300M steel is one of most important aerial materials, which can be used for landing gear and flap & slat track. Some surface engineering technologies are needed to be adopted on its surface, because of its bad corrosion performance. WC10Co4Cr Coatings by high velocity oxygen-fuel spray processing (HVOF) is an environmental friendly method for this protection. In this paper, WC10Co4Cr coatings were prepared on 300M by optimized HVOF processing. And their corrosion performance has been estimated by neutral salt fog test, according with ASTM B117. The results indicate that the porosity gets larger and the hardness gets higher for the dissolution of bonding phases after the test. And for the optimized coatings, there are no corrosion products in the surface and interface between the coating and 300M steel, after 2000 hours ASTM B117 test. So the coatings have a good corrosion performance.

TiAl 3 -Al composite coatings are believed to hold promise for extending the service temperature range of titanium alloys used as structural materials. In this study, 0.6 x 40 mm Ti-6Al-4V specimens are coated with a 30 μm thick layer of TiAl 3 -Al by low-temperature HVOF spraying. Cross-sectional imaging shows that the as-sprayed coatings have a dense laminar microstructure and are well bonded to the substrate. Following the initial examination, the coating samples were placed in a muffle furnace, where they were held at 700 °C for up to 1000 h. Mass gain was detected starting at 200 h and remained nearly constant for the remainder of the test. This is an indication of excellent corrosion resistance, which is verified by SEM cross-sectioning and elemental EDS analysis. A brief explanation of the protective mechanism of the coating is provided.

This study investigates a new zirconia-based ceramic for potential use in thermal barrier coatings. In the experiments, Sc 2 O 3 -Gd 2 O 3 -Yb 2 O 3 -ZrO 2 (SGYZ) powder was synthesized by coprecipitation and calcination, then agglomerated and sintered to facilitate spraying. The structure, morphology, and phase stability of the powder and plasma-sprayed SGYZ coatings were analyzed and thermal conductivity was measured. Test results show that the powders and coatings have good phase stability even after 500 h at 1400 °C and do not undergo tetragonal-to-monoclinic phase transition upon cooling. Plasma-sprayed SGYZ also has a lower thermal conductivity than YSZ, which is currently used in gas turbine engines.

Zirconia stabilized with a combination of scandia and yttria (ScYSZ) powder for plasma spraying was synthesized by chemical coprecipitation process in the experiment, and the ScYSZ powder contains 7.0mol% scandia and 1.5mol% yttria. The microstructure, phase stability and thermal conductivity of plasma sprayed ScYSZ thermal barrier coatings (TBCs) were investigated. The results revealed that the ScYSZ TBCs had excellent stability to retain single metastable tetragonal t′phase even after high temperature (1500 °C) exposure for 300 hours and did not undergo a tetragonal-to-monoclinic phase transition upon cooling. Furthermore, the ScYSZ TBCs had lower thermal conductivity than 3.5-4.5mol% yttria-stabilized zirconia TBCs currently used in gas turbine engine industry. ScYSZ TBCs could be developed as a novel TBCs for advanced gas turbine engines.

In this study, boron-rich iron-nickel coatings were deposited on stainless steel by air-plasma spraying. Coating microstructure was characterized by SEM, EDS, and XRD analysis and adhesion strength, tensile properties, and residual stress were measured. The shielding effectiveness of the coating samples, including their ability to absorb thermal neutrons and attenuate γ rays, was investigated as well. The results show that the coating samples possess the microstructure and properties necessary for possible use in radiation shielding systems.

Nanostructured chromium oxide coatings were deposited on stainless steel with an axial powder feeding plasma spray system. Friction and wear properties of the coatings were investigated in view of friction coefficient and volumetric wear loss of the coatings with a SRV oscillating friction and wear tester in a ball-on-disc configuration. The morphology and microstructure of the coatings were evaluated by light microscopy, field emission scanning electron microscopy and X-ray diffraction. The results showed that the nanostructured chromium oxide coatings were harder and had a lower friction coefficient and much better wear resistance than the conventional chromium oxide coatings.

Titanium is widely used in aerospace, highly corrosive environments and implants due to unique properties such as high strength to weight ratio and excellent corrosion resistance. Cold gas dynamic spray (cold spray) technology in contrast to current fabrication technologies has provided the potential for titanium to be utilised in broader industrial applications and at lower cost. Particle velocity is the most important parameter in cold spray process that leads to successful deposition of titanium at supersonic speeds. In this study, particle image velocimetry (PIV) is used to determine particle velocities for a commercially pure (CP) titanium powder in respect to cold spray parameters such as temperature and pressure. The results show the significance of flow field measurements using PIV in optimization of the nozzle configuration to achieve the maximum velocity for particles. Further more, PIV results can be used to validate the current models developed for cold spray process.

The technology and thermal shock properties and thermal conductivity of plasma sprayed nanostructured yttria-stabilized zirconia thermal barrier coatings (TBCs) are studied in this paper. The TBCs on the substrate of Ni 3 Al based alloy IC-10 were fabricated by using the nanostructured yttria-stabilized zirconia powder under certain plasma spraying conditions. By manipulating the plasma spray process, nanostructured TBCs were obtained. The specimens were thermally shocked from 1000°C, 1100 °C and 1200°C into 20°C water and the morphology and microstructure of the TBCs were evaluated by light microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The thermal diffusivity was tested by a laser pulse method. The results showed that the nanostructured TBCs had more than 30% reduction in thermal conductivity and the thermal shock lifetimes were much longer than that of the conventional TBCs.