Now showing 1 - 2 of 2
  • Publication
    Ultrafine grain formation and coating mechanism arising from a blast coating process: a transmission electron microscopy analysis
    This article examines the substrate/coating interface of a coating deposited onto mild steel and stainless steel substrates using an ambient temperature blast coating technique known as CoBlast. The process uses a coincident stream of an abrasive blast medium and coating medium particles to modify the substrate surface. The hypothesis for the high bond strength is that the abrasive medium roughens the surface while simultaneously disrupting the passivating oxide layer of the substrate, thereby exposing the reactive metal that then reacts with the coating medium. The aim of this study is to provide greater insight into the coating/substrate bonding mechanism by analysing the interface between a hydroxyapatite coating on both mild and stainless steel substrates. The coating adhesion was measured via a tensile test, and bond strengths of approximately 45 MPa were measured. The substrate/coating interface was examined using transmission electron microscopy and selected area diffraction. The analysis of the substrate/ coating interface revealed the presence of ultrafine grains in both the coating and substrate at interface associated with deformation at the interface caused by particle impaction during deposition. The chemical reactivity resulting from the creation of these ultrafine grains is proposed to explain the high adhesive strength of CoBlast coatings.
      471Scopus© Citations 5
  • Publication
    Nanostructured apatite-mullite glass-ceramics for enhanced primary human osteoblast cell response
    This work investigates the difference in viability of primary human foetal osteoblast cells on a glass-ceramic surface with nanoscale topography relative to viability on a smooth glass-ceramic surface containing a bioactive phase. Apatite-mullite glass-ceramics containing bioactive fluorapatite (Ca10(PO4)6F2) and bioinert mullite (Si2Al6O13) were synthesised and subsequent heat-treatment was optimised to form nano-sized fluorapatite crystals. Etching was used to selectively remove the bioactive phase, producing a surface with disordered nanoscale topography. Cells were seeded onto a smooth polished glass-ceramic substrate with the bioactive phase intact, an etched nanostructured glass-ceramic with the bioactive phase removed, and a borosilicate glass control. Cell viability after 24 h and 48 h was significantly greater on the nanostructured surface compared to the smooth bioactive surface, while cell viability at both time points was significantly greater on both nanostructured and smooth bioactive surfaces compared to the control.
      254Scopus© Citations 4