Papers by Keyword: Particle Dispersing

Abstract: The laser surface-treatment methods have been quickly developed by appearing of lasers with high power beam and can increase the hardness, of the surface. A very hard, wear-resisting layer can be produced by the dispersing of ceramic grains. The essence of the technology is, that such a material (compound-phase, e.g.: metal-oxide, carbide, nitride, etc.) is added to the surface layer melted by laser, which does not solve or solves only partly in the metal-melt. This work studies the effect of the different technological parameter (such as, power of the laserbeam, motion speed, amount of the ceramic particles etc.) on the different microstructure accrued during the laser surface alloying. The desired microstructure has homogeneous carbide distribution in the matrix. But it is embarrassed by several conditions. The aim of this present work is to find out the reasons for the inhomogeneous ceramic particle distribution inside the matrix and to discover these embarrassing conditions.

Abstract: The present work aims to analyze the dispersion process (path) of the solid particles by moving a spherical particle from the feeding-nozzle outlet till the penetration of the melted surface (by the laser beam) and then its path in the metal bath. In laser surface treatment technologies with injection of hard particles in the melting bath it is necessary for the particles to work against the surface stress to penetrate through the surface of the bath into the melt. The theory shown was used in precalculations for the experiments carried out dispersing carbide particles (WC, TaC, NbC). Powder of particles of all three types were dispersed by means of the Ar carrying gas into an C15 steel melt by CO₂ laser. Evaluating the results of this process taking into consideration different specific technological parameters (speed of the beam, powder feeding speed) one can conclude that all three carbide types can penetrate into the melt.