Font Size: a A A

Effect Of Ternary Rare Earth Compounds On Microstructure And Properties Of Plasma Sprayed Ti-Al/WC Cermet Composite Coatings

Posted on:2020-08-18Degree:MasterType:Thesis
Country:ChinaCandidate:S C JinFull Text:PDF
GTID:2381330575994270Subject:Mechanical engineering
Abstract/Summary:PDF Full Text Request
The addition of multiple rare earth compounds to the cermet coating modified the composite coating.Due to the different atomic structure and chemical activity of different rare earth compounds,the effects on the strengthening and toughening mechanism of the composite coating are different,including with Ti-Al/ceramics.Other elements of the composite coating react chemically,change the morphology and properties of the second phase or harmful inclusions in the coating,improve the microstructure of the coating,increase the fluidity of the liquid cermet,the effect of solid solution strengthening,lattice Deformation and activation,etc.,so it is important to explore the influence of CeO2,La2O3 and Y2O3 on the strengthening and toughening mechanism of composite coatings.The Ti-Al/WC cermet composite coating with CeO2,La2O3 and Y2O3 rare earth oxides was prepared on the 45 steel substrate by plasma spraying method,and was measured by scanning electron microscopy,microhardness tester and X-ray powder diffractometer.The microstructure,microhardness,phase composition and residual stress of the coating were tested by friction and wear test using a friction and wear tester.The wear morphology was observed by scanning electron microscopy and the bond strength was tested by a tensile tester.The effects of CeO2,La2O3 and Y2O3 on its microstructure and tribological properties were analyzed.The mechanism of strengthening and toughening and mutual influence of ternary rare earth compound doping on Ti-Al/WC ceramic composite coatings was explored.The results show:?1?The structure of the ternary rare earth oxide coating is obviously refined,and the rare earth oxide can adsorb harmful elements,so that the coating structure changes from layered to flocculent,which improves the mechanical properties and promotes the fluidity of the droplets.The pores become smaller and the number is reduced,the porosity is lowered,and the coating density is better;the coating is found to have inherent strengthening by the phase,and the second phase is formed,which increases the hard phase distributed in the structure and improves the texture of the structure.And promote droplet peristalsis,so that the hard phase is more evenly distributed in the tissue,improving the strength and hardness of the coating.?2?The friction property is changed,which is changed from adhesive wear to abrasive wear,which improves the mechanical properties of the coating,reduces the formation of surface cracks,has good self-lubricity,reduces the friction coefficient,and shows better performance.?3?The residual stress of the ternary rare earth oxide coating is greatly reduced,and the damage resistance of the coating can be improved.The grain refinement increases the area of the coating and the substrate,promotes the penetration of the coating element into the substrate,and becomes a diffusion bond by mechanical bonding,which reduces the gap between the coating and the substrate,and increases the gap between the coating and the substrate.The bonding force can increase the service life of the coating.
Keywords/Search Tags:Plasma spraying, multi-element rare earth oxide, microstructure, wear resistance, mechanical propert
PDF Full Text Request
Related items