%0 Journal Article
%T Effect of Diacetyl Monoxime Thiosemicarbazone on the Corrosion of Aged 18 Ni 250 Grade Maraging Steel in Sulphuric Acid Solution
%A T. Poornima
%A Jagannath Nayak
%A A. Nityananda Shetty
%J Journal of Metallurgy
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/723687
%X The corrosion inhibition of the aged 18£¿Ni 250 grade maraging steel in 0.5£¿M sulphuric acid by diacetyl monoxime thiosemicarbazone (DAMTSC) at 303¨C323£¿K has been investigated by potentiodynamic polarization, EIS, and SEM techniques. Good inhibition efficiency of DAMTSC was revealed even at low concentrations, which increased with the increase in DAMTSC concentration and decreased with the increase in temperature. The activation energies, , as well as other thermodynamic parameters ( ; ; ), were evaluated and discussed. The adsorption of DAMTSC on the aged maraging steel surface was found to obey the Langmuir adsorption isotherm model and shows mixed type inhibition behavior. 1. Introduction Corrosion of structural elements is a major issue for any industry because of the chemical environment of chemical processing. Maraging steels are special class of ultrahigh strength steels that differ from conventional steels in that they are hardened by a metallurgical reaction that does not involve carbon [1]. They derive high strength from age hardening of low carbon, Fe-Ni martensitic matrix [2]. The need for highly reliable substances of high strength and high ductility is gradually increasing with the development of aerospace industry. According to available literature, atmospheric exposure of 18 Ni maraging steel leads to corrosion in a uniform manner and the steel becomes completely rust covered [3]. Pit depths tend to be shallower than high strength steels [4]. Critical and passive current densities increase as the structure is varied from fully annealed to fully aged [5]. Maraging steels are found to be less susceptible to hydrogen embrittlement than common high strength steels owing to significantly low diffusion of hydrogen in them [6]. Several technical papers covering alloy design, material processing, thermo-mechanical treatments, welding, strengthening mechanisms, and so forth, have been published [7]. Search in the literature reveals very little work being reported on the corrosion behavior and on the use of inhibitors in controlling corrosion of maraging steel except some of our publications [8, 9]. Metals and alloys frequently come in contact with acid solutions during cleaning, pickling, descaling, acidising, and so forth. Materials used in acid environment should have good corrosion resistance. The present work is intended to study the corrosion inhibition of aged 18 Ni 250 grade maraging steel in 0.5£¿M sulphuric acid medium using DAMTSC as inhibitor. The majority of the well known inhibitors are organic compounds containing heteroatom, such as
%U http://www.hindawi.com/journals/jm/2012/723687/