Minimally invasive surgery(MIS)robots,such as single-arm stapling robots,are key to oral and maxillofacial surgery because they overcome space constraints in the oral cavity and deep throat.However,biodegradable sutur...Minimally invasive surgery(MIS)robots,such as single-arm stapling robots,are key to oral and maxillofacial surgery because they overcome space constraints in the oral cavity and deep throat.However,biodegradable suture staples should be developed for the single-arm stapling robots to avoid a secondary operation.For this aim,a new type of Mg-3Zn-0.2Ca-2Ag biodegradable alloy wire was developed in this study applied as suture staples.Its tensile strength,yield strength,and elongation are 326.1 MPa,314.5 MPa,and 19.6%,respectively.Especially,the alloy wire attains the highest yield strength value reported among all the biodegradable Mg wires,which is mainly attributed to fine grain strengthening and second phase strengthening such as Mg_(2)Zn_(11) nano phase strengthening.Moreover,the corrosion rate of this alloy wire in simulated body fluid(SBF)reaches 26.8 mm/y,the highest value among all the biodegradable Mg alloy wires reported so far,which is mainly from the intensified galvanic corrosion between the Ag17Mg54 phase and the Mg matrix.In vitro studies demonstrate that the alloy wire exhibits good blood compatibility and low cytotoxicity.The cone beam computed tomography(CBCT)data shows that the suture staple made of the Mg alloy wire provides better mechanical support in the early postoperative period.From the single arm robot tests,it confirms that suture staples can close the wound tightly and remain stable over time.This research provides a good material selection for the automated suturing in oral and throat surgery robots.展开更多
Dual equal channel lateral extrusion(DECLE)process with various passes followed by sheet extrusion process was performed to produce fine-grained ZK60 alloy sheets.The coarse grain structure of the annealed sample afte...Dual equal channel lateral extrusion(DECLE)process with various passes followed by sheet extrusion process was performed to produce fine-grained ZK60 alloy sheets.The coarse grain structure of the annealed sample after applying sheet extrusion(size:68μm)changed to fine grains of 6.0 and 5.2μm after 3 and 5 passes of DECLE and following extrusion.The hot shear deformation behavior of samples was studied by developing constitutive equations based on shear punch test(SPT)results.SPT was carried out in the temperature range of 200−300℃ and strain rate range of 0.003−0.33 s^(–1).The activation energy of 125−139 kJ/mol and the stress exponent of 3.5−4.2 were calculated for all conditions,which indicated that dislocation creep,controlled by dislocation climb and solute drag mechanism,acted as the main hot deformation mechanism.It was concluded that material constants of n and Q are dependent on the microstructural factors such as grain size and second phase particle fraction,and the relationship of which was anticipated using a 3D surface curve.Moreover,the similar strong basal texture of extruded sheets gave rise to the same deformation mechanisms during SPT and similar n and Q values for ZK60 alloy.展开更多
Dual equal channel lateral extrusion (DECLE), as a severe plastic deformation (SPD) process, was employed forimproving the mechanical properties of AA5083 aluminum alloy. Several experiments were conducted to study th...Dual equal channel lateral extrusion (DECLE), as a severe plastic deformation (SPD) process, was employed forimproving the mechanical properties of AA5083 aluminum alloy. Several experiments were conducted to study the influences of theroute type, namely A and B, and pass number on mechanical properties of the material. The process was conducted up to 6 passeswith decreasing process temperature, specifically from 573 to 473 K. Supplementary experiments involving metallography, hardnessand tensile tests were carried out in order to evaluate the effects of the process variables. The hardness measurements exhibitedreasonably uniform distributions within the product with a maximum increase of 64% via a 6-pass operation. The yield and ultimatestrengths also amended 107% and 46%, respectively. These significant improvements were attributed to the severe shear deformationof grains and decreasing pass temperature, which intensified the grain refinement. TEM images showed an average grain sizereduction from 100 μm for the annealed billet to 200 nm after 6 passes of DECLE. Finally, the experimental findings for routes A andB were compared and discussed and some important conclusions were drawn.展开更多
基金supported by the National Key R&D Program of China(grant number:2020YFB1312801)the National Natural Science Foundation of China(No.51971020,No.52171097)+4 种基金the Opening Research Fund of State Key Laboratory for Advanced Metals and Materials(2021-Z08)the Fundamental Research Funds for the Central Universities(grant number:PKU2022XGK005)the Non-profit Central Research Institute Fund of Chinese Academy of Medical Sciences(2022-JKCS-24)the Key Scientific Research Project in Shanxi Province(202102050201003)the“Dingxinbeike”Project(G20200001105).
文摘Minimally invasive surgery(MIS)robots,such as single-arm stapling robots,are key to oral and maxillofacial surgery because they overcome space constraints in the oral cavity and deep throat.However,biodegradable suture staples should be developed for the single-arm stapling robots to avoid a secondary operation.For this aim,a new type of Mg-3Zn-0.2Ca-2Ag biodegradable alloy wire was developed in this study applied as suture staples.Its tensile strength,yield strength,and elongation are 326.1 MPa,314.5 MPa,and 19.6%,respectively.Especially,the alloy wire attains the highest yield strength value reported among all the biodegradable Mg wires,which is mainly attributed to fine grain strengthening and second phase strengthening such as Mg_(2)Zn_(11) nano phase strengthening.Moreover,the corrosion rate of this alloy wire in simulated body fluid(SBF)reaches 26.8 mm/y,the highest value among all the biodegradable Mg alloy wires reported so far,which is mainly from the intensified galvanic corrosion between the Ag17Mg54 phase and the Mg matrix.In vitro studies demonstrate that the alloy wire exhibits good blood compatibility and low cytotoxicity.The cone beam computed tomography(CBCT)data shows that the suture staple made of the Mg alloy wire provides better mechanical support in the early postoperative period.From the single arm robot tests,it confirms that suture staples can close the wound tightly and remain stable over time.This research provides a good material selection for the automated suturing in oral and throat surgery robots.
文摘Dual equal channel lateral extrusion(DECLE)process with various passes followed by sheet extrusion process was performed to produce fine-grained ZK60 alloy sheets.The coarse grain structure of the annealed sample after applying sheet extrusion(size:68μm)changed to fine grains of 6.0 and 5.2μm after 3 and 5 passes of DECLE and following extrusion.The hot shear deformation behavior of samples was studied by developing constitutive equations based on shear punch test(SPT)results.SPT was carried out in the temperature range of 200−300℃ and strain rate range of 0.003−0.33 s^(–1).The activation energy of 125−139 kJ/mol and the stress exponent of 3.5−4.2 were calculated for all conditions,which indicated that dislocation creep,controlled by dislocation climb and solute drag mechanism,acted as the main hot deformation mechanism.It was concluded that material constants of n and Q are dependent on the microstructural factors such as grain size and second phase particle fraction,and the relationship of which was anticipated using a 3D surface curve.Moreover,the similar strong basal texture of extruded sheets gave rise to the same deformation mechanisms during SPT and similar n and Q values for ZK60 alloy.
基金partially supported by the Iran National Science Foundation(INSF) with grant number 92014140
文摘Dual equal channel lateral extrusion (DECLE), as a severe plastic deformation (SPD) process, was employed forimproving the mechanical properties of AA5083 aluminum alloy. Several experiments were conducted to study the influences of theroute type, namely A and B, and pass number on mechanical properties of the material. The process was conducted up to 6 passeswith decreasing process temperature, specifically from 573 to 473 K. Supplementary experiments involving metallography, hardnessand tensile tests were carried out in order to evaluate the effects of the process variables. The hardness measurements exhibitedreasonably uniform distributions within the product with a maximum increase of 64% via a 6-pass operation. The yield and ultimatestrengths also amended 107% and 46%, respectively. These significant improvements were attributed to the severe shear deformationof grains and decreasing pass temperature, which intensified the grain refinement. TEM images showed an average grain sizereduction from 100 μm for the annealed billet to 200 nm after 6 passes of DECLE. Finally, the experimental findings for routes A andB were compared and discussed and some important conclusions were drawn.
