(昆明理工大学 材料科学与工程学院，昆明 650093)
摘 要: 以Ti和Al在高温下的化学反应热力学条件为依据，利用激光熔覆技术在ZL117铝活塞零件表面制备金属间化合物TiAl3增强的Al基复合涂层。借助XRD、EDS和XPS分析涂层的物相组成和结构特征，通过OM和SEM观察涂层的表面宏观形貌及其内部显微组织，运用马弗炉测试了熔覆涂层在静态空气中的高温抗氧化性能。结果表明，复合涂层主要由浅灰色网状组织TiAl3、暗灰色网状间隙相α(Al)和少量晶须状Si组成。复合涂层中Ti以TiAl3形式存在，在TiAl3中结合能分别为460.53 eV (Ti2p1峰)和454.96 eV (Ti2p3峰)；Al则以TiAl3、Al2O3和Al的形式存在，3种物相中Al的结合能分别为73.60、75.82和72.90 eV。600℃恒温80 h下的氧化动力学曲线显示，相同氧化条件下，涂层氧化增质较为平缓，氧化速率小，具有较好的相对高温抗氧化性能，相对高温抗氧化值最大为2.64。熔覆涂层表面氧化产物为Al2O3和TiO2，铝合金基体表面氧化产物为Al2O3和少量SiO2。
关键字: 激光熔覆；金属间化合物；复合涂层；显微组织；抗氧化
（School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, China）
Abstract:In order to improve high temperature oxidation resistance of aluminum alloy, according to the chemical reaction thermodynamic conditions of Ti and Al at high temperature, TiAl3 intermetallic compound particles reinforced Al-based composite coatings were fabricated on ZL117 aluminum piston parts by laser cladding. The chemical composition, phase characteristics and microstructure of the composite coatings were analyzed using X-ray diffractometry (XRD), energy dispersive spectrum (EDS), optical microscopy (OM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The high temperature oxidation resistance of the composite coatings was tested by Muffle furnace in static air. The results show that the composite coatings are mainly composed of light gray meshwork phase TiAl3, dark gray mesh interstitial phase α(Al) and a small amount crystal whisker phase Si. Ti in the laser cladding composite coating is in the form of TiAl3 intermetallic compound, the binding energy of Ti in TiAl3 are 460.53 eV (Ti2p1 peak) and 454.96 eV (Ti2p3 peak), respectively. Al in the laser cladding composite coating is in the form of TiAl3, Al2O3 and Al, the binding energy of Al in three kinds of phases are 73.60, 75.82 and 72.90 eV, respectively. Compared with the aluminum alloy substrate, the oxidation kinetics curves at 600 ℃ for 80 h exhibit that the oxidation mass gain of the laser cladding coatings is more slowly, and the oxidation rate is low. The laser cladding coating has a good oxidation resistance at relatively high temperature and the maximum value of relatively high-temperature oxidation is 2.64. The surface oxidation products of laser cladding coatings are Al2O3 and TiO2, but the aluminum substrate surface oxidation products are Al2O3 and a small amount of SiO2.
Key words: laser cladding; intermetallic compound; composite coating; microstructure; oxidation resistance
