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

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

Paroles et regards de jeunes: comment le quartier peut-il devenir un lieu de socialisation pour les jeunes ?

La période de l’adolescence est devenue, dans notre société occidentale actuelle, centre de polémiques diverses. L’image véhiculée par les médias n’arrange en rien cette situation, et nous pensons qu’elle est même en partie responsable. L’un des centres de tensions entre les adolescents et les adultes est la fréquentation des espaces publics, tels que préaux d’école, parcs, etc. Afin d’évoquer une problématique globale, la socialisation des jeunes, nous avons choisi de nous intéresser au local, et avons ciblé un quartier bien particulier. « Paroles et regards de jeunes » nous emmène à la découverte d’un quartier populaire, vivant et multiculturel, où les jeunes font des bêtises, comme cela a toujours été, mais nous montrent bien d’autres facettes de leur vie. Nous avons rencontré cinq jeunes, Béchir, Besnik, Besart, Richard et Durim, qui ont accepté de témoigner et nous parler de leur réalité, leur passion, leurs amis, leurs « coups de gueule », leurs besoins, leur regard sur la société et les difficultés qu’ils rencontrent. Cinq professionnels témoignent également. Ils partagent leurs pratiques, leurs expériences, leurs apprentissages et nous font découvrir une facette de cette population trop souvent oubliée. Ce travail de recherche amène des pistes de réflexion, à propos d’un modèle de socialisation, au travers d’un quartier soutenant et sur lequel ces jeunes peuvent se reposer afin de se construire et pouvoir intégrer le monde des adultes au mieux. Nous voulons montrer qu’ils ne sont pas seuls responsables de tous les maux dont les médias et la société les accuse

Supplementary X-ray studies of the Ni-Sn-Bi system

Phase equilibria were studied in the system Ni-Sn-Bi. Special attention has been paid to the identification of the recently found ternary phase. For this purpose samples were synthesized using intimately mixed powders. After annealing and quenching, all alloys were analyzed by scanning electron microscope and by X-ray diffraction. The results give evidences about the existence of a ternary compound with approximate formula Ni6Sn2Bi to Ni7Sn2Bi. Overlapping of some neighboring diffraction peaks of this phase with NiBi and Ni3Sn_LT is the reason for the difficulties related to the X-ray diffraction identification of the ternary phase

Note sur l'involution utérine chez le zébu Gobra

La durée de l'involution utérine chez le zébu Gobra est de 29 plus ou moins 1 jours. Ce résultat a été obtenu par palpation des appareils génitaux de quatre-vingt-trois femelles durant la saison de vêlage 197

Incidencia de gustos musicales compartidos en la formación de grupos de pares al interior del aula : un estudio de caso de alumnos de 8° año básica B del Colegio El Patrocinio de San José

Tesis (Profesor de Educación Musical para la Educación Preescolar y Básica, Licenciado en Educación)Pensando en el marco educativo en el cual los investigadores del presente estudio se desenvolverán como futuros profesores de música, se torna necesario el conocimiento de nuestros alumnos para generar una cercanía con ellos que propicie y favorezca el proceso de aprendizaje, bajo esta premisa el presente estudio se enfoca principalmente en reconocer los estilos musicales que son de preferencia de un grupo específico de alumnos de 8°básico pertenecientes al colegio El Patrocinio de San José, y cómo éstos pudieran incidir en diversos áreas del comportamiento mostrado por el grupo adolescente, de su forma de ser y la forma de relacionarse entre ellos. Bajo una perspectiva constructivista conoceremos algunos ámbitos de la realidad de este curso, el cual pertenece al colegio El Patrocinio de San José, ya que se describe el lugar de estudio y los sujetos estudiados tal como son en la realidad y no como se espera que sean (Hernández et al, 2006) ; además el análisis de la información recabada así como las conclusiones finales se definen y edifican a partir del conocimiento construido en el proceso de este estudio, tanto por parte de los investigadores como de los sujetos de estudio. Así, a partir de dos instrumentos de recolección de datos, se busca observar y comprender los aspectos que más definen y caracterizan a los adolescentes estudiados, en relación a sus intereses, formas de comportarse y cómo influye el ser parte o no de algún subgrupo social al interior del aula, principalmente en relación a las preferencias musicales. Mientras que como principal resultado de esta investigación se destacan las reflexiones que dicho proceso ha otorgado a los investigadores en pro de acercarse a conocer la realidad de un grupo de jóvenes que bien el día de mañana podrían representar un grupo de alumnos; así como la importancia de lograr entender que el cuerpo docente y paradocente debe ser consciente de los aspectos integrales que deben conocerse y desarrollarse, pensando en el ámbito académico y personal de los alumnos.Thinking on the educational frame in which the investigators of the present study will develop as future music teachers, it is absolutely necessary the knowledge of our pupils in order to generate a closeness with them that propitiates and strengthens the learning process. Under this premise the present study focuses principally in recognizing the musical styles which are of the preference of an specifical group of pupils of the 8th basic school and how these styles could incide in the diverse areas of the behaviour shown by the adolescent group, about their way of being and the way of relating among them. Under a constructivist prospect we will learn about certain contours of the reality of this class, that belongs to the El Patrocinio de San José School, since in it the place of the study and the studied subjects are described such as they are indeed and not as they are extected to be /Hernández et al., 2006); besides the analysis of the obtained information as well as the final conclusions are defined and built from the knowledge constructed in the process of this study both by the investigators and the study subjects. So, based on two data collection instruments, it is looked for observing and understanding the aspects that better define and characterize the studied adolescents, in relation to their interests, ways of behaving, and how being part or not being part of a certain social subgroup within the classroom has an influence, principally in relation to the musical preferences. So, as the main result of this investigation, it is stood out the reflections that the process has given to the investigators in order to come close to the reality of a group of young people that perfectly tomorrow represent a pupils group; as well as the importance of reaching the understanding that the teachers and teaching assistants staff must be conscious of the integral aspects that have to be known and developed, thinking on the pupils academic and personal environment

A molecular insight into algal-oomycete warfare: cDNA analysis of <i>Ectocarpus siliculosus</i> infected with the basal oomycete <i>Eurychasma dicksonii</i>

Brown algae are the predominant primary producers in coastal habitats, and like land plants are subject to disease and parasitism. Eurychasma dicksonii is an abundant, and probably cosmopolitan, obligate biotrophic oomycete pathogen of marine brown algae. Oomycetes (or water moulds) are pathogenic or saprophytic non-photosynthetic Stramenopiles, mostly known for causing devastating agricultural and aquacultural diseases. Whilst molecular knowledge is restricted to crop pathogens, pathogenic oomycetes actually infect hosts from most eukaryotic lineages. Molecular evidence indicates that Eu. dicksonii belongs to the most early-branching oomycete clade known so far. Therefore Eu. dicksonii is of considerable interest due to its presumed environmental impact and phylogenetic position. Here we report the first large scale functional molecular data acquired on the most basal oomycete to date. 9873 unigenes, totalling over 3.5Mb of sequence data, were produced from Sanger-sequenced and pyrosequenced EST libraries of infected Ectocarpus siliculosus. 6787 unigenes (70%) were of algal origin, and 3086 (30%) oomycete origin. 57% of Eu. dicksonii sequences had no similarity to published sequence data, indicating that this dataset is largely unique. We were unable to positively identify sequences belonging to the RXLR and CRN groups of oomycete effectors identified in higher oomycetes, however we uncovered other unique pathogenicity factors. These included putative algal cell wall degrading enzymes, cell surface proteins, and cyclophilin-like proteins. A first look at the host response to infection has also revealed movement of the host nucleus to the site of infection as well as expression of genes responsible for strengthening the cell wall, and secretion of proteins such as protease inhibitors. We also found evidence of transcriptional reprogramming of E. siliculosus transposable elements and of a viral gene inserted in the host genome

The mammalian circadian timing system: from gene expression to physiology

Many physiological processes in organisms from bacteria to man are rhythmic, and some of these are controlled by self-sustained oscillators that persist in the absence of external time cues. Circadian clocks are perhaps the best characterized biological oscillators and they exist in virtually all light-sensitive organisms. In mammals, they influence nearly all aspects of physiology and behavior, including sleep-wake cycles, cardiovascular activity, endocrinology, body temperature, renal activity, physiology of the gastro-intestinal tract, and hepatic metabolism. The master pacemaker is located in the suprachiasmatic nuclei, two small groups of neurons in the ventral part of the hypothalamus. However, most peripheral body cells contain self-sustained circadian oscillators with a molecular makeup similar to that of SCN (suprachiasmatic nucleus) neurons. This organization implies that the SCN must synchronize countless subsidiary oscillators in peripheral tissues, in order to coordinate cyclic physiology. In this review, we will discuss some recent studies on the structure and putative functions of the mammalian circadian timing system, but we will also point out some apparent inconsistencies in the currently publicized model for rhythm generatio