摘要
Abstract
Under high-temperature service conditions,friction and wear are key factors affecting the performance of coatings and substrates.Especially under high-temperature and high-speed service conditions of aero-engine components,friction and wear will directly affect the performance of γ-TiAl alloys,resulting in shorter service life.The work aims to address the inherent low surface hardness and poor wear resistance of the alloy by developing and characterizing a TiAlCrY/YSZ composite coating deposited onto γ-TiAl.A functionally graded coating system was fabricated through double-glow plasma surface alloying(DG-PSA)to create a TiAlCrY diffusion/bonding layer and multi-arc ion plating(MAIP)to deposit an yttria-stabilized zirconia(YSZ)topcoat.X-ray diffraction(XRD)and scanning electron microscopy(SEM)were utilized to analyze the surface phase and morphology of the coating and digital micro-hardness tester and micron scratch tester were used to analyze the mechanical properties and bonding force of the coating.To analyze the wear patterns and differences between the coating and the substrate,reveal the synergistic mechanisms of adhesive wear,abrasive wear and oxidative wear under complex conditions and provide a theoretical basis for the coating design,CET-I type reciprocating friction and wear tester and UMT-2 type ball and disk friction and wear tester were used to conduct wear experiments on the substrate and the coating and SEM and laser confocal scanning microscope were employed to observe the surface wear morphologies of the substrate and the coating and make a comprehensive comparison and analysis.The XRD confirmed that the tetragonal zirconia(t-ZrO2)had good thermal stability as the dominant surface phase of the coating.The SEM revealed a dense,uniform coating structure:the YSZ layer was 14-16 μm and the underlying TiAlCrY diffusion/bonding layers were 8-10 μm,resulting in a total coating thickness of 24 μm.The results of mechanical property tests showed that the TiAlCrY diffusion layer effectively alleviated the difference between the interfacial properties of the substrate and the YSZ coating,and improved the bond strength and microhardness.The friction and wear results showed that the coefficient of friction of the coating was stable and significantly lower than that of the substrate and the wear volume of the coating was only 12% of that of the substrate under a load of 6.2 N.The main wear mechanism of the substrate was severe abrasive and adhesive wear.The main wear mechanism of the coating was mild abrasive wear.At 500℃,the substrate experienced oxide film formation and spallation,the degree of wear increasedand the abrasive wear predominated,accompanied by varying degrees of adhesive and oxidative wear.The coating,on the other hand,primarily experienced slight oxidative and adhesive wear and the specific wear rate was only 15% of that of the substrate.By depositing TiAlCrY/YSZ composite coatings on γ-TiAl alloys,the behavioral characteristics and failure mechanisms of the coatings under frictional wear conditions are studied,improving the application performance of γ-TiAl alloys in practical engineering,effectively solving the problem of insufficient bonding between the YSZ ceramic layer and γ-TiAl,and significantly improving its resistance to high-temperature wear performance.关键词
γ-TiAl/双辉等离子渗金属/多弧离子镀技术/TiAlCrY/YSZ复合涂层/摩擦磨损/磨损机制Key words
γ-TiAl/double-glow plasma surface alloying/multi-arc ion plating technology/TiAlCrY/YSZ composite coating/friction and wear分类
矿业与冶金
