Problems in metal-on-metal (MoM) hip replacement systems still persist due to high wear rates, low corrosion resistance and release of toxic ions and nanoparticles. As a consequence of these effects, failure, infectio...Problems in metal-on-metal (MoM) hip replacement systems still persist due to high wear rates, low corrosion resistance and release of toxic ions and nanoparticles. As a consequence of these effects, failure, infections, loosening or bone resorption is the typical problems in the hip prosthesis. In order to reduce failure due to corrosion and/or releasing ions and particles, this study presents some works in a novel nanoscale surface modification of cobalt-chromium alloy (CoCr) for obtaining improved surface conditions in these alloys for these applications. Improving corrosion resistant of these alloys and achieving a low wear rate are possible to reduce the total released ions and particles released from the surface of this material. According to it, three different treatments using oxygen at temperatures of 300°C, 350°C and 400°C were carried out by plasma immersion ion implantation technique (PI3). X-ray diffraction (XRD) analysis shows an increase in the formation of chromium oxides in the outer surface of the CoCr alloy. It allows improving in corrosion resistant in CoCr alloys. Moreover, total quantity of released Co, Cr and Mo ions have been reduced. Wear rate studies showed a very similar behaviour after the treatments in relation to untreated CoCr alloy and release rate from the treated surface of CoCr alloys was reduced in comparison with untreated CoCr alloy.展开更多
Plasma electrolytic oxidation(PEO) processes were carried out to produce ceramic layers on 6061 aluminum substrates in four kinds of electrolytes such as silicate and aluminate solution with and without sodium fluoros...Plasma electrolytic oxidation(PEO) processes were carried out to produce ceramic layers on 6061 aluminum substrates in four kinds of electrolytes such as silicate and aluminate solution with and without sodium fluorosilicate.The PEO processes were carried out under a hybrid voltage(260 V DC combined with 200 V,60 Hz AC amplitude) at room temperature for 5 min.The composition,microstructure and element distribution analyses of the PEO-treated layers were carried out by XRD and SEM & EDS.The effect of the electrolyte contents on the growth mechanism,element distribution and properties of oxide layers were studied.It is obvious that the layers generated in aluminate solutions show smoother surfaces than those in silicate solutions.Moreover,an addition of fluorine ion can effectively control the layer porosity;therefore,it can enhance the properties of the layers.展开更多
Plasma electrolytic oxidation （PEO） is carried out on 6061 Al-alloys in a weak alkaline electrolyte containing NaOH, Na2SiO3 and NaCl. Centered on the correlation of composition and structure, analyses by means of X...Plasma electrolytic oxidation （PEO） is carried out on 6061 Al-alloys in a weak alkaline electrolyte containing NaOH, Na2SiO3 and NaCl. Centered on the correlation of composition and structure, analyses by means of X-ray diffration （XRD）, scanning electron microscope （SEM） and energy dispersive spectrometry （EDS） are conducted on the specimens, which have been PEO-treated under hybrid voltages of different direct current （DC） values （140-280 V） with constant alternate current （AC） amplitude （200 V）. Attention is paid to the composition, properties and growth mechanism of oxide layers formed with hybrid voltages. Moreover, the main effects of DC value are discussed. Ceramic layers with a double-layer structure which combines hard outer and soft inner layers are found to be consist of α-Al2O3,γ-Al2O3 and mullite. With the DC values increasing, the growth of the ceramic layers tends to have increasingly obvious three-stage feature.展开更多
The corrosion product films of two kinds of B30 tubes(similar to CDA 715)exposed to seawat- er for various periods of time were investigated by SEM,AES and XPS.The results show that the pro- tective corrosion product ...The corrosion product films of two kinds of B30 tubes(similar to CDA 715)exposed to seawat- er for various periods of time were investigated by SEM,AES and XPS.The results show that the pro- tective corrosion product film is thin,uniform and adherent.FeOOH is found to be present in the film surface,which confirms the hypothesis that iron hydroxide segregates at the surface of the film.The FeOOH promotes Ni enrichment in the corrosion layer by preventing Ni from running off.The corro- sion product film with no protectiveness is of lay- ered structure,loose and bad adherence.The for- mer film is formed through direct oxidation and the latter by precipitation and redeposition from dis- solved species.展开更多
In this study,the effects of in vivo(head flexion-extension,lateral bending,and axial rotation)and in vitro(ISO 18192-1)working conditions on the wear of ultrahigh mo-lecular weight polyethylene(UHWMPE)-based cervical...In this study,the effects of in vivo(head flexion-extension,lateral bending,and axial rotation)and in vitro(ISO 18192-1)working conditions on the wear of ultrahigh mo-lecular weight polyethylene(UHWMPE)-based cervical disc prosthesis were studied via numerical simulation.A finite-element-based wear prediction framework was built by using a sliding distance and contact area dependent Archard wear law.Moreover,a pre-developed cervical spine multi-body dynamics model was incorporated to obtain the in vivo conditions.Contact mechanic analysis stated that in vitro conditions normally led to a higher contact stress and a longer sliding distance,with oval or crossing-path-typed sliding track.In contrast,in vivo conditions led to a curvilinear-typed sliding track.In general,the predicted in vivo wear rate was one order of magnitude smaller than that of in vitro.According to the yearly occurrence of head movement,the estimated total in vivo wear rate was 0.595 mg/annual.While,the wear rate given by the ISO standard test condition was 3.32 mg/annual.There is a significant impact of loading and kinematic condition on the wear of UHMWPE prosthesis.The work conducted in the present study provided a feasible way for quantitatively assessing the wear of joint prosthesis.展开更多
基金the Ministry of Science and Innovacion&Navarra Government for FUNCOAT projectthe Ministry of Economy and Competitiveness for MoM for LIFE(MAT2011-29698-C03-02)and for providing financial support to these projects.
文摘Problems in metal-on-metal (MoM) hip replacement systems still persist due to high wear rates, low corrosion resistance and release of toxic ions and nanoparticles. As a consequence of these effects, failure, infections, loosening or bone resorption is the typical problems in the hip prosthesis. In order to reduce failure due to corrosion and/or releasing ions and particles, this study presents some works in a novel nanoscale surface modification of cobalt-chromium alloy (CoCr) for obtaining improved surface conditions in these alloys for these applications. Improving corrosion resistant of these alloys and achieving a low wear rate are possible to reduce the total released ions and particles released from the surface of this material. According to it, three different treatments using oxygen at temperatures of 300°C, 350°C and 400°C were carried out by plasma immersion ion implantation technique (PI3). X-ray diffraction (XRD) analysis shows an increase in the formation of chromium oxides in the outer surface of the CoCr alloy. It allows improving in corrosion resistant in CoCr alloys. Moreover, total quantity of released Co, Cr and Mo ions have been reduced. Wear rate studies showed a very similar behaviour after the treatments in relation to untreated CoCr alloy and release rate from the treated surface of CoCr alloys was reduced in comparison with untreated CoCr alloy.
基金Korea Research Foundation Grant (KRF-2006-005-J02703)
文摘Plasma electrolytic oxidation(PEO) processes were carried out to produce ceramic layers on 6061 aluminum substrates in four kinds of electrolytes such as silicate and aluminate solution with and without sodium fluorosilicate.The PEO processes were carried out under a hybrid voltage(260 V DC combined with 200 V,60 Hz AC amplitude) at room temperature for 5 min.The composition,microstructure and element distribution analyses of the PEO-treated layers were carried out by XRD and SEM & EDS.The effect of the electrolyte contents on the growth mechanism,element distribution and properties of oxide layers were studied.It is obvious that the layers generated in aluminate solutions show smoother surfaces than those in silicate solutions.Moreover,an addition of fluorine ion can effectively control the layer porosity;therefore,it can enhance the properties of the layers.
基金Changwon National University in 2008 and National IT Industry Program Agency(NIPA-2009-C-C1090-0903-0007)
文摘Plasma electrolytic oxidation （PEO） is carried out on 6061 Al-alloys in a weak alkaline electrolyte containing NaOH, Na2SiO3 and NaCl. Centered on the correlation of composition and structure, analyses by means of X-ray diffration （XRD）, scanning electron microscope （SEM） and energy dispersive spectrometry （EDS） are conducted on the specimens, which have been PEO-treated under hybrid voltages of different direct current （DC） values （140-280 V） with constant alternate current （AC） amplitude （200 V）. Attention is paid to the composition, properties and growth mechanism of oxide layers formed with hybrid voltages. Moreover, the main effects of DC value are discussed. Ceramic layers with a double-layer structure which combines hard outer and soft inner layers are found to be consist of α-Al2O3,γ-Al2O3 and mullite. With the DC values increasing, the growth of the ceramic layers tends to have increasingly obvious three-stage feature.
文摘The corrosion product films of two kinds of B30 tubes(similar to CDA 715)exposed to seawat- er for various periods of time were investigated by SEM,AES and XPS.The results show that the pro- tective corrosion product film is thin,uniform and adherent.FeOOH is found to be present in the film surface,which confirms the hypothesis that iron hydroxide segregates at the surface of the film.The FeOOH promotes Ni enrichment in the corrosion layer by preventing Ni from running off.The corro- sion product film with no protectiveness is of lay- ered structure,loose and bad adherence.The for- mer film is formed through direct oxidation and the latter by precipitation and redeposition from dis- solved species.
基金National Natural Science Foundation of China,Grant/Award Number:51675508Natural Science Foundation of Shaanxi Province,China,Grant/Award Number:2020JQ-728。
文摘In this study,the effects of in vivo(head flexion-extension,lateral bending,and axial rotation)and in vitro(ISO 18192-1)working conditions on the wear of ultrahigh mo-lecular weight polyethylene(UHWMPE)-based cervical disc prosthesis were studied via numerical simulation.A finite-element-based wear prediction framework was built by using a sliding distance and contact area dependent Archard wear law.Moreover,a pre-developed cervical spine multi-body dynamics model was incorporated to obtain the in vivo conditions.Contact mechanic analysis stated that in vitro conditions normally led to a higher contact stress and a longer sliding distance,with oval or crossing-path-typed sliding track.In contrast,in vivo conditions led to a curvilinear-typed sliding track.In general,the predicted in vivo wear rate was one order of magnitude smaller than that of in vitro.According to the yearly occurrence of head movement,the estimated total in vivo wear rate was 0.595 mg/annual.While,the wear rate given by the ISO standard test condition was 3.32 mg/annual.There is a significant impact of loading and kinematic condition on the wear of UHMWPE prosthesis.The work conducted in the present study provided a feasible way for quantitatively assessing the wear of joint prosthesis.
