The laser surface modification of advanced ceramics: A modeling approach

Abstract

A numerical approach for predicting microstructures during the laser surface modification of ceramics has been proposed. Laser surface modification is a near-non-equilibrium or non-equilibrium process involving high cooling rates (10 2 -10 8 K/s) leading to rapid solidification. As the basic governing solidification theory behind conventional processes like casting and laser processing is the same, the approach and the theory behind the conventional processes can be extended to such near-non-equilibrium processes by adequately modifying the conventional models. This study looks at various challenges in modeling the laser processing phenomena and elaborates on present efforts and future modeling goals.

Laser beam operation mode dependent grain morphology of alumina

“…The high cooling rates ͑10 2 -10 8 K / s͒ encountered during the rapid solidification process such as laser surface processing generate near or nonequilibrium conditions, 9 which can lead to solidification of the melt at a temperature different from the equilibrium melting temperature of alumina ͑ϳ2323 K͒. The difference between the melting point of the ceramic and the temperature at which actual solidification occurs is the undercooling.…”

“…Porous alumina has also been widely used as a grinding wheel material and laser dressing of these wheels is gaining importance, as it is a noncontact process providing better automation and control. [5][6][7][8][9][10] Porosity is maintained in alumina for various reasons including but not limited to thermal expansion, thermal conductivity, toughness, and for lodging of metal particles during grinding operation.…”

“…11 cw lasers have been extensively used for porous alumina surface modification and generated microstructures have been diligently discussed in the past. [5][6][7][8][9][10] However, the effect of pulsed laser processing on surface microstructure of porous alumina ceramic has not been carefully studied yet. Hence, the present study aims at comparing the microstructures in surface modified region of porous alumina due to PM laser operation with those obtained by cw laser operation and understanding the physical phenomena underlying these two processes which could cause the transition in microstructure.…”

Microstructure and Tribological Behavior of Laser in Situ Synthesized TiC-Reinforced Fe-Based Composite Coatings

“…Laser surface engineering (LSE) technology is based on manipulating laser as a heat source to modify the surface properties of components [6][7][8][9][10][11]. It represents an advanced hardfacing technology for the deposition of hard layer with controlled thickness onto the selected area of a metallic substrate.…”

Laser modified microstructures in ZrB2, ZrB2/SiC and ZrC

“…Moreover, laser surface modification (LSM) has emerged as a flexible and convenient technique for improving the surface properties of oxide ceramics including of porous alumina. [19][20][21][22] The objectives of this paper are to demonstrate the feasibility of using laser heating techniques to study: (a) the oxidation characteristics of ZrB 2 -based UHTCs in air at temperatures between 2000 and 3000 • C; (b) the thermo-physical behaviour of ZrC in vacuum at temperatures approaching 4000 • C; and (c) the surface microstructural evolution of non-oxide ceramics, i.e. Zr-based UHTCs.…”