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On the Densification Kinetics of Metallic Powders Under Hot Uniaxial Pressing
J. M. Montes,F. G. Cuevas,J. Cintas,F. Ternero,E. S. Caballero 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.3
A new model undertaking the densification kinetics of uniaxially pressed metallic powders at constant temperature is proposed. This model is developed according to the power law of creep, and the expression of the ‘net pressure’ derived by theauthors in a previous work. This net pressure describes the ‘geometrical hardening’ experienced by the powder mass, duringcompression. In order to validated the model three different powders were uniaxially pressed, aluminium, tin and lead, beingobtained data from hot compaction experiments. The similarity between the model predicted curves and the experimentaldata is quite acceptable. In addition, the goodness of the model is contrasted with two other theoretical models addressing thesame problem. The approach developed can be useful to model hot uniaxial pressing and electrical consolidation processes,which start with loose powders, i.e., not previously cold compacted powders.
A. Algora,D. Jordan,J. L. Tain,B. Rubio,J. Agramunt,L. Caballero,E. Nacher,A. B. Perez-Cerdan,F. Molina,A. Krasznahorkay,M. D. Hunyadi,J. Gulyas,A. Vitez,M. Csatlos,L. Csige,J. Aysto,H. Penttila,S. Ri 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
The decay heat of fission products plays an important role in predictions of the heat released by nuclear fuel in reactors. In this contribution we present results of the analysis of the measurement of the beta decay of some refractory isotopes that were considered possible important contributors to the decay heat in reactors. The measurements presented here were performed at the IGISOL facility of the University of Jyvakyla Finland. In our measurements we have combined for the first time a Penning trap (JYFLTRAP), which was used as a high resolution isobaric separator, with a total absorption spectrometer. The results of the measurements as well as their consequences for decay heat summation calculations are discussed.
Modelling and Simulation of the Electrical Resistance Sintering Process of Iron Powders
J. M. Montes,F. G. Cuevas,F. J. V. Reina,F. Ternero,R. Astacio,E. S. Caballero,J. Cintas 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.7
In this paper, the process known as Electrical Resistance Sintering under Pressure is modelled, simulated and validated. Thisconsolidation technique consists of applying a high-intensity electrical current to a metallic powder mass under compression. The Joule effect acts heating and softening the powders at the time that pressure deforms and makes the powder mass todensify. The proposed model is numerically solved by the finite elements method, taking into account the electrical–thermal–mechanical coupling present in the process. The theoretical predictions are validated with data recorded by sensorsinstalled in the electrical resistance sintering equipment during experiments with iron powders. The reasonable agreementbetween the theoretical and experimental curves regarding the overall porosity and electrical resistance suggests that themodel reproduces the main characteristics of the process. Also, metallographic studies on porosity distribution confirm themodel theoretical predictions. Once confirmed the model and simulator efficiency, the evolution of the temperature and theporosity fields in the powder mass and in the rest of elements of the system can be predicted. The influences of the processingparameters (intensity, time and pressure) as well as the die material are also analyzed and discussed.