Browsing by Author "Yong, Sun"

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    Effect of environments on the tribological behaviour of pure and graphene coated nickel against stainless steel counterpart
    (Inderscience, 2023) Zahra, Iram; Yong, Sun; Zeeshan, Anjum; Meysam, Azadani; Ambreen, Tajmal
    Friction and wear are a major cause of failure experienced by the mechanical components. Service life of these components can be improved by the application of different surface modifications and lubricating techniques. In this research work, tribological investigation of pure and graphene coated nickel specimens, in contact with stainless steel ball was conducted using pin-on-disc (PoD) tribometer test setup. Multilayered graphene coatings, approximately 20 nm in thickness, were applied using atmospheric pressure chemical vapor deposition (APCVD). Tests were conducted under similar loading conditions in four different environments: dry ambient, distilled water, saline water (3% NaCl) and mineral oil. Maximum coefficient of friction (COF), wear debris and wear track width were observed when pure nickel specimens were tested under dry ambient conditions. Graphene coating caused significant reduction in COF as well as in the width of wear scars. A minimum COF of 0.05 was achieved in graphene coated specimens under dry and mineral oil environments. Abrasive wear was the dominant phenomenon in case of pure nickel and stainless steel tribopair, while adhesive wear was observed in graphene coated and stainless steel tribopair. Microscopic analysis also revealed corrosive phenomenon in NaCl environment.
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    ItemOpen Access
    Insight into the mechanical properties of 3D printed strut-based lattice structures
    (Springer, 2022-12-15) Ali, Hafiz Muhammad Asad; Abdi, Meisam; Yong, Sun
    Since the development of additive manufacturing (3D printing), there has been a growing interest in the use of 3D printed lattice structures for a range of mechanical and biomedical applications. This study investigates the elastic properties of different types of strut-based lattice structures obtained through a series of compression tests and compares them against numerically calculated properties of intended designs. Two different 3D printing processes are employed for the fabrication of lattice structures, including selective laser sintering (SLS) and digital light processing (DLP). Gibson-Ashby power-law for cellular structures has been initially utilised as a framework for the comparison of numerical and experimental results. The results are normalised, allowing the comparison of elastic properties of lattices made in different polymer materials independent of the bulk material properties. This study suggests that although the mechanical properties of the fabricated parts are heavily dependent on the design of lattice unit-cell, the mechanical properties can be significantly different to those of intended designs depending on the 3D printing process used for the fabrication of lattice structures.