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Commercial‐grade Si3N4–TiN composites with 0, 10, 20, and 30 wt% TiN content have been characterized. Submicrometer grain‐size Si3N4 was reinforced with fine TiN grains. Density, Young's modulus, coefficient of thermal expansion, and fracture toughness increased linearly with TiN content. Increased strength was observed in the Si3N4+20 wt% TiN, and Si3N4+30 wt% TiN composites. Fractography was used to characterize the different types of fracture origins. Improvements in toughness and strength are due to residual stresses in the Si3N4 matrix and the TiN particles. A threefold improvement in dry wear resistance of the Si3N4+30 wt% TiN composite over the Si3N4 matrix was observed.

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In this paper, experiments for determining the adhesion properties have been performed using two test methods; tensile adhesive test which is widely used in industry and interfacial indentation test still under development in research laboratories. Therefore, only few experimental data on the accuracy of the methods and on the potential in an industrial context are available. For that reason, dissimilar coating-substrate combinations covering different ranges of type of thermal spray coating-substrate systems were tested. Ceramic (Al 2 O 3 ) and metallic (80Ni-20Cr) coatings were deposited by flame spraying system with two different thicknesses on titanium alloy and steel substrates exhibiting each two distinct roughness levels. The distinguished coating properties include the interfacial toughness and adhesive strength. The impacts of interfacial roughness and the thickness of the coating on the adhesion were conducted, and some adhesion tendency was also observed. Typical bond strength values measured were from 40 up to 100 MPa, and the interfacial toughness obtained from 1 to 4 MPa m 0?5 . The correlation of tensile adhesive strength and interfacial toughness has been discussed.