In order to clarify the bonding mechanism and to control the quality of cold-sprayed coatings, it is necessary to accurately measure the in-flight velocity and impact velocity of a projectile. In this study, the in-flight velocity of an aluminum alloy (A2017) 1 mm sphere shot from a small two-stage light gas gun was measured as being 1 km/s using a laser-cut velocity measurement technique. So as to estimate the impact velocity of the projectile, the projectile was caused to impact targets made of aluminum (A1050), copper (C1012), mild steel (SPCC), and stainless steel (SUS304). After the impact tests, the impact crater shapes of the targets was measured using scanning electron microscopy(SEM), energy dispersive X-ray spectroscopy (EDS), and laser microscopy. The impact velocity of a projectile was estimated from obtained crater depth of the targets. In addition, microstructures of the interface between projectile and target were analyzed by EDS, electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM).

This study evaluates Fe-Si intermetallic powders as an alternative to powders currently used to coat furnace walls in pulverized coal fired boilers. The developed powder mainly consists of Fe 2 Si, which has a relatively low melting point among iron silicides. The powders were deposited on CrMo steel substrates by HVOF and atmospheric plasma spraying and the resulting coatings were subjected to corrosion and erosion testing. Under conditions simulating the operating environment in a low NO X boiler, the HVOF sprayed Fe-Si coatings exhibited sulfidation resistance nearly equal to that of Cr-Ni layers, and in high-temperature erosion tests, the APS intermetallic coatings with boron additions were found to be more erosion resistant than conventional Cr 3 C 2 -NiCr coatings.

This paper focuses on the key properties of newly developed high-strength, heat-resistant steels for application in ultra-supercritical (USC) boilers. For some ferritic steels, improvements made to enhance their resistance to steam oxidation are highlighted. The latest welding techniques employed for these steels are introduced. Additionally, the high-temperature strength and weldability of Alloy 617 (52Ni-22Cr-13Co-9Mo-Ti-Al), a potential candidate material for the next generation of 700°C USC boilers, are described. The paper provides insights into the materials and welding technologies crucial for the development of advanced USC boilers operating at higher temperatures.