Trans. Nonferrous Met. Soc. China 24(2014) s99−s105 Mechanical alloying of platinum with 5% ZrO 2 nanoparticles for glass making tools Taek-Kyun JUNG 1 , Dong-Woo JOH 1 , Seung-Yub LEE 2 , Myung-Sik CHOI 1, 3 , Soong-Keun HYUN 3 , Hyo-Soo LEE 1 1. Korea Institute of Industrial Technology, 7-47 Songdo-dong, Yenosu-gu, Incheon 406-840, Korea; 2. Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY 10027, USA; 3. School of Materials Science and Engineering, Inha University, 253 Yonghyun-Dong, Incheon 405-751, Korea Received 18 June 2013; accepted 10 October 2013 Abstract: Synthesis and characterization of mechanically alloyed Pt−5%ZrO 2 (volume fraction) for structural components in the glass industry were described. Zirconia (ZrO 2 ) nanoparticles (<100 nm) were produced by the electrical explosion of zirconium (Zr) wires, and blended with platinum (Pt) powders (<44 μm) for 2−72 h in ambient atmosphere. The Pt particle size followed the typical decreasing trend of the normal ball milling process up to 48 h, but particle agglomeration was observed at 72 h. The grain size evolution was similar to that of the particle size, dropping down to around 50 nm at 48 h. The root mean square strain of the Pt crystallites showed the opposite behavior, maximizing at 48 h with a subsequent relaxation process. For the 48 h ball milled powders, spark plasma sintering was carried out to form a bulk disk. The measured mass loss of the sintered bulk sample shows a decent thermal stability despite its relatively low density. Key words: platinum; zirconia; nanoparticle; electrical wire explosion; mechanical alloying 1 Introduction Platinum (Pt) and platinum group metals are highly valuable because only a few hundred tons are produced annually. In spite of their high price, platinum metals have been widely used in the glass industry because of their physical properties and excellent corrosion resistance against aggressive glass melts in the high temperature range [1]. Typical applications of platinum and its alloys are feeder systems, bubble tubs, drain bushings, tank linings, melting crucibles and glass fiber bushings. Depending on the specific application, these components usually operate at temperatures of about 1223 K in atmospheres composed of a mixture of ammonia and air, 1523 K in the liquid glass environments, and up to 1873 K in atmospheres of air or industrial gases [2]. However, the use of pure platinum in the glass industry is not suitable for glass making tools owing to its low strength and coarsening at high temperature. A significant increase in strength can be achieved by alloying through a solid solution hardening mechanism. Rhodium (Rh) and iridium (Ir) have been considered promising elements in Pt-X solid solution hardened alloy because they are not detrimental to the chemical stability of the platinum. Nevertheless, the use of these elements is limited considering that the dissolution of the smallest traces of the alloying elements in the glass melts, resulting in an undesirable change in the optical properties of glass products [3]. Furthermore, at high temperature around 1873 K, Pt-Rh and Pt-Ir solid solution hardened alloys provide a limited increase in mechanical strength, and could not prevent extreme grain from growth [4]. For this reason, oxide dispersion strengthened (ODS) Pt has been developed for both pure Pt and Pt alloys [5]. The provided finely dispersed oxide particles of zirconia (ZrO 2 ) or yittria (Y 2 O 3 ) in the Pt matrix are very small (<1 μm) and their inter-particle spacing is also small (<10 μm), the particles will hinder the movement of dislocations in the matrix and thus give an increase in strength [6]. Furthermore, the dispersed particles hinder the movement of grain boundaries at high temperature Foundation item: Project (10037339) supported by the Industrial Strategic Technology Development Program of the Ministry of Knowledge & Economy, Korea Corresponding author: Hyo-Soo LEE; Tel: +82-32-850-0492; Fax: +82-32-850-410; E-mail: todd3367@kitech.re.kr DOI: 10.1016/S1003-6326(14)63294-5