A binary Mg-6Zn biodegradable alloy was solution treated to evaluate the effects of resulting microstructure changes on the alloy＇s degradation rate and mechanisms in-vitro. The treatment was conducted at 350 °C...A binary Mg-6Zn biodegradable alloy was solution treated to evaluate the effects of resulting microstructure changes on the alloy＇s degradation rate and mechanisms in-vitro. The treatment was conducted at 350 °C for 6-48 h. Optical and scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction were used to analyze the as-cast and treated samples. Immersion and electrochemical tests were performed in simulated body fluid at 37 °C to assess the samples corrosion resistance. To confirm the results of the corrosion tests, p H measurement was carried out. It is found that over 24 h solution treatment dissolves intermetallic phases in matrix and produces an almost single phase microstructure. Decreasing the intermetallic phases results in lower cathode/anode region ratios and lowers corrosion rates. The results of the electrochemical and mass loss tests reveal that extended solution treatment improves the corrosion resistance of the alloy. The results also show that solution at 350 °C for 24 h enhances the corrosion resistance of the as-cast alloy more than 60%. In addition, decreasing intermetallic phases in the microstructure accompanied a lower p H rise reduced corrosion rate. Solution treatment is suggested as a corrosion improving process for the application of Mg-Zn alloys as biodegradable implant materials.展开更多
Metallic implants are commonly used in various orthopaedic surgeries, like fracture fixation, spinal instrumentation, joint replacement and bone tumour surgery.Patients may need to adapt to the fixed dimensions of the...Metallic implants are commonly used in various orthopaedic surgeries, like fracture fixation, spinal instrumentation, joint replacement and bone tumour surgery.Patients may need to adapt to the fixed dimensions of the standard implants. It may result in suboptimal fit to the host bones and possible adverse clinical results. The standard traditional implants may not address the reconstructive challenges such as severe bone deformity or bone loss after implant loosening and bone tumour resection. With the advent of digital technologies in medical imaging, computer programming in three-dimensional（3 D） modelling and computer-assisted tools in precise placement of implants, patient-specific implants（PSI） have gained more attention in complex orthopaedic reconstruction. Additive manufacturing technology, in contrast to the conventional subtractive manufacturing, is a flexible process that can fabricate anatomically conforming implants that match the patients’ anatomy and surgical requirements. Complex internal structures with porous scaffold can also be built to enhance osseointegration for better implant longevity. Although basic studies have suggested that additive manufactured（AM） metal structures are good engineered biomaterials for bone replacement, not much peer-reviewed literature is available on the clinical results of the new types of implants. The article gives an overview of the metallic materials commonly used for fabricating orthopaedic implants, describes the metal-based additive manufacturing technology and the processing chain in metallic implants; discusses the features of AM implants;reports the current status in orthopaedic surgical applications and comments on the challenges of AM implants in orthopaedic practice.展开更多
基金the Ministry of Higher Education of Malaysia for the financial support (Vote No. Q.J130000.2524.04H18)Faculty of Mechanical Engineering of Universiti Teknologi Malaysia (UTM) for providing research facilities
文摘A binary Mg-6Zn biodegradable alloy was solution treated to evaluate the effects of resulting microstructure changes on the alloy＇s degradation rate and mechanisms in-vitro. The treatment was conducted at 350 °C for 6-48 h. Optical and scanning electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction were used to analyze the as-cast and treated samples. Immersion and electrochemical tests were performed in simulated body fluid at 37 °C to assess the samples corrosion resistance. To confirm the results of the corrosion tests, p H measurement was carried out. It is found that over 24 h solution treatment dissolves intermetallic phases in matrix and produces an almost single phase microstructure. Decreasing the intermetallic phases results in lower cathode/anode region ratios and lowers corrosion rates. The results of the electrochemical and mass loss tests reveal that extended solution treatment improves the corrosion resistance of the alloy. The results also show that solution at 350 °C for 24 h enhances the corrosion resistance of the as-cast alloy more than 60%. In addition, decreasing intermetallic phases in the microstructure accompanied a lower p H rise reduced corrosion rate. Solution treatment is suggested as a corrosion improving process for the application of Mg-Zn alloys as biodegradable implant materials.
文摘Metallic implants are commonly used in various orthopaedic surgeries, like fracture fixation, spinal instrumentation, joint replacement and bone tumour surgery.Patients may need to adapt to the fixed dimensions of the standard implants. It may result in suboptimal fit to the host bones and possible adverse clinical results. The standard traditional implants may not address the reconstructive challenges such as severe bone deformity or bone loss after implant loosening and bone tumour resection. With the advent of digital technologies in medical imaging, computer programming in three-dimensional（3 D） modelling and computer-assisted tools in precise placement of implants, patient-specific implants（PSI） have gained more attention in complex orthopaedic reconstruction. Additive manufacturing technology, in contrast to the conventional subtractive manufacturing, is a flexible process that can fabricate anatomically conforming implants that match the patients’ anatomy and surgical requirements. Complex internal structures with porous scaffold can also be built to enhance osseointegration for better implant longevity. Although basic studies have suggested that additive manufactured（AM） metal structures are good engineered biomaterials for bone replacement, not much peer-reviewed literature is available on the clinical results of the new types of implants. The article gives an overview of the metallic materials commonly used for fabricating orthopaedic implants, describes the metal-based additive manufacturing technology and the processing chain in metallic implants; discusses the features of AM implants;reports the current status in orthopaedic surgical applications and comments on the challenges of AM implants in orthopaedic practice.
