Laser additive manufacturing of bulk and powder ceramic materials: mathematical modeling with experimental correlations

Abstract

Purpose This paper aims to develop efficient and simple models for thermal distribution, melt pool dimensions and controlled phase change in the laser additive manufacturing (AM) of bulk and powder particles ceramic materials. Design/methodology/approach This paper proposes new analytical models for the AM of bulk and powder bed ceramic materials. A volumetric moving heat source, along with the complete melting of bulk and powder particle materials, is taken into account. Different values of laser absorption coefficient in solid and liquid states have been used to investigate the phase transformation. Furthermore, the pores and voids dimensions are also included in the modeling. Theoretical predictions have been compared with the experimental analyses and finite element simulations in laser to silicon nitride and laser to alumina interaction. The analysis focuses on the impact of laser power and scanning speed on the melt pool width and depth evolution into the bulk substrate and powder bed. Findings This study shows that the powder particles exhibit a higher thermal distribution value than the bulk substrate because of voids in the powder layer. The laser beam experiences multiple reflections in the presence of porosity/voids, thus increasing the surface absorption coefficient, which becomes relevant with the increment in the pore/void dimension. A direct relationship has been found between the laser power and melt pool dimensions, while the scanning speed displayed an inverse relationship for the melt pool width and length. Larger melt dimensions were inferred in the case of laser–powder particle interaction compared with laser–bulk substrate interaction. A close correlation was found between the analytical simulations, experimental investigations and numerical simulation results within the range of 4%–8%. Originality/value This paper fulfills an identified need to develop efficient and simplified models for ceramics laser AM by taking into account different laser absorption coefficients in solid and liquid form, voids and pores dimensions and controlled phase transformation to avoid vapors and plasma formation. The limitation of the finite element simulation model is that the solution is strongly dependent on the mesh quality and accuracy directly linked to the computation efficiency and time. A finer mesh requires a longer computing time than a coarse mesh. Finite element simulations require, however, specialized skills.

Thermal History Mapping in Powder Bed Laser Sintering at the Micrometer Scale

“…More recently, several authors have presented modeling results combined with experimental measurements on materials other than metals, such as polymers. − Concerning ceramic materials, only a few studies comparing numerical model/experimental results have been found in the literature. However, we can cite the work of Mahmood et al, who developed a mathematical model using MATLAB software to study the temperatures reached during laser sintering on a bulk substrate of silicon nitride (Si 3 N 4 ) and on a alumina powder bed (Al 2 O 3 ) . With their numerical model, they can predict the temperature distribution during the laser radiation–matter interaction with 8% accuracy.…”

“…However, we can cite the work of Mahmood et al, who developed a mathematical model using MATLAB software to study the temperatures reached during laser sintering on a bulk substrate of silicon nitride (Si 3 N 4 ) and on a alumina powder bed (Al 2 O 3 ). 23 With their numerical model, they can predict the temperature distribution during the laser radiation–matter interaction with 8% accuracy. Thus, numerical modeling is appropriate to simulate the thermal diffusion inside metallic or polymer layers during the SLS process.…”