Author(s)

S. Lamprakopoulos, V. Karayannis, G. Papapolymerou, S. Zaoutsos, K. Ntampegliotis, X. Spiliotis

Abstract

In the present work, mixtures of mill scale (MS), an industrial by-product derived from the flaky surface of hot rolled steel, and lignite power station fly ash (FA), both originating from Greek industries, are examined as 100% the starting materials for the sustainable development of ceramics employing powder metallurgy (P/M) fabrication procedures. It should be emphasized that the safe management of such low price and largely available industrial secondary resources by their utilization as 100% the feedstock for another industrial sector (ceramic industry) is strongly prioritized by current EU policies.

FA and MS were mixed in various proportions (30–80% wt. in MS), cold compacted at 20 tn using an automated hydraulic press to form a series of 5 cm diam. disc-shaped specimens, and then sintered at three different peak temperatures (1000°C, 1100°C and 1140°C) for 3 h.

The experimental results are encouraging, showing that the mechanical performance (diametral tensile strength) of the integral ceramic materials so-produced sharply increases, from 0.77 MPa up to as much as 13.42 MPa, with the temperature increase from 1000°C up to 1140°C, for a 50–50 %wt. FA–MS mixture. Scanning electron microscopy mapping enables a better understanding of the microstructural changes occurring at higher sintering temperatures. On the other hand, the coefficient of thermal conductivity increases with temperature and the MS content in the mixture.

Keywords

fly ash, mill scale, sintering temperature, thermal conductivity, diametral tensile strength