TJ462 : Investigation of mechanical properties of a titanium implant processed by equal channel angular pressing
Thesis > Central Library of Shahrood University > Mechanical Engineering > MSc > 2017
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Abstarct: Equal channel angular pressing (ECAP) as one of the most important methods of severe plastic deformation, has a significant effect on enhancing the strength of light mextals. Today, titanium implants are widely used due to the good biocompatibility, specific strength, toughness, formability and machinability. In this thesis, fabrication of an endosseous dental implant fixture using commercially pure titanium grade 2, proceed by hot ECAP has been investigated. The new design of ECAP die with 90° channel angle resolves the problem of unwanted mextal flow in die parting line which leads to excessive load and workpiece adhesion. After trial and errors, by using the solid film of copper foil and mixed film lubricant of molybdenum disulfide, the ECAP process was performed at 240 °C up to 4 passes successfully. By carrying out the micro-hardness test in different points of cross section it has been revealed that increasing the passes of ECAP leads to increasing the hardness and homogeneity, simultaneously. Also axial compression test showed that the maximum improving rate of yield stress happens at first ECAP pass and it continues with lower rate at subsequent stages. The temperature reduction at final step plays an important role for attaining simultaneous high strength and toughness. SEM images show that the first ECAP pass has the greatest effect on the grain refinement and the its rate has been decreased in subsequent passes. Furthermore, in comparison with similar studies the presented ECAP tooling results in more strength improvement, significantly. After achieving the optimum condition of process, dental implants fabricated by a precision machining method with a special CNC machine using as-received and ECAPed specimen. In order to evaluate the performance of the implant, mechanical tests were performed according to ISO 14801. The cell culture test was performed to investigate the biocompatibility properties. Also, SEM imaging of fracture zone was carried out. The results indicated an improve in biocompatibility and mechanical strength using implants fabricated by ECAP process.
Keywords:
#Commercially pure titanium #Dental implant #Ultra-fined Grained (UFG) #Severe Plastic Deformation (SPD) #Hot Equal Channel Angular Pressing (ECAP)
Keeping place: Central Library of Shahrood University
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Keeping place: Central Library of Shahrood University
Visitor: