In this study, dense multicomponent NiCoCrAlTaY bond coats and feather-structured YSZ topcoats are deposited on DZ40M alloy vane surfaces by the PS-PVD method. Based on thickness measurements and microstructure examination, it is shown that the double vane surface was completely covered by both layers. The thickest portion of the coating was found close to the leading and trailing edges of the vane. The results show that it is possible to manufacture TBCs, including the bond coat and topcoat, on first-stage turbine blades by a single PS-PVD process.

In plasma spray-physical vapor deposition (PS-PVD), deposition takes place not only from liquid splats, but also from nanosized clusters as well as the vapor phase. As a result, thin, dense, and porous ceramic coatings can be produced for special applications using this method. In this study, columnar-structured YSZ coatings were deposited by PS-PVD on graphite and zirconia substrates and the effect of substrate temperature on coating microstructure was investigated. A deposition mechanism of heterogeneous nucleation is presented based on the observations and findings of the study.

Low-temperature HVOF spraying finds its potential applications in the preparation of high-performance metallic coatings with low oxygen content and porosity. In this study, the spraying method is used to deposit fine WC-10Co4Cr powders on stainless steel substrates at different spraying distances and the effects on microstructure, microhardness, fracture toughness, splat morphology, and surface roughness are investigated and discussed.

Advanced materials are the crucial factors determining the successful application of future nuclear fusion energy. Plasma facing materials (PFMs) are one of the most important armor materials in nuclear fusion experiment devices for direct facing with the extremely high thermal load, thermal shock and strong irradiation of high energy particles. W coated CuCrZr substrate has been considered as one of the candidates to the armor materials due to its high melting point, chemical stability and good thermal conductivity. However it was a challenge to obtain high strength thick W coatings because of the major difference of CTE between the W and CuCrZr substrate. In this paper, graded W/Cu layers were deposited as the bond layer via Low Pressure Plasma Spraying (LPPS) on the CuCrZr substrate. Subsequently, thick LPPS W coatings over 1.5 mm were prepared as the top layer. The adhesive and cohesive strengths for thick W coatings on CuCrZr substrates were evaluated according to the standard of ASTM C633. The results showed that the oxide formation on the W coating surface rapidly deteriorated the coating microstructure and properties.

Fundamental properties of Titanium coating prepared by low temperature HVOF process aided by injection of water had been published by our research group. The results showed that low temperature HVOF process provided as a good means for the deposition of comparatively dense Ti coating, however the interconnected pores observed in Ti coating degraded corrosion resistance of Ti coating, therefore it was necessary to manufacture denser Ti coating. Two processes were respectively applied for the densification of Ti coating. One process was to perform post heat treatment for as-sprayed Ti coating with conventional Ti powder as feedstock. The other process was to modify thermal spray powder. Ti powder mixing with spherical glass powder was used to deposit denser Ti coating as a result of shot peening effect of hard glass powder. Finally the corrosion resistance for densified Ti coatings was evaluated by electrochemical characterization.

A research program has been initiated to develop the first predictive methodology for corrosion fatigue life in steam turbine blades, addressing a critical gap in current understanding despite extensive research into corrosion pitting and fatigue failure. The study focuses initially on dual-certified 403/410 12% Cr stainless steel, utilizing a newly developed test facility capable of conducting high-cycle fatigue tests in simulated steam environments at 90°C with controlled corrosive conditions. This testing platform enables the investigation of various steady and cyclic stress conditions, establishing a foundation for future testing of other blade steels and the development of comprehensive blade life estimation techniques.

Titanium exhibits very good corrosion resistance property because of the formation of very dense oxide coating. Especially the good corrosion against Cl- solution for titanium material makes it wide applications in sea industry. It is very difficult to deposit titanium coating under atmospheric condition due to the strong affinity with oxygen and nitrogen especially in high temperature plume. Except the expensive LPPS process, much attention has been paid to the newly developed cold spraying. Unfortunately the stringent requirement for the starting power and low production efficiency limit the application of the cold spraying. A modified HVOF process was developed by reducing the outlet diameter of chamber and by directly introducing water into chamber, therefore lower plume temperature and higher chamber pressure than conventional HVOF process can be achieved. Attempts to deposit Titanium coating were carried out, and immersion of Titanium coated A3 steel into artificial seawater was performed in order to evaluate the density of as-sprayed Titanium coating. The results showed that dense Titanium coating could be obtained after parameter optimization and very few corrosion spot was observed on the surface of Titanium coated A3 steel after immersion into artificial seawater for 120 h.

Low pressure plasma spray (LPPS) technology has exhibited its advantage in deposition of yttria stabilized zirconia (YSZ) coating. The YSZ coatings deposited under different chamber pressures were characterized by XRD and SEM in this paper. Preliminary results showed that as-sprayed coatings contained partially-melted zone, and increased chamber pressure was beneficial to the melting of particle. It was revealed that as-sprayed coatings were mainly composed of metastable tetragonal phase except for minor content of cubic phase analyzed by XRD. Compared to air plasma spray (APS) coating, the microhardness and toughness of well-flatten LPPS coating are respectively high and excellent.

Continuously graded yttria stabilized ZrO 2 (YSZ) /NiCoCrAlY coatings were prepared using a high efficiency supersonic plasma-spray system and the thermal shock properties of the coatings were studied. The specimens were so prepared that the two kinds of powders with different melting point were fed to the different regions of the plasma jet by using two powder feeders. The two powders melted perfectly at the same power, and the overheating of the powder with lower melting point was avoided. In this way, a continuously graded transition layer was obtained. The Results show that the continuous change of the coefficients of thermal expansion and thermal conductivity in the transition layer leads to a excellent thermal shock resistance of the totally 0.9mm thick TBCs. The thermal shock cycles of the specimens which underwent heating by oxygen-acetylene flam to 1200 and then quenching into water reached more than 200. The coatings’ surface was still perfect without any visible cracks after the thermal shock test. The analysis shows that the dense structure and the sufficient plastic deformation of the particles depressed the formation of TGOs, which, together with the continuously graded thermal expansion coefficient and thermal conduction coefficient, contributes to the long thermal shock resistance of the coatings.