Preparation, Mechanical Properties and Cyclic Oxidation Behavior of the Nanostructured NiCrCoAlY-TiB2 Coating

TiB2-Metal composite coatings with excellent oxidation resistance become ideal candidates using at high temperature ranging from 600 to 1000 °C. In order to maintain both the superior mechanical properties and oxidation resistance in severe working conditions, the nanostructured NiCrCoAlY-TiB2 coating was fabricated by the activated combustion high velocity air-fuel spraying (AC-HVAF) with the composite powders prepared by ball milling and plasma spheroidization. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to observe the phase constituents and microstructure. It was found that the coating with nanostructured TiB2 particles uniformly distributed in the NiCrCoAlY matrix has the same structure as the composite powders. The coating shows excellent mechanical properties, such as high microhardness (991.43 HV0.3), good fracture toughness (4.12 MPa m−1/2) and large bonding strength (75.43 MPa), and excellent oxidation resistance with low weight gain (1.56 × 10−6 mg2 cm−4 s−1). The cyclic oxidation behavior is in accordance with the parabolic law.