The Cyclic Oxidation and Hardness Characteristics of Thermally Exposed Titanium Prepared by Inductive Sintering-Assisted Powder Metallurgy

Abstract

The oxidation and hardness of thermally exposed titanium (Ti) prepared using inductive sintering-assisted powder metallurgy was evaluated through cyclic tests in air at 700-900 • C for 100 h (5 cycles). In general, the oxidation kinetics of the Ti samples followed the parabolic law and their oxidation rates increased with increasing oxidation temperatures. The rutile form of titanium dioxide (TiO 2 ) was detected by X-ray diffraction in the oxide scales after oxidation at 700 • C and 900 • C. Furthermore, the TiO 2 grain size and thickness were significantly influenced by an increase in the oxidation temperature. Lastly, the formation of rutile as a single-phase on the surface of oxidized Ti enhanced the hardness of the oxide scales, whereas the substrate had lower hardness values than the oxide scales due to diffusion of Ti atoms at the surface to form the TiO 2 oxide scales.

Development, Characterization and High-Temperature Oxidation Behaviour of Hot-Isostatic-Treated Cold-Sprayed Thick Titanium Deposits

“…That may be due to the forming of a protective layer of titanium oxide. However, no stabilization in mass gain was observed in the studies available in the literature, even after 1500 cycles of oxidation in air at a 700 • C temperature for pure bulk titanium [25]. This concretes that cold-sprayed HIP-treated pure titanium deposit is more advantageous for high-temperature applications.…”

“…The value of Kp for the cold-sprayed HIP-treated pure titanium sample is found to be 1.17 × 10 −11 g 2 mm −4 s −1 , which describes the cyclic oxidation rate quantitatively. The magnitude of Kp was observed to be less than that of titanium specimens prepared via the powder metallurgy process assisted with inductive sintering (1.43 × 10 −11 g 2 mm −4 s −1 ) [25]. The mass of the cold-sprayed HIP-treated pure titanium sample was found to increase during the first 67th cycles.…”

Effect of oxide layers formed by thermal oxidation on mechanical properties and NaCl-induced hot corrosion behavior of TC21 Ti-alloy

“…The dissolved oxygen atoms in the lattice distortion let to increase in c/a ratio so that hardness increases after thermal oxidation treatment 32 . The oxide layer was mainly formed of the TiO 2 rutile phase with the properties of high hardness and good thermal stability 43 . According to Guleryuz and Cimenoglu 44 , microhardness values of thermal oxidation of Ti alloys increased with increasing oxidation temperature and time.…”

“…The oxide layer was mainly formed of the TiO 2 rutile phase with the properties of high hardness and good thermal stability 43 . According to Guleryuz and Cimenoglu 44 , microhardness values of thermal oxidation of Ti alloys increased with increasing oxidation temperature and time.…”