TA32钛合金高温连续氧化行为研究

The Isothermal Oxidatian Behavior of TA32 Titanium Alloy at Elevated Temperature

摘要:

本文采用增重法研究了表面有/无喷涂高温润滑剂的TA32钛合金在热成形温度750℃~850℃范围内氧化10min-240h的氧化行为,通过SEM和EDS等微观分析方法对氧化层的表面形貌和成分、截面厚度和成分进行分析,并对氧化机理进行探讨。结果表明,750℃-850℃内的氧化行为均符合直线-抛物线规律,800℃～850℃内氧化速率迅速增加,氧化程度剧烈,温度是TA32钛合金氧化行为的重要影响因素之一。750℃时,氧化膜基本没有脱落,800℃时氧化膜部分脱落,温度升高到850℃时,氧化皮大块脱落。750℃-850℃内,随着保温时间的增加,氧化膜逐渐增厚,氧化物由颗粒状变为短棒状和针状,氧化皮逐渐由致密变得疏松多孔,抗氧化能力逐渐下降。TA32钛合金在750℃保温240h时,氧化层结构为：TiO₂和Al₂O₃/ TiO₂/ Al₂O₃/ TiO₂/基体；在800℃下氧化240h时,氧化层结构为：TiO₂和Al₂O₃/ Al₂O₃/ TiO₂/ Al₂O₃/ TiO₂/ Al₂O₃/ TiO₂/ Al₂O₃/ TiO₂/基体；在850℃下氧化240h时,表层氧化膜完全脱落。表面无喷涂试样和表面喷涂氮化硼的试样氧化规律一样,均符合直线-抛物线规律,但表面无喷涂试样的单位面积增重、氧化速率高于表面喷涂氮化硼的试样,氧化膜厚度也更厚,说明氮化硼有很好的抗氧化性能。表面喷涂氮化硼的TA32钛合金在750℃保温240h时,氧化层结构为：TiO₂和Al₂O₃/ TiO₂/ Al₂O₃/ TiO₂/Ti₃Al/基体。

Abstract:

The weight gain method is used to study oxidation behaviors of the TA32 titanium alloy with/without coated high-temperature lubricants during 10min-240h oxidation within 750℃~850℃ thermoforming temperature in this paper. The surface topography and ingredients and section thickness and ingredients of the oxidation layer are analyzed by using the microscopic analysis method such as SEM and EDS and the oxidation mechanism is discussed. The results show that the oxidation behaviors abide by the line-parabola law within 750℃～850℃. The oxidation rate will quickly increase and oxidation becomes drastic within 800℃～850℃. The temperature is one of the significant factors affecting oxidation behaviors of the TA32 titanium alloy. The oxidation films seldom fall off at 750℃ and some oxidation films fall off at 800℃. When the temperature increases to 850℃, some bulky oxidation shells will fall off. With growth of the heat preservation time within 750℃～850℃, the oxidation film will become thicker, the oxidants will change from particles to short stick and needles, the oxidation shell will gradually change from compact structure to loose and porous structure, and the oxidation resistance will gradually reduce. When TA32 titanium alloy keeps at 750℃ for 240h, the oxidation layer structure is TiO₂and Al₂O₃/ TiO₂/ Al₂O₃/ TiO₂/substrate;When TA32 titanium alloy keeps at 800℃ for 240h, the oxidation layer structure is TiO₂ and Al₂O₃/ Al₂O₃/ TiO₂/ Al₂O₃/ TiO₂/ Al₂O₃/ TiO₂/ Al₂O₃/ TiO₂/substrate;When the TA32 titanium alloy is oxidized for 240h at 850℃, the surface oxidation film will fully fall off. The oxidation laws of the non-coated samples and samples coated with the boron nitride are same and abide by the line-parabola law, but the weight gain and oxidation rate of the unit area of the non-coated samples will be higher than that of the samples coated with the cubic boron nitride and the oxidation film of the non-coated samples is thicker. It indicates that the boron nitride can resist oxidation. When the TA32 titanium alloy coated with the boron nitride keeps at 750℃ for 240h, the oxidation structure is TiO₂and Al₂O₃/ TiO₂/ Al₂O₃/ TiO₂/Ti₃Al/substrate.