.; Bordes, M.; Salvador Moya, MD.; Rayón Encinas, E.... (2011). Microstructure and photocatalytic activity of suspension plasma sprayed TiO2 coatings on steel and glass substrates. Surface and Coatings Technology. 206(2):378-386. https://doi.org/10.1016/j.surfcoat.2011.07.039S378386206