Estudio del envejecimiento acelerado bajo radiación solar concentrada de vidrios de oxicarburo como receptores de alta temperatura

Abstract

Solar energy and especially concentrated solar power systems (CSP) need materials that can tolerate the demanding working conditions. In this sense, the receivers are exposed to large fluxes of solar radiation that produce very high temperatures. In addition, due to the operational conditions of receivers large temperature variations occur during day and night, or on cloudy days being these the main aging factors. However, other factors such as humidity, salines environments or pollutans in industrial zones can not be ruled out. Silicon oxycarbide glasses (SiOC) are composite materials formed by a SiOC glass phase (matrix phase) and a C phase (reinforcing phase) homogeneously dispersed and they can be very promising candidates for this type of applications due to their excellent intrinsic properties like their high resistante against to both oxidation and very aggressive environments, good mechanical properties, etc. In this work we have focused in the evaluation of the composite materials (SiOC porous and dense) against thermal shock produced by Frenel lens that concentrated solar radiation more than 2600 times. In every cycle materials they have been heated (32 oC s-1) an cooled (27 oC s-1) at very high rates from room temperature to 1000 oC. This process has been repeated 100 times or lesser in the case of catastrophic material damage. The evolution of material surface during thermal shock cycles has been followed by several techniques such confocal and electronic microscopies and Raman, Infrarred and UV-Visible spectroscopies. Porous silicon oxycarbide materials experiencied a rapid and severe degradation during the first cycles but dense one tolerates quite well the exposure againts concentrated solar radiation.