Heat Treatment of TiH<SUB>2</SUB> Powder to Control Decomposition Phenomenon for Aluminum Foam Fabrication by Melt Route

Abstract

TiH 2 powder has been used to fabricate aluminum foams as a blowing agent for more than two decades. The aim of this paper is to understand the detailed decomposition behavior of TiH 2 powder and to control the phenomenon by a heat treatment for the fabrication of fine aluminum foams by the melt route. TiH 2 powders whose qualities were different, were characterized using TG-DTA and XRD. As heat treatment factors, temperature and time were applied. We have found differences in the decomposition behavior between the as-received TiH 2 powders. Regardless of quality of TiH 2 powder, increasing temperature and time of the heat treatment in air elevates the decomposition temperature and decreases the amount of released hydrogen during reheating due to the oxide barrier layer formed on the powder surface. The influence of the heat treatment temperature on the decomposition modification is more significant than that of the time. To control the decomposition phenomenon of TiH 2 powder, the heat treatment condition has to be optimized taking into account the quality and the purity of the powder.

Microstructural and mechanical properties of Al–SiO2 nanocomposite foams produced by an ultrasonic technique

“…Silicon dioxide powder with particles size from 40 to 80 nm was selected as reinforcement material because of its good wettability with aluminum alloys. TiH 2 powder was used as foaming agent with purity more than 98% and was heat treated at 450°C for 3 h to improve gas releasing behavior [6,19].…”

“…Kadoi [6] showed that the decomposition of TiH 2 starts at around 420°C, but in aluminum foam fabrication by the melt route technique, the samples are heated between 600°C and 700°C. Thus, the temperature difference between the TiH 2 decomposition and foam fabrication strongly influences the yield and the foaming phenomenon.…”

Classification of Mechanical Properties of Aluminum Foam by Machine Learning

“…36) However, it is difficult to evaluate how each pore structure affects the mechanical properties of Al foam. In particular, the Al foam produced by the casting 7,8) or precursor 9,10) method undergo a foaming process in which it is slightly difficult to control the pore structures. Thus, there are some variations in the mechanical properties of the obtained Al foam.…”

In Situ Synchrotron Radiation Study of TiH2-6Al-4V and Ti-6Al-4V: Accelerated Alloying and Phase Transformation, and Formation of an Oxygen-Enriched Ti4Fe2O Phase in TiH2-6Al-4V

“…By contrast, there were virtually no oxide phases detectable in the TiH 2 -6Al-4V powder mixture below 898 K (625°C). After that, due to less release of H 2 from the initial TiH 2 powder and increased temperature, oxide phases [Ti 3 O, Ti 6 O, and TiO 2 (H: hexagonal with a = 2.96 Å , c = 4.85 Å )] [18][19][20][21][22][23] started to build up on the freshly exposed Ti powder surfaces but the process still occurred to a less extent than the case with the HDH Ti-6Al-4V alloy. The dehydrogenation of TiH 2 has clearly affected the formation and/or growth of oxide films on the particle surfaces.…”

“…The oxides were determined to be TiO 2 (tetragonal with a = 4.59 Å and c = 2.96 Å ), [18][19][20][21] showing a preferential growth along its (200) plane. At about 898 K (625°C), the presence of other titanium oxide phases, Ti 3 O (hexagonal with a = 5.15 Å and c = 9.56 Å ) [18,19,22] and Ti 6 O (hexagonal with a = 5.13 Å and c = 9.48 Å ), [22,23] were detected. Ti 3 O and Ti 6 O have almost identical crystal structure and lattice parameters, making their peaks often overlap.…”