Corrosion behaviour of several aluminium alloys in contact with a thermal storage phase change material based on Glauber’s salt A. García-Romero a, * , A. Delgado a , A. Urresti b , K. Martín b , J.M. Sala b a Universidad del País Vasco-Euskal Herriko Unibertsitatea, Dpto. Ing. Minera, Metalúrgica y Ciencias de los Materiales, Escuela Universitaria de Ingeniería Técnica de Minas y de Obras Públicas, Beurko s/n, Barakaldo 48902, Spain b Universidad del País Vasco-Euskal Herriko Unibertsitatea, Dpto. de Máquinas y Motores Térmicos, Escuela Superior de Ingeniería Industrial, Alameda Urkijo s/n, Bilbao 48013, Spain article info Article history: Received 19 December 2008 Accepted 5 March 2009 Available online 19 March 2009 Keywords: A. Aluminium B. XRD B. SEM C. Alkaline corrosion C. Pitting corrosion abstract This article presents the results of a study about the corrosion behaviour of four aluminium alloys (EN AW 2024, 3003, 6063, and 1050) in contact with a commercial thermal storage material based in the Gla- uber ´s salt (Na 2 SO 4 Á10 H 2 O). Results indicate that the Al 2024 alloy is not compatible with this material due to the extense formation of NaAlCO 3 Á(OH) 2 in contact with air. The aluminium alloys 3003, 6063 and 1050 showed to be fully compatible with the material. Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction and state of the art Since early 70s, much research has been done for the develop- ment of efficient thermal storage devices based in latent heat in a phase change. The materials employed for this application are widely known as PCMs, or phase change materials, and the results attained so far have rendered some interesting industrial applica- tions. Presently, the global warming and the energy crisis have re- newed the interest in the topic. In spite of the extense bibliography and the large social and commercial interest in this subject, only some few works have been devoted to the study of the degradation of the systems containing PCMs, and no more than a dozen inter- national references have been found regarding the corrosion of metals with potentially corrosive hydrated salts used as PCMs. Ta- ble 1 gathers these references, together with the PCMs and alloys evaluated in them. This article presents the results of a study on the corrosion behaviour of several aluminium alloys with a commercial material developed for the storage of thermal energy in the form of latent heat by means of a solid-liquid phase change. The materials em- ployed for this purpose are commonly known as PCMs, phase change materials. The work has been carried out in the frame of a project where the objective is to develop modular components for thermal storage at temperatures between 30 and 40 °C. The main requirements of these modules are that they have to be com- pact, light, with high thermal conductivity, and must be produced of comercially available materials and procedures, at a marketable price. According to these requirements, three commercial alumin- ium products were selected, capable of containing the PCM while maximizing the thermal conductivity, at a reasonable price and with good availability. These products were made of four different aluminium alloys, specifically Al alloys 3003-H19, 6063, 2024-T3 and 1050-H24. And two of them required a sealing stage with epoxy adhesives. It has to be remarked that the alloy selection for the PCM containers was made according to market availability in shapes and prices to produce the designed modules. As a result, the materials selection has not been based in the corrosion resis- tance of the alloys. The selection of the PCM was an important part of the study. Inorganic commercial PCMs were preferred, and a commercial product with phase change at 32 °C was selected, called PLUS ICE E32. This product is produced and supplied by EPS LTD, Cam- bridgeshire (UK). The active PCM in this product was not disclosed by the supplier, but its analysis showed that Glauber ´s salt was the main component. The first studies about the corrosion behaviour of the PCM hy- drated salts in contact with metallic containers were reported by Abhat, Heine, and other researchers at the end of the 70s and beginning of the 80s. Abhat made a summary of those results in a review [1]. His main conclusions were that stainless steel was fully compatible with all the evaluated hydrated salts and (liter- ally) the evaluated aluminium alloys were incompatibility with all the evaluated hydrated salts, with the exception of the hydrated 0010-938X/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.corsci.2009.03.006 * Corresponding author. Tel.: +34 94601 4982; fax: +34 94601 7800. E-mail address: anemiren.garcia@ehu.es (A. García-Romero). Corrosion Science 51 (2009) 1263–1272 Contents lists available at ScienceDirect Corrosion Science journal homepage: www.elsevier.com/locate/corsci