Advanced surface engineering : evaluation of SprayStir

  • Tom Peat

Student thesis: Doctoral Thesis

Abstract

The objective of this study was the development of an innovative surface engineering technology, referred to as SprayStir, which combines two existing surface engineering processes; cold spray (CS) and friction stir processing (FSP).Cold spray facilitated the deposition of particle reinforced metal matrix composite (MMC) coatings, which were subsequently refined and imbedded within the near-surface region of the substrate by FSP.SprayStir was employed to produce particle reinforced MMC surfaces that demonstrated superior erosion performance than that of unreinforced substrate alloy. Throughout this study, SprayStir was applied to several coating and substrate combinations, and their respective erosion performance established through slurry erosion testing. The volume of the resulting war scars was measured to compare the erosion performance of SprayStirred MMCs containing different particle reinforcements.Furthermore, the microstructure of the as-received substrate alloys, the cold spray deposited coatings, and the SprayStirred MMCs were characterised to establish the influence of FSP on the distribution of the particle reinforcements within the near-surface region. Whilst the primary aim of this investigation was to enhance the erosion performance of the as-received substrate, the contribution of erosion, corrosion and synergy of the total mass loss was also measured to identify if the corrosion performance of the as-received substrate was adversely affected by the application of SprayStir.The results presented herein show that the erosion performance of the SprayStirred specimens is superior to that of the cold spray deposited coatings and the as-received substrate alloy. The improved erosion performance was attributed to the presence of fine, evenly dispersed reinforcing particles within the near-surface region that restrict the amount of material removed during the slurry erosion testing by altering the erosion mechanisms that operate on the specimen surface. The results from this investigation have therefore provided a proof of concept for the SprayStir technology when applied to the aluminium and steel substrates discussed throughout this study.
Date of Award1 Mar 2017
LanguageEnglish
Awarding Institution
  • University Of Strathclyde
SponsorsUniversity of Strathclyde
SupervisorAlexander Galloway (Supervisor) & (Supervisor)

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