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Development of Copper-Ferrite Spinel Coating on AISI 430 Steel Used as Solid Oxide Fuel Cell
S. N. Hosseini, F. Karimzadeh, M. H. Enayati,
Volume 39, Issue 4 (2-2021)
Abstract
The bare and pre-oxidized AISI 430 pieces were screen printed by copper ferrite spinel coatings. Good bonding between the coating and the substrate was achieved by the reactive sintering process of the reduced coating. The energy dispersive X-ray spectroscopy (EDS) analysis revealed that the scale is a double layer consisting of a chromia-rich subscale and an outer Cu/Fe-rich spinel. The results showed that the spinel protection layer not only significantly decreased the area specific resistance (ASR), but also inhibited the subscale growth by acting as a barrier to the inward diffusion of oxygen. ASRs of 19.7 and 32.5 mΩ.cm2, much lower than that of the bare substrate (153.4 mΩ.cm2), at 800 °C after 400 h oxidation were achieved for the bare and pre-oxidized copper ferrite spinel coated samples, respectively. Excellent, stable ASR (20.5 mΩ.cm2) was obtained with copper ferrite coating after 600 h of exposure at 800 °C. The high electrical conductivity of CuFe2O4 and its doping by Mn, the growth reduction of Cr2O3 oxide scale and the good coating to substrate adherence are proposed to be responsible for substantial improvement in electrical conductivity.

Pressureless Sintering & Mechanical & Thermal Properties of ZrB2-ZrC-SiC Nanocomposite
I. Forooghi , M. Mashhadi,
Volume 39, Issue 4 (2-2021)
Abstract
Due to their unique features, Ultra-High Temperature Ceramics (UHTCs) have potential applications in aerospace, military and industry. ZrB2-SiC composite as one of these ceramics has been at the center of researches due to its attractive mechanical, thermal and oxidation resistance. In this study, the effect of ZrC addition on pressureless sintering behavior, mechanical, microstructural and thermal properties of ZrB2-SiC nanocomposite were investigated. For this purpose, micron-sized ZrB2 and ZrC powders and nano-sized SiC powder were used. ZrB2-20vol% SiC nanocomposites with addition of (3, 6, 9, 12, 15) vol% ZrC were sintered by pressureless sintering method at 2100 ºC. The results showed that the addition of ZrC improved relative density, hardness and fracture toughness of ZrB2-20vol% SiC nanocomposite. Optimum properties were obtained in a sample containing 12 vol% ZrC and the relative density, hardness and fracture toughness of this sample were reported to be 99.01%, 16.95 Gpa and 5.43 Mpa.m0.5, respectively. Thermal analysis of the samples showed that by adding ZrC, thermal diffusivity of this nanocomposite reduced. The highest thermal diffusivity at room temperature equaled 35.3 mm2 /s and was obtained for ZS composite.

STUDY OF STRUCTURAL EVOLUTION OF AMORPHOUS CARBON FILMS ON Ni-Cu ALLOY AND ITS CORRELATION WITH DEPOSITION TEMPERATURE AND ION BEAM ENERGY
E. Mohagheghpour, R. Gholamipour, M. Rajabi, M. Mojtahedzadeh Larijani,
Volume 40, Issue 3 (11-2021)
Abstract
In this study, the amorphous carbon thin films were deposited by ion beam sputtering deposition method on the glass and Ni–Cu alloy substrates. The structural evolution of amorphous carbon and its correlation with the kinetic energy of carbon atoms during the growth of thin film was investigated. The effect of substrate material, deposition temperature, and ion beam energy on the structural changes were examined. Raman spectroscopy indicated a structural transition from amorphous carbon to diamond-like amorphous carbon (DLC) due to an increase in deposition temperature up to 100°C and ion beam energy from 2 keV to 5 keV. The size of graphite crystallites with sp2 bonds (La) were smaller than 1 nm in the amorphous carbon layers deposited on Ni-Cu alloy. The results of residual stress calculation using X-ray diffractometer (XRD) analysis revealed a decreasing trend in the tensile residual stress values of the amorphous carbon thin films with increasing the ion beam energy.

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