高度稳定化β型阻燃钛合金Ti40的氧化和氧化层剥落机理

Oxidation and Peel-Off Mechanisms of Oxide Layer of the Highly Stabilized β Type Burn Resistant Alloy Ti40

对高度稳定化β型阻燃钛合金 Ti40的氧化机理和氧化层剥落机理进行研究表明 :合金氧化增重随温度升高明显增加 ,至 10 5 0℃反而降低 ;6 0 0℃的氧化膜主要为 Ti O2 和 V2 O5 ,高于 70 0℃氧化 ,因 V2 O5 的挥发 ,氧化膜主要为 Ti O2 ,随温度升高 ,氧化物晶粒粗化 ,氧化膜疏松多孔 ,与基体黏附性降低 ,不低于 90 0℃时开裂和剥落 ,不低于 80 0℃氧化 ,氧化层疏松处还存在 Si O化合物 ,温度升高 ,Si O数量增多 ,由圆球形变为星形 ,至 10 5 0℃随氧化层剥落而消失 ;剥落后的基体氧化层仍为疏松状 ,有不连续分布的 Cr2 O3膜存在。同时还分析了 Ti40合金不抗氧化的原因及氧化机理 ,提出了氧化机理模型。在分析氧化膜内应力产生及内应力释放机制基础上 ,提出了 Ti40合金氧化层开裂、剥落机理。

The alloy Ti40 is a highly stabilized β type burn resistant titanium alloy. The oxidation and peel off mechanisms of oxide layer of this alloy have been studied. The experimental results indicate that weight gain increases greatly with increasing temperature, however, the weight gain decreases for oxidizing at 1 050℃. The main products oxidized at 600℃ are TiO 2 and V 2O 5. If oxidizing temperature is higher than 700℃, TiO 2 is the main products because of the vaporization of V 2O 5. With increasing temperature and time, the grains of oxide become coarse, the oxide film is porous, and the coherence force between oxide scale and matrix decreases. The oxide scale cracks and peels if temperature is not less than 900℃. There are SiO compound in porous oxide scale if temperature is not less than 800℃. The amount of SiO increases with increasing temperature. The SiO compound changes from ball to star state, and vanishes after peel of oxide scale at 1 050℃. There are non continuous Cr 2O 3 product at the interface between oxide scale and matrix. The reason is that the alloy Ti40 does not possess good oxidation resistance. The oxidation mechanism is also analyzed, and a oxidation model is proposed. The mechanisms of crack and peel of oxide scale are discussed in detail.