Mechanical Properties and Thermal Shock Resistance of HVOF Sprayed NiCrAlY Coatings Without and With Nano Ceria

Rouhaghdam

2021

Sci Rep

Conventional and nanocrystalline MCrAlY coatings were applied by the high-velocity oxy-fuel (HVOF) deposition process. The ball-milling method was used to prepare the nanocrystalline MCrAlY powder feedstock. The microstructure examinations of the conventional and nanocrystalline powders and coatings were performed using X-ray diffraction (XRD), high-resolution field emission scanning electron microscope (FESEM) equipped with energy-dispersive X-ray spectroscopy (EDX), transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS). Williamson–Hall analyzing method was also used for estimation of the crystalline size and lattice strain of the as-milled powders and sprayed coatings. Owing to the investigation of the oxidation behavior, the freestanding coatings were subjected to isothermal and cyclic oxidation testing at 1000 and 1100 °C under static air. The results showed that the conventional as-sprayed MCrAlY coating had a parabolic behavior in the early stage and prolonged oxidation process. On the contrary, in the case of the nanocrystalline MCrAlY coating, the long-term oxidation behavior has deviated from parabolic to sub-parabolic rate law. Moreover, the results also exemplified that the nanocrystalline MCrAlY coating had a greater oxidation resistance following the creation of a continuous and slow-growing Al2O3 scale with a fine-grained structure. The nucleation and growth mechanisms of the oxides formed on the nanocrystalline coating have also been discussed in detail.

Section: Resultsmentioning

confidence: 99%

A comprehensive study on the microstructure evolution and oxidation resistance of conventional and nanocrystalline MCrAlY coatings

Rouhaghdam

2021

Sci Rep

“…At present, the NiCrAlY coating prepared by thermal spraying technology is layer‐structured with many internal voids and has relatively low hardness. Pure Ni–22Cr–10Al–1Y coating prepared by thermal spraying has microhardness less than 400 HV or even lower . The material microstructure prepared by laser engineered net shaping technology is more dense and the hardness of pure NiCrAlY material can be up to 420 HV.…”

Section: Experimental Results and Analysismentioning

confidence: 99%

Microstructure and Mechanical Properties of Inconel718–NiCrAlY Composites Prepared by Laser Engineered Net Shaping

et al. 2018

Near-defect-free block Inconel718-NiCrAlY composites prepared by laser engineered net shaping are investigated in this study. XRD, SEM, and EDS are applied to analyze the phase composition and microstructure characteristics. The mechanical properties are evaluated by microhardness tester and friction-wear tester. The results show that NiAl brittle intermetallic compounds precipitate in the matrix when NiCrAlY content reaches 60% or more. With the increase of NiCrAlY ratio, the distribution of NiAl changes from intergranular precipitation to intragranular precipitation, and the dendrites growth directions become chaotic. The microhardness of composites improves as the NiCrAlY content rises, reaching to 419 HV for 100% NiCrAlY, and solid solution strengthening has better strengthening effect on microhardness than precipitation strengthening. The wear loss has a clear decrease only when 80% or more NiCrAlY is added, with the maximum wear loss drop of 15.66% for 100%NiCrAlY. The wear mechanisms change from the coexistence of adhesive wear and abrasive wear to mainly abrasive wear with micro brittle fractures when NiCrAlY content is high.

“…Sun et al [97] explored the effects of ceria addition to the NiCrAlY powders via an ultrasonic gas atomization process. They reported that the modified powder particles were refined and had more uniform and narrow size distribution.…”

Section: Adhesionmentioning

confidence: 99%

A Review on the Enhancement of Mechanical and Tribological Properties of MCrAlY Coatings Reinforced by Dispersed Micro and Nanoparticles

2022

The application of metal-matrix composite coatings for protecting and improving the service life of sliding components has demonstrated to have the potential of meeting the requirements of a diverse range of engineering industries. Recently, a significant body of research has been devoted to studying the mechanical and tribological performance of dispersion-strengthened MCrAlY coatings. These coatings belong to a class of emerging wear-resistant materials, offering improved properties and being considered as promising candidates for the protection of engineering structural materials exposed to tribological damage, especially at elevated temperature regimes. This paper attempts to comprehensively review the different reinforcements used in the processing of MCrAlY-based alloys and how they influence the mechanical and tribological properties of the corresponding coatings. Furthermore, the major fabrication techniques together with their benefits and challenges are also reviewed. Discussion on the failure mechanisms of these coatings as well as the main determining factors are also included. In addition, a comprehensive survey of studies and investigations in recent times are summarized and elaborated to further substantiate the review.