Fabrication of non-oxide ceramic powders by carbothermal-reduction from industrial minerals Ljiljana Kljajević 1 , Aleksandra Šaponjić n,1 , Svetlana Ilić, Snežana Nenadović, Maja Kokunešoski, Adela Egelja, Aleksandar Devečerski Laboratory of Materials Science, Institute of Nuclear Science Vinča, University of Belgrade, Belgrade, Serbia article info Article history: Received 15 December 2015 Received in revised form 2 February 2016 Accepted 2 February 2016 Available online 8 February 2016 Keywords: B. Composites D. Carbides E. Structural applications CRR-method abstract The most promising method for obtaining a large variety of non-oxide products having important technical uses is carbothermal-reduction reaction (CRR). By using this procedure, SiC and ZrC/SiC pow- ders are obtained from diatomaceous earth and zircon powder. In this way the synthesized powders are obtained at a relatively low temperature due to good homogenization. Starting C/ZrSiO 4 admixtures having different molar ratios (3:1, 4:1, 5:1 and 7:1) and C/SiO 2 having ratios 1:1, 3:1, 4:1, and 7:1 were heated at temperatures between 1300 and 1600 °C in a controlled Ar flow atmosphere. The phase evolution was a function of the raw materials molar ratios and sintering temperature. The optimal parameters for the synthesis of SiC and ZrC/SiC powders were obtained. The results obtained by EDS analysis are in good agreement with those obtained by XRD analysis for the synthesized carbide pow- ders. & 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved. 1. Introduction In the recent years, significant progress has been done in the development of engineering ceramic materials. A new generation of ceramics which is expected to find a wide use in high tem- perature applications has been developed. Non-oxide ceramics based on the carbides, nitrides, and borides of group IVB and VB transition metals have received a considerable attention due to their unique combination of properties, such as high melting temperature, hardness, high electrical and thermal conductivities, as well as chemical inertness [1]. Silicon carbide is an important engineering material due to its high temperature strength, ther- mal shock resistance, and resistance to wear and corrosion [2]. Many authors have studied the formation of SiC powders from the commercially mined geological materials known as industrial minerals, such as high purity quartz sand, aluminosilicates, dia- tomaceous earth, zircon, mulite, clay as a SiO 2 source [3–7]. These minerals may be used in their natural state or after beneficiation as raw materials in a wide range of applications. The required quality of a final product depends on the starting materials and processing technology. Among the most utilized industrial mi- nerals are diatomaceous earth and zircon [7]. The admixture of carbon and diatomaceous earth yields SiC in the temperature range from 1480 °C to 1700 °C [5]. Among the raw materials that may be used for SiC powder production, the above mentioned diatomaceous earth has some advantageous properties such as high specific surface area, high silica content, and low price [8]. Beside SiC, zirconium carbide is one of the most promising cera- mics for ultrahigh temperature applications due to its high melting point (up to 3540 °C), ability to form refractory oxide scales at high temperatures, and a relatively low density (6.7 g/cm 3 ) compared to HfC (12.2 g/cm 3 ) [9]. Also, ZrC powders can be produced by using naturally occurring minerals, mainly zircon beach sands (ZrSiO 4 ) and badeleyite (ZrO 2 ) [9]. Various routes for preparing homogenous ceramic powders have been developed so far. Good homogenization and high purity of pro- duced powders are obtained by chemical routes, but these methods are expensive in terms of industrial manufacturing in comparison with the conventional milling techniques. One of the most promising methods for production of the non-oxide ceramic powders with im- portant technical uses is carbothermal-reduction reaction (CRR) [10]. This procedure offers the possibility of an economically attractive production route from naturally occurring materials and the obtained powders are well homogenized. This method has been used as a preferred route to process oxidic ores and for elimination of the silica component from mineral silicates [11–14]. During the carbothermal reduction reaction between two so- lids, oxide and carbon, one solid (carbide) and one gaseous (CO) Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/ceramint Ceramics International http://dx.doi.org/10.1016/j.ceramint.2016.02.017 0272-8842/& 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved. n Corresponding author. E-mail address: acavuc@vinca.rs (A. Šaponjić). 1 Contributed equally to this article. Ceramics International 42 (2016) 8128–8135