Many ceramic materials are microstructurally stable at high temperatures, but exhibit poor mechanical properties under load. In this study, a Ni-base superalloy wire mesh is used as a reinforcement to strengthen a 6.15 mm thick layer of plasma-sprayed YSZ. The flexural performance of the ceramic matrix composite (CMC), as determined by a three-point bend test, exceeds that of monolithic YSZ in terms of peak load and displacement before fracture. Heat treatment of the CMC further increases the load at the onset of crack initiation due to enhanced bonding between the constituent materials.

In this study, a design of experiment (DOE) approach is used to investigate the influence of powder size and mixing ratio on the microstructure and properties of thermal spray coatings. Nano and micro sized WC-12Co powders combined in different proportions with Inconel 625 were deposited on carbon steel substrates by HVOF spraying. The resulting coatings are examined and the effect of different powder combinations on hardness and yield strength is assessed. Spraying procedures and test methods are described and the findings are discussed. Of the various coatings produced, one shows great promise for wear protection, particularly in oil and gas applications.

Four powder blends of Al and Ti were cold sprayed on Ti-Al-Nb substrates at 300°C. Test samples were heat treated in Ar at 500 °C then exposed to 950 °C air for 100-500 h. It was found that oxidation rates were significantly reduced by the coatings, especially those with lower Ti content. However, four-point bending tests revealed that the deposition of the protective layer reduced the flexural strength of the coated substrate. The results indicate that oxidation is not the only factor influencing the mechanical properties of intermetallics at high temperatures.

This study analyzes the mechanical properties of aluminum alloy substrates, in particular, changes in flexural behavior of laser-textured surfaces. Bending tests are conducted on samples treated by laser texturing and by conventional methods such as chemical degreasing and sandblasting. A comparison of flexural strengths caused by the different surface pre-treatments method is presented.

WC-Co/copper coatings with 8 layers were fabricated by warm spray deposition in order to investigate the effect of ductile layer inclusion on their fracture behavior. Bending strength, work of fracture, and surface hardness of freestanding coatings were examined by three point bending tests after removal of the substrates. The multilayered samples showed nonlinear stress-strain curves due to cracks in the WC-Co layers and plastic elongation of the copper layers. The multilayered samples with lower volume fraction of copper showed even lower bending strength than the monolithic samples of WC-Co and copper and no beneficial feature in mechanical performance was found. On the other hand, the samples containing higher volume fraction of copper exhibited more than twice higher work of fracture and moderately better bending strength than the monolithic WC-Co coatings, while the surface hardness was almost identical among all samples instead of the monolithic copper. The ductility of copper layers and the plastic constraint by the intact WC-Co layers attributed to enhance their mechanical properties. It has been concluded that cermet/metal laminate coatings can be one alternative approach to further improvement of the mechanical properties of thermal sprayed cermet coatings.

The physico-chemical and thermo-mechanical properties of aluminosilicate ceramics (high melting point, low thermal expansion coefficient, excellent thermal shock resistance, low density and good corrosion resistance) make this class of materials a good option for high temperature structural applications. Al 2 O 3 -SiO 2 compounds show an excellent refractory behaviour allowing a wide use as wear resistant thermal barrier coatings, in metallurgical and glass plants and in high temperature heat exchangers. Moreover the low values of thermal expansion coefficient and of complex permittivity allow to extend the use of this ceramic for microelectronic devices, radome for antennas and electromagnetic windows for microwaves and infrared. The present paper presents the results of an extensive experimental activity carried out to produce thick aluminosilicate coatings by plasma spray technique. APS deposition parameters were optimized on the basis of a surface response approach, as specified by design of experiments (DoE) methodologies. Samples were tested for phase composition, total porosity, microstructure, microhardness, deposition efficiency, fracture toughness and modulus of rupture. Finally, coatings were characterized for their particularly interesting electromagnetic properties: complex permittivity was measured at microwave frequency using a network analyzer with wave guide.

Physical characteristics of Atmospheric Plasma Sprayed (APS) Alumina coating and Low Pressure Plasma Sprayed (VPS) Alumina coating were investigated. High purity Alumina powder was used for thermal spraying in this test. As electrical properties, the volume resistivity, dielectric constant, and the dielectric breakdown voltage were measured at R.T. to 873K. And the coefficient of thermal expansion, and the thermal conductivity were measured at also R.T. to 873K, as thermal properties. Mechanical properties, such as the Young’s modulus, the bending strength, and the cross-sectional hardness value were measured at R.T. As a test result, the Alumina coatings using both APS and VPS have similar properties except for the cross-sectional hardness value that was higher when sprayed by VPS.