Effect of infill strategy on the flexural strength of 3Y-TZP bars fabricated by thermoplastic 3D printing (T3DP)

Thermoplastic 3D printing (T3DP) is a ceramic additive-manufacturing (AM) process that uses a thermoplastic feedstock. During T3DP, parts are manufactured by rapid deposition of micron-sized droplets, which fuse and solidify to form lines that fuse further to form layers. This building logic allows modifying the direction of droplet (and line) deposition, and can affect the mechanical properties. Here, we have studied, for the first time, the effect of 0 degrees and 90 degrees infill strategies as well as their combination (0 degrees + 90 degrees) on the strength of fabricated and sintered 3Y-TZP bending bars. The 0 degrees infill strategy had the highest characteristic strength and Weibull modulus. Unlike fused filament fabrication, the strength and Weibull modulus for the 90 degrees infill strategy were not significantly inferior to 0 degrees strategy, due to the better fusion of subsequent lines. However, the 0 degrees + 90 degrees infill strategy had the least strength due to alternating infill strategies each layer.