Nick Tepylo

Urban air mobility (UAM) is projected to be a major part of the future transportation landscape. It has the potential to reduce trip times and is viewed as a low-emission option. However, little is known about the public’s willingness to fly in these vehicles. In this study, a survey was conducted to assess willingness to fly on an air taxi. The survey of 1022 Canadians found that 39.4% were willing to fly after being shown an image of a specific UAM concept aircraft and given a short description about UAM, with another 29.1% stating that they would consider it. Factors leading to a higher level of support included gender, age, career, previous flight behavior, and support for other novel technologies. These results indicate that there is a desire for short-distance air travel, and the recommended next steps include assessing infrastructure needs and investigating regulatory and certification requirements for the introduction of UAM.

In this study, three alumina-forming austenitic (AFA) steels (Fe-18Ni-12Cr-AlNbC, Fe-18Ni-12Cr-Al, and Fe-18Ni-16Cr-AlNbC) were exposed to superheated steam (SHS) at 700 °C for 1000 h to study their oxidation behavior. The Fe-18Ni-16Cr-AlNbC alloy showed the best performance as it had the least weight gain due to a denser surface oxide layer and the lack of internal oxidation. The Fe-18Ni-12Cr-AlNbC alloy suffered from internal oxidation and had a greater weight gain than Fe-18Ni-16Cr-AlNbC, while Fe-18Ni-12Cr-Al experienced weight loss due to perhaps external oxide spallation, leaving a less protective Fe-oxide on the external surface.

The performance of S16, a CoCrWC alloy, was evaluated in superheated steam (SHS) at 625°C and 800°C (at 0.1 MPa), and in supercritical water (SCW) at 625°C and 26 MPa for 500 hours. S16 experienced weight loss under the SHS conditions (625°C and 800°C) and weight gain under the SCW condition. Weight loss was associated with scale spallation and pitting while oxide growth on the surface contributed to weight gain. Formation of CoCr₂O₄ and Cr₂O₃ was observed in the oxide layer of samples tested under the three conditions, however, the Cr-rich oxide on SCW tested samples was found to be continuous. A thin, continuous Co₃W subscale was believed to have provided an oxidation barrier under the SCW test condition. Based on the limited weight change and surface oxide formation, S16 has the potential to be used as a coating material for ultra-supercritical power generation systems at temperatures up to 625°C.

Additive manufacturing (AM) is a transformative technology that has rapidly grown over the past decade. AM processes build parts layer by layer and have found applications in the aerospace, biomedical, and automotive fields. The technology holds particular promise for the aerospace industry due to the reduced process time, weight savings of parts, and opportunities for new material development. Herein, a review of laser‐based AM processes, existing AM systems, and aerospace parts being fabricated is presented. It further explores the material properties and microstructure of printed samples with both powder bed fusion and direct energy deposition processes. The benefits and challenges associated with the widespread use of the technology are discussed with emphases on the aerospace sector. Finally, the steps required for parts produced by AM processes to become certified for use in aerospace applications are presented.

Coating application to superalloys provides oxidation and corrosion resistance. One of the key elements in gas turbine coatings is aluminium (Al) which forms a thin, dense alumina layer upon exposure to oxygen and impedes further oxygen diffusion into the alloy. However, Al in the coating depletes due to inward diffusion and oxide formation. The rate of Al depletion is a function of the coating composition/structure, substrate alloy composition/structure and service conditions. In this study, a PtAl diffusion coating, was applied onto polycrystalline IN738LC and single crystal CMSX-4. The coated systems were exposed to 1080°C for 1000 h. Both SEM and XRD analyses were carried out on the as-coated and tested samples. It was found that despite the much higher Al content in CMSX-4, Al depletion was greater. With the higher Cr in IN738LC, a diffusion barrier enriched in Cr/Mo was able to form and reduce the Al depletion.

The choice of materials is of great concern in the construction of Gen IV supercritical water reactors (SCWR), particularly the fuel cladding, due to the harsh environment of elevated temperatures and pressures. A material's performance under simulated conditions must be evaluated to support proper material selection by designers. In this study, aluminide and Cr-modified aluminide coated 304, as well as bare stainless steel 304 as a reference material, were tested in supercritical water (SCW) at 700 °C and 25 MPa for 1000 h. The results showed that all three samples experienced weight loss. However, the aluminide coated 304 had 20 to 40 times less weight loss compared to Cr-modified aluminide coated and bare stainless steel 304 specimens, respectively. Based on scanning electron microscope/energy dispersive X-ray spectroscopy (SEM/EDS) and X-ray diffraction (XRD) analysis results, spinel and hematite Fe2O3 formed on bare 304 after 1000 h in SCW while alumina was observed on both coated specimens, i.e., aluminide and Cr-modified aluminide surfaces. Oxide spallation was observed on the bare 304 and Cr-modified aluminide surface, contributing to a larger weight loss. Based on the results from this study, pure aluminide coating with Al content of 10–11 wt % demonstrated superior performance than bare 304 and Cr-modified aluminide coated 304.

Alloy 3033 was evaluated in superheated steam (SHS) at 800°C for a duration of 3000 hours. The SHS was able to simulate the supercritical water (SCW) condition at higher temperatures which no commercial SCW rig is currently capable of reaching. After exposure to the SHS, the weight change and surface oxide formation of Alloy 3033 were analyzed. Alloy 3033 had an initial weight gain after 1000 hours; however, the net weight gain reduced after 2000 and 3000 hours of exposure, suggesting oxide spallation. Formation of both Cr₂O₃ and MnCr₂O₄ was observed on the surface after 2000 and 3000 hours of SHS exposure. However, as exposure progressed, the XRD peak intensity ratio of MnCr₂O₄ to Cr₂O₃ decreased, in addition to the observation of more exposed Cr₂O₃. Based on this preliminary investigation, Alloy 3033 may not be suitable for extended use in SHS due to weight loss associated with oxide spallation.