In the present study, bond-coats for thermal barrier coatings were deposited via air plasma spraying（APS） techniques onto Inconel 800 and Hastelloy C-276 alloy substrates. Scanning electron microscopy（SEM）, transm...In the present study, bond-coats for thermal barrier coatings were deposited via air plasma spraying（APS） techniques onto Inconel 800 and Hastelloy C-276 alloy substrates. Scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, X-ray diffraction（XRD）, and atomic force microscopy（AFM） were used to investigate the phases and microstructure of the as-sprayed, APS-deposited Co Ni Cr Al Y bond-coatings. The aim of this work was to study the suitability of the bond-coat materials for high temperature applications. Confirmation of nanoscale grains of the γ/γ′-phase was obtained by TEM, high-resolution TEM, and AFM. We concluded that these changes result from the plastic deformation of the bond-coat during the deposition, resulting in Co Ni Cr Al Y bond-coatings with excellent thermal cyclic resistance suitable for use in high-temperature applications. Cyclic oxidative stability was observed to also depend on the underlying metallic alloy substrate.展开更多
Silver-clad （Bi,Pb）2Sr2Ca2Cu3O10＋x long wires produced by powder-in-tube techniques, which have been recognized as the first generation of the High Temperature Superconducting （HTS） wires, are expected to apply w...Silver-clad （Bi,Pb）2Sr2Ca2Cu3O10＋x long wires produced by powder-in-tube techniques, which have been recognized as the first generation of the High Temperature Superconducting （HTS） wires, are expected to apply widely especially in strong current applications. In this work, the processing, characterization and application of the silver-clad （Bi,Pb）2Sr2Ca2Cu3Ol0＋x HTS wires are summarized. The HTS wires are fabricated using the combination of powder-in-tube technique, and the resulting wires are fully characterized by the means of chemical analyses, microstructural observation, electrical and magnetic measurements. The relationship among fabrication parameters, chemical and microstructural characteristics, and electrical and magnetic properties are analyzed. Applications of the HTS wires have also been introduced according to their strong current behaviors with various prototype devices made.展开更多
Ternary Laves phases with transition metals and aluminium were overviewed with respect to their use for structural high temperature applications. The relation between constitution, phase stability, crystal structure a...Ternary Laves phases with transition metals and aluminium were overviewed with respect to their use for structural high temperature applications. The relation between constitution, phase stability, crystal structure and basic mechanical properties was discussed. The crystal structure-hexagonal C14 structure or cubic C15 structure-is a function of atomic radii and valence electron concentration. A strong positive correlation of basic mechanical properties-hardness, yield stress-with the sublimation energy of the phases was found. The brittle to ductile transition temperature was observed at about 60% of the melting temperature. The regarded ternary Laves phases allow alloying to form stable equilibria with the less hard and brittle B2 aluminides. Advantageous examples are alloys of type NbNiAl NiAl, TaNiAl NiAl, and TaFeAl FeAl. Multiphase NiAl Ta Cr alloys are regarded as promising for structural high temperature applications and have been selected for a materials development which aims at applications in gas turbines at temperatures above those of Ni base superalloys, such alloy can be prepared by ingot metallurgy and powder metallurgy and hot forming is possible. Characteristic data were presented with respect to mechanical behaviour. The alloys showed a high thermoshock resistance in spite of the comparatively high brittle to ductile transition temperature. The prospects of alloy development were discussed.展开更多
基金provided by Technical Education Quality Improvement Programme-Ⅱ(TEQIP-Ⅱ)at MNNIT Allahabad
文摘In the present study, bond-coats for thermal barrier coatings were deposited via air plasma spraying（APS） techniques onto Inconel 800 and Hastelloy C-276 alloy substrates. Scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, X-ray diffraction（XRD）, and atomic force microscopy（AFM） were used to investigate the phases and microstructure of the as-sprayed, APS-deposited Co Ni Cr Al Y bond-coatings. The aim of this work was to study the suitability of the bond-coat materials for high temperature applications. Confirmation of nanoscale grains of the γ/γ′-phase was obtained by TEM, high-resolution TEM, and AFM. We concluded that these changes result from the plastic deformation of the bond-coat during the deposition, resulting in Co Ni Cr Al Y bond-coatings with excellent thermal cyclic resistance suitable for use in high-temperature applications. Cyclic oxidative stability was observed to also depend on the underlying metallic alloy substrate.
文摘Silver-clad （Bi,Pb）2Sr2Ca2Cu3O10＋x long wires produced by powder-in-tube techniques, which have been recognized as the first generation of the High Temperature Superconducting （HTS） wires, are expected to apply widely especially in strong current applications. In this work, the processing, characterization and application of the silver-clad （Bi,Pb）2Sr2Ca2Cu3Ol0＋x HTS wires are summarized. The HTS wires are fabricated using the combination of powder-in-tube technique, and the resulting wires are fully characterized by the means of chemical analyses, microstructural observation, electrical and magnetic measurements. The relationship among fabrication parameters, chemical and microstructural characteristics, and electrical and magnetic properties are analyzed. Applications of the HTS wires have also been introduced according to their strong current behaviors with various prototype devices made.
文摘Ternary Laves phases with transition metals and aluminium were overviewed with respect to their use for structural high temperature applications. The relation between constitution, phase stability, crystal structure and basic mechanical properties was discussed. The crystal structure-hexagonal C14 structure or cubic C15 structure-is a function of atomic radii and valence electron concentration. A strong positive correlation of basic mechanical properties-hardness, yield stress-with the sublimation energy of the phases was found. The brittle to ductile transition temperature was observed at about 60% of the melting temperature. The regarded ternary Laves phases allow alloying to form stable equilibria with the less hard and brittle B2 aluminides. Advantageous examples are alloys of type NbNiAl NiAl, TaNiAl NiAl, and TaFeAl FeAl. Multiphase NiAl Ta Cr alloys are regarded as promising for structural high temperature applications and have been selected for a materials development which aims at applications in gas turbines at temperatures above those of Ni base superalloys, such alloy can be prepared by ingot metallurgy and powder metallurgy and hot forming is possible. Characteristic data were presented with respect to mechanical behaviour. The alloys showed a high thermoshock resistance in spite of the comparatively high brittle to ductile transition temperature. The prospects of alloy development were discussed.
