摘要
Abstract： An effective approach was conducted for estimating fracture toughness using the crack opening displacement （COD） method for plasma enhanced chemical vapor deposition （PECVD） coating materials. For this evaluation, an elastoplastic analysis was used to estimate critical COD values for single edge notched bending （SENB） specimens. The relationship between fracture toughness （Kic） and critical COD for SENB specimens was obtained. Microstructure of the interface between AleO3-TiO2 composite ceramic coatings and AISI 1045 steel substrates was studied by using scanning electron microscope （SEM）. Chemical compositions were clarified by energy-dispersive X-ray spectroscopy （EDS）. The results show that the interface between of Al203-TiO2 and substrate has mechanical combining. The nanohardness of the coatings can reach 1 200 GPa examined by nanoindentation. The Klc was calculated according to this relationship from critical COD. The bending process produces a significant relationship of COD independent of the axial force applied. Fractographic analysis was conducted to determine the crack length. From the physical analysis of nanoindentation curves, the elastic modulus of 1045/AI2O3-TiO2 is 180 GPa for the 50 μm film. The highest value of fracture toughness for 1045/A1203-TiO2-250 μm is 348 MPa·mv2.
An effective approach was conducted for estimating fracture toughness using the crack opening displacement (COD) method for plasma enhanced chemical vapor deposition (PECVD) coating materials.For this evaluation,an elastoplastic analysis was used to estimate critical COD values for single edge notched bending (SENB) specimens.The relationship between fracture toughness (KIC) and critical COD for SENB specimens was obtained.Microstructure of the interface between Al2O3-TiO2 composite ceramic coatings and AISI 1045 steel substrates was studied by using scanning electron microscope (SEM).Chemical compositions were clarified by energy-dispersive X-ray spectroscopy (EDS).The results show that the interface between of Al2O3-TiO2 and substrate has mechanical combining.The nanohardness of the coatings can reach 1 200 GPa examined by nanoindentation.The KIC was calculated according to this relationship from critical COD.The bending process produces a significant relationship of COD independent of the axial force applied.Fractographic analysis was conducted to determine the crack length.From the physical analysis of nanoindentation curves,the elastic modulus of 1045/Al2O3-TiO2 is 180 GPa for the 50 μm film.The highest value of fracture toughness for 1045/Al2O3-TiO2-250 μm is 348 MPa·ml/2.
基金
Project supported by the National Research Foundation of Korea(2011-0030804)
the Korea Research Foundation(KRF2009-0076450)funded by the Korea Government(MEST)
