This study evaluates candidate coatings for potential use in the manufacture of metal-seated ball valves for hydrometallurgy service. All coatings were deposited on grit-blasted titanium coupons by air plasma spraying to a nominal layer thickness of 500 µm. The feedstock powders used were selected based on literature review and field experience and include Cr2O3, TiO2-Cr2O3, nano TiO2, and a novel mixture of nano TiO2 and conventional Cr2O3. The resulting coatings are compared based on microhardness, shear strength, friction properties, and wear resistance. Specimen preparation procedures and test methods are described in the paper along with the findings and potential implications of the study.
A custom-designed tensile machine is developped to characterize the mechanical properties of ink micro-filaments deposited by Direct-Write method. The Direct-Write method has been used for the fabrication of a wide variety of microsystems such as microvascular networks, chaotic mixers and laboratory on-chips. The tensile machine was used to measure the induced force in ink filaments during tensile and tension-relaxation tests as a function of the applied strain rate, the ink composition and the filament diameter. Experimental data was fitted by a linearly viscoelastic model using a data reduction procedure in order to identify the constitutive theory parameters of the deposited ink filaments. The model predictions based on the defined constitutive theory parameters were closed to the experimental data generated in this study. Such models will be useful in the development and optimization of future 3D complex structures made by direct-write method.
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