Determination of Nanocrystalline Fe&lt;sub&gt;80&lt;/sub&gt;Cr&lt;sub&gt;20&lt;/sub&gt; Powder Based Alloys Using Williamson-Hall Method

et al. 2014

AMM

Self Cite

Abstract-Solid oxide fuel cells (SOFC) are the current research having several potential to obtain high efficiency, high energy-density power generation which operated at relatively higher temperature. Yttrium oxide (Y2O3) contributions at high temperature are accelerating to the development oxide layer of FeCr alloy. The aim of this research is to investigate the microstructure of Fe/Cr added with Y2O3 acting as a reactive element. The purpose is to improve macrostructure of Fe/Cr powders which can be applied at steel industry. In this study the mixing process of Fe/Cr and Y2O3 powder was conducted via ultrasonic treatment at a frequency of 22 kHz, and at two different holding time of 2.5 h and 3.5 h. The particle size of chromium (Cr) can be reduced by ultrasonic treatment at from 60µm to 30µm through threshing the cluster of Cr particle. It shows that the ultrasonic vibration effectively removes oxides and other contaminates on a surface coating. Therefore, homogeneity of the parent material, segregation, and uniform distribution of second phase were increased..

Section: Resultsmentioning

confidence: 99%

Microstructure Study on Fe/Cr Based Alloys Added with Yttrium Oxide (Y2O3) Prepared via Ultrasonic Technique for Solid Oxide Fuel Cell (SOFC) Application

Feriyanto

Idris

et al. 2014

AMM

Self Cite

“…The experimental error for the density measurement was estimated to be ¡1% based on the resolution of the scale (0?001 g) used for these tests. The theoretical (100%) density of the alloys at this composition (Fe-20 wt-%Cr) is estimated ,7?71 g cm 23 (density of Fe is 7?86 g cm 23 and for Cr is 7?19 g cm 23 ). The results for all the studied specimens, both as sintered and as received specimens, are presented in Table 2.…”

Section: Crystallite Size and Densitymentioning

confidence: 88%

“…The as mechanically alloyed Fe-Cr in the form of powder 23 with nominal weight composition of iron/Fe and chromium/Cr close to 80 : 20 wt-% was consolidated via two different sintering methods: SPS and HP. In the SPS process, the as mechanically alloyed Fe-Cr powders were poured into graphite die with an inner diameter of 20 and 5 mm in thickness and sintered in a vacuum using SPS model 10-3 apparatus (Thermal Technology LLC, USA) at a loading pressure of 120 MPa.…”

Section: Experimental Preparation Of Materialsmentioning

confidence: 99%

Thermal stability of nanostructured iron–chromium alloys for interconnect application of solid oxide fuel cells

Khaerudini

Corrosion Engineering, Science and Technology

Mahzan

et al. 2012

The thermal expansion mismatch between a metallic substrate and its external oxide scale generates a strain on cooling that is the primary cause of spallation of protective oxide scales. This study investigates the thermal stability, by means of thermal expansion and oxidation behaviour, of the nanostructured FeCr alloy prepared by different consolidation techniques by means of the spark plasma sintering (SPS) method and to compare with conventional sintering technique by means of hot pressing (HP). This has potential application as interconnect in solid oxide fuel cell. Commercially available ferritic steel is chosen as a comparison of another high Cr ferritic model alloy. The beneficial effect of the reactive element by means of lanthanum onto the alloy surface that is introduced using ion implantation is also explored. The specific aspects studied were the effects of nanocrystalline structure, influenced by sintering method and surface treatment through La ion implantation of chromia forming alloys, which may improve their high thermal stability. Oxidation testing was conducted at 900-1100uC for 100 h in laboratory air. Characterisations using X-ray diffraction, scanning electron microscopy and energy dispersive Xray spectroscopy were carried out before and after each route or process to investigate the microstructure, phase change and formation of the oxide layer. The results revealed that the FeCr alloy prepared by SPS were more effective to retain nanocrystalline and better properties than those prepared by HP and the commercially available ferritic alloy. For all types of specimens, the presence of La had no detectable effect on thermal expansion but a major effect on scale adherence. The coefficients of thermal expansion for the alloy prepared by SPS were lower than those prepared by HP, and the scale adherence to the La implanted alloy was generally superior. The results consistently showed that a better reduction in oxidation resistance corresponds to excellent nanostructured alloy and La implantation.

“…The average crystallite size of specimens were calculated and found to be 53.33, 38.51, 76.60, and 77.30 nm for Fe 80 Cr 20 40, 60, 80 h, and commercial ferritic steel, respectively. The detail explanations of crystallite sizes evaluation and calculation have been reported previously [13]. High temperatures oxidation resistance for unimplanted and implanted specimens were tested in laboratory air at atmospheric pressure in a PROTHERM box furnace; exposed at 1173 -1373 K for 100 h and interrupted every 20 h for mass gain measurement on a microbalance with a weighting accuracy of 0.01 mg.…”

Section: Materials and Experimental Proceduresmentioning

confidence: 99%

Effect of Nanocrystalline and Ti Implantation on the Oxidation Behaviour of Fe80Cr20 Alloy and Commercial Ferritic Steel

Khaerudini

Saryanto

et al. 2011

KEM

Self Cite

Abstract. The oxidation behaviour of developed Fe 80 Cr 20 alloy and commercial ferritic steel at 1173 -1373 K in air is studied. Effects of crystallite size and titanium implantation on the oxidation behaviour of specimens were analyzed based on oxide morphologies and microstructures. Oxide scales characterisations of specimen after oxidized were identified by X-ray diffraction (XRD). The surface morphology of oxide scales were examined with scanning electronic microscope (SEM) and energy dispersive X-ray analysis (EDX). The rate constant of oxidation were determined using Wagner method. The results show that crystallite size and titanium implantation has remarkably enhanced the oxidation resistance. The oxidation kinetics indicate that the developed Fe 80 Cr 20 as the finer crystallite size both unimplanted and implanted specimens show better performance.