Corrosion of Artificial Aged Magnesium Alloy AZ80 in 3.5 wt pct NaCl Solutions

The corrosion morphologies of aged magnesium alloy AZ80 were investigated by immersion corrosion tests, scanning electron microscopy （SEM）, electrochemical measurement. The T5 heat treatment was carried out in a vacuum furnace, holding for 16 h at 177℃, and then cooling in air. The results showed intergranular corrosion （IGC） occurred as an aged AZ80 sample was immersed in 3.5 wt pct NaCI aqueous solution for 1 h and the narrow path attack progressed predominantly along the bulk β phase in the grain boundaries or took place in the eutectic areas. IGC was attributed to the network distribution of β phase along the grain boundaries, the depleted aluminium in the precipitation areas and the breakdown potential.

Advances in functional coatings on biliary stents

Biliary stenting is an important interventional method for the prevention and treatment of biliary tract diseases.However,complications,such as postoperative biliary infection and re-stenosis,frequently occur due to the extensive scope of the biliary system and the complex composition of bile.The com-bination of coating technology and biliary stents is expected to bring new approaches to the solution of these problems.The cutting-edge advance on functional coatings on biliary stents is reviewed from seven perspectives:anticorrosion,-bacterial,-tumor,stone-dissolving,X-ray visibility,anti-stent migration and functional composite coatings.The de-velopment trend is also discussed.Overall.the performance of the numerous functional coatings for various purposes is generally up to expectations,but the balance between the medica tions'effectiveness and their safety needs to be further adjusted.Many contemporary investigations have advanced to the leve of animal experiments,offering crucial fundamental assurance for broader human studies.The combination of biliary stent and functional coatings is an innovative idea with great potential for future development.

Layered double hydroxide coatings on magnesium alloys: A review

Layered double hydroxides（LDHs） as a class of anionic clays have extensive applications due to their unique structures. Nowadays, the emphasis is laid on the development of LDH coatings for corrosion resistance and medical applications. Thus, this review highlights synthetic methods of LDH coatings and LDH-based composite coatings on magnesium alloys. Special attention is focused on self-healing,biocompatible and self-cleaning LDH-based composite coatings on magnesium alloys.

In vitro and in vivo biodegradation and biocompatibility of an MMT/BSA composite coating upon magnesium alloy AZ31

The performance of biodegradable magnesium alloy requires special attention to rapid degradation and poor biocompatibility, which can cause the implant to fail. Here, a sodium montmorillonite(MMT)/bovine serum albumin(BSA) composite coating was prepared upon magnesium alloy AZ31 via hydrothermal synthesis, followed by dip coating. We evaluated the surface characterization and corrosion behavior in vitro, and the biocompatibility in vitro and in vivo. Biodegradation progress of the MMT-BSA coated Mg pieces was examined through hydrogen evolution, immersion tests, and electrochemical measurements in Hank’s solution. In vitro biocompatibility studies were evaluated via hemolysis tests, dynamic cruor time tests, platelet adhesion, MTT testing and live-dead stain of osteoblast cells(MC3 T3-E1). It was found that the MMT-BSA coating had good corrosion resistance and a marked improvement in biocompatibility in comparison to bare Mg alloy AZ31. in vivo studies were carried out in rat model and the degradation was characterized by computed tomography scans. Results revealed that the MMT-BSA coated Mg alloy AZ31 implants maintained their structural integrity and slight degradation after 120 d of post-implantation. A100% survival rate for the rats was observed with no obvious toxic damages on the organs and tissues.Additionally, we proposed a sound coating formation mechanism. Considering the good corrosion protection and biocompatibility, the MMT-BSA coated Mg alloy AZ31 is a promising candidate material for biomedical implants.

Self-Assembled Silane Film and Silver Nanoparticles Coating on Magnesium Alloys for Corrosion Resistance and Antibacterial Applications

Contamination resulting from microbial adhesion on magnesium alloys is very common in many applications. Self-assembly technology was employed to prepare an antibacterial composite coating by fixing silver nanoparticles （AgNPs） onto the surface of magnesium alloys. The AgNPs were immobilized on the surface of 3-aminopropyltrimethoxysilane （APTMS）-modified magnesium alloy AZ31 （APTMS/Mg） through electrosta- tic inter-attraction between partially protonated amino groups and negatively charged citrate-capped AgNPs, resulting in the AgNPs attached APTMS/Mg （AgNPs/APTMS/Mg） substrate. The prepared Ag colloid and functionalized AZ31 alloy were characterized by ultraviolet-visible （UV-vis） spectroscopy, Fourier transform infrared （FTIR） spectroscopy, scanning electron microscopy （SEM）, and electrochemical methods. Finally, the bactericidal activity of AgNPs/APTMS/Mg substrate against Escherichia coli was assessed by the inhibition zone. The results demonstrated that Si-O-Si covalent bonds existed on the substrate with the formation of inorganic Si-O-Mg bonds. AgNPs were immobilized and well-dispersed, forming a uniform submonolayer on the silane film in two dimensions. The AgNPs/APTMS-pretreated AZ31 alloys exhibited better corrosion resistance and excellent antibacterial performance.

Mg-Li-Ca合金的体外降解行为与生物相容性:锂元素含量的影响（英文）

基于良好的延展性,Mg-Li基合金作为潜在的生物材料,引起了大家的广泛注意.由于锂元素的存在,Mg-Li二元合金表现出较低的机械强度与人们对其生物相容性的担忧.而在Mg-Li合金中添加钙元素则有利于提高其机械强度与生物相容性.本文中,通过光学显微镜、X射线衍射、拉力拉伸、浸泡实验以及电化学极化测试等综合评估了三种类型(α,α+β,β)的挤压态Mg-Li(1,9以及15 wt.%)-1Ca合金的微观结构、力学性能以及腐蚀行为.体外生物相容性通过细胞毒性、溶血以及凝血四项表征.结果表明,Mg-1Li-1Ca和Mg-15Li-1Ca合金分别由α-Mg、β-Li以及Mg_2Ca相构成;而Mg-9Li-1Ca则由α-Mg、β-Li双相以及Mg_2Ca相构成.Mg-1Li-1Ca合金表现出最高的最大抗拉强度和屈服强度,但其延伸率最低,仅为10.1±1.24%;Mg-9Li-1Ca合金的延伸率最高,为52.2±0.01%.长时间浸泡实验表明,随着锂元素含量的增加,合金的耐蚀性逐渐降低.毒性试验结果表明,在10%浸提液中Mg-Li-Ca合金对L-929细胞无明显毒性反应.Mg-1Li-1Ca表现出人体可以接受的溶血率.凝血四项实验结果指出,除Mg-15Li-1Ca外,Mg-1Li-1Ca和Mg-9Li-1Ca合金无促凝性反应产生.

Fabrication of the Superhydrophobic Surface on Magnesium Alloy and Its Corrosion Resistance

The superhydrophobic surface was fabricated on the AZ31 alloy by the combination of the hydrotherreal treatment method and post modification with stearic acid. The superhydrophobic surface showed a static water contact angle of 157.6°. The characteristics of the coatings were characterized by scanning electron microscopy （SEM）, X-ray diffraction （XRD） and Fourier transform infrared spectroscopy （FTIR）. The corrosion resistance of the superhydrophobic coatings was investigated by potentiodynamic polarization test and electrochemical impedance spectroscopy （EIS）. The results revealed that the superhydrophobic coatings, characterized by petal-like structure significantly improved the corrosion resistance of the AZ31 ahoy.