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Zirconia-toughened alumina (ZTA) is widely applied in total hip arthroplasty (THA). However, problems with insufficient fracture toughness and lubrication remain, leading to wear, squeaking, and fracturing. In this study, the Cu doping of ZTA (Cu-ZTA) is proposed to solve these problems. To further promote the use of Cu-ZTA, the role of Cu doping on its tribological properties must be studied. In this study, the microstructure, mechanical properties, and stability capacity in a physiological environment, as well as the tribological behaviors of Cu-ZTA in phosphate-buffered saline (PBS) and bovine serum albumin (BSA), were systematically studied with varying amounts of Cu. The results demonstrated that holes and soft Cu-rich phases appeared, and grains grew after Cu doping, causing a decrease in hardness. The fracture toughness increased after Cu doping because the Cu-rich particles formed "bridges" during crack propagation and release energy. The incorporation of Cu improved the stability of ZTA in physiological environments, which enhanced the long-term stability of Cu-ZTA. The protein adsorption results indicated that a higher hydrophobicity and roughness contributed to a greater protein adsorption on the Cu-ZTA surfaces after Cu incorporation. In the BSA solution, the 5.0 wt% Cu-ZTA ceramics achieved a lower coefficient of friction (COF) and wear rate compared to ZTA, and a higher protein adsorption and formation of the denatured protein layer catalyzed by Cu ions in the wear track during friction, thus clearly improving the tribological properties of the Cu-ZTA. [ABSTRACT FROM AUTHOR]

Cu-doped, ZrO 2 -toughened alumina (ZTA) ceramics with varying amounts of Cu (0, 1.5, 3.0, and 5.0 wt%), denoted as Cu/ZTA, were prepared using a fast hot pressing sintering furnace. The microstructure, mechanical properties, tribological properties, and wear mechanism of Cu/ZTA ceramics were subsequently studied. The results showed that Cu doping can cause the formation of holes in the ZTA ceramics. The formation of holes originated from the O 2 produced by CuO decomposition at high temperatures and the phase transformation of ZrO 2. Cu/ZTA ceramics with 5.0 wt% Cu exhibited significantly improved toughness and tribological properties but diminished hardness. The worn surface analysis of the Cu/ZTA ceramics revealed that their wear mechanism primarily involved abrasive wear and material transfer. The ZrO 2 and Cu particles were first pulled out from the wear track to form wear debris during friction. The 5.0 wt% Cu/ZTA ceramic exhibited decreased hardness and high toughness, which made it easier for the abrasive debris to adhere to the surface and holes. Additionally, the wear debris was crushed into the holes formed by Cu doping. The results indicated that a reduction in the number of wear particles at the friction interface could impede the wear of the abrasive particles. Overall, the Cu/ZTA ceramic with 5.0 wt% Cu was found to be a promising structure material with excellent tribological properties. [ABSTRACT FROM AUTHOR]

Pitting corrosion of steel bars can greatly impair mechanical properties of steel bars, so detecting pitting corrosion timely and accurately is crucial for assessing the health of structures. However, most current corrosion detection methods have some difficulties measuring pitting corrosion level of steel bars effectively. Considering that corrosion pits can cause strain redistribution of steel bar in the tensile state, this study proposes a method to quantitatively determine the pitting corrosion level through monitoring the steel strain distribution. Distributed optical fiber sensors (DOFS) based on Rayleigh scattering and capable of achieving the spatial resolution in millimeter scale were adopted to monitor the strain distributions of notched HRB400E steel bars subjected to tensile stress, and finite element (FE) method was employed to analyze the strain distributions of steel bars with different pit geometries. Experimental results showed that the bare fiber sensors (PI-FS) measured steel strain more accurately than jacketed fiber sensors. From strain distributions monitored by PI-FS, the pit location and pit length can be directly determined. Further, FE results revealed that the strain distribution along the fiber sensor position was significantly affected by the fiber sensor position relative to the pit mouth. Finally, the procedures to determine the pitting corrosion level from DOFS data and FE results were presented by mathematically comparing the similarity of strain curves given by the fiber sensor on a pitting-corroded bar and FE analyses of steel bars with different corrosion levels. In the end, the issues related to the practical applicability of the proposed method were discussed and limitations of this study were addressed. Although with limitations, this study provided a novel and promising way to quantitatively monitor the pitting corrosion level based on the strain distribution of steel bars. • New method to monitor pitting corrosion level by DOFS was proposed. • Position of fiber sensors relative to the pit mouth governed the strain distribution according to FEM. • Pitting corrosion quantification was achieved by matching strain distributions from DOFS and FEM. [ABSTRACT FROM AUTHOR]