In this article, the authors report on the use of Radio Frequency (RF) Magnetron Sputtering combined with Plasma-Based Ion Implantation (PBII) technique to synthesize the Boron-Carbon (B-C) films. High purity of boron...In this article, the authors report on the use of Radio Frequency (RF) Magnetron Sputtering combined with Plasma-Based Ion Implantation (PBII) technique to synthesize the Boron-Carbon (B-C) films. High purity of boron carbide (99.5%) disk was used as a target with an RF power of 300 W. The mixtures of Argon (Ar)-Methane (CH4) ware used as reactive gas under varying CH4 partial flow pressure at the specified range of 0 - 0.15 Pa and fixed total gas pressure and total gas flow at 0.30 Pa and 30 sccm, respectively. The effect of CH4 flow ratio on the friction coefficient of B-C films was studied. The friction coefficient of the film depended on the concentration of B. When it was 10% or lower, the coefficient decreased to 0.2 or lower. In this concentration range of B, the specific wear rate also decreased to the order of 10-7 mm3/Nm, and excellent wear resistance was displayed.展开更多
Si wafers with a 220 nm top oxide layer were sequentially implanted at room temperature with 40 keV He and 35 keV H ions at fluence of 5× 10^16/cm2 and 1× 10^16/cm2, respectively. Techniques of scanning elec...Si wafers with a 220 nm top oxide layer were sequentially implanted at room temperature with 40 keV He and 35 keV H ions at fluence of 5× 10^16/cm2 and 1× 10^16/cm2, respectively. Techniques of scanning electron microscopy, atomic force microscopy and cross-sectional transmission electron microscopy （XTEM） were used to characterize the thermal evolution of surface damage as well as defect microstructures. Surface blisters as well as the localized exfoliation （～ 0.42 μm in depth） have been observed for samples annealed at temperatures of 500 ℃ and above. XTEM observations reveal a variety of defect microstructures, including cavities, platelets, nanometer or micrometer sized cracks and dislocations. The platelets and cracks are mainly distributed at the depth of about 0.42 μm parallel to the sample surface, which are responsible for the occurrence of the observed surface features. The relations between surface damage and defect microstructures are described in detail.展开更多
室温下将40 ke V的H离子以不同剂量注入到单晶Si样品中,部分H预注入的样品又进行了190 ke V O离子注入。采用光学显微镜和透射电子显微镜分析比较了注入及退火后单晶Si样品的表面损伤以及注入层微观缺陷的形貌。光学显微镜结果表明,只...室温下将40 ke V的H离子以不同剂量注入到单晶Si样品中,部分H预注入的样品又进行了190 ke V O离子注入。采用光学显微镜和透射电子显微镜分析比较了注入及退火后单晶Si样品的表面损伤以及注入层微观缺陷的形貌。光学显微镜结果表明,只有高剂量H离子注入的单晶Si经过450℃退火后出现了表面发泡和剥离,而总剂量相同的H、O离子顺次注入单晶Si的样品没有出现任何表面损伤。透射电子显微镜结果表明,低剂量H离子注入单晶Si经过高温退火可以在样品内部形成一个由空腔构成的损伤带。附加O离子注入对损伤形貌产生了重要影响,空腔消失,损伤带由大量板状缺陷构成。展开更多
特征提取和健康状态的辨识是复杂系统健康状态评估中的关键问题。提出一种新的健康状态评估方法,该方法分为3个步骤:首先,采用经验模态分解(empirical model decomposition,EMD)和奇异值分解(singular value decomposition,SVD)来提取...特征提取和健康状态的辨识是复杂系统健康状态评估中的关键问题。提出一种新的健康状态评估方法,该方法分为3个步骤:首先,采用经验模态分解(empirical model decomposition,EMD)和奇异值分解(singular value decomposition,SVD)来提取振动信号的特征变量。然后,运用马田系统(Mahalanobis-Taguchi system,MTS)构造马氏空间,并对其进行优化,从而降低特征变量的维度。最后,提出了一种健康度(health index,HI)的概念,并且用来对复杂系统健康问题进行评估。该方法成功地应用在轴承的健康状态评估中。展开更多
文摘In this article, the authors report on the use of Radio Frequency (RF) Magnetron Sputtering combined with Plasma-Based Ion Implantation (PBII) technique to synthesize the Boron-Carbon (B-C) films. High purity of boron carbide (99.5%) disk was used as a target with an RF power of 300 W. The mixtures of Argon (Ar)-Methane (CH4) ware used as reactive gas under varying CH4 partial flow pressure at the specified range of 0 - 0.15 Pa and fixed total gas pressure and total gas flow at 0.30 Pa and 30 sccm, respectively. The effect of CH4 flow ratio on the friction coefficient of B-C films was studied. The friction coefficient of the film depended on the concentration of B. When it was 10% or lower, the coefficient decreased to 0.2 or lower. In this concentration range of B, the specific wear rate also decreased to the order of 10-7 mm3/Nm, and excellent wear resistance was displayed.
基金Supported by National Natural Science Foundation of China(10975107)Foundation of Tianjin High School Science and Technology Planning Project(20100911)
文摘Si wafers with a 220 nm top oxide layer were sequentially implanted at room temperature with 40 keV He and 35 keV H ions at fluence of 5× 10^16/cm2 and 1× 10^16/cm2, respectively. Techniques of scanning electron microscopy, atomic force microscopy and cross-sectional transmission electron microscopy （XTEM） were used to characterize the thermal evolution of surface damage as well as defect microstructures. Surface blisters as well as the localized exfoliation （～ 0.42 μm in depth） have been observed for samples annealed at temperatures of 500 ℃ and above. XTEM observations reveal a variety of defect microstructures, including cavities, platelets, nanometer or micrometer sized cracks and dislocations. The platelets and cracks are mainly distributed at the depth of about 0.42 μm parallel to the sample surface, which are responsible for the occurrence of the observed surface features. The relations between surface damage and defect microstructures are described in detail.
文摘室温下将40 ke V的H离子以不同剂量注入到单晶Si样品中,部分H预注入的样品又进行了190 ke V O离子注入。采用光学显微镜和透射电子显微镜分析比较了注入及退火后单晶Si样品的表面损伤以及注入层微观缺陷的形貌。光学显微镜结果表明,只有高剂量H离子注入的单晶Si经过450℃退火后出现了表面发泡和剥离,而总剂量相同的H、O离子顺次注入单晶Si的样品没有出现任何表面损伤。透射电子显微镜结果表明,低剂量H离子注入单晶Si经过高温退火可以在样品内部形成一个由空腔构成的损伤带。附加O离子注入对损伤形貌产生了重要影响,空腔消失,损伤带由大量板状缺陷构成。
文摘特征提取和健康状态的辨识是复杂系统健康状态评估中的关键问题。提出一种新的健康状态评估方法,该方法分为3个步骤:首先,采用经验模态分解(empirical model decomposition,EMD)和奇异值分解(singular value decomposition,SVD)来提取振动信号的特征变量。然后,运用马田系统(Mahalanobis-Taguchi system,MTS)构造马氏空间,并对其进行优化,从而降低特征变量的维度。最后,提出了一种健康度(health index,HI)的概念,并且用来对复杂系统健康问题进行评估。该方法成功地应用在轴承的健康状态评估中。
