Fabricación de recubrimientos de alta resistencia por LMD para estampación en caliente

EUSKERA: Beroko estanpazio prozesuak txapa konformaketaren fabrikazio teknologia da, deformatu beharreko materiala aurreberotu ostean pieza konformatu eta tenplatu egiten da; non trokelaren gune aktiboak higadura latzak jasaten dituen. Balio gehigarri altuko trokel hauen bizi zikloa luzatzeko, takoak kolpeak jasateko ijeztutako altzairu harikor batekin fabrikatzea proposatzen da, gainetik laser prozesu gehigarriaren bidez (LMD) errendimendu altuko estaldura bat gehituko zaio bere gogortasunari esker abrasio bidezko higadura minimizatzen dituena. Horretarako gradiente funtzional (FGM) bidezko estaldura egitea planteatzen da, material ezberdinak konbinatuz, piezaren konposizioa aldatu ahala barne propietateak aldatuko dituena.CASTELLANO: El proceso de estampación en caliente es una tecnología de fabricación de conformado de chapas, en los que se calienta previamente el material a deformar y se procede al conformado y temple de la pieza; donde la parte activa de los troqueles sufre un gran desgaste. Para aumentar la vida de estos útiles de alto valor añadido, se propone fabricar los tacos con un material base de acero laminado dúctil que pueda resistir los continuos impactos de la estampación, sobre el que se aportará mediante aporte por láser (LMD) un recubrimiento de alto rendimiento que gracias a su alta dureza minimice el desgaste por abrasión. Para ello se plantea realizar un recubrimiento con gradiente funcional (FGM), combinando distintos materiales, dotando así a la pieza de distintas propiedades a medida que varía la composición.ENGLISH: The hot stamping process is a manufacturing technology for sheet metal forming, in which the material to be deformed is heated beforehand and the part is formed and hardened; where the active part of the dies suffers a great deal of wear. In order to increase the life of these high added value tools, it is proposed to manufacture the blocks with a ductile laminated steel base material that can resist the continuous impacts of the stamping, on which a high performance coating will be provided by means of a laser contribution (LMD) which, thanks to its high hardness, minimizes wear by abrasion. For this purpose, a coating with a functional gradient (FGM) is proposed, combining different materials, thus providing the part with different properties as the composition varies

Gas proportional scintillation counter pulse-signature analysis using digital techniques

The use of short shaping time-constants (50 ns) followed by digital sampling of gas proportional scintillation counter pulses is investigated. Such short shaping time causes each pulse to closely resemble the scintillation light burst, allowing for an effective pulse-signature analysis. Pulse amplitude is obtained by numerical integration of the digital pulse samples. The shorter total pulse durations, lead to pulse-height distributions that are much less dependent on the total interaction rate occurring in the detector. Total interaction rates up to 12 k s-1 can be tolerated without significant degradation of the obtained pulse-height distribution. It was also verified that the maximum throughput achieved by the digital pulse-height analyser improves from 1 to 1.7 k s-1 when using the short shaping time-constants.http://www.sciencedirect.com/science/article/B6TJM-3VR1CVW-2F/1/2e9e952e1c3752048a2954b0dbbdec2

Energy non-linearity effects in the response of ionic crystal scintillators to X-rays with energy in the region of the K-absorptions edges: experimental results

The response of a YAP, NaI(Tl) and BaF2 scintillators to X-rays with energies around the Y, I, and Ba K-absorption edges, respectively, was investigated. For all the scintillators, the amplitude response follows different linear trends for X-ray energies below and above the respective K-edges, presenting a discontinuity at these energies. An abrupt decrease of about 3%, 5% and 2% were observed in the detector amplitude at the K-edges, for the YAP, the NaI(Tl) and the BaF2 scintillator, respectively, corresponding to a decrease of 0.5±0.1, 1.7±0.3 and 0.8±0.2 keV in the energy calibration line. These discontinuities result in a region within 0.5±0.1, 1.6±0.3 and 0.9±0.2 keV where the X-ray energy cannot be obtained unambiguously. The scintillation yields for X-rays present abrupt decreases of about 3%, 4% and 2%, respectively, at the K-edges. The measured non-linearity effects are significantly larger than those obtained for gaseous and semiconductor detectors. The higher amplitude non-linearity observed in NaI(Tl) is attributed to the larger light yield non-linearity in the electron response of this crystal.http://www.sciencedirect.com/science/article/B6TJM-49N7V56-3/1/6bc7816ad91bca6e857e9a848f8eb8a

The X-ray performance of a driftless gas proportional scintillation counter using short shaping-time constants for pulse analysis

Performance characteristics are evaluated for a xenon driftless gas proportional scintillation counter (GPSC), for which detector pulses are formatted using very short shaping-time constants (~50 ns), and directly analyzed by the MCA without previous pulse time duration analysis and amplitude correction. The present detector and method allow the achievement of detector energy linearity and energy resolution similar to those of conventional GPSCs, reducing background levels and maximizing the detector count-rate capability. However, the obtained peak tails can be somewhat larger than those obtained with conventional GPSCs for X-ray energies above ~30 keV. Energy resolutions of 7.7%, 4.5% and 3.8% can be achieved for 5.9, 22.1 and 59.6 keV X-rays, respectively.http://www.sciencedirect.com/science/article/B6TJM-4BRJ561-J/1/7e1da2da1ab9696753720d39add33d5