摘要
为了提高γ-TiAl合金的抗高温氧化性能,采用冷喷涂技术在γ-TiAl合金基体上喷涂纯Al层后进行热扩散处理,制备了厚约250μm的TiAl3-Al复合涂层,研究了该涂层在950℃下的长时间高温氧化行为,用X射线衍射仪(XRD)分析了复合涂层的相组成,用场发射电子显微镜研究了其形貌,用电子探针分析了其成分。结果表明:冷喷涂纯Al层致密,存在少量微裂纹和微气孔;TiAl3-Al复合涂层和基体之间生成了TiAl3相,TiAl3与Al的界面有空洞;γ-TiAl合金高温氧化70 h即失重,氧化产物为TiO2和Al2O3的混合物;TiAl3-Al复合涂层进入稳态氧化阶段后,增重缓慢,遵循近抛物线规律,高温氧化1 000 h后涂层仍完好,氧化产物主要为Al2O3相,还有微量的TiO2及钛氮化合物;TiAl3-Al复合涂层提高了γ-TiAl合金的抗高温氧化性能。
TiAl3-Al composite coating with an average thickness of 250 μm was prepared on γ-TiAl alloy by cold spraying and subsequent heat-treatment.The phase structure,morphology and composition of as-sprayed composite coating were analyzed using an X-ray diffractometer,a field emission electron microscope and an electron probe.The long time high-temperature oxidation behavior of the coating at 950 ℃ was investigated.It was found that cold-sprayed Al coating was compact and contained a small amount of micro-cracks and gas holes.TiAl3 phase was formed between TiAl 3-Al compo site coating and substrate,and pores existed at the interface of TiAl 3 and Al.The alloy substrate(γ-TiAl) lost weight after 70 h of oxidation at 950 ℃,generating TiO2 and Al2O3 as the mixed oxidized products.The composite coating gained weight slowly in the steady oxidation period where the oxidation kinetics curve approximately followed a parabolic rate law.Even after 1000 h of oxidation at 950℃,the composite coating kept almost intact,and its oxidized product consisted of alumina and trace of titanium dioxide and titanium nitrides.In general,the composite coating could significantly improve the oxidation resistance of γ-TiAl alloy at elevated temperature.
出处
《材料保护》
CAS
CSCD
北大核心
2012年第4期9-11,72,共3页
Materials Protection
基金
国家自然科学基金资助项目(50971127)
