Macro to Atomic Scale Characterization of 3 mol% Yttria‑Stabilized Tetragonal Zirconia Polycrystalline (3Y‑TZP) Ceramics for Welding Pin Applications

摘要

This study aims to develop a zirconia-based ceramic with high mechanical properties for welding pin applications. 3 mol%yttria-stabilized tetragonal zirconia polycrystalline (3Y-TZP) nanopowders were synthesized by the hydrothermal method.According to the powder characteristics, the obtained powders only consisted of t-ZrO_2 grains with high surface area(107 ± 1.1 m~2/g) and nano-sized individuals (7.2 ± 0.2 nm average) as well as Y_(0.05)ZrO_(1.5) at % chemical composition.The 3Y-TZP nanopowders were densified up to 99.10 ± 0.1% relative density by pressureless sintering at 1500 °C for 2 h.Crystalline phases were determined as 73.5 ± 1 vol.% t-ZrO_2 and 26.5 ± 1 vol.% m-ZrO_2 in the sintered body using X-raydiffraction (XRD) analysis. Vickers hardness and indentation fracture toughness values were measured as 9.5 ± 0.4 GPaand 15.17 ± 0.2 MPa·m~(1/2) in 3Y-TZP sintered ceramics,respectively. Scanning electron microscopy (SEM) observationsshowed homogeneous microstructure with submicron grains (780 ± 5 nm) in sintered samples. Aberration-corrected scanningtransmission electron microscopy (AbC-STEM) revealed the presence of t-ZrO_2 to m-ZrO_2 phase transformation intwinning grains giving rise to high fracture toughness in 3Y-TZP ceramics. As an end-product, ceramic welding pins wereproduced from hydrothermally synthesized 3Y-TZP nanopowders. They withstood the 300,000.00 ± 5000.00 welded nutsin the performance test. This makes the 3Y-TZP ceramics an outstanding material in the projection nut welding process.