Study On Coated TiH₂ Powders As The Foaming Agent Of Foamed Aluminum

Foamed aluminum is a kind of versatile material made of metal skeleton and cells. It has sound absorption, energy absorbing, electromagnetic shielding, light, heat insulation and other excellent characteristics. Therefore, it can be widely used in aerospace, machinery, buildings, telecommunications, transportation and other fields. There are many ways to prepare the foamed aluminum. Melt foaming method is considered to be one of the most promising preparations. In the melt foaming method, TiH2 is the most popular foaming agent. However, the hydrogen release temperature of TiH2 is so low that H2 releases too quickly in the melted aluminum. As a result, the holes of aluminum foam product are uneven, and the foaming process is difficult to control. This is the biggest technical difficulty in the melt foaming method.In this study, pure TiH2 powder was coated with TiO2 oxide layer by sol-gel method. And this study is about solving the melt foaming problem of fast hydrogen release rate by this way. Orthogonal experiment was done to determine the main factors of the coating experiment. The best method for preparing coated foaming agent was obtained and the coated foaming agent which can meet the effects of hydrogen release requirement was prepared.The SEM, XRD, and TG-DTA were used to characterize the coated foaming agent prepared under different experimental conditions. The material structure, main ingredient and heat absorption under heating conditions were in-depth understood. The results showed that the new foaming agent has a structure that TiO2 is coated on the surface of TiH2. The cladding layer is dense and about 2μm thick for good foaming agent. And the fastest hydrogen release temperature of the new foaming agent transfers to the higher temperature zone.Foamed aluminum was prepared with the coated and uncoated foaming agent. The results showed that the foamed aluminum products prepared with coated foaming agent have more uniform pore size and stronger energy-absorbing ability, the macropores ratio reduced significantly, and the foaming process is easier to control.