We have prepared polyion complex （PIC） hydrogel consisting of poly（3-（methacryloylami no）propyl-trimethylamonium chloride） and poly（sodium p-styrenesulfonate） polyelectrolytes via a two-step polymerization pro...We have prepared polyion complex （PIC） hydrogel consisting of poly（3-（methacryloylami no）propyl-trimethylamonium chloride） and poly（sodium p-styrenesulfonate） polyelectrolytes via a two-step polymerization procedure and have investigated specific ion effects on the self- healing of the PIC hydrogel. Our study demonstrates that the mechanical properties of the PIC hydrogel are strongly dependent on the type of the ions doped in the hydrogel. The ion-specific effects can be used to modulate the self-healing efficiency of the PIC hydrogel. As the doped anions change from kosmotrops to chaotropes, the self-healing efficiency of the PIC hydrogel increases. A more chaotropic anion has a stronger ability to break the ionic bonds formed within the hydrogel, leading to a higher efficiency during the healing.展开更多
Electroless nickel (copper)-phosphorus-silicon carbide (SiC)-polytetrafluoroethylene (PTFE) composite coatings were prepared by adding SiC and PTFE into electroless nickel (copper)-phosphorus alloy baths. The effects ...Electroless nickel (copper)-phosphorus-silicon carbide (SiC)-polytetrafluoroethylene (PTFE) composite coatings were prepared by adding SiC and PTFE into electroless nickel (copper)-phosphorus alloy baths. The effects of addition of SiC and PTFE on depositing rate, microhardness, wear resistance and anti-friction of the resulted composite coatings were studied. The results indicated that electroless nickel (copper)-phosphorus alloy coatings were greatly improved in depositing rate, microhardness, wear resistance and antifriction by co-deposited proper amount of SiC and PTFE.展开更多
Feo.eCoo.^seHfTBsCu! nanocrystalline alloy obtained in isothermal annealing process from amorphous precursor was investigated as candidate of soft magnetic materials for high temperature applications. Co substitution ...Feo.eCoo.^seHfTBsCu! nanocrystalline alloy obtained in isothermal annealing process from amorphous precursor was investigated as candidate of soft magnetic materials for high temperature applications. Co substitution for Fe can enhance the curie temperature of amorphous alloy (Tc = 630 °C) and improve the magnetization of nanocrystalline alloy at high temperature ( = 1.56T at 550 °C). After annealing amorphous precursor at 550 °C for 1 hour, the optimum nanocrystalline alloy can be obtained which shows the local minimum coercivity ( = 16 A/m). The coercivity increases with the increase of annealing temperature corresponding to the formation of ferromagnetic phase in the secondary crystallization. Furthermore, additions of Hf and B elements reduce the melting temperature of the alloy studied comparing with the Fe-Co binary alloy.展开更多
The acicular ferrite in austempered ductile iron (ADI) matrix around graphite wascorroded preferentially in wet condition, promoting crack origination and propagationand resulting in the disappearance of ADI fatigue l...The acicular ferrite in austempered ductile iron (ADI) matrix around graphite wascorroded preferentially in wet condition, promoting crack origination and propagationand resulting in the disappearance of ADI fatigue limit. ADI fatigue strength wasgradually reduced with increasing the time of test and was reduced by 50% in wetcondition at 10~7 cycles compared with the fatigue limit in dry condition. The fativiprength variation of ferritic ductile iron in wet condition was similar to that of ADI.The ferritic ductile iron, however, has better corrosion resistance so that the fativiprength was lowered only by 10% in wet condition at 10~7 cycles compared with thefatigue limit in dry condition. On the other hand, the fatigue limits of ADI and ferriticductile iron were dropped by 32% and 25% in tap water dipping 480h/dry conditionrespectively compared with those in dry condition. The reduction of fatigue limit wasattributed to corrosion pits formation correlated with stress concentration, resultingin origination and propagation of fatigue crack.展开更多
Micro-properties of the oxide scale and near-surface zone of a type 316 steel annealed in air and vacuum have been systematically investigated. Microstructures of the specimens have been examined using optical microsc...Micro-properties of the oxide scale and near-surface zone of a type 316 steel annealed in air and vacuum have been systematically investigated. Microstructures of the specimens have been examined using optical microscopy and scanning and transmission electron microscopy (TEM). Chemical compositions for the oxide scale and near surface zone were also analysed. The results obtained show that the oxide scale developed in vacuum exhibits a distinct structure from that developed in air. Comparing to the vacuum-developed scale, the air-developed scale possesses a more complicated structure and relatively poor adhesion to the matrix. TEM observations reveal a difference in the dislocation density in the vicinity of the free surface, near-surface zone and the core of the specimens examined.展开更多
Nanosized palladium particles were incorporated into mesoporous silica matrix to obtain nanocomposites using the sol-gel technique. Effects of the finely dispersed metallic palladium on the microstructure and properti...Nanosized palladium particles were incorporated into mesoporous silica matrix to obtain nanocomposites using the sol-gel technique. Effects of the finely dispersed metallic palladium on the microstructure and properties of the nanocomposites were investigated. By means of X-ray diffraction and optical absorption, it was found that palladium particles were 5~9 nm in diameter and their uniform dispersion in the mesoporous silica depended on both the content of the palladium and the structural features of the silica matrix. The results showed that the mixing method of preparation led to wider size distribution of the nanosized particles as compared to the immersion method, but dispersed degree was reduced. Although the incorporation of nanosized palladium particles could not substantially induce significant structural changes of the matrix, the apparent red-shifted optical absorptions for the nanocomposites were observed as compared to the parent monolithic silica, particularly with increase in palladium loading and calcination temperature.展开更多
This paper presents the preparation of ultrafine powders of Fe3O4 and Ni by a chemical method, followed by mixing the prepared powders with mica and other ultrafine powders for synthesizing microwave absorption coatin...This paper presents the preparation of ultrafine powders of Fe3O4 and Ni by a chemical method, followed by mixing the prepared powders with mica and other ultrafine powders for synthesizing microwave absorption coatings. The microwave attenuation rate of the coatings was measured by the Microwave Network Analyzer in the frequency range of 8-12 GHz at room temperature. The results indicate that microwave could be absorbed by the coatings with an effectiveness strongly dependent on the powder sort and content and the coating thickness.展开更多
文摘We have prepared polyion complex （PIC） hydrogel consisting of poly（3-（methacryloylami no）propyl-trimethylamonium chloride） and poly（sodium p-styrenesulfonate） polyelectrolytes via a two-step polymerization procedure and have investigated specific ion effects on the self- healing of the PIC hydrogel. Our study demonstrates that the mechanical properties of the PIC hydrogel are strongly dependent on the type of the ions doped in the hydrogel. The ion-specific effects can be used to modulate the self-healing efficiency of the PIC hydrogel. As the doped anions change from kosmotrops to chaotropes, the self-healing efficiency of the PIC hydrogel increases. A more chaotropic anion has a stronger ability to break the ionic bonds formed within the hydrogel, leading to a higher efficiency during the healing.
文摘Electroless nickel (copper)-phosphorus-silicon carbide (SiC)-polytetrafluoroethylene (PTFE) composite coatings were prepared by adding SiC and PTFE into electroless nickel (copper)-phosphorus alloy baths. The effects of addition of SiC and PTFE on depositing rate, microhardness, wear resistance and anti-friction of the resulted composite coatings were studied. The results indicated that electroless nickel (copper)-phosphorus alloy coatings were greatly improved in depositing rate, microhardness, wear resistance and antifriction by co-deposited proper amount of SiC and PTFE.
基金supported by the 5^(th)framework Program of European Community,research project“Soft Magnetic.Nanomaterials for High Temperature and High Frequency Functional Application in Power Electronics",contract No.GSRD-CT-2001-03009.the key project of National Natural Science Foundation of China(50235030).
文摘Feo.eCoo.^seHfTBsCu! nanocrystalline alloy obtained in isothermal annealing process from amorphous precursor was investigated as candidate of soft magnetic materials for high temperature applications. Co substitution for Fe can enhance the curie temperature of amorphous alloy (Tc = 630 °C) and improve the magnetization of nanocrystalline alloy at high temperature ( = 1.56T at 550 °C). After annealing amorphous precursor at 550 °C for 1 hour, the optimum nanocrystalline alloy can be obtained which shows the local minimum coercivity ( = 16 A/m). The coercivity increases with the increase of annealing temperature corresponding to the formation of ferromagnetic phase in the secondary crystallization. Furthermore, additions of Hf and B elements reduce the melting temperature of the alloy studied comparing with the Fe-Co binary alloy.
基金supported by the Postdoctoral Science Foundation of China
文摘The acicular ferrite in austempered ductile iron (ADI) matrix around graphite wascorroded preferentially in wet condition, promoting crack origination and propagationand resulting in the disappearance of ADI fatigue limit. ADI fatigue strength wasgradually reduced with increasing the time of test and was reduced by 50% in wetcondition at 10~7 cycles compared with the fatigue limit in dry condition. The fativiprength variation of ferritic ductile iron in wet condition was similar to that of ADI.The ferritic ductile iron, however, has better corrosion resistance so that the fativiprength was lowered only by 10% in wet condition at 10~7 cycles compared with thefatigue limit in dry condition. On the other hand, the fatigue limits of ADI and ferriticductile iron were dropped by 32% and 25% in tap water dipping 480h/dry conditionrespectively compared with those in dry condition. The reduction of fatigue limit wasattributed to corrosion pits formation correlated with stress concentration, resultingin origination and propagation of fatigue crack.
文摘Micro-properties of the oxide scale and near-surface zone of a type 316 steel annealed in air and vacuum have been systematically investigated. Microstructures of the specimens have been examined using optical microscopy and scanning and transmission electron microscopy (TEM). Chemical compositions for the oxide scale and near surface zone were also analysed. The results obtained show that the oxide scale developed in vacuum exhibits a distinct structure from that developed in air. Comparing to the vacuum-developed scale, the air-developed scale possesses a more complicated structure and relatively poor adhesion to the matrix. TEM observations reveal a difference in the dislocation density in the vicinity of the free surface, near-surface zone and the core of the specimens examined.
文摘Nanosized palladium particles were incorporated into mesoporous silica matrix to obtain nanocomposites using the sol-gel technique. Effects of the finely dispersed metallic palladium on the microstructure and properties of the nanocomposites were investigated. By means of X-ray diffraction and optical absorption, it was found that palladium particles were 5~9 nm in diameter and their uniform dispersion in the mesoporous silica depended on both the content of the palladium and the structural features of the silica matrix. The results showed that the mixing method of preparation led to wider size distribution of the nanosized particles as compared to the immersion method, but dispersed degree was reduced. Although the incorporation of nanosized palladium particles could not substantially induce significant structural changes of the matrix, the apparent red-shifted optical absorptions for the nanocomposites were observed as compared to the parent monolithic silica, particularly with increase in palladium loading and calcination temperature.
文摘This paper presents the preparation of ultrafine powders of Fe3O4 and Ni by a chemical method, followed by mixing the prepared powders with mica and other ultrafine powders for synthesizing microwave absorption coatings. The microwave attenuation rate of the coatings was measured by the Microwave Network Analyzer in the frequency range of 8-12 GHz at room temperature. The results indicate that microwave could be absorbed by the coatings with an effectiveness strongly dependent on the powder sort and content and the coating thickness.
