Anodizing of AZ31 Mg alloy in NaOH solution by co-precipitation of cerium oxide was investigated.The chemical composition and phase structure of the coating film were determined via optical microscopy,SEM and XRD.The ...Anodizing of AZ31 Mg alloy in NaOH solution by co-precipitation of cerium oxide was investigated.The chemical composition and phase structure of the coating film were determined via optical microscopy,SEM and XRD.The corrosion properties of the anodic film were characterized by using potentiodynamic polarization curves in 17 mmol/L NaCl and 0.1 mol/L Na2SO4 solution at 298 K.The corrosion resistance of AZ31 magnesium alloy is significantly improved by adding cerium oxide to alkaline solution.In addition,the surface properties are enhanced and the film contains no crack.展开更多
The chemical conversion coating was formed on Mg alloy for low cost and harmlessness in environment by using the colloidal silica as the main component.The film formed at 298 K was thick,which was thought to be the co...The chemical conversion coating was formed on Mg alloy for low cost and harmlessness in environment by using the colloidal silica as the main component.The film formed at 298 K was thick,which was thought to be the combination of Si and O.In salt spray test,the ratio of black rust on the specimen that did not conducted chemical conversion treatment was five times or more than those of the chemical conversion treated specimen.The film of chemical conversion coating produced by alkali treatment process was thinner than the specimen produced in basic chemical conversion treatment solution.展开更多
The corrosion protection property and morphology of colloidal silica conversion films as an alternative to chemical conversion coating(CCC) films were examined. The corrosion behavior was investigated in 3% NaCl solut...The corrosion protection property and morphology of colloidal silica conversion films as an alternative to chemical conversion coating(CCC) films were examined. The corrosion behavior was investigated in 3% NaCl solution using electrochemical techniques. Corrosion was implied by the appearance of red rust on the specimen surface. The results show that in 3% NaCl solution, red rust appears at 15-20, 55-70, and 75-85 d on Zn-electroplated steel, colloidal silica conversion-coated specimens, and chemical conversion-coated, specimens, respectively. In the salt spray test, the colloidal silica film provides better corrosion protection than CCC film, i.e., red rust appears at 96 h on the Zn-electroplated steel sheet, at 432 h on the CCC films, and at 888 h on silica conversion coating.展开更多
Zirconium and its alloys are more suitable materials for implant surgery to be performed in a magnetic resonance imaging scanner compared with other implant materials. Although they have high anticorrosion properties ...Zirconium and its alloys are more suitable materials for implant surgery to be performed in a magnetic resonance imaging scanner compared with other implant materials. Although they have high anticorrosion properties in the body, as do titanium and its alloys, they have little use as implants in contact with bone because of their low osteoconductivity (bone-implant contact ratio). To improve the osteoconductivity of zirconium, niobium, and Zr-9Nb-3Sn alloy, we applied a single- step hydrothermal surface treatment using distilled water at a temperature of 180°C for 3 h. The hydrothermally treated samples were stored in a ×5 phosphate-buffered saline (PBS(-)) solution to keep or to improve the water contact angle (WCA), which has a strongly positive effect on osteoconductivity. The specimen surfaces were characterized using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, surface roughness, and contact angle measurement using a 2 μL droplet of distilled water. The relationship between WCA and osteoconductivity for various surface modifications was examined using in vivo tests. The results showed that a superhydrophilic surface with a WCA ≤ 10° and a high osteoconductivity of up to 40% in cortical bone, about four times higher than the as-polished Zr-9Nb-3Sn and its pure alloy elements, was provided by the combination of hydrothermal surface treatment and storage in ×5 PBS(-).展开更多
The relatively uniform bismuth-copper film was electrodeposited between -15 and -20 mV in the sulfate electrolyte containing 4 mmol/L bismuth ion and 2 mmol/L copper ion.Only copper was electrodeposited at -5 mV.The d...The relatively uniform bismuth-copper film was electrodeposited between -15 and -20 mV in the sulfate electrolyte containing 4 mmol/L bismuth ion and 2 mmol/L copper ion.Only copper was electrodeposited at -5 mV.The dendritic bismuth-copper film was electrodeposited under -20 mV.The cathodic current became constant between -20 and -400 mV.Therefore,bismuth-copper electrodeposition changes from charge transfer controlling to diffusion controlling at -20 mV.On the other hand,the uniform bismuth-copper film was electrodeposited between -5 and -35 mV in the methanesulfonate electrolyte containing 4 mmol/L bismuth ion and 2 mmol/L copper ion.The dendritic bismuth-copper film was electrodeposited under -35 mV.The potential region for good electrodepositon in methanesulfonate electrolyte is wider than that in sulfate electrolyte.Therefore,it is easy to control electrodeposition conditions by using methanesulfonate electrolyte.展开更多
Most reports on the fabrication of high-quality Gallium nitride (GaN) are typically based on physical techniques that require very expensive equipment. Therefore, the electrodeposition was adopted and examined to deve...Most reports on the fabrication of high-quality Gallium nitride (GaN) are typically based on physical techniques that require very expensive equipment. Therefore, the electrodeposition was adopted and examined to develop a simple and economical method for GaN synthesis. GaN films are synthesized on aluminum substrates that are heat-treated at various temperatures using a low-cost and low-temperature electrochemical deposition technique. The electrochemical behavior of source ions in aqueous solutions is examined by cyclic voltammetry (CV).?In the solution at pH 1.5 containing 0.1M Ga(NO3)3, 2.5 M NH4NO3 and 0.6 M H3BO3, reduction of gallium and nitrate ions are observed in CV. The presence of hexagonal GaN and gallium oxide (Ga2O3) phases is detected for the films deposited on Al substrates at -3.5 mA•cm-2 for 3 h. The energy dispersive X-ray and mapping results reveal that Ga, O, and N coexist in these films. Raman analysis shows hexagonal GaN formation on Al substrates. The changes in the morphology and preferred orientation of GaN were found, which was caused by the reactivity of aluminum surface and the aluminum oxide layer formed by the heat treatment.展开更多
Surface hydrophilicity is considered to have a strong influence on the biological reactions of bone-substituting materials. However, the influence of a hydrophilic surface on osteoconductivity is not completely clear,...Surface hydrophilicity is considered to have a strong influence on the biological reactions of bone-substituting materials. However, the influence of a hydrophilic surface on osteoconductivity is not completely clear, especially for superhydrophilic surfaces. In this study, we conferred superhydrophilic properties on anodized TiO2 coatings using a hydrothermal treatment, and developed a method to maintain this surface until implantation. The osteoconductivity of these coatings was evaluated with in vivo tests. A hydrothermal treatment made the surface of as-anodized samples more hydrophilic, up to a water contact angle of 13 (deg.). Storage in both air and distilled water increased the water contact angle after several days because of the adsorption of hydrocarbon. However, storage in phosphate buffered solution led to a reduction in the water contact angle, because of the adsorption of the inorganic ions in the solution, and the sample retained its high hydrophilicity for a long time. As the water contact angle decreased, the hard tissue formation ratio increased continuously up to 58%, which was about four times higher than the hard tissue formation ratio on as-polished Ti.展开更多
Surface properties of Ti implants (especially surface hydrophilicity) influence biological responses at the interface between the bone tissue and the implant. However, only a little research reported the effect of sur...Surface properties of Ti implants (especially surface hydrophilicity) influence biological responses at the interface between the bone tissue and the implant. However, only a little research reported the effect of surface hydrophilicity on osteoconductivity by in vivo test. We have investigated the surface characteristics and osteoconductivity of titanium implant produced by hydrothermal treatment using distilled water at temperature of 180°C for 3 h, and compared with as-polished and those of implants produced by anodizing in 0.1 M H2SO4 with applied voltage from 0 V to 100 V at 0.1 Vsˉ1 and anodizing followed by hydrothermal treatment. The relationship between hydrophilic surface and osteoconductivity in various surface modifications was examined by in vivo test. In order to maintain the hydrophilicity of the hydrothermal sample surface, it was kept in to the phosphate buffered saline solution (PBS) with 5 times concentration: 5PBS(-) in room temperature. The surface characteristics were evaluated by scanning electron microscopy, XRD, X-ray photoelectron spectroscopy, surface roughness and contact angle measurement using a 2 μL droplet of distilled water. In in vivo testing, the rod samples (Φ2 × 5 mm) were implanted in male rat’s tibiae for 14 days and the bone-implant contact ratio, RB-I, was used to evaluate the osteoconductivity in the cortical and cancellous bone parts, respectively. As a result, hydrothermal treatment without anodizing still produced a smooth surface like an initial surface roughness of as-polished samples, Ra/μm B-I = 50% in cortical bone part (about four times higher than as-polished Ti) were provided by only hydrothermal process without anodizing after immersing into 5PBS(-).展开更多
Anodizing is expected to be an effective method to improve the osteoconductivity of the Ti-29Nb-13Ta-4.6Zr (TNTZ) alloy because the bioactivity of anodized Ti is good. However, it is not known how the alloy elements i...Anodizing is expected to be an effective method to improve the osteoconductivity of the Ti-29Nb-13Ta-4.6Zr (TNTZ) alloy because the bioactivity of anodized Ti is good. However, it is not known how the alloy elements influence the surface roughness, composition, hydrophilicity, and osteoconductivity of the anodized film on the Ti alloy. In this study, we investigated the effects of anodizing on the surface properties and the osteoconductivity of the anodized TNTZ alloy, focusing on the functions of the individual alloy elements. The anodized oxides of the Nb, Ta, and Zr metals were hydrophobic at all the voltages applied, in contrast to the anodized oxide of Ti. As well as pure Ti, a TiO2-based oxide film formed on TNTZ after anodizing. However, the oxide film also contained large amounts of Nb species and the molar Nb/Ti ratio in the TNTZ alloy was high, which makes the surface more hydrophobic than the anodized oxide on Ti. In vivo tests showed that the osteoconductivity of the TNTZ alloy was sensitive to both its surface roughness and hydrophilicity. When the TNTZ alloy was anodized, the process increased either the surface hydrophobicity or the surface roughness at the voltage used in this study. These changes in the surface properties did not improve its osteoconductivity.展开更多
The influence of LiCl coexistence with Al electrodeposition was investigated in a dimethyl sulfone, DMSO2, bath containing AlCl3 at 403 K. The electrochemical behaviors of Li and Al ions were examined using Pt electro...The influence of LiCl coexistence with Al electrodeposition was investigated in a dimethyl sulfone, DMSO2, bath containing AlCl3 at 403 K. The electrochemical behaviors of Li and Al ions were examined using Pt electrodes in the bath and the deposition mechanism was analyzed by cyclic voltammetry, CV, with an Al reference electrode in the bath. The coexistence of LiCl in the AlCl3-DMSO2 bath inhibited the cathodic current corresponding to Al deposition in the CV experiment. The amount of ca. 500 μmol Al deposits was obtained in constant potential electrolysis for 1 h at –2 V in the bath with 10 mol% AlCl3. However, it decreased to 140 μmol Al in the bath with 10 mol% AlCl3 and 5 mol% LiCl. It was clarified that LiCl addition led to the formation of Li(DMSO2)+ more than the formation of ?from NMR measurement for the baths. This results in the suppression of Al deposition because LiCl inhibits the formation of complex ions, which is said to be necessary for Al electrodeposition.展开更多
Metallic materials, such as Ti, Zr, Nb, Ta, and their alloys, and also stainless steels are widely attractive as osteoconductive materials in the dental and orthopedic fields. Ceramics and polymers are also commonly u...Metallic materials, such as Ti, Zr, Nb, Ta, and their alloys, and also stainless steels are widely attractive as osteoconductive materials in the dental and orthopedic fields. Ceramics and polymers are also commonly used as biomaterials. However, they do not have high osteoconductivity in their pure form, and surface coatings with bioactive substances, such as hydroxyapatite or TiO2, are needed before implantation into the bone. Many reports claim that the surface chemical properties of implants, in particular, hydrophilicity and hydrophobicity, strongly affect the biological reactions. However, the effect of surface properties on osteoconductivity is not clear. In this review, we focus on the relationship between the surface hydrophilicity of metallic implants and osteoconductivity using in vivo evaluation, and the control of the osteoconductivity is discussed from the viewpoint of protein adsorption in implants.展开更多
Polyetheretherketone (PEEK) is known as one of the “super-engineering plastics” and is used as an intervertebral disk spacer in the body. PEEK has a hydrophobic surface (water contact angle (WCA) > 80°) and ...Polyetheretherketone (PEEK) is known as one of the “super-engineering plastics” and is used as an intervertebral disk spacer in the body. PEEK has a hydrophobic surface (water contact angle (WCA) > 80°) and high chemical resistance, and it is thus difficult to perform any surface treatment, such as hydrophilization. In this study, we aimed to form a hydrophilic surface on PEEK without coating layers by using hydroprocessing (aqueous solution processing), and we examined the osteoconductivity and anti-inflammatory properties of surface-treated PEEK in vivo compared with Ti implants. The WCA value of PEEK reached ~20° using a combination of immersion in a solution of >16.2 M H2SO4 and ultraviolet irradiation (172 nm). In in vivo testing, the hydrophilization of PEEK by surface modification without a coating layer improved the osteoconductivity and anti-inflammatory properties. The relationship between the bone-implant contact ratio and the WCA values of the surface-modified PEEK agreed well with that of the surface-treated Ti.展开更多
文摘Anodizing of AZ31 Mg alloy in NaOH solution by co-precipitation of cerium oxide was investigated.The chemical composition and phase structure of the coating film were determined via optical microscopy,SEM and XRD.The corrosion properties of the anodic film were characterized by using potentiodynamic polarization curves in 17 mmol/L NaCl and 0.1 mol/L Na2SO4 solution at 298 K.The corrosion resistance of AZ31 magnesium alloy is significantly improved by adding cerium oxide to alkaline solution.In addition,the surface properties are enhanced and the film contains no crack.
文摘The chemical conversion coating was formed on Mg alloy for low cost and harmlessness in environment by using the colloidal silica as the main component.The film formed at 298 K was thick,which was thought to be the combination of Si and O.In salt spray test,the ratio of black rust on the specimen that did not conducted chemical conversion treatment was five times or more than those of the chemical conversion treated specimen.The film of chemical conversion coating produced by alkali treatment process was thinner than the specimen produced in basic chemical conversion treatment solution.
文摘The corrosion protection property and morphology of colloidal silica conversion films as an alternative to chemical conversion coating(CCC) films were examined. The corrosion behavior was investigated in 3% NaCl solution using electrochemical techniques. Corrosion was implied by the appearance of red rust on the specimen surface. The results show that in 3% NaCl solution, red rust appears at 15-20, 55-70, and 75-85 d on Zn-electroplated steel, colloidal silica conversion-coated specimens, and chemical conversion-coated, specimens, respectively. In the salt spray test, the colloidal silica film provides better corrosion protection than CCC film, i.e., red rust appears at 96 h on the Zn-electroplated steel sheet, at 432 h on the CCC films, and at 888 h on silica conversion coating.
文摘Zirconium and its alloys are more suitable materials for implant surgery to be performed in a magnetic resonance imaging scanner compared with other implant materials. Although they have high anticorrosion properties in the body, as do titanium and its alloys, they have little use as implants in contact with bone because of their low osteoconductivity (bone-implant contact ratio). To improve the osteoconductivity of zirconium, niobium, and Zr-9Nb-3Sn alloy, we applied a single- step hydrothermal surface treatment using distilled water at a temperature of 180°C for 3 h. The hydrothermally treated samples were stored in a ×5 phosphate-buffered saline (PBS(-)) solution to keep or to improve the water contact angle (WCA), which has a strongly positive effect on osteoconductivity. The specimen surfaces were characterized using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, surface roughness, and contact angle measurement using a 2 μL droplet of distilled water. The relationship between WCA and osteoconductivity for various surface modifications was examined using in vivo tests. The results showed that a superhydrophilic surface with a WCA ≤ 10° and a high osteoconductivity of up to 40% in cortical bone, about four times higher than the as-polished Zr-9Nb-3Sn and its pure alloy elements, was provided by the combination of hydrothermal surface treatment and storage in ×5 PBS(-).
文摘The relatively uniform bismuth-copper film was electrodeposited between -15 and -20 mV in the sulfate electrolyte containing 4 mmol/L bismuth ion and 2 mmol/L copper ion.Only copper was electrodeposited at -5 mV.The dendritic bismuth-copper film was electrodeposited under -20 mV.The cathodic current became constant between -20 and -400 mV.Therefore,bismuth-copper electrodeposition changes from charge transfer controlling to diffusion controlling at -20 mV.On the other hand,the uniform bismuth-copper film was electrodeposited between -5 and -35 mV in the methanesulfonate electrolyte containing 4 mmol/L bismuth ion and 2 mmol/L copper ion.The dendritic bismuth-copper film was electrodeposited under -35 mV.The potential region for good electrodepositon in methanesulfonate electrolyte is wider than that in sulfate electrolyte.Therefore,it is easy to control electrodeposition conditions by using methanesulfonate electrolyte.
文摘Most reports on the fabrication of high-quality Gallium nitride (GaN) are typically based on physical techniques that require very expensive equipment. Therefore, the electrodeposition was adopted and examined to develop a simple and economical method for GaN synthesis. GaN films are synthesized on aluminum substrates that are heat-treated at various temperatures using a low-cost and low-temperature electrochemical deposition technique. The electrochemical behavior of source ions in aqueous solutions is examined by cyclic voltammetry (CV).?In the solution at pH 1.5 containing 0.1M Ga(NO3)3, 2.5 M NH4NO3 and 0.6 M H3BO3, reduction of gallium and nitrate ions are observed in CV. The presence of hexagonal GaN and gallium oxide (Ga2O3) phases is detected for the films deposited on Al substrates at -3.5 mA•cm-2 for 3 h. The energy dispersive X-ray and mapping results reveal that Ga, O, and N coexist in these films. Raman analysis shows hexagonal GaN formation on Al substrates. The changes in the morphology and preferred orientation of GaN were found, which was caused by the reactivity of aluminum surface and the aluminum oxide layer formed by the heat treatment.
文摘Surface hydrophilicity is considered to have a strong influence on the biological reactions of bone-substituting materials. However, the influence of a hydrophilic surface on osteoconductivity is not completely clear, especially for superhydrophilic surfaces. In this study, we conferred superhydrophilic properties on anodized TiO2 coatings using a hydrothermal treatment, and developed a method to maintain this surface until implantation. The osteoconductivity of these coatings was evaluated with in vivo tests. A hydrothermal treatment made the surface of as-anodized samples more hydrophilic, up to a water contact angle of 13 (deg.). Storage in both air and distilled water increased the water contact angle after several days because of the adsorption of hydrocarbon. However, storage in phosphate buffered solution led to a reduction in the water contact angle, because of the adsorption of the inorganic ions in the solution, and the sample retained its high hydrophilicity for a long time. As the water contact angle decreased, the hard tissue formation ratio increased continuously up to 58%, which was about four times higher than the hard tissue formation ratio on as-polished Ti.
文摘Surface properties of Ti implants (especially surface hydrophilicity) influence biological responses at the interface between the bone tissue and the implant. However, only a little research reported the effect of surface hydrophilicity on osteoconductivity by in vivo test. We have investigated the surface characteristics and osteoconductivity of titanium implant produced by hydrothermal treatment using distilled water at temperature of 180°C for 3 h, and compared with as-polished and those of implants produced by anodizing in 0.1 M H2SO4 with applied voltage from 0 V to 100 V at 0.1 Vsˉ1 and anodizing followed by hydrothermal treatment. The relationship between hydrophilic surface and osteoconductivity in various surface modifications was examined by in vivo test. In order to maintain the hydrophilicity of the hydrothermal sample surface, it was kept in to the phosphate buffered saline solution (PBS) with 5 times concentration: 5PBS(-) in room temperature. The surface characteristics were evaluated by scanning electron microscopy, XRD, X-ray photoelectron spectroscopy, surface roughness and contact angle measurement using a 2 μL droplet of distilled water. In in vivo testing, the rod samples (Φ2 × 5 mm) were implanted in male rat’s tibiae for 14 days and the bone-implant contact ratio, RB-I, was used to evaluate the osteoconductivity in the cortical and cancellous bone parts, respectively. As a result, hydrothermal treatment without anodizing still produced a smooth surface like an initial surface roughness of as-polished samples, Ra/μm B-I = 50% in cortical bone part (about four times higher than as-polished Ti) were provided by only hydrothermal process without anodizing after immersing into 5PBS(-).
文摘Anodizing is expected to be an effective method to improve the osteoconductivity of the Ti-29Nb-13Ta-4.6Zr (TNTZ) alloy because the bioactivity of anodized Ti is good. However, it is not known how the alloy elements influence the surface roughness, composition, hydrophilicity, and osteoconductivity of the anodized film on the Ti alloy. In this study, we investigated the effects of anodizing on the surface properties and the osteoconductivity of the anodized TNTZ alloy, focusing on the functions of the individual alloy elements. The anodized oxides of the Nb, Ta, and Zr metals were hydrophobic at all the voltages applied, in contrast to the anodized oxide of Ti. As well as pure Ti, a TiO2-based oxide film formed on TNTZ after anodizing. However, the oxide film also contained large amounts of Nb species and the molar Nb/Ti ratio in the TNTZ alloy was high, which makes the surface more hydrophobic than the anodized oxide on Ti. In vivo tests showed that the osteoconductivity of the TNTZ alloy was sensitive to both its surface roughness and hydrophilicity. When the TNTZ alloy was anodized, the process increased either the surface hydrophobicity or the surface roughness at the voltage used in this study. These changes in the surface properties did not improve its osteoconductivity.
文摘The influence of LiCl coexistence with Al electrodeposition was investigated in a dimethyl sulfone, DMSO2, bath containing AlCl3 at 403 K. The electrochemical behaviors of Li and Al ions were examined using Pt electrodes in the bath and the deposition mechanism was analyzed by cyclic voltammetry, CV, with an Al reference electrode in the bath. The coexistence of LiCl in the AlCl3-DMSO2 bath inhibited the cathodic current corresponding to Al deposition in the CV experiment. The amount of ca. 500 μmol Al deposits was obtained in constant potential electrolysis for 1 h at –2 V in the bath with 10 mol% AlCl3. However, it decreased to 140 μmol Al in the bath with 10 mol% AlCl3 and 5 mol% LiCl. It was clarified that LiCl addition led to the formation of Li(DMSO2)+ more than the formation of ?from NMR measurement for the baths. This results in the suppression of Al deposition because LiCl inhibits the formation of complex ions, which is said to be necessary for Al electrodeposition.
文摘Metallic materials, such as Ti, Zr, Nb, Ta, and their alloys, and also stainless steels are widely attractive as osteoconductive materials in the dental and orthopedic fields. Ceramics and polymers are also commonly used as biomaterials. However, they do not have high osteoconductivity in their pure form, and surface coatings with bioactive substances, such as hydroxyapatite or TiO2, are needed before implantation into the bone. Many reports claim that the surface chemical properties of implants, in particular, hydrophilicity and hydrophobicity, strongly affect the biological reactions. However, the effect of surface properties on osteoconductivity is not clear. In this review, we focus on the relationship between the surface hydrophilicity of metallic implants and osteoconductivity using in vivo evaluation, and the control of the osteoconductivity is discussed from the viewpoint of protein adsorption in implants.
文摘Polyetheretherketone (PEEK) is known as one of the “super-engineering plastics” and is used as an intervertebral disk spacer in the body. PEEK has a hydrophobic surface (water contact angle (WCA) > 80°) and high chemical resistance, and it is thus difficult to perform any surface treatment, such as hydrophilization. In this study, we aimed to form a hydrophilic surface on PEEK without coating layers by using hydroprocessing (aqueous solution processing), and we examined the osteoconductivity and anti-inflammatory properties of surface-treated PEEK in vivo compared with Ti implants. The WCA value of PEEK reached ~20° using a combination of immersion in a solution of >16.2 M H2SO4 and ultraviolet irradiation (172 nm). In in vivo testing, the hydrophilization of PEEK by surface modification without a coating layer improved the osteoconductivity and anti-inflammatory properties. The relationship between the bone-implant contact ratio and the WCA values of the surface-modified PEEK agreed well with that of the surface-treated Ti.
