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1 – 10 of 17Jialin Yang, Yunting Guo, Wei Zai, Siyuan Ma, Liang Dong and Guangyu Li
This paper aims to find a way to improve the surface insulation, corrosion resistance and mechanical properties of Fe-Cr-Al electrothermal alloy, exploring the best oxidation…
Abstract
Purpose
This paper aims to find a way to improve the surface insulation, corrosion resistance and mechanical properties of Fe-Cr-Al electrothermal alloy, exploring the best oxidation condition and analyzing the oxidation mechanism.
Design/methodology/approach
Electrochemical workstation was used for anodic oxidation, and the effect of current density, ethylene glycol concentration and oxidation time on properties of the film were investigated by resistivity test, scanning electron microscope, electrochemical tests (potentiodynamic polarization and electrochemical impedance spectroscopy) and mechanical tests, and the oxidation process was analyzed by X-ray photoelectron spectroscopy (XPS).
Findings
According to the potential-time curves of anodic oxidation and the analysis of XPS, the whole oxidation process can be divided into four stages. When the current density is 0.8 A/dm2, the ethylene glycol concentration is 10%, and the oxidation time is 60 min, the film has the best corrosion protection, mechanical properties and surface morphology. The resistivity of the samples is about 13 orders magnitude than that of the matrix.
Originality/value
In this paper, a protective electrically insulating film was prepared by anodic oxidation in an alkaline electrolyte solution. The oxidation conditions were optimized and the oxidation mechanism was analyzed.
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Zhenyu Ma, Yupeng Zhang, Xuguang An, Jing Zhang, Qingquan Kong, Hui Wang, Weitang Yao and Qingyuan Wang
The purpose of this study is to investigate the effect of nano ZrC particles on the mechanical and electrochemical corrosion properties of FeCrAl alloys, providing a beneficial…
Abstract
Purpose
The purpose of this study is to investigate the effect of nano ZrC particles on the mechanical and electrochemical corrosion properties of FeCrAl alloys, providing a beneficial reference basis for the development of high-performance carbide reinforced FeCrAl alloys with good mechanical and corrosion properties in the future.
Design/methodology/approach
Nano ZrC reinforced FeCrAl alloys were prepared by mechanical alloying and spark plasma sintering. Phases composition, tensile fractography, corrosion morphology and chemical composition of nano ZrC reinforced FeCrAl alloys were analyzed by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy, respectively. Microhardness and tensile properties of nano ZrC reinforced FeCrAl alloys were investigated by mechanical testing machine and Vickers hardness tester. Electrochemical corrosion properties of nano ZrC reinforced FeCrAl alloys were investigated by electrochemical workstation in 3.5 wt.% NaCl solution.
Findings
The results showed that addition of nano ZrC can effectively improve the mechanical and corrosion properties. However, excessive nano ZrC could decrease the mechanical properties and reduce the corrosion resistance. In all the FeCrAl alloys, FeCrAl–0.6 wt.% ZrC alloy exhibits the optimum mechanical properties with an ultimate tensile strength, elongation and hardness of 990.7 MPa, 24.1% and 335.8 HV1, respectively, and FeCrAl–0.2 wt.% ZrC alloy has a lower corrosion potential (−0.179 V) and corrosion current density (2.099 µA/cm2) and larger pitting potential (0.497 V) than other FeCrAl–ZrC alloys, showing a better corrosion resistance.
Originality/value
Adding proper nano ZrC particles can effectively improve the mechanical and corrosion properties, while the excessive nano ZrC is harmful to the mechanical and corrosion properties of FeCrAl alloys, which provides an instruction to develop high-performance FeCrAl cladding materials.
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The purpose of this paper is to obtain a single setting (optimal setting) of various input parameters of pack cementation process, i.e. halide salt activator, powder of master…
Abstract
Purpose
The purpose of this paper is to obtain a single setting (optimal setting) of various input parameters of pack cementation process, i.e. halide salt activator, powder of master alloy and wt% of Y2O3 to obtain a single output characteristic as a whole namely resistance of hot corrosion for T91 steel.
Design/methodology/approach
The multi-criterion methodology based on Taguchi approach and utility concept has been used for optimization of the multiple performance characteristics namely hot corrosion rate KP1, KP2 and KP3 for pack cementation coated T91 steel in chlorine and vanadium environment.
Findings
All the three pack cementation parameters, namely, halide salt activator, powder of master alloy and wt% of Y2O3 had a significant effect on the utility function based on analysis of variance for multiple performances. The percentage contribution of halide activator (1.54 percent), master alloy powder (4.66 percent) and wt% Y2O3 (93.79 percent). The results indicated the beneficial influence of yttrium on the chemical stability of the protective layer in presence of chlorine and vanadium environments. The optimal parameter settings obtained in this study is A2B2C1, i.e. halide salt activator (NaCl), powder of master alloy (92Cr-8Al) and 1wt% of Y2O3.
Research limitations/implications
The outcome of this study shall be useful to explore the possible use of the developed coating for high temperature components. Unfortunately, the pack cementation was normally limited by the diffusion and reaction kinetics involved, which has a detrimental effect on the mechanical properties of work pieces. Therefore, reducing pack cementation temperature is required for widespread application of the pack coatings.
Social implications
Pack coating at optimum conditions can be used for surface coating technologies to economically improve high temperature oxidation, corrosion resistance of components.
Originality/value
The multi-criterion methodology based on Taguchi approach and utility concept has been used for first time for parametric optimization of wt% Y2O3 modified chromium- aluminide coatings for T91 steel.
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Anicon, Inc. have recently appointed Friedrich Weiler as Managing Director, Anicon Europa, GmbH, and have announced the opening of Anicon's European headquarters facility in…
FRANCE. Internal corrosion in pipes. Mild‐steel pipes as used in town gas distribution networks are corroded by the mixture of water vapour, carbon dioxide and oxygen. Corrosion…
Abstract
FRANCE. Internal corrosion in pipes. Mild‐steel pipes as used in town gas distribution networks are corroded by the mixture of water vapour, carbon dioxide and oxygen. Corrosion occurs only if changes in temperature will cause condensation. The condensate forming on the metal is a heavily corroding agent. Once formed, the corrosion products will act as protective layers in certain circumstances.—(J. Morlet and G. Geoffray, paper read at the 74th Congress of the Association Technique de l'Industrie du Gaz en France, June 1957.)
J.A. von Fraunhofer and G.A. Pickup
THE oxidation behaviour of low binary iron alloys with aluminium, chromium and silicon in air has been discussed at length. Rather less work has been performed on the ternary…
Abstract
THE oxidation behaviour of low binary iron alloys with aluminium, chromium and silicon in air has been discussed at length. Rather less work has been performed on the ternary systems, Fe‐Cr‐Al and Fe‐Cr‐Si, and very little on Fe‐Al‐Si alloys.
Somrerk Chandra-Ambhorn, Neramit Krasaelom, Tummaporn Thublaor and Sirichai Leelachao
This study aims to apply the pack cementation to develop the Fe-Al layers on the surface of FC 25 cast iron in order to increase the high-temperature corrosion resistance of the…
Abstract
Purpose
This study aims to apply the pack cementation to develop the Fe-Al layers on the surface of FC 25 cast iron in order to increase the high-temperature corrosion resistance of the alloy.
Design/methodology/approach
Pack cementation was applied on the surface of FC 25 cast iron at 1,050°C. The bare and aluminised alloys were subjected to the oxidation test in 20 per cent O2-N2 at 850 °C. Scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy and X-ray diffraction (XRD) were used for characterisation.
Findings
The layers of pack cementation consisted of Fe2Al5, FeAl2 and FeAl, and solid solution alloyed with Al. The oxidation kinetics of the bare cast iron was parabolic. Mass gain of the aluminised cast iron was significantly decreased compared with that of the bare cast iron. This was because of the protective alumina formation on the aluminised alloy surface. Al in the Fe–Al layer also tended to be homogenised during oxidation.
Originality/value
Even though the aluminising of alloys was extensively studied, the application of that process to the FC 25 cast iron grade was originally developed in this work. The significantly reduced mass gain of the aluminised FC 25 cast iron makes the studied alloy be promising for the use as a valve seat insert in an agricultural single-cylinder four-stroke engine, which might be run by using a relatively cheaper fuel, i.e. LPG, but as a consequence requires the higher oxidation resistance of the engine parts.
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Gongjun Cui, Jin Wei and Gongxiong Wu
The purpose of this study is to prepare new Fe-Cr-B alloys which have better wear resistance and investigate the wear mechanisms of these alloys tribotesting against SiC ceramic…
Abstract
Purpose
The purpose of this study is to prepare new Fe-Cr-B alloys which have better wear resistance and investigate the wear mechanisms of these alloys tribotesting against SiC ceramic balls under dry sliding process.
Design/methodology/approach
Fe-Cr matrix alloys were fabricated using powder metallurgy route. The tribological behaviors of Fe-Cr alloys tribotesting against SiC ceramic balls using a ball-on-disc tribotester were studied at different testing conditions. Meanwhile, microstructure, phases and morphology of worn surfaces were investigated.
Findings
The element boron improved mechanical properties and tribological behavior of alloys. The friction coefficients of Fe-Cr matrix alloys did not show obvious difference. The specific wear rates of alloys decreased and then increased because of the brittleness of alloys with the increase of boron content. Fe-21 weight per cent Cr-7 weight per cent B alloy showed the best tribological properties in dry sliding. The wear mechanism of Fe-Cr alloy was plastic deformation and abrasive wear. However, the Fe-Cr-B alloys showed fatigue spalling characteristics.
Originality/value
This paper reported a new, cheap and wear-resistant Fe matrix material to prepare mechanical parts in food and mining industrial fields.
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To improve the wear resistance of the sliding boot, the wear-resistant Fe-21 Wt.% Cr-5 Wt.% B alloy is prepared, and the wear mechanism is studied under dry sliding condition.
Abstract
Purpose
To improve the wear resistance of the sliding boot, the wear-resistant Fe-21 Wt.% Cr-5 Wt.% B alloy is prepared, and the wear mechanism is studied under dry sliding condition.
Design/methodology/approach
The anti-wear Fe-21 Wt.% Cr-5 Wt.% B alloy is prepared by powder metallurgy technique. The tribological behavior of Fe-Cr-B alloy sliding against ASTM 1045 steel pin is studied at 30-60 N and 0.03-0.12 m/s using a reciprocating pin-on-disk tribometer under dry sliding condition. Meanwhile, the ASTM 5140 and 3316 steel are studied as compared samples.
Findings
The friction coefficients of tested specimens increase with the increasing normal load. However, this effect is the opposite in case of different sliding speeds. The specific wear rates increase as the sliding speed and normal load increase. The Fe-Cr-B alloy shows the best tribological properties under the dry sliding condition and the wear mechanism is mainly ploughing.
Originality/value
This wear-resistant Fe-21 Wt.% Cr-5 Wt.% B alloy can replace the traditional materials to process the sliding shoes and improve the service life of coal mining machine.
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Guang Chen, Bomin Huang, Hui Liu, Y.C. Chan, Zirong Tang and Fengshun Wu
The purpose of this paper is to investigate microstructure and properties of Sn3.0Ag0.5Cu-XAl2O3 composite solder which were prepared through powder metallurgy route.
Abstract
Purpose
The purpose of this paper is to investigate microstructure and properties of Sn3.0Ag0.5Cu-XAl2O3 composite solder which were prepared through powder metallurgy route.
Design/methodology/approach
Sn3.0Ag0.5Cu (SAC305)-XAl2O3 (X = 0.2, 0.4, 0.6, 0.8 Wt. %) composite solders were prepared through the powder metallurgy route. The morphology of composite solder powders which consists of Al2O3 particles and SAC solder powders after ball milling was observed. The retained ratio of Al2O3 nanoparticles in composite solder billets and solder joints were also quantitatively measured. Furthermore, the as-prepared composite solder alloys were studied extensively with regard to their microstructures, thermal property, wettability and mechanical properties.
Findings
After ball milling, the Al2O3 nanoparticles added were observed embedded into the surface of SAC solder powders. Only about 5-10 per cent of the initial Al2O3 nanoparticles added were detected in the composite solder joints after reflow. In addition, finer ß-Sn grains were achieved with addition of Al2O3 nanoparticles; the Al2O3 nanoparticles were found retained in the composite solder matrix. Besides, negligible changes in melting temperature and the considerably reduced undercooling were obtained in composite solder alloys. Wettability was improved by appropriate addition of Al2O3 nanoparticles. Microhardness and shear strength of composite solders were both improved after Al2O3 nanoparticles addition.
Originality/value
This paper indicated that powder metallurgy route offered a feasible approach to produce nanoparticle reinforced composite solder. In addition, the quantitative analysis of the actual retained ratio of the Al2O3 nanoparticles in solder joints provided practical implications for the manufacture of composite solders.
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