Microstructure and properties of jet pulse electrodeposited Ni-TiN nanocoatings

The current work investigates the successful preparation of Ni-TiN coatings via the jet electrodeposition method. The x-ray diffraction, high-resolution transmission electron microscopy, electrochemical workstation, and triboindenter were used to analyze the structure, mechanical deformation response, and corrosion properties of the coatings. The results reveal that the Ni-TiN coating produced by the deposition method had a fine and uniform microstructure at a 5 g/L concentration of TiN. The mean sizes of TiN nanoparticles and Ni grains were found to be 23.3 and 43.9 nm, respectively. The corrosion potential of the Ni-based TiN coating obtained at 5 g/L by electrodeposition was as minimum as − 0.396 V with a corrosion current density of 1.06 × 10−3 mA/cm2. The Ni-TiN coatings prepared, respectively, at three different concentrations (3, 5, and 8 g/L) under the applied load of 1500 µN were about 34.9, 28.2, and 30.3 µm in vertical depth, respectively. The coatings obtained at 5 g/L had the maximum nanohardness of 34.5 GPa when compared to the other coatings. In addition, the coatings were then subjected to three sliding scans, and the Ni-TiN coating prepared at 5 g/L showed the least magnitude of wear damage and plastic deformation when compared to the other coatings.This work has been supported by the Natural Science Foundation of China (Grant No. 51974089)

A Fluid-Solid-Magnetic Coupling Algorithm of Internal Crack Growth in the Weld of Oil and Gas Pipelines

In order to characterize the dynamic process of the crack growth in the weld of oil and gas pipelines, a mathematical model of fluid-solid-magnetic multifield coupling was constructed in this paper. Based on this model, the bidirectional fluid-solid coupling and unidirectional magnetic structure coupling caused by the weld deformation were achieved by dynamic application of the fluid permeation pressure, calculating the internal crack growth in the pipe weld, reconstructing the computational grid near the internal crack, and discussing the characteristics of the magnetic leakage field in the process of the internal crack growth in pipe weld. Thus, a fluid-solid-magnetic coupling algorithm for the internal crack growth in pipe welds considering fluid permeation pressure is established. According to the characteristics of the internal crack opening distance, internal crack growth length, crack tip energy release rate, peak values of magnetic induction intensity level, and vertical component, the process of the internal crack growth is measured. The results show that the fluid osmotic pressure accelerates the process of the internal crack growth and this algorithm can solve the problem of the characterization and evaluation of crack growth in pipe welds under fluid-solid-magnetic coupling action

Effect of different heat-treated temperatures upon structural and abrasive performance of Ni-TiN composite nanocoatings

This study reports the synthesis of Ni-TiN composite nanocoatings on a Q235 steel matrix using the electrodeposition technique, and were then treated at different temperatures. The surface morphology, structure, hardness, and abrasion performances of composite nanocoatings were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), and friction-abrasion testing machine. SEM images illustrated smooth/dense surface morphology for Ni-TiN composite nanocoatings treated at 250 °C. XRD patterns revealed Ni and TiN phase appearance within Ni-TiN composite nanocoatings. The broader and low-intensity XRD peaks were observed for the composite following heat treatment at 250 °C, indicating the smallest size of TiN particle and Ni grain. Furthermore, Ni-TiN composite nanocoatings exhibited the highest hardness of 821 Hv following heat treatment at 250 °C. The frictional coefficient, wear rate, and indentation depth for Ni-TiN composite nanocoatings were found to be lowest at 0.45, 0.58 mg/min, and 13.8 μm, respectively after heat treatment at 250 °C. Furthermore, the Ni-TiN composite nanocoatings had peak abrasion resistance across three composite nanocoatings following heat treatment at 250 °C