학술논문
Srovnání kontaktního a optického měření povrchu laserem natavených vrstevComparison of contact and optical measuring of laser remelting layers
Document Type
TEXT
Source
Subject
Language
Czech
Multiple Languages
Multiple Languages
Abstract
Jednou z mnoha aplikací pulsního Nd:YAG laseru je přetavování tenkých nitridových vrstev, nanesených metodou PVD (Physical Vapor Deposition) na ocelové substráty. Očekávaným výsledkem je snížení porosity vrstev a zvýšení adheze k základnímu materiálu. Pro optimalizaci parametrů procesu byla provedena řada experimentů s proměnnou energií, délkou a frekvencí pulsu a v různých vzdálenostech povrchu vzorku od ohniska. Se zvyšující se hustotou plošné energie laserového svazku dochází k vypařování základního materiálu a trhlinám ve vrstvách. Proto je důležitá následná analýza, která byla provedena moderními metodami: laserovou konfokální mikroskopií a snímáním povrchu na kontaktním profilometru Talysurf. Získaná data převádí počítačové programy na plošná a prostorová zobrazení v různých modifikacích - profily, kontury, fotosimulace apod.
Laser beam of the infrared pulsed Nd:YAG laser was used to re- melting PVD (Physical Vapour Deposition) coatings on the steel substrates. Processing parameters such as pulse energy, pulse length and frequency were optimized according surface temperature. Multimode beam diameters about some millimetres were computed and adjusted in the suitable distance from focus plane. High laser power re-melting decreases their porosity, increases adhesion to basic material. In case of high laser energy gas vapours escape from basic material and cause fissures, re-melted surfaces have to be carefully controlled. New approach to evaluation of the quality surface structure was realized by laser confocal microscopy. Direct measuring or 3D surface model is possible with resolution less than hundred nanometres, depressions along laser beam path or rises on the laser spot edges were determined. Particles and grains with dimensions about one micron in re-melting structures can be observed better then by optical microscopy. Parallel measurements of the surface roughness were realized by the contact inductive profilometer Talysurf, collected data were displayed by software tool Talymap in a plane or spatial pictures.
Laser beam of the infrared pulsed Nd:YAG laser was used to re- melting PVD (Physical Vapour Deposition) coatings on the steel substrates. Processing parameters such as pulse energy, pulse length and frequency were optimized according surface temperature. Multimode beam diameters about some millimetres were computed and adjusted in the suitable distance from focus plane. High laser power re-melting decreases their porosity, increases adhesion to basic material. In case of high laser energy gas vapours escape from basic material and cause fissures, re-melted surfaces have to be carefully controlled. New approach to evaluation of the quality surface structure was realized by laser confocal microscopy. Direct measuring or 3D surface model is possible with resolution less than hundred nanometres, depressions along laser beam path or rises on the laser spot edges were determined. Particles and grains with dimensions about one micron in re-melting structures can be observed better then by optical microscopy. Parallel measurements of the surface roughness were realized by the contact inductive profilometer Talysurf, collected data were displayed by software tool Talymap in a plane or spatial pictures.