0000000000489773
AUTHOR
A.b. Vannes
MoSi2 laser cladding—a comparison between two experimental procedures: Mo–Si online combination and direct use of MoSi2
International audience; There are very strong interests in developing low density advanced material systems for service at temperatures up to 1300°C. These materials should mainly have moderate fracture toughness at low and intermediate temperatures and should exhibit oxidation resistant behaviour. The intermetallic compound, MoSi2 has been considered to be an attractive candidate due to its melting point (2030°C) and excellent oxidation resistance at high temperatures. In this paper, we compare the results obtained with two different techniques for laser cladding, one using an online combination between Mo and Si powders, the second using direct injection of the MoSi2 powder.
A theoretical model for laser and powder particles interaction during laser cladding
Abstract Interactions between the laser and the powder particles lead to attenuation of the laser and make the powder particles temperatures raise. According to given stream spread and speed of the powder particles, their temperature distribution at the surface of the workpiece is calculated. The attenuation of the laser induced by the cloud is also computed. These results are plotted for the case of a Gaussian distribution. Results show that with the increasing of the powder jet incidence angle, both temperature distribution of powder particles and attenuation of the laser have very different profiles. Their effects on the clad should be considered for modelling of laser cladding.
Dépôts par projection de poudre dans un faisceau laser Nd:YAG : cas des faibles puissances
Ce travail fait suite a celui de F. Lemoine [1]. Il concerne la modelisation des depots realises par projection d'une poudre metallique dans un faisceau laser Nd:YAG. Son originalite concerne notamment l'utilisation de faibles puissances laser (P < 800 W). Dans ce domaine, nous avons montre l'existence, en fonction de la puissance laser, de deux seuils associes a la masse des revetements realises. L'etude theorique est fondee sur le calcul de la fluence (J/cm- 2 ) fournie au substrat et l'utilisation d'un modele de transfert de chaleur a l'interieur de celui-ci. Les hypotheses emises et verifiees sont que: i) le premier seuil correspond a la puissance laser minimale a mettre en oeuvre afin …
Numerical investigation of laser beam shaping for heat transfer control in laser processing
This article presents a thermal finite volume model adapted to investigate laser processes. It is specially developed to treat moving heat sources with phase changes, melting and vapourisation. Heat transfer control in laser processing is particularly useful when processes must respect prescribed temperatures, or more generally, prescribed constraints. These processes involve generally several laser sources, or non-conventional power distribution. Hence, they have numerous parameters to set. Experimental optimisation is difficult and may be expansive. The numerical model is a useful and cheaper tool for development of those complex processes. For example in this article, two special laser p…