Effects of variable thermal properties on evaporative cutting with a moving CW laser
Abstract
Evaporative cutting of a semi-infinite body by a moving, high power, CW, Gaussian laser beam is considered. The convective losses in such a situation are small and the conductive losses have been taken into account by using a simple integral method. The materials considered in this study are silicon based ceramics, which show strong variations of thermal diffusivity and absorptivity with temperature. These property variations have been included in the present model. Groove shapes are presented using this simple model for both, constant properties and variable properties for different speeds and power levels for two ceramics. The results indicate that variable property effects increase as the beam intensity at the surface is reduced. This is attributed to the increase in conduction losses under these conditions. Comparisons are also made with available experimental results for material removal rates of Silicon Nitride. The present results show good agreement with experiment. However, radiative properties need to be known more accurately at the evaporation temperature, if groove shapes and material removal rates are to be predicted with greater accuracy.
- Publication:
-
Heat Transfer in Space Systems; Proceedings of the Symposium, AIAA/ASME Thermophysics and Heat Transfer Conference
- Pub Date:
- January 1990
- Bibcode:
- 1990asme.conf..101R
- Keywords:
-
- Continuous Wave Lasers;
- Laser Cutting;
- Thermodynamic Properties;
- Brittle Materials;
- Ceramics;
- High Power Lasers;
- Thermal Diffusivity;
- Lasers and Masers