Contents lists available at ScienceDirect Corrosion Science journal homepage: www.elsevier.com/locate/corsci The SDS and steel surface interaction behaviour in case of high mass flux spray cooling from very high temperature Lily Das a , B. Swain b , B. Munshi a , S.S. Mohapatra a, ⁎ , A. Behera b a Department of Chemical Engineering, National Institute of Technology Rourkela, 769008, India b Department of Metallurgical and Material Science Engineering, National Institute of Technology Rourkela, 769008, India ARTICLE INFO Keywords: SDS Stainless steel Reaction Morphology XRD ABSTRACT The use of additives as a coolant enhances the heat transfer rate as it alters the thermo physical properties of the fluid in the favourable direction of heat transfer. Although the aforesaid technology mitigate the requirements depicted in Time Temperature Transformation diagram; however, the quenching from high temperature, which may lead to a reaction with coolant, deposition and modification of surface morphology has not been addressed in the open literature. Therefore, in the current work, the interaction of coolant with the surface has been tried to disclose in terms of surface reaction, deposition or physical changes leading to variation in morphology. In the current work, AISI 304 steel plates are quenched by water with varied concentration of SDS to mitigate the cooling requirement and by using EDS, XRD and SEM analysis, the surface interaction is revealed. The elemental analysis by EDS and XRD clearly indicate the formation of new compounds resulted from the reaction between hot steel and the coolant. Based on the identified compounds formed on the surface, the possible reactions on the surface due to interaction among the hot surface, water, oxygen and adsorbed SDS are proposed and also va- lidated. 1. Introduction Heat treatment of steel is an integral part of the entire manu- facturing process defining the quality of steel [1,2]. The major re- quirements of very sophisticated steel are high quenching rate on Run out table (ROT) and unaltered surface morphology [3]. The former requirement is achieved by using novel coolants [4,5]. However, the latter one has not been addressed in the literature. The open literature confirms that the use of additives enhances the cooling rate. Qiao et al. [6] performed the cooling of steel by using sodium dodecyl sulfate (SDS) added water. They observed that the heat transfer rate is en- hanced up to 110%. The observation was for low mass flux and Bhatt et al. [7] and Pati et al. [8] further extended the work of Qiao et al. for high mass flux. They observed enhancement in case of high mass flux case also. In the follow up research, Bhatt et al. used benzene, acetone and n-hexane added water as coolants in spray cooling. They reported that the presence of above mentioned coolants in water augments the critical heat flux (CHF). In addition to the above, the mechanism by which augmentation in corrosion resistance behaviour of stainless steel can be accomplished has also been studied [9]. Ives et al. [10] used molybdenum ions for increasing the pitting corrosion resistance of austenite stainless steel. As steel at high temperature depicts reactive tendency with used coolant and therefore, the reactions on the surface and in turn altera- tion of the surface morphology are expected [11–13] as depicted in Fig. 1. In the schematic diagram, water + SDS is considered as the coolant and this is depicted as blue colour spherical ball and AISI-304 steel molecules are represented as red colour spherical balls. Before the quenching, the state of the steel molecules and SDS + water molecules are illustrated on stage I of the schematic diagram. The post impinge- ment characteristics are presented in Stage II. In this stage, heat transfer occurs from steel molecules to SDS + water and as a result, water evaporates and a very thin solid layer of SDS deposits on the hot sur- face. Due to deposition at very high temperature (> 700 °C), pyrolysis is expected and in turn SDS decomposes. Due to this, the formed new elements or unstable molecules react with the elements of steel and forms new compounds which are described as the daughter in the current work. Different daughter molecules have different intensity of force of adhesion with steel molecules. The molecules depicting the comparatively lower intensity of aforementioned force washes away by the coolant and the remaining molecules are retained on the surface. Due to the aforesaid phenomenon, roughness develops or morphology of the plate alters. The discussed process is presented in Stage III. In addition to the above, during the cooling, the deposition of the https://doi.org/10.1016/j.corsci.2019.06.007 Received 14 October 2018; Received in revised form 10 May 2019; Accepted 10 June 2019 ⁎ Corresponding author at: Spray Boiling Heat Transfer Laboratory, Room No-114, First floor, Department of Chemical Engineering, NIT Rourkela, 769008, India. E-mail address: mohapatras@nitrkl.ac.in (S.S. Mohapatra). Corrosion Science xxx (xxxx) xxx–xxx 0010-938X/ © 2019 Elsevier Ltd. All rights reserved. Please cite this article as: Lily Das, et al., Corrosion Science, https://doi.org/10.1016/j.corsci.2019.06.007