Fracture toughness determines materials＇ resistance to fracture, which is measured often using impact or bending tests. However, it is difficult to evaluate fracture toughness of coatings and small samples.In this ar...Fracture toughness determines materials＇ resistance to fracture, which is measured often using impact or bending tests. However, it is difficult to evaluate fracture toughness of coatings and small samples.In this article, using white irons as sample materials, we explore a possible approach of using electron work function（EWF） as an indicator in evaluating fracture toughness of hard metallic materials. This parameter is promising for being utilized to analyze toughness of protective coatings and small objects as well as bulk materials. Through comparison with results obtained from impact tests and elastic modulus measurement, effectiveness of this EWF approach is demonstrated.展开更多
The work functions before and after crystallization of two glassy alloys,Pd_(83.5)Si_(16.5) and Cu_(70)Ti_(30) have been measured by means of the con- tact potential difference method in the secondary electron field a...The work functions before and after crystallization of two glassy alloys,Pd_(83.5)Si_(16.5) and Cu_(70)Ti_(30) have been measured by means of the con- tact potential difference method in the secondary electron field at room temperature under 10^(-5) Pa vacuum.The results show that the work functions of both glassy alloys are higher than those of the corresponding crystalline alloys.展开更多
Ultraviolet photoemission spectroscopy is used to investigate the electronic structure of epitaxial graphene grown by the thermal decomposition of the carbon face of 4H SiC. We find that the growth of the film on the ...Ultraviolet photoemission spectroscopy is used to investigate the electronic structure of epitaxial graphene grown by the thermal decomposition of the carbon face of 4H SiC. We find that the growth of the film on the chemical mechanically polished and hydrogen etched surface enhances spectral features in the valence band structure compared to the film grown on an unpolished hydrogen etched substrate. This result is indicative of a more highly ordered surface structure compared to the morphologically rough material and shows that substrate preparation plays an important role in the quality of the film. The work function of the smooth surface film is found to be 0.4 eV higher than that for graphite and 0.1 eV less than for the rough surface growth.展开更多
利用原子力显微镜、电化学测试、电子功函数和钝化膜接触电阻显微划擦方法研究了机械剧烈压入形变和稳定化处理对Cu30Ni合金表面梯度组织和耐腐蚀行为的影响。结果发现,对机械剧烈压入和稳定化处理的试样,表层晶粒尺寸呈梯度变化。从基...利用原子力显微镜、电化学测试、电子功函数和钝化膜接触电阻显微划擦方法研究了机械剧烈压入形变和稳定化处理对Cu30Ni合金表面梯度组织和耐腐蚀行为的影响。结果发现,对机械剧烈压入和稳定化处理的试样,表层晶粒尺寸呈梯度变化。从基体到表层,随着晶粒尺寸从40μm逐渐细化到50 nm,电子功函数从4.55 e V提高至4.85 e V,表面电子稳定性提高,钝化膜粘附性能和致密性较好,耐腐蚀性能提高,ip从1.750×10-5A/cm2逐渐降低到0.119×10-5A/cm2,而腐蚀电位EV从-212 m V提高到-193 m V,这是由于机械剧烈压入形变和稳定化处理诱发晶粒呈梯度细化和组织结构中大量结构缺陷存在。展开更多
基金financial support from the Natural Science and Engineering Research Council of CanadaCamber Technology Corporation+3 种基金Suncor Energy Inc.Shell Canada Ltd.Magna International Inc.Volant Products Inc.
文摘Fracture toughness determines materials＇ resistance to fracture, which is measured often using impact or bending tests. However, it is difficult to evaluate fracture toughness of coatings and small samples.In this article, using white irons as sample materials, we explore a possible approach of using electron work function（EWF） as an indicator in evaluating fracture toughness of hard metallic materials. This parameter is promising for being utilized to analyze toughness of protective coatings and small objects as well as bulk materials. Through comparison with results obtained from impact tests and elastic modulus measurement, effectiveness of this EWF approach is demonstrated.
文摘The work functions before and after crystallization of two glassy alloys,Pd_(83.5)Si_(16.5) and Cu_(70)Ti_(30) have been measured by means of the con- tact potential difference method in the secondary electron field at room temperature under 10^(-5) Pa vacuum.The results show that the work functions of both glassy alloys are higher than those of the corresponding crystalline alloys.
文摘Ultraviolet photoemission spectroscopy is used to investigate the electronic structure of epitaxial graphene grown by the thermal decomposition of the carbon face of 4H SiC. We find that the growth of the film on the chemical mechanically polished and hydrogen etched surface enhances spectral features in the valence band structure compared to the film grown on an unpolished hydrogen etched substrate. This result is indicative of a more highly ordered surface structure compared to the morphologically rough material and shows that substrate preparation plays an important role in the quality of the film. The work function of the smooth surface film is found to be 0.4 eV higher than that for graphite and 0.1 eV less than for the rough surface growth.
文摘利用原子力显微镜、电化学测试、电子功函数和钝化膜接触电阻显微划擦方法研究了机械剧烈压入形变和稳定化处理对Cu30Ni合金表面梯度组织和耐腐蚀行为的影响。结果发现,对机械剧烈压入和稳定化处理的试样,表层晶粒尺寸呈梯度变化。从基体到表层,随着晶粒尺寸从40μm逐渐细化到50 nm,电子功函数从4.55 e V提高至4.85 e V,表面电子稳定性提高,钝化膜粘附性能和致密性较好,耐腐蚀性能提高,ip从1.750×10-5A/cm2逐渐降低到0.119×10-5A/cm2,而腐蚀电位EV从-212 m V提高到-193 m V,这是由于机械剧烈压入形变和稳定化处理诱发晶粒呈梯度细化和组织结构中大量结构缺陷存在。
