Additive manufacturing (AM), while enabling the production of parts with complex geometries, presents new challenges. In particular, the achievement of the basic mechanical properties of the alloy must be ensured. In ...Additive manufacturing (AM), while enabling the production of parts with complex geometries, presents new challenges. In particular, the achievement of the basic mechanical properties of the alloy must be ensured. In general, the strength-ductility properties of metals depend strongly on their microstructure, and controlling these properties requires paying attention to the alloy composition, processing technique and heat treatments. Austenite 316L stainless steel parts produced by AM demonstrate good ductility and high yield strength—higher than that obtained with annealed 316L. Some preferred orientation of the mechanical properties was found as a function of the laser path, namely, the Young’s modulus varied with respect to the angle between the build direction and the normal to the build direction. In the present study, samples of AM 316L in three orientations relative to the print direction (0˚, 45˚and 90˚) are compared to a forged sample. Mechanical properties, scanning electron microscopy-SEM fractography, energy dispersive X-ray spectroscope-EDS analysis of the fracture and optical cross section images of the samples along the stress tension after the failure are presented.展开更多
The Cu2O/TiO2 p-n heterojunction composite photoelectrodes were prepared by depositing Cu 2 O nanoparticles on the surface of TiO 2 nanotubes via anodic oxidation and constant current deposition.Field emission scannin...The Cu2O/TiO2 p-n heterojunction composite photoelectrodes were prepared by depositing Cu 2 O nanoparticles on the surface of TiO 2 nanotubes via anodic oxidation and constant current deposition.Field emission scanning electron microscopy(SEM)and high-resolution transmission electron microscopy(HRTEM)analyses showed that Cu 2 O nanoparticles not only deposited on the surface of TiO 2 nanotube array,but also on the wall of TiO 2 nanotubes.The Cu 2 O deposition amount could be adjusted by changing the deposition time.The photoelectrochemical cathodic protection(PECCP)performance of the prepared photoelectrodes for 316L stainless steel(SS)was tested under visible light.The constant current deposition time had a signifi cant eff ect on the PECCP performance of Cu 2 O/TiO 2-X photoelectrodes and Cu 2 O/TiO 2-20 had the best PECCP performance for the coupled 316L SS.This was attributed to the appropriate amount and thickness of Cu 2 O to form p-n heterojunctions with TiO 2,in which separation of the photogenerated carriers was accelerated and transfer of the photogenerated electrons to 316L SS for PECCP was facilitated.展开更多
316L stainless steel(SS)is widely applied as microimplant anchorage(MIA)due to its excellent mechanical properties.However,the risk that the oral microorganisms can corrode 316L SS is fully neglected.Microbiologically...316L stainless steel(SS)is widely applied as microimplant anchorage(MIA)due to its excellent mechanical properties.However,the risk that the oral microorganisms can corrode 316L SS is fully neglected.Microbiologically influenced corrosion(MIC)of 316L SS is essential to the health and safety of all patients because the accelerated corrosion caused by the oral microbiota can trigger the release of Cr and Ni ions.This study investigated the corrosion behavior and mechanism of subgingival microbiota on 316L SS by 16S rRNA and metagenome sequencing,electrochemical measurements,and surface characterization techniques.Multispecies biofilms were formed by the oral subgingival microbiota in the simulated oral anaerobic environment on 316L SS surfaces,significantly accelerating the corrosion in the form of pitting.The microbiota samples collected from the subjects differed in biofilm compositions,corrosion behaviors,and mechanisms.The oral subgingival microbiota contributed to the accelerated corrosion of 316L SS via acidic metabolites and extracellular electron transfer.Our findings provide a new insight into the underlying mechanisms of oral microbial corrosion and guide the design of oral microbial corrosion-resistant materials.展开更多
Stainless steels have received wide attention as a substitute material for bipolar plates in high temperature proton exchange membrane fuel cell(HT-PEMFC).In the present work,the CrN,CrAlN and multilayer CrN/CrAlN coa...Stainless steels have received wide attention as a substitute material for bipolar plates in high temperature proton exchange membrane fuel cell(HT-PEMFC).In the present work,the CrN,CrAlN and multilayer CrN/CrAlN coatings were deposited on 316 L SS to increase the corrosion resistance and decrease the interfacial contact resistance.The deposited coatings exhibited face centered cubic phase structure and it was verified from the X-ray diffraction pattern.X-ray photo electron spectroscopy results showed the formation of both CrN and CrAlN layers on 316 L SS.CrN/CrAlN coating is more helpful in water management due to low surface roughness and high contact angle in the HT-PEMFC environment.The corrosion resistance behavior of all the samples were studied in 85%H_(3)PO_(4)solution at 140℃purged with H_(2)(HT-PEMFC anode)and O_(2)(HT-PEMFC cathode)gases.The results showed that all the coatings considerably improved the performance of 316 L SS and superior corrosion resistance was observed for CrN/CrAlN multilayer coating,whose protective efficiency was 98.12%and 96.14%in the two simulated HT-PEMFC environments.The results of electrochemical impedance spectroscopic studies demonstrated higher impedance for CrN/CrAlN coating.Surface morphological studies performed after corrosion studies revealed that protection ability of CrN/CrAlN coating still remained acceptable.A very low interfacial contact resistance value of 6 mΩ cm^(2) at 140 N/cm;was observed for CrN/CrAlN coating.Moreover,after corrosion studies,the interfacial contact resistance value of CrN/CrAlN coated 316 L was much lower than that of CrN and CrAlN coatings due to the increased oxidation resistance.The maximum power density of about 0.93 W/cm^(2) at 2 A/cm^(2) and output voltage of 0.96 V was observed for CrN/CrAlN coating.展开更多
文摘Additive manufacturing (AM), while enabling the production of parts with complex geometries, presents new challenges. In particular, the achievement of the basic mechanical properties of the alloy must be ensured. In general, the strength-ductility properties of metals depend strongly on their microstructure, and controlling these properties requires paying attention to the alloy composition, processing technique and heat treatments. Austenite 316L stainless steel parts produced by AM demonstrate good ductility and high yield strength—higher than that obtained with annealed 316L. Some preferred orientation of the mechanical properties was found as a function of the laser path, namely, the Young’s modulus varied with respect to the angle between the build direction and the normal to the build direction. In the present study, samples of AM 316L in three orientations relative to the print direction (0˚, 45˚and 90˚) are compared to a forged sample. Mechanical properties, scanning electron microscopy-SEM fractography, energy dispersive X-ray spectroscope-EDS analysis of the fracture and optical cross section images of the samples along the stress tension after the failure are presented.
基金Supported by the National Natural Science Foundation of China(Nos.41576114,41676069)the State Key Laboratory for Marine Corrosion and Protection,Luoyang Ship Material Research Institute,China(No.614290101011703)the Qingdao Innovative Leading Talent Foundation(No.15-10-3-15-(39)-zch)。
文摘The Cu2O/TiO2 p-n heterojunction composite photoelectrodes were prepared by depositing Cu 2 O nanoparticles on the surface of TiO 2 nanotubes via anodic oxidation and constant current deposition.Field emission scanning electron microscopy(SEM)and high-resolution transmission electron microscopy(HRTEM)analyses showed that Cu 2 O nanoparticles not only deposited on the surface of TiO 2 nanotube array,but also on the wall of TiO 2 nanotubes.The Cu 2 O deposition amount could be adjusted by changing the deposition time.The photoelectrochemical cathodic protection(PECCP)performance of the prepared photoelectrodes for 316L stainless steel(SS)was tested under visible light.The constant current deposition time had a signifi cant eff ect on the PECCP performance of Cu 2 O/TiO 2-X photoelectrodes and Cu 2 O/TiO 2-20 had the best PECCP performance for the coupled 316L SS.This was attributed to the appropriate amount and thickness of Cu 2 O to form p-n heterojunctions with TiO 2,in which separation of the photogenerated carriers was accelerated and transfer of the photogenerated electrons to 316L SS for PECCP was facilitated.
基金supported by grants from the National Key Research and Development Program of China(2020YFA0907300)the National Natural Science Foundation of China(Nos.U2006219 and 51871050)+2 种基金the Fundamental Research Funds for the Central Universities(Nos.N180203019 and N2002019)Liaoning Revitalization Talents Program(No.XLYC1907158)Basic Scientific Research Project of Education Department of Liaoning Province and Shenyang Young and middle-aged Scientific and Technological Innovation Talents Support Program(RC210001).
文摘316L stainless steel(SS)is widely applied as microimplant anchorage(MIA)due to its excellent mechanical properties.However,the risk that the oral microorganisms can corrode 316L SS is fully neglected.Microbiologically influenced corrosion(MIC)of 316L SS is essential to the health and safety of all patients because the accelerated corrosion caused by the oral microbiota can trigger the release of Cr and Ni ions.This study investigated the corrosion behavior and mechanism of subgingival microbiota on 316L SS by 16S rRNA and metagenome sequencing,electrochemical measurements,and surface characterization techniques.Multispecies biofilms were formed by the oral subgingival microbiota in the simulated oral anaerobic environment on 316L SS surfaces,significantly accelerating the corrosion in the form of pitting.The microbiota samples collected from the subjects differed in biofilm compositions,corrosion behaviors,and mechanisms.The oral subgingival microbiota contributed to the accelerated corrosion of 316L SS via acidic metabolites and extracellular electron transfer.Our findings provide a new insight into the underlying mechanisms of oral microbial corrosion and guide the design of oral microbial corrosion-resistant materials.
基金the financial assistance received from Science and Engineering Research Board(SERB PDF/2017/002594),New Delhi,India。
文摘Stainless steels have received wide attention as a substitute material for bipolar plates in high temperature proton exchange membrane fuel cell(HT-PEMFC).In the present work,the CrN,CrAlN and multilayer CrN/CrAlN coatings were deposited on 316 L SS to increase the corrosion resistance and decrease the interfacial contact resistance.The deposited coatings exhibited face centered cubic phase structure and it was verified from the X-ray diffraction pattern.X-ray photo electron spectroscopy results showed the formation of both CrN and CrAlN layers on 316 L SS.CrN/CrAlN coating is more helpful in water management due to low surface roughness and high contact angle in the HT-PEMFC environment.The corrosion resistance behavior of all the samples were studied in 85%H_(3)PO_(4)solution at 140℃purged with H_(2)(HT-PEMFC anode)and O_(2)(HT-PEMFC cathode)gases.The results showed that all the coatings considerably improved the performance of 316 L SS and superior corrosion resistance was observed for CrN/CrAlN multilayer coating,whose protective efficiency was 98.12%and 96.14%in the two simulated HT-PEMFC environments.The results of electrochemical impedance spectroscopic studies demonstrated higher impedance for CrN/CrAlN coating.Surface morphological studies performed after corrosion studies revealed that protection ability of CrN/CrAlN coating still remained acceptable.A very low interfacial contact resistance value of 6 mΩ cm^(2) at 140 N/cm;was observed for CrN/CrAlN coating.Moreover,after corrosion studies,the interfacial contact resistance value of CrN/CrAlN coated 316 L was much lower than that of CrN and CrAlN coatings due to the increased oxidation resistance.The maximum power density of about 0.93 W/cm^(2) at 2 A/cm^(2) and output voltage of 0.96 V was observed for CrN/CrAlN coating.
