Investigation of delamination mechanisms during a laser drilling on a cobalt-base superalloy

Temperatures in the high pressure chamber of aircraft engines are continuously increasing to improve the engine efficiency. As a result, constitutive materials such as cobalt and nickel-base superalloys need to be thermally protected. The first protection is a ceramic thermal barrier coating (TBC) cast on all the hot gas-exposed structure. The second protection is provided by a cool air layer realized by the use of a thousand of drills on the parts where a cool air is flowing through. The laser drilling process is used to realize these holes at acute angles. It has been shown on coated single crystal nickel-base superalloy that the laser drilling process causes an interfacial cracking (also called delamination), detected by a cross section observation. The present work aims at characterizing interfacial cracking induced by laser drilling on coated cobalt-base super alloy. On the one hand, this work attempted to quantify the crack by several microscopic observations with regards to the most significant process parameters related as the angle beam. On the other hand, we studied the difference of the laser/ceramic and the laser/substrate interaction with real time observation by using a fast movie camera

Fütterungsrichtlinien nach Bio Suisse

Knospe-Tiere sollen artgerecht und möglichst vollständig mit Knospefutter gefüttert werden. Das Ziel «100 % Biofutter» ist bei den Wiederkäuern, Pferden und Kaninchen erreicht. Schweine und Geflügel dürfen noch höchstens fünf Prozent konventionelles Futter fressen, sofern es sich dabei um Eiweisskomponenten handelt. Der Anteil an ausländischem Knospe-Futter für Wiederkäuer wird reduziert

Affouragement 2023 Directives de Bio Suisse

Les animaux Bourgeon doivent être affouragés de manière à respecter l’espèce et si possible entièrement avec des aliments Bourgeon. L’objectif «affouragement 100 % bio» est atteint pour les ruminants, les chevaux, les lapins, les porcs d’engraissement et d’élevage, ainsi que les volailles. Les porcelets et les jeunes volailles peuvent encore être affouragés avec des aliments conventionnels à hauteur de 5 %, pour autant qu’il s’agisse de protéines. Pour les ruminants, 100 % des fourrages doivent provenir de productions Bourgeon suisses

Simulation of the laser drilling process with the Constraint Natural Element Method

These works present a numerical alternative to the simulation of the laser drilling process. The use of the finite element method to modeling the hole creation during a laser pulse shows difficulties in front of a moving boundary problem. This moving boundary is induced by a fast phase transformation and also by high thermal gradient. The C-NEM (Constraint Natural Element Method) was tested in order to solve these numerical difficulties and to use the high potential of this original method. The physical interaction of the laser drilling will be reminded and the chosen mathematical model will be specified. A simulation was made with the data for pure iron in order to validate the numerical choice

Simulation numérique du perçage laser par la méthode C-NEM

Ces travaux présentent une alternative numérique au problème de simulation du procédé de perçage par laser. L’utilisation des éléments finis pour modéliser la propagation du trou au cours du temps montre des limites face à un problème de frontières mobiles induit par un changement de phase rapide et des forts gradients thermiques. L’utilisation d’un code C-NEM a donc été testé avec comme objectif de résoudre ces difficultés numériques et d’utiliser le fort potentiel de cette méthode originale. Le principe physique du perçage laser sera rappelé et le modèle mathématique choisi pour le modéliser sera précisé. Un cas test de simulation a été réalisé avec les grandeurs physiques du fer pur afin de valider le choix du code C-NEM

Simulation of the laser drilling process with the Constraint Natural Element Method

These works present a numerical alternative to the simulation of the laser drilling process. The use of the finite element method to modeling the hole creation during a laser pulse shows difficulties in front of a moving boundary problem. This moving boundary is induced by a fast phase transformation and also by high thermal gradient. The C-NEM (Constraint Natural Element Method) was tested in order to solve these numerical difficulties and to use the high potential of this original method. The physical interaction of the laser drilling will be reminded and the chosen mathematical model will be specified. A simulation was made with the data for pure iron in order to validate the numerical choice

Betriebsmittelliste 2010 für die Schweiz

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Study of spatter ejections during laser-powder bed fusion process for aluminum alloys

During L-PBF process on aluminum alloys, instabilities such as spatter ejections result from the laser-matter interaction. These spatters create a variety of defects and affect the mechanical properties of the final parts. To help understanding this phenomenon, a global method was developed, combining experimental study and image analysis. This system provides statistic information on spatter population (radius, velocity, direction and emission rate) and the idea of pollutant spatter is defined. Four aluminum alloys are compared. The results show the oxygen content in the fabrication chamber has no effect on the spatter ejection dynamic. The spatter velocity, angle of ejection and size increase with the intensity. Also, significant differences are noticed between the different alloys