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Journal of Magnesium and Alloys 2021年第6期9卷 2155-2168页

作者： Xiyu Yao Jincheng Tang Yinghao Zhou Andrej Atrens Matthew S.Dargusch Bjoern Wiese Thomas Ebel Ming Yan School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China Department of Materials Science and Engineering Southern University of Science and TechnologyShenzhen 518055China The University of Queensland School of Mechanical and Mining EngineeringCentre for Advanced Materials Processing and Manufacturing(AMPAM)QLD 4072 Australia Institute of Materials Research Helmholtz-Zentrum GeesthachtGeesthacht 21502Germany

Magnesium alloys such as Mg–Ca and Mg–Zn–Ca are good orthopaedic materials;however their tendency to corrode is high.Herein we utilize selective laser melting(SLM)to modify the surface of these Mg alloys to simultaneously improve the corrosion behaviour and microhardness.The corrosion rate decreased from 2.1±0.2 mm/y to 1.0±0.1 mm/y for the laser-processed Mg–0.6Ca,and from 1.6±0.1 mm/y to 0.7±0.2 mm/y for laser-processed Mg–0.5Zn–0.3Ca.The microhardness increased from 46±1 HV to 56±1 HV for Mg–0.6Ca,and from 47±3 HV to 55±3 HV for Mg–0.5Zn–0.3Ca.In addition,good biocompatibility remained in the laser processed Mg alloys.The improved properties are attributed to laser-induced grain refinement,confined impurity elements,residual stress,and modified surface chemistry.The results demonstrated the potential of SLM as a surface engineering approach for developing advanced biomedical Mg alloys.

关键词： Mg alloys Selective laser melting Surface modification corrosion behaviour Microhardness

corrosion evolution and behaviour of Al-2.1Mg-1.6Si alloy in chloride media

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Rare Metals 2021年第4期40卷 908-919页

作者： Ya-Ya Zheng Bing-Hui Luo Chuan He Yang Gao Zhen-Hai Bai College of Materials Science and Engineering Central South UniversityChangsha 410083China Key Laboratory of Safety Design and Reliability Technology for Engineering Vehicle Changsha University of Science and TechnologyChangsha 410114China

Owing to the importance of finding better methods and technologies for protecting against corrosion of aluminium alloys,research into the electrochemical characteristics of the corrosion is an ongoing concern.In this paper,the corrosion behaviour of Al-Mg-Si alloys in 3.5 wt% NaCl solution was investigated using multiple methods,including scanning electron microscopy(SEM),transmission electron microscopy(TEM),potentiodynamic polarisation measurement and electrochemical impedance spectroscopy(EIS).The results suggest that corrosion begins with dealloying of Mg,followed by conversion of MgSi particles into Al-Fe-Mn-Si particles.The corrosion rate increased until it reached a peak and then decreased.The increase in the corrosion rate may be attributed to an increased electrochemical driving force,which is produced by anodic dissolution between the matrix and residual MgSi particles.Additionally,the thin re-deposited layer of inert elements also plays an important role in accelerating the anodic process of the corrosion pit.The passivated corrosion pit and narrowed intergranular corrosion(IGC)pathway cause the area of active dissolution to decrease,thus reducing the corrosion rate.

关键词： Al-Mg-Si alloys corrosion behaviour Electrochemical corrosion rate IGC corrosion pathway

Mechanical properties and corrosion resistance of powder metallurgical Mg-Zn-Ca/Fe bulk metal glass composites for biomedical application

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Journal of Materials Science & Technology 2022年第8期103卷 73-83页

作者： Kun Li Luxin Liang Peng Du Zeyun Cai Tao Xiang Hiroyasu Kanetaka Hong Wu Guoqiang Xie School of Materials Science and Engineering Harbin Institute of Technology(Shenzhen)Shenzhen 518055China State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China Graduate School of Biomedical Engineering Tohoku UniversitySendai980-8579Japan Graduate School of Dentistry Tohoku UniversitySendai 980-8575Japan State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China

Magnesium(Mg)alloys can be regarded as the most promising biodegradable implant materials for orthopedic and stent applications due to their good biocompatibility and low Young’s modulus which is near to that of natural bone.However,its applicability is hindered because it exhibits a high corrosion rate in the physiological environments.In this work,we fabricated Mg_(66)Zn_(30)Ca_(4)/Fe bulk metallic glass composites via spark plasma sintering(SPS).We studied the influence of different contents of Fe on the properties of the composites.The results indicated that Fe was uniformly distributed on the surface of Mg_(66)Zn_(30)Ca_(4) metallic glass(MG)as a second phase,which led to an improvement in the corrosion resistance and mechanical strength.The standard potential of Mg_(66)Zn_(30)Ca_(4)/Fe bulk metallic glass(BMG)composites increased as compared to Mg_(66)Zn_(30)Ca_(4),while their mechanical strength improved from 355 MPa to 616 MPa.Furthermore,cytotoxicity was investigated via the CCK-8 assay and calcein-AM staining,which revealed that the extraction mediums diluted 6 times(EM×6)of the Mg_(66)Zn_(30)Ca_(4) and Mg_(66)Zn_(30)Ca_(4)/Fe did not cause cell toxicity on day 3 and 5,while the EM×6 of the Mg_(66)Zn_(30)Ca_(4) showed cytotoxicity on day 1,3 and 5.Thus,Mg_(66)Zn_(30)Ca_(4)/Fe BMG composites exhibit significant potential for fabricating implants with good mechanical strength and corrosion resistance.

关键词： Mg_(66)Zn_(30)Ca_(4)/Fe bulk metallic glass composites Spark plasma sintering corrosion behaviour Mechanical strength

The Study on the corrosion behaviour of Welded and Unwelded Medium Carbon Steel in Sodium Chloride(Nacl)Solutions

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Journal of Metallic Material Research 2020年第2期3卷 1-16页

作者： Cyril Ocheri Hebert A.Obiorah Romanus Egwuonwu Njoku Nnaemeka Anthony Urama Joseph Babalola Agboola Christopher Nwankwo Mbah Johnson NwaemezieEzeanyanwu Chikezie Walter Onyia Department of Metallurgical and Materials Engineering University of NigeriaNsukka Department of Metallurgical and Materials Engineering Federal University of TechnologyMinnaNiger State Department of Metallurgical and Materials Engineering Enugu State University of Science and TechnologyEnugu

The research work was based on the study of the corrosion behaviour of the welded and un-welded medium carbon steel in sodium chloride solutions.The Sodium chloride solutions used are 1ml,2ml,3ml and 4ml for both welded and un-welded medium carbon steel in NaCl.The experiments were conducted in two ways,the weight loss analyses of measurements and using the electrochemical analyzer workstation to determine the potential dynamic of the samples.The samples for the weight loss measurements were prepared from rolled products obtained at the foundry shop.Two medium carbon steel materials were sourced with different chemical compositions as sample A and B.The materials were prepared to accommodate the experiments for the determination of welded and un-welded medium carbon steel.A total of sixty-eight(68)samples were produced,prepared and used for the weight loss measurements/analyses the experiments.Thirty-four of the samples each were prepared for both the welded and un-welded experiments.All the samples were produced and prepared through the use of various machining processes with the use of a lathe machine for planning,milling.Thirty-four(34)of the sample preparation were further welded in readiness of the experiments.Sixty-eight breakers were sourced for and used.Ten(10)other samples were used for the determination with the use of the electrochemical analyzer.The chemical compositions of the medium carbon steel were determined with the use of SPECTRO Analytical Instruments.A metallurgical inverted optical microscope was used to determine the microstructures of the materials.The Scanning Electron Microscopy with EDS was used to determine the morphologies of the materials.The thirty-four of the samples were welded this process was performed to determine the effects of welding on the material surrounding the weldments.These materials were made into sizes with the use of power hacksaw(i.e.2cm by 2cm).Other materials were prepared to 1cm x 1cm thickness from the same materials.The Tafel plot experiments and that of the

关键词： corrosion behaviour Welded Un-welded Medium carbon steel Sodium chloride solution

corrosion behaviours of the dental magnetic keeper complexes made by different alloys and methods

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International Journal of Oral Science 2016年第3期8卷 155-163页

作者： Min-Ke Wu Ning Song Fei Liu Liang Kou Xiao-Wen Lu Min Wang Hang Wang Jie-Fei Shen State Key Laboratory of Oral Diseases West China Hospital of Stomatology Sichuan University Chengdu China Ningbo Dental Hospital Ningbo China

The keeper and cast dowel-coping, as a primary component for a magnetic attachment, is easily subjected to corrosion in a wet environment, such as the oral cavity, which contains electrolyte-rich saliva, complex microflora and chewing behaviour and so on. The objective of this in vitro study was to examine the corrosion resistance of a dowel and coping-keeper complex fabricated by finish keeper and three alloys （cobalt-chromium, CoCr; silver-palladium-gold, PdAu; gold-platinum, AuPt） using a laser- welding process and a casting technique. The surface morphology characteristics and microstructures of the samples were examined by means of metallographic microscope and scanning electron microscope （SEM）. Energy-dispersive spectroscopy （EDS） with SEM provided elements analysis information for the test samples after 10% oxalic acid solution etching test. Tafel polarization curve recordings demonstrated parameter values indicating corrosion of the samples when subjected to electrochemical testing. This study has suggested that massive oxides are attached to the surface of the CoCr-keeper complex but not to the AuPt-keeper complex. Only the keeper area of cast CoCr-keeper complex displayed obvious intergranular corrosion and changes in the Fe and Co elements, Both cast and laser-welded AuPt-keeper complexes had the highest free corrosion potential, followed by the PdAu-keeper complex. We concluded that although the corrosion resistance of the CoCr-keeper complex was worst, the keeper surface passive film was actually preserved to its maximum extent. The laser-welded CoCr- and PdAu-keeper complexes possessed superior corrosion resistance as compared with their cast specimens, but no significant difference was found between the cast and laser-welded AuPt-keeper complexes. The Fe-poor and Cr-rich band, appearing on the edge of the keeper when casting, has been proven to be a corrosion-prone area.

关键词： cobalt-chromium alloy corrosion behaviour dental magnets gold-platinum alloy magnetic attachment silver-palladium-gold alloy

corrosion behavior of Al_(0.4)CoCu_(0.6)NiSi_(0.2)Ti_(0.25) high-entropy alloy coating via 3D printing laser cladding in a sulphur environment

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Journal of Materials Science & Technology 2021年第1期60卷 197-205页

作者： Hongxia Wan Dongdong Song Xiaolei Shi Yong Cai Tingting Li Changfeng Chen Beijing Key Laboratory of Failure Corrosion and Protection of Oil/Gas Facility MaterialsDepartment of Materials Science and EngineeringChina University of Petroleum(Beijing)Beijing 102249China Institute of Advanced Wear&corrosion Resistant and Functional Materials Jinan UniversityGuangzhou 510632China

High-entropy alloys(HEAs) are of great interest in materials science and engineering communities owing to their unique phase structure.HEAs are constructed with five or more principal alloying elements in equimolar or near-equimolar ratios.Therefore,they can derive their performance from multiple principal elements ratherthan a single element.In this work,three-dimensional printing laser cladding was applied to produce an Al_(0.4)CoCu_(0.6)NiSi_(0.2)Ti_(0.25) HEA coating.The experimental results confirmed that the laser cladding could be used to produce a thin coating of 120 μm in thickness.In the high-temperature laser cladding process,some Fe elements diffused from the substrate to the coating,forming a combination of face-centred cubic and body-centred cubic phase structures.The HEA coating metallurgically bonded well with the substrate.Owing to the increased dislocation density and number of grain boundaries,the HEA coating was harder and had a stronger hydrophobicity than X70 steel.The electrochemistry results showed that the HEA coating had better corrosion resistance than X70 steel.Aluminium oxides formed on the surface of the HEA coating had a certain protective effect.However,because of the laser cladding,the HEA coating generated cracks.In future work,the laser cladding technology will be improved and heat treatment will be implemented to prevent formation of cracks.

关键词： High-entropy alloy coating(HEA coating) Laser cladding corrosion behaviour

Microstructural, mechanical and corrosion characterization of an as-cast Mg-3Zn-0.4Ca alloy for biomedical applications

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Journal of Magnesium and Alloys 2020年第2期8卷 510-522页

作者： N.Pulido-Gonzalez B.Torres P.Rodrigo N.Hort J.Rams Department of Applied Mathematics Materials Science and Engineering and Electronics Technology.ESCETRey Juan Carlos UniversityC/Tulipan s/n28933 MdstolesMadridSpain Magnesium Innovation Centre Helmholtz-Zentrum Geesthacht21502 GeesthachtGermany

The as-cast Mg-3Zn-0.4Ca alloy shows a great potential to be used in biomedical applications due to its composition,mechanical properties and biodegradability.Zn and Ca appear naturally in the organism accomplishing vital functions.The alloy consists of an a-Mg matrix and a eutectic composed of a-Mg4-Ca2Mg6Zn3.The eutectic product enhances the mechanical properties of the studied alloy,causing strengthening and providing superior hardness values.In this alloy,cracks initiate at the intermetallic compounds and progress through the matrix because of the open network formed by the eutectics.Attending to the corrosion results,the eutectic product presents a noble potential compared to the a-Mg phase.For this reason,the corrosion progresses preferentially through the matrix,avoiding the(α-Mg+Ca2Mg6Zri3)eutectic product,when the alloy is in direct contact to Hank's solution.

关键词： Mg-Zn-Ca alloys Biomaterials Biodegradable implants Nanoindentation Three-point bending test corrosion behaviour

Effect of Temperature and Chloride Ion Concentration on the Electrochemical behaviour of Stainless Steel

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Journal of Materials Science & Technology 1989年第3期5卷 203-206页

作者：李冬贵 J.P.Simpson R.Schenk Dalian Acid Proof Pump Plant China Sulzer Bros.Ltd WinterthurSwitzerland

The effect of temperature and chloride ion concentration on the electrochemical behaviour of austenitic-ferritic duplex stainless steel COR 25 in an aqueous solution of 60%H_3PO_4+4%H_2SO_4 is studied in this paper. The experiments show that the anodic active peak current on potentiodynamic polarization increases by an order of magnitude with an in- crease of temperature from 50℃ and with an increase of chloride ion fromcorrosion characteristics in electrochemical tests,being comparable to the fully austenitic alloy Sanicro 28,which has a higher chromium and nickel content,and is much better than GX3CrNiMo2010.corrosion of the duplex material is normally phase selec- tive,with phase boundary attack after unfavour- able heat treatments.

关键词： temperature chloride corrosion behaviour duplex stainless steel