Thermodynamic analysis of Ti powder synthesized by
SHS thermitreaction
SHS thermitreaction
(1. State Key Laboratory of Gansu Advanced Nonferrous Metal Materials,
Lanzhou University of Technology, Lanzhou 730050, China;
2. Key Laboratory of Non-ferrous Metal Alloys, Ministry of Education,
Lanzhou University of Technology, Lanzhou 730050, China;
3. College of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China)
Lanzhou University of Technology, Lanzhou 730050, China;
2. Key Laboratory of Non-ferrous Metal Alloys, Ministry of Education,
Lanzhou University of Technology, Lanzhou 730050, China;
3. College of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China)
Abstract: According to the thermodynamics theories, the reactive Gibbs free energies, the reactive adiabatic temperature, the melting rate of Ti and the gasification mass of Mg in the Mg-TiO2 and Al-TiO2 systems were theoretically calculated and analyzed respectively. The results show that the reactions of Mg-TiO2 and Al-TiO2 are very easy to take place and the reaction of producing various suboxides of Ti may occur in Mg-TiO2 and Al-TiO2 reaction system; the adiabatic temperature of Mg-TiO2 becomes lower with increasing mass fraction of Mg. The adiabatic temperature is below 1 800 K when the mass fraction of excessive Mg exceeds 25%; The adiabatic temperature of Al-TiO2 also becomes lower with increasing mass fraction of Al, but it becomes higher with the preheat temperature increment. The adiabatic temperature plateau is the result of Ti melting endotherm; owing to the gasification of a great deal of Mg in Mg-TiO2 reaction process, Mg should be properly excessive in order to get Ti.
Key words: self-propagating high-temperature synthesis(SHS); thermodynamic analysis; adiabatic temperature; Mg-TiO2; Al-TiO2