Quantitative characteristics of FeCrAl films deposited by arc and high-velocity arc spraying Giumin Liu*, K. Roz ˙niatowski, K.J. Kurzydlowski Faculty of Materials Science and Engineering, Warsaw University of Technology, ul. Woloska 141, 02-507, Warsaw, Poland Received 30 November 2000; accepted 1 January 2001 Abstract FeCrAl coatings were deposited on grade 45 steel substrates by arc spraying (AS) and high-velocity arc spraying (HVAS) under the same spray conditions, and their characteristics were quantitatively compared. Observations of the surface morphology of the coatings were conducted in a scanning electron microscope (SEM). Microhardness values of the coatings and the substrates as a function of distance along the direction perpendicular to the coating – substrate interface were measured. The profile roughness coefficients of coatings and substrates were also measured and analysed in this paper. From the results obtained in the present work, it can be concluded that FeCrAl coatings deposited by HVAS have better microproperties than that deposited by AS. D 2001 Elsevier Science Inc. All rights reserved. Keywords: Quantitative characteristic; FeCrAl film; Arc spray; High-velocity arc spray 1. Introduction Arc spraying (AS) is a technique that utilises an electric arc as the heat source to melt wires into droplets, which are subsequently sprayed onto sub- strate by the flow of compressed air [1]. High-velocity AS (HVAS) technology was developed on the basis of AS (see Fig. 1). A special tube designed according to the principle of aerodynamics has been mounted at the exit of compressed air. As a result, the velocity and spatial distribution of compressed air become higher and more uniform, respectively. Hence, higher velo- city and better atomising of melted droplets are obtained, as well as high quality of deposited coatings. In recent years, Fe – Cr alloys have received much attention as high-temperature oxidation resistance materials [2,3]. The FeCrNi and FeCrAl coatings have been successfully applied in the contexts of corrosion and oxidation resistance at elevated temperatures [4,5]. During the past 30 years, quantitative descrip- tions of the microstructure of materials based on methods of stereology and image analysis have become standard in physical metallurgy and related areas of materials science [6–8]. The quantitative approach has also more recently been used to char- acterise the structure of thin films [9,10]. Reference [11] has given a detail quantitative description of arc- sprayed FeCrNi coatings. The purpose of this work is to present a quantitative description for the structure and mechanical properties of arc and high-velocity arc-sprayed FeCrAl coatings. The emphasis is to reveal the characteristic difference between AS and HVAS FrCrAl coatings. To this end, the surface morphology, chemical composition and profile rough- ness were examined, as well as microhardness of the coatings and the substrates. Observations of the sur- face morphology of the coatings were conducted in a 1044-5803/01/$ – see front matter D 2001 Elsevier Science Inc. All rights reserved. PII:S1044-5803(01)00108-5 * Corresponding author. B B Materials Characterization 46 (2001) 99 – 104