Effects of titanium diboride on the mechanical, tribological, and microstructural properties of alumina toughened co-doped (Y-Mg) stabilized zirconia composites
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For the first time, this work purposes a novel composite production from alumina-toughened zirconia titanium diboride (ATZ-TiB2). In designing the composites, the matrix was composed of 3 mol % yttria (Y2O3) stabilized tetragonal zirconia polycrystalline (3Y-TZP) and 8 mol % magnesia (MgO) partially stabilized zirconia (8 Mg-PSZ) phases at an equal molar ratio. Besides, alumina (α-Al2O3) and TiB2 were added to the 3Y-TZP/8 Mg-PSZ matrix with 1 wt% and 0.5–2 wt% ratios, respectively. The composites were densified up to ~ 97% of their theoretical density (TD) through pressureless sintering at 1500–1600 °C for 1–2 h. The mechanical and tribological characteristics of ATZ-TiB2 composites were characterized by Vickers hardness (HV), indentation fracture toughness (KIc), flexural strength (σ), and wear tests. According to the best results, ATZ-0.5 wt% TiB2 composite (at 1500 °C-1 h) revealed the HV = 8.05 ± 0.25 GPa and KIc = 6.35 ± 0.25 MPa m1/2, whereas that of the reference sample no including TiB2 (at 1500 °C-1 h) exhibited the HV = 5.95 ± 0.25 GPa and KIc = 4.92 ± 0.25 MPa m1/2, respectively. The highest σ value was measured as 431 ± 18 MPa for ATZ-1% wt. TiB2 composite (at 1500 °C-2 h), while the reference sample’s σ value was seen as 409 ± 25 MPa (at 1500 °C-2 h). The wear rate W = 12 × 10–5 mm3 m−1 for ATZ-0.5 wt% TiB2 was quite lower than the reference sample’s W = 2710 × 10–5 mm3 m−1 (at 1500 °C-1 h). Based on the advanced electron microscopy and crystallographical analyses, thermally assisted t-ZrO2 → m-ZrO2 phase transformation and TiB2’s intrinsic hardness were crucial for enhancing mechanical and tribological properties. Therefore, it is anticipated that the ATZ-TiB2 composites can be considered a potential candidate for structural applications such as ceramic bushings and welding pins. Graphical abstract: [Figure not available: see fulltext.] © 2021, The Author(s), under exclusive licence to Springer Nature Switzerland AG.