Thermal Barrier (thermal + barrier)

Distribution by Scientific Domains

Terms modified by Thermal Barrier

  • thermal barrier coating

  • Selected Abstracts

    Modeling of Coating Process, Phase Changes, and Damage of Plasma Sprayed Thermal Barrier Coatings on Ni-Base Superalloys,

    Tilmann Beck
    The paper gives an overview on the modeling activities on plasma sprayed thermal barrier coating in the frame of TFB 63. In the first part, through-process modeling of the APS deposition of a ZrO2 based TBC is described. Starting from simulation of the plasma jet, heat transfer into the powder particles, particle melting, particle impact on the substrate surface, and solidification is simulated. A homogenization method is introduced to describe the mechanical properties of the resulting TBC. The second part shows simulation of interdiffusion and phase transformations of MCrAlY and intermetallic oxidation protection coatings on several cast Ni-base alloy substrates. Finally, FEM-based damage simulation of oxidation protection coatings by transversal fatigue cracks during thermomechanical fatigue loading as well as by delamination of the TBC during thermocyclic loading is discussed. [source]

    Flame retardancy finish with an organophosphorus retardant on silk fabrics

    FIRE AND MATERIALS, Issue 6 2006
    Jin-Ping Guan
    Abstract The paper mainly deals with flame retardancy of silk fabrics treated with a commercial organophosphorus flame retardant [N-hydroxymethyl (3-dimethyl phosphono) propionamide (HDPP), also known as Pyrovatex CP], using the pad-dry-cure-wash method. The structures and properties of the treated and control sample are discussed. The Limiting Oxygen Index (LOI) value of the modified sample is above 30%. After 50 laundry cycles, it still has some flame retardancy left. HDPP and a cross-linking agent (HMM) were bound to silk fabrics which is confirmed by FT-IR spectra and amino analysis. The reaction degree of the flame retardant with silk is also high; almost all the tyrosine units have reacted, which can be confirmed by amino acid analysis. The reaction between flame retardant and silk only occurs in the amorphous region of silk fibre, which is confirmed by X-ray diffraction analysis and amino acid analysis. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis show that the flame retardant causes silk fabrics to decompose below its ignition temperature (600°C) and formed carbonaceous residue or char when exposed to fire. The char behaves as a thermal barrier to fire, so silk fabrics show good flame retardancy. The treatment has a little effect on the whiteness of the silk fabrics and the tensile strength of treated silk fabrics slightly decreased; both effects are negligible. Copyright © 2006 John Wiley & Sons, Ltd. [source]

    An investigation of the effect of thermal cycling on plasma-sprayed zirconia/NiCoCrAlY thermal barrier coating

    A. El-Turki
    Abstract The microstructural change, crack initiation and spallation of a vacuum plasma sprayed (VPS) thermal barrier coating on an INCONEL-738 superalloy substrate were investigated after successive 300 h thermal cycles at 1050°C. The coating was characterised using Raman spectroscopy, scanning electron microscopy (SEM) energy dispersive X-ray analysis (EDX) and Auger electron spectroscopy (AES). Localised micro-cracks at the yttrium (III) oxide stabilised zirconium (IV) oxide (YSZ) ceramic coating/thermally grown oxide (TGO) interface were observed after 8 cycles. Spallation of the YSZ coating occurred after approximately 21 cycles. Significant amounts of the elements titanium, tantalum and chromium were found within the TGO together with the formation of nickel, cobalt and chromium-rich oxides at this TGO/YSZ interface. [source]

    Homogenization of a composite medium with a thermal barrier

    Mongi Mabrouk
    Abstract In this work, we consider a heat transfer problem between two periodic connected media exchanging a heat flux throughout their common interface. The interfacial exchange coefficient , is assumed to tend to zero or to infinity following a rate ,=,(,) when the size ,of the basic cell tends to zero. Three homogenized problems are determined according to the value of ,=lim,,0,/,. Copyright © 2004 John Wiley & Sons, Ltd. [source]

    Convertibility of conductivity type in reactively sputtered ZnO thin films

    S. Tüzemen
    Abstract Possible negative- U behavior of the VO donor may explain rather unusual free carrier properties in as-sputtered ZnO thin films grown at extremely Zn-rich conditions. VO can act as a source of free electron concentration at sample temperatures above 210 K. Below this temperature it changes its charge state to an inactive neutral charge state where it cannot act as a donor because of a thermal barrier with a threshold temperature of 170,210 K. The thermal barrier for an electron to go to neutral charge state from positive charge state is approximately 162 meV. Material can be converted to p-type by annealing VO centers. O-rich growth conditions with low [VO] may result in p-type conductivity. [source]

    The use of fire-retardant intumescent mats for fire and heat protection of glass fibre-reinforced polyester composites: Thermal barrier properties

    FIRE AND MATERIALS, Issue 1 2010
    Everson Kandare
    Abstract This study investigates the use of integral, hybrid intumescent thermal barriers (mats) to provide surface protection to the core fibre-reinforced polyester composite structural integrity when exposed to a fire or heat source. Glass fibre-reinforced composites protected by intumescent mats/fabrics containing silicate fibres, expandable graphite and in some cases borosilicate glass bounded together by an organic matrix have been evaluated for fire performance under a constant heat flux of 50kW/m2. The effect of insulative fabric thickness as well as chemical composition on the flammability of the resultant hybrid composites is evaluated. Glass fibre-reinforced polyester (GRP) composites without any surface protection have a relatively higher time-to-ignition and peak heat release rate values when compared with core composites protected by insulative fabrics. Thermograms representing the variation of temperature on the reverse side of the hybrid composites with time when exposed to a constant heat flux show that the inclusion of intumescent surface barriers results in retarded temperature increments within the core GRP composites. Copyright © 2009 John Wiley & Sons, Ltd. [source]