Role of Cu During Sintering of Fe0.96Cu0.04 Nanoparticles (original) (raw)
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This overview paper describes the interaction of powder metallurgical iron-base alloys with the atmosphere during sintering. The methods of thermal analysis serve to clarify the processes that take place especially during the heating stage of the sintering cycle. After a discussion of the physical and chemical fundamentals of the sintering process, the methods of thermal analysis are explained. The differences between plain iron and alloyed systems are discussed in detail. Classical PM low alloy steels with alloying elements, such as Cu, Ni and Mo, react in a similar way as unalloyed carbon steels. The situation changes dramatically, when oxygen sensitive elements as chromium, manganese and even more silicon come into play. The removal of the surface oxygen is much more crucial, and there are several competing reactions, which have to be considered when these systems should be sintered in industrial scale to reach the desired mechanical and dimensional properties.
Liquidlike sintering behavior of nanometric Fe and Cu powders: Experimental approach
Metallurgical and Materials Transactions A, 1998
Nanometric Fe and Cu powders were sintered in vacuum, He, and H 2 atmospheres after uniaxial cold pressing. The shrinkage behavior of samples was studied using three different dilatometric techniques: constant heating rate, isothermal annealing, and the Dorn method. Density greater than 90 pct was obtained at sintering temperatures of 900 ЊC. In nanometric powders, densification and grain coarsening occurred in a narrow temperature interval. Despite the low oxide content in the starting powders (1.5 to 4 wt pct), the reducing atmosphere plays a relevant role in the sintering process. The self-diffusion activation energies obtained for nanometric Fe were 116 and 60 kJ/mole in vacuum and H 2 , and those obtained for nanometric Cu were 70 and 43 kJ/mole in He and H 2 . According to the present results, the activation energies obtained from both nanometric powders in H 2 could be associated with those for self-diffusion in liquid Fe (65 kJ/mole) and Cu (41 kJ/mole).
IOP Conference Series: Materials Science and Engineering, 2018
This paper presents the outcomes of an experimental investigation on the effects of forming temperature and sintering schedule to the final characteristics of FeCuAl powder mass formed at different temperature and sintered at different schedule. A lab-scale uni-axial die compaction rig was designed and fabricated which enabled the compaction of powder mass at room temperature as well as elevated temperature. Iron (Fe) powder ASC 100.29 was mechanically mixed with other elemental powders, namely copper (Cu), and aluminum (Al) for 60 minutes and compacted at three different temperature, i.e., 30°C, 150°C, and 200°C by applying 425 MPa of simultaneous downward and upward axial loading to generate green compacts. The as-pressed samples were inspected visually and the defect-free green compacts were subsequently sintered in an argon gas fired furnace at 800°C for 60 min at three different heating/cooling rates, i.e., 5, 10, and 15°C/min, respectively. The sintered samples were then characterised for their physical, electrical, and mechanical properties. The microstructures of the sintered samples were also analysed. The results revealed that a forming temperature of 150°C and a sintering rate of 10°C/min could produce a product with better characteristics.
Reduction and sintering of ultrafine copper powders
Journal of Materials Science Letters, 1989
Slow oxidation treatment is generally adopted to avoid the spontaneous combustions of metal or nitride ultrafine powders (UFPs) with oxygen [1, 2]; however, the study of the effect of the slow oxidation treatment on the characteristics of UFPs is limited [3-6]. The sintering of copper U F P in a vacuum is greatly influenced by the adsorbed gases and oxides which are produced by the slow oxidation treatment and the succeeding exposure to air [3, 4]. The purpose of the present study is to examine the effect of slow oxidation treatment of copper UFP on the sintering characteristics in an H 2 atmosphere. Copper UFPs were produced by a vacuum evaporation technique at Vacuum Metallurgical Co. Ltd. Sintering characteristics in an H2 atmosphere were examined by measuring the dimensional changes of two kinds of copper UFP. One is the slow oxidationtreated copper (Oxidized Cu) UFP; the other is nonoxidation-treated copper (Fresh Cu) UFP. Oxygen
Liquid Phase Sintering of Ferrous Powder Metallurgical Materials
Journal of Iron and Steel Research, International, 2007
Liquid phase sintering is an attractive means of reaching near full densification of sintered powder metallurgical materials. In order to successfully realise the desired densification and intended properties of the final sintered material, the tailoring of the powder composition, powder mixture and sintering cycle is decisive. One attractive way is to use an appropriate mixture of powder where at least one powder constituentthe master alloy powderis given such composition that it fully or partially melts while another powder constituentthe base powderremains solid. This classical way of persistent liquid phase sintering has been developed for various combinations of alloys of the Fe-C-P-Cu-Si system and results demonstrate the capabilities of reaching near full density for mixtures of powder of sizes commonly used for traditional uniaxial die pressing. Another way explored has been the design of sintering approaches for supersolidus liquid phase sintering of high speed steel powder. This approach has been extensively studied by several research groups and the benefit of in-situ nitrogen alloying during sintering to yield high density and the precipitation of vanadium nitride hac been realised. In this study, this approach is explored for a high-vanadium alloy and the results show how almost full density with appropriate microstructure can be reached from pressureless-shaped specimens using so-called starch consolidation.
In this study, iron-based powder-metal (PM) compacts were sintered using a medium-frequency induction-heating system. The effects of copper amounts on mechanical properties were investigated. Iron-based powders were mixed with mass fractions w = 1 % to 6 % copper (Cu) and 0.8 % zinc stearate in a V-type mixer. During the sintering process, PM compacts were sintered at a frequency of 30–50 kHz (medium frequency), at 12 kW and 1120 °C for 400 s in an atmospheric environment. Mechanical properties, microstructural properties, densities and microhardness values were investigated for the sintered material. The highest mechanical properties were obtained for the iron-based PM compacts including 3 % Cu. Keywords: induction sintering, powder metal, iron, copper V tej {tudiji so bili kovinski stisnjenci iz prahùeleza (PM) sintrani v srednjefrekven~nem indukcijskem ogrevalnem sistemu. Preiskovan je bil vpliv vsebnosti bakra na mehanske lastnosti. Me{anica osnovnega prahùeleza z masnimdelèem w...
2018
The effect of ball milling on the compaction and sintering of nanocrystalline copper steel powder (FC-0205) was evaluated within this work. The as-received micron-sized FC-0205 copper steel powder was subjected to High Energy Ball Milling (HEBM) in an argon atmosphere at different milling times of 0, 16, 20 and 24 hours to obtain nanocrystalline structures. Unmilled, 8 and 16 hours milled powders were compacted using uniaxial die compression at pressures ranging from 274 MPa to 775 MPa to obtain a relative density range of 74% to 95%, respectively. The steel powder compacts were sintered at temperatures ranging from 400 °C to 1120 °C in high purity hydrogen and nitrogen atmospheres. X-ray Diffraction (XRD) and microscopy analysis were performed on the milled powder specimens to evaluate particle size, morphology, and extent of porosity; to establish a relationship between milling time and particle size, and to establish a correlation between grain size and milling time.
Global Journal of Research In Engineering, 2018
The effect of ball milling on the compaction and sintering of nanocrystalline copper steel powder (FC-0205) was evaluated within this work. The as-received micron-sized FC-0205 copper steel powder was subjected to High Energy Ball Milling (HEBM) in an argon atmosphere at different milling times of 0, 16, 20 and 24 hours to obtain nanocrystalline structures. Unmilled, 8 and 16 hours milled powders were compacted using uniaxial die compression at pressures ranging from 274 MPa to 775 MPa to obtain a relative density range of 74% to 95%, respectively. The steel powder compacts were sintered at temperatures ranging from 400 °C to 1120 °C in high purity hydrogen and nitrogen atmospheres. X-ray Diffraction (XRD) and microscopy analysis were performed on the milled powder specimens to evaluate particle size, morphology, and extent of porosity; to establish a relationship between milling time and particle size, and to establish a correlation between grain size and milling time.
IOP Conference Series: Materials Science and Engineering, 2018
This paper presents the outcomes of an experimental investigation on the effect of sintering schedule, i.e., holding time and temperature to the final properties of FeCrAl powder compacts prepared through uniaxial die compaction process at above room temperature. The feedstock was prepared by mechanically mixing iron powder ASC 100.29 with chromium (22 wt%) and aluminium (11 wt%) for 30 min at room temperature. A cylindrical shape die was filled with the powder mass and heated for one hour for uniform heating of the die assembly together with the powder mass. Once the temperature reached to the setup temperature, i.e., 150°C, the powder mass was formed by applying an axial pressure of 425 MPa simultaneously from upward and downward directions. The as-pressed green compacts were then cooled to room temperature and subsequently sintered in argon gas fired furnace at a rate of 5°C/min for three different holding times, i.e., 30, 60, and 90 min at three different sintering temperatures, i.e., 800, 900, and 1000°C. The sintered samples were characterized for their density, electrical resistivity, bending strength, and microstructure. The results revealed that the sample sintered at 1000°C for 90 min achieved the better characteristics.