High Temperature Decomposition Behavior of CaZrO 3 Coating on Graphite for TiNi Alloy Melting
- PDF / 1,454,041 Bytes
- 6 Pages / 595.276 x 841.89 pts (A4) Page_size
- 21 Downloads / 224 Views
980 DOI
https: //doi. org/10.1007/s11595-020-2345-y
High Temperature Decomposition Behavior of CaZrO3 Coating on Graphite for TiNi Alloy Melting ZHAN Bin, ZHANG Yue, WANG Caifen, WANG Xiaoying
(Institute of Materials, China Academy of Engineering Physics, Mianyang 621907, China)
Abstract: In order to restrain the carbon pollution, the feasibility of CaZrO3 coating was studied. The precursor powder was synthesized via solid-state reaction using metal calcium as a raw material. The protective coating on graphite was prepared by impregnation sintering method, and the effects of slurry viscosity, graphite density and coating thickness for coating were compared. The phase composition and microstructure of coatings were characterized, and the thermodynamic process was analyzed when the coating composition changed from CaZrO3 to ZrC. The results show that vacuum sintering can result in the decomposition of CaZrO3 and an intact ZrC coating with beautiful porous structure can be obtained. Key words: CaZrO3; ZrC; impregnation; coated graphite; decomposition
1 Introduction TiNi-based alloy shows the excellent shape memory effect and superelasticity, as well as good damp ability, anticorrosion and biocompatibility. It has been widespread used in aerospace, machine, energy, electronic and medicine field[1-3]. However, titanium is a highly active metal, which can react with almost all known fire-resistant materials (such as Al 2O 3, MgO) to form brittle compound under molten state. Therefore, it is difficult to melt Ti-based alloys, and the industry production of such materials is mainly applied by vacuum arc skull furnace with water cooled copper crucible or cold-hearth furnace refining[4]. These technics all presence high-energy consumption, hence researchers are looking for better melting methods with low cost. Vacuum induction melting is a common method for metal smelting, which exhibits two significant advantages: the energy consumption is reduced without water cooled system and an intensely electromagnetic stirring effect is produced that can maintain a higher © Wuhan University of Technology and Springer-Verlag GmbH Germany, Part of Springer Nature 2020 (Received: June 29, 2019; Accepted: June 18, 2020) ZHAN Bin(詹斌): Assoc. Researcher; Ph D; E-mail: [email protected] Funded by the National Natural Science Foundation of China (No. 51702299)
superheat (150-200 ℃), which is propitious to remove segregation and obtain high quality Ti alloys [5,6] . However, the prerequisite of vacuum induction melting is to own a suitable crucible material that is unreactive with Ti-based melt[7]. The common crucible materials include graphite[8], oxides[9] and BN[10], whereas they exhibit some shortcomings, such as carbon pollution, low inertia, high cost. Among them, graphite shows good conduction and anticorrosion, low expansible coefficient, finer machinability, repeated usability and abundant resource that is regarded as a favorable crucible material for alloy melting. In order to avoid its carbon pollution, a series of approache
Data Loading...
