PVD coated mill rolls for cold rolling of stainless steel strips - Tribological and mechanical laboratory tests

Voir : PVD Coated Mill Rolls for Cold Rolling of Stainless Steel Strips: Tribological and Mechanical Laboratory Tests, Ould C., Badiche X., Montmitonnet P., Gachon Y., Dans Proceedings of NAMRI/SME - 40th NAMRC - North American Manufacturing Research Conference, Notre-Dame, Indiana : États-Unis (2012) - http://hal-ensmp.archives-ouvertes.fr/hal-00724779International audienceThe cost of rolling is determined in particular by productivity and lifetime of rolls before regrinding. Adhesive wear of the sheet gives rise to transfer on the roll surface. Its occurrence depends on rolling conditions and is one of the determining factors of the maximal reduction for a given rolling speed. Abrasive wear of the roll is the second factor for roll lifetime. Both phenomena are strongly related to tribological and mechanical characteristics of the surface layer of rolls. Stainless steel is known for its high adhesiveness. Coatings with good tribological properties could help extend the roll service. In this paper, the potential of different PVD coatings (CrN, TiN and TiBN) is explored. The impact of these coatings on influential phenomena during rolling is analyzed thanks to well-adapted tribological and mechanical laboratory tests. The results show that TiN has a good potential in cold rolling of stainless steel strips

Feasibility of TiBN PVD Coating for Mill Rolls - Laboratory Testing of Anti-adhesive and Fatigue Resistance Properties

International audienceThe ceramic coatings deposited by Physical Vapour Deposition (PVD) are known for their high hardness. They offer a wide variety of friction coefficients. They have been used for a number of years for the coating of cutting tools; they have shown high efficiency in this field. Considering this, some of these coatings might prove efficient in the field of metal rolling. Yet to the best of the authors' knowledge, they have never been used industrially for rolling mill rolls. TiBN is one of the PVD coatings with the highest hardness. It is also known for its anti-adhesive property. In this study, the interest of TiBN in cold rolling is analyzed. In this application, the potential productivity is determined by the maximum pair (reduction, speed) above which seizure and transfer degrade tribological properties. The fatigue resistance is also studied and therefore, the potential influence of the coating on the roll life under conditions similar to those of rolling. Two well adapted tribological tests have been used for these two purposes: a plate-on-ring test, and a twin-disk Amsler test. The results of this study show a high potential of TiBN as coating for rolling mill rolls: good anti-adhesive property, very high resistance to wear and fatigue. It shows better performance than hard chromium, which is now widely used in this applicatio

Tests Tribologiques et mécaniques de différents revêtements PVD pour cylindres de laminoirs à bandes en acier Haut Carbone

International audienceOn étudie l'application aux cylindres de laminoir de revêtements PVD initialement développés pour l'usinage : TiN, TiBN, CrN, aux fins de remplacement du revêtement existant, le chrome dur. Les propriétés essentielles sont comparées à l'aide de l'essai bague plan (cet essai en glissement total est très sensible à l'usure adhésive) et de l'essai Amsler (roulement avec glissement sous forte charge hertzienne, qui teste la résistance de l'interface à l'écaillage). On montre que CrN, peut-être du fait de fortes contraintes résiduelles, est le seul à s'écailler dans les conditions de l'essai Amsler (2 GPa de pression maximale de Hertz, 106 cycles). Contre l'adhésion, TiN est décevant, alors que CrN et TiBN, aussi bien que Cr, empêchent le grippage jusqu'à la charge maximale de l'essai bague - plan

Preharvest Use of y-Aminobutyric Acid (GABA) as an Innovative Treatment to Enhance Yield and Quality in Lemon Fruit

-Aminobutyric acid (GABA) occurs naturally at a low concentration in fruits, but can be increased following several stress events, playing a physiological effect. Lemon trees were preharvest treated with GABA at three concentrations (10, 50, and 100 mM) during two consecutive seasons (2019–2020 and 2020–2021). Fruit growth (diameter) and crop yield (kg tree1 and number of fruits tree1) and quality traits were evaluated at harvest. Results showed that treatments were effective at increasing lemon size (a 5% higher) and yield, especially for GABA at 100 mM, for the two assayed seasons. Thus, yield was increased between 13 and 18% with respect to the control trees for the two harvest dates. With respect to the quality traits, GABA treatments did not impact any negative effects on the quality attributes, since the total soluble solids (7–8 Brix), total acidity (5–6 g 100 g1), and fruit firmness (13–14 N mm1) were similar to the control fruits. Therefore, GABA applied as preharvest treatment could be considered as a potent tool to enhance the yield of lemon fruits

Elastic properties of highly anisotropic thin poly(propylene) foams

In this letter, elastic properties of highly anisotropic cellular poly(propylene) films are reported. The material shows peculiar elastic properties compared to other foams in the literature. The data is displayed as the relative Young's modulus $E^*/E_s$ versus relative density $\rho^*/\rho_s$. Almost all the data from the literature are located on the region $E^*/E_s=(\rho^*/\rho_s)^n$ with $1\le n\le6$. The introduced material on the other hand have lower relative Young's modulus at high relative densities, $n\ge6$

Efectos de los tratamientos post-cosecha con flujo de aire caliente sobre la calidad de limones ‘fino’

Los productores de limón demandan herramientas que incrementen la vida útil de los frutos durante la comercialización. En este trabajo se ha estudiado el efecto de realizar una cuarentena de 24 h a 37 °C y a 42 °C, previo al almacenamiento a 10 ºC. Se han evaluado los principales parámetros de calidad del limón: pérdidas de peso (PP), firmeza y color. Además, se ha determinado la tasa de respiración (TR) y la incidencia de podredumbres. Los resultados mostraron un descenso en las PP y la incidencia de podredumbres, mientras que la firmeza y el color no presentaron diferencias entre los frutos expuestos a 37 °C y los frutos sin tratar. A 42 °C la calidad del fruto disminuyó drásticamente. Por lo tanto, el uso de cuarentenas a 37 °C durante 24 horas podrían ser consideradas como herramientas efectivas para mantener la calidad del limón durante el almacenamiento a 10 ºC

Computational Homogenization of Architectured Materials

Architectured materials involve geometrically engineered distributions of microstructural phases at a scale comparable to the scale of the component, thus calling for new models in order to determine the effective properties of materials. The present chapter aims at providing such models, in the case of mechanical properties. As a matter of fact, one engineering challenge is to predict the effective properties of such materials; computational homogenization using finite element analysis is a powerful tool to do so. Homogenized behavior of architectured materials can thus be used in large structural computations, hence enabling the dissemination of architectured materials in the industry. Furthermore, computational homogenization is the basis for computational topology optimization which will give rise to the next generation of architectured materials. This chapter covers the computational homogenization of periodic architectured materials in elasticity and plasticity, as well as the homogenization and representativity of random architectured materials

Comment saisir les occasions thérapeutiques lors d'une première consultation en médecine générale avec un toxicomane aux opiacés

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