Effect of sintered neck distribution on strength of 3D printing coated Al₂O₃ parts

Abstract

The influence of the particle size distribution on the strength of the coated Al2O3 parts was studied, through the size and distribution of the sintered neck. The powder was heated in situ by a UV laser, and the relationship between the sintered neck waist diameter and the particle diameter was obtained under an image measuring apparatus. A particle packing model was established, and the distribution of the sintered neck was corresponding to the particle coordination point, then the projected area ratio of the sintered neck that was broken in a certain section was calculated. As for the coated Al2O3 powder with the resin content of 2%(mass fraction), the results indicate that the sintered neck waist diameter increases from 40μm to 100μm as the particle diameter increases from 75μm to 375μm. The packing simulation results show that the projected area ratio decreases from 0.2557 to 0.0823, as the particle diameter increases from 75-107μm to 300-375μm, which is consistent with the experimentally measured tensile strength of the coated Al2O3 powder. The 70/100, 100/140 mesh powder are mixed to simulate based on the mass ratios of 0:10, 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, 9:1, 10:0. The projected area ratio decreases from 0.1772 to 0.1264 and the porosity increases from 0.4511 to 0.4633. Considering the tensile strength and gas permeability, the optimization result is that the ratio is 7:3, the projected area ratio is 0.1481 and the porosity is 0.4596.

Keywords

• sintered neck
• particle packing
• coated Al₂O₃ powder
• tensile strength
• 3D printing
• select-ive laser sintering