The adhesive strength in a coating-substrate system is of primary importance for the coating lifetime in service.However,the underlying mechanism is not fully understood due to the complex internal structure of compos...The adhesive strength in a coating-substrate system is of primary importance for the coating lifetime in service.However,the underlying mechanism is not fully understood due to the complex internal structure of composite coatings.In this study,the effect of substrate roughness on the adhesive strength of WCCo coatings was investigated by experiment and simulation.Results show that the adhesive strength is significantly affected by the roughness.In the case of the Ra<2μm,the adhesive strength is approximately 35–46 MPa.When the Ra is 4μm,the adhesive strength increases to nearly 60 MPa.A finite element model was developed to correlate the roughness with adhesive strength.It is found that the predicted values are well consistent with the experimental data.In addition,with the increase of the roughness,the residual stress would be changed from concentrated state to widespread state,which decreases the critical stress to result in crack propagation.That’s why a larger roughness can cause a higher adhesive strength.This study gives understanding on the mechanism of adhesive strength affected by roughness,which contributes to the parameter optimization with better performance.展开更多
Multilayer iridium coating was manufactured on tungsten carbide substrates by a double glow plasma process.As comparison,monolayer was also produced.The microstructure and morphology were observed using scanning elect...Multilayer iridium coating was manufactured on tungsten carbide substrates by a double glow plasma process.As comparison,monolayer was also produced.The microstructure and morphology were observed using scanning electron microscopy.Grain orientation and phase were determined using X-ray diffraction.The residual stress of the coating was studied by glancing incidence X-ray diffraction.The adhesive force of the coating was measured by a scratch tester.The results showed that both monolayer and multilayer had a polycrystalline phase with a strong（110） reflection.The coating had an excellent adhesion with no evidence of delamination.The adhesive force of the monolayer and multilayer was about 50 and 43 N,respectively.The interfacial reaction between the substrate and the layer occurred and a new WIr phase was found due to the high-temperature deposition process.The residual stress in the monolayer and multilayer was-1.6 and-1.1 GPa,respectively.展开更多
基金supported financially by the China Scholarship Council(CSC,No.2017GXZ020849)the Fundamental Research Funds for the Central Universitiesthe National Program for Support of Top-notch Young Professionals.
文摘The adhesive strength in a coating-substrate system is of primary importance for the coating lifetime in service.However,the underlying mechanism is not fully understood due to the complex internal structure of composite coatings.In this study,the effect of substrate roughness on the adhesive strength of WCCo coatings was investigated by experiment and simulation.Results show that the adhesive strength is significantly affected by the roughness.In the case of the Ra<2μm,the adhesive strength is approximately 35–46 MPa.When the Ra is 4μm,the adhesive strength increases to nearly 60 MPa.A finite element model was developed to correlate the roughness with adhesive strength.It is found that the predicted values are well consistent with the experimental data.In addition,with the increase of the roughness,the residual stress would be changed from concentrated state to widespread state,which decreases the critical stress to result in crack propagation.That’s why a larger roughness can cause a higher adhesive strength.This study gives understanding on the mechanism of adhesive strength affected by roughness,which contributes to the parameter optimization with better performance.
基金Funded by the National Natural Science Foundation of China(No.50872055/E020703)the Natural Science Foundation of Jiangsu Province(No.BK20150260)
文摘Multilayer iridium coating was manufactured on tungsten carbide substrates by a double glow plasma process.As comparison,monolayer was also produced.The microstructure and morphology were observed using scanning electron microscopy.Grain orientation and phase were determined using X-ray diffraction.The residual stress of the coating was studied by glancing incidence X-ray diffraction.The adhesive force of the coating was measured by a scratch tester.The results showed that both monolayer and multilayer had a polycrystalline phase with a strong（110） reflection.The coating had an excellent adhesion with no evidence of delamination.The adhesive force of the monolayer and multilayer was about 50 and 43 N,respectively.The interfacial reaction between the substrate and the layer occurred and a new WIr phase was found due to the high-temperature deposition process.The residual stress in the monolayer and multilayer was-1.6 and-1.1 GPa,respectively.
