Browsing School of Applied Sciences (SAS) (2006-July 2014) by Author "Nicholls, John R."

Browsing School of Applied Sciences (SAS) (2006-July 2014) by Author "Nicholls, John R."

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  • Carbon and titanium diboride (TiB2) multilayer coatings. 
    Rao, Jeff; Cruz, R.; Lawson, K. J.; Nicholls, John R. (2004-11-01)
    Titanium Diboride, (TiB2) is a metal-based refractory ceramic material that has been investigated in industrial applications ranging from, cutting tools to wear parts and for use in the aerospace industry. The unique ...
  • Carbon Brainprint Case Study: ceramic coatings for jet engine turbine blades 
    Parsons, David J.; Chatterton, Julia C.; Nicholls, John R. (2011-07-31)
    Ceramic thermal barrier coatings (TBCs) are applied to jet turbine blades to protect them from the high temperature gases leaving the combustion chamber and to increase the efficiency of the engine. Professor John Nicholls ...
  • CMAS corrosion of EB PVD TBCs: Identifying the minimum level to initiate damage 
    Wellman, R. G.; Whitman, G.; Nicholls, John R. (2010-01-01)
    Over the last decade a significant amount of research has been conducted into the durability of thermal barrier coatings (TBCs) focusing mainly on issues of oxidation, erosion and foreign object damage (FOD). However, ...
  • Effect of microstructure and temperature on the erosion rates and mechanisms of modified EB PVD TBCs 
    Wellman, R. G.; Nicholls, John R.; Murphy, K. S. (Elsevier Science B.V., Amsterdam., 2009-10-29)
    Thermal barrier coatings (TBCs) have now been used in gas turbine engines for a number of decades and are now considered to be an accepted technology. As there is a constant drive to increase the turbine entry temperature, ...
  • The effect of TBC morphology on the erosion rate of EB PVD TBCs 
    Wellman, Richard G.; Deakin, M. J.; Nicholls, John R. (Elsevier Science B.V., Amsterdam., 2005-01-31)
    Since thermal barrier coatings (TBCs) have been used in gas turbines most of the research conducted on them has involved the bond coat and the growth of the thermally grown oxide (TGO) as failure of the bond coat and the ...
  • Effects of oxidation and hot corrosion in a nickel disc alloy 
    Encinas-Oropesa, Adriana; Drew, G. L.; Hardy, M. C.; Leggett, A. J.; Nicholls, John R.; Simms, Nigel J. (2008-12-31)
    This paper describes work to study oxidation and hot corrosion damage in nickel disc alloy RR1000. Oxidation damage has been characterised via mass change data from thermogravimetric analyses at temperatures from 700 to ...
  • Electrodeposition of aluminium film on P90 Li-Al alloy as protective coating against corrosion 
    Bardi, U.; Caporali, S.; Craig, M.; Giorgetti, A.; Perissi, I.; Nicholls, John R. (Elsevier Science B.V., Amsterdam., 2009-02-28)
    In this paper we report on the electrodeposition of thin aluminium layers on P90 lithium–aluminium alloy at room temperature from a chloroaluminate ionic liquid (1-butyl-3-methyl imidazolium heptachloroaluminate ...
  • Erosion and high temperature oxidation resistance of new coatings fabricated by a sol-gel route for a TBC application. 
    Viazzi, Céline; Wellman, R. G.; Oquab, Djar; Nicholls, John R.; Monceau, Daniel; Bonino, Jean-Pierre; Florence, Ansart (Trans Tech Publications, 2008)
    This paper examines the erosion and cyclic oxidation performance of novel thermal barrier coatings produced via the sol-gel route. The ceramic top coat, with a thickness of 5- 25µm, was deposited via a sol-gel route onto ...
  • Erosion of gadolinia doped EB-PVD TBCs 
    Steenbakker, R J L; Wellman, R. G.; Nicholls, John R. (Elsevier Science B.V., Amsterdam., 2006-12-01)
    Gadolinia additions have been shown to significantly reduce the thermal conductivity of EB-PVD TBCs. The aim of this paper is to further the understanding on the effects of dopants on the erosion resistance of EB-PVD ...
  • Erosion, corrosion and erosion-corrosion of EB PVD thermal barrier coatings 
    Wellman, R. G.; Nicholls, John R. (Elsevier Science B.V., Amsterdam., 2008-07-01)
    Electron beam (EB) physical vapour deposited (PVD) thermal barrier coatings (TBCs) have been used in gas turbine engines for a number of years. The primary mode of failure is attributed to oxidation of the bond coat and ...
  • Evolution of stress and morphology in thermal barrier coatings 
    Wang, Xin; Atkinson, Alan; Chirivi, Laura; Nicholls, John R. (Elsevier Science B.V., Amsterdam., 2010-08-25)
    Residual stress in the thermally grown oxide (TGO) in thermal barrier coatings (TBCs) was measured by photoluminescence piezospectroscopy (PLPS) and stress maps created to track local stress changes as a function of ...
  • High Temperature Erosion-Oxidation Mechanisms, Maps and Models 
    Wellman, R. G.; Nicholls, John R. (Elsevier Science B.V., Amsterdam., 2004-05-01)
    The aim of this paper is to provide an overview of erosion-oxidation studies by reviewing the work that has been done on mechanisms, maps and models. High temperature erosionoxidation is a major cause of wear in both ...
  • The influence of imposed strain rate on fracture of surface oxides. 
    Hancock, P.; Nicholls, John R.; Mahmood, K. (Elsevier Science B.V., Amsterdam., 1993-01-01)
    The mechanical properties of chromium rich scales formed on 304 stainless steel have been investigated as a function of deformation rate and operating temperature. At 900C at slow strain rates < 10-6 per second no ...
  • A Mechanism for the Erosion of EB PVD TBCS 
    Wellman, R. G.; Nicholls, John R. (Trans Tech Publications, Switzerland., 2000-07-10)
    Since the introduction of electron beam (EB) physical vapour deposition (PVD) TBCs and their application to moving components in the hot gas stream, erosion has become a prime concern. This project has been involved in ...
  • Methods to reduce the thermal conductivity of EB-PVD TBCs. 
    Nicholls, John R.; Lawson, K. J.; Johnstone, A.; Rickerby, David S. (Elsevier Science B.V., Amsterdam., 2002-03-01)
    This paper reviews the advantages and disadvantages of various thermal barrier coating (TBC) systems, with the aim of custom designing a TBC system to be both strain tolerant and have a low thermal conductivity. Methods ...
  • A Monte Carlo model for predicting the erosion rate of EB PVD TBCs 
    Wellman, R. G.; Nicholls, John R. (Elsevier Science B.V., Amsterdam., 2004-05-01)
    Since the introduction of electron beam (EB) physical vapour deposition (PVD) thermal barrier coatings (TBCs) and their application to moving components in the hot gas stream, erosion has become a prime concern. EB PVD ...
  • Multi-layered Ruthenium-modified Bond Coats for Thermal Barrier Coatings 
    Tryon, B.; Feng, Q.; Wellman, R. G.; Murphy, K. S.; Yang, J.; Levi, C.G.; Nicholls, John R.; Pollock, T. M. (Springer Verlag, 2006-11)
    Diffusional approaches for fabrication of multi-layered Ru-modified bond coats for thermal barrier coatings have been developed via low activity chemical vapor deposition and high activity pack aluminization. Both processes ...
  • Nano and Micro indentation studies of bulk zirconia and EB PVD TBCs 
    Wellman, R. G.; Dyer, A.; Nicholls, John R. (Elsevier Science B.V., Amsterdam., 2004-01-01)
    In order to model the erosion of a material it is necessary to know the material properties of both the impacting particles as well as the target. In the case of electron beam (EB) physical vapour deposited(PVD) thermal ...
  • Nano and microhardness testing of aged EB PVD TBCs 
    Wellman, R. G.; Tourmente, H.; Impey, Susan A.; Nicholls, John R. (Elsevier Science B.V., Amsterdam., 2004-11-01)
    Previous studies on the erosion of electron beam physical vapour deposited thermal barrier coatings (EB PVD TBCs) has shown that aging the coatings at between 1100 and 1500 à °C before erosion increases the erosion rate. ...
  • A New Reactive Atom Plasma Technology (RAPT) for Precision Machining: the Etching of ULE® Surface 
    Fanara, C.; Shore, Paul; Nicholls, John R.; Lyford, N.; Kelley, J.; Carr, J.; Sommer, P. (John Wiley & Sons, Ltd, 2006-01-01)
    Results on reactive atom plasma etching performed on ULE® (Corning Ultra Low Expansion) glass samples at atmospheric pressure are presented for the first time. A reactive atomic plasma technology (RAPT®), has been developed ...

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