Research On Super-high Temperature Oxidation And Combustion Behavior Of Ti40

As its extraordinary comprehensive function, titanium alloys are widely used in aircraft industry. However, during to the intrinsic characteristic of titanium alloys, they can easy emerge “titanium-burning” phenomenon when the normal titanium alloys were served in the aero-engine application environment, which limits its usage in the advanced aero-engine. In order to avoid accident like the “titanium-burning”, and satisfy the special requirement of material of the thrust-weight ratio aero-engine, it’s necessary to do a further systematic research on the combustion titanium alloy problem.This paper analyzed the oxidation behavior of titanium alloy and its combustion products. The super-high temperature oxidation behavior of Ti40 alloy and Ti17 alloy has also been studied as well as the similarity and differences of the results of the combustion zones and combustion products caused by different lighting ways. The oxidation experimental results indicate that in the oxidation process under the temperature 1000℃~1500℃ the oxide layer of Ti40 will craze and peel off. After the peel-off of the oxide layer, the sub-surface, which is rich in Cr, will turn into the Cr2O3 oxidation surface. The mixture layer, formed by Cr2O3 and TiO2, increases the density of oxide layer markedly. An enrichment zone of V and Cr exists between the oxide layer and the matrix. The mixture oxide layer formed by Cr2O3 and TiO2, and the enrichment zone of V and Cr provide a protective screen, which prevents the oxygen from diffusion the matrix. Compared with the Ti40 alloy, the Ti17 alloy has a different super-high temperature oxidation behavior. After the peel-off of the surface oxide layer, the oxidation of sub-surface repeats the oxidation process of the previous surface. In the whole super-high temperature oxidation process, the protective screen, which prevents the oxygen from diffusion, does not appear. It shows that the oxidation of Ti17 under the temperature 1000℃~1500℃ is a single oxidation process. No mechanism for preventing the oxygen from spreading into the matrix or slowing down the oxidation process has been formed.After the comparison research of different combustion experimental method, we can find that the result of the combustion of titanium alloy has nothing to do with the way of lighting. Different ways of lighting only affects the shape and size range of different combustion zone, but has no influences upon the characteristics of combustion products. After the combustion, it’s mainly composed of a single TiO2 in Ti17’s surface, while Ti40 contains TiO2 and amounts of Cr2O3. Ti40 has compact MT, which has plenty of V and Cr in the TZ, affects organization mutations in IZ, and shows the matrix organization. From the CS to different organization area of the substrate have been presented by the O element and no sign of organization mutations. Extended from the CS to the matrix, there is an obvious drop of Oxygen element when the Ti40 pass by the TZ. On the contrary, the change of Oxygen element in the whole process is gradual together with the organizational change.The Ti40 alloy has unique Cr2O3 and TiO2 compact MZ and rich V and Cr element in the TZ, which can effectively prevent from transferring the oxygen. Due to Ti40 all-o y has oxidation behavior in super-high temperature and combustion character, it can pro vide a good theoretical basis on its burn-resistant mechanism.