Effects of Ausforming Procedure and Following Annealing Treatment on Microstructural Characteristics in Cobalt

The effects of ausforming procedure and subsequent annealing treatments on microstructures of cobalt(Co)samples are investigated by electron channeling contrast and electron backscatter diffraction techniques. Results show that the ausformed Co samples consist of coarsen blocky laths(single ε phase) with the irregular morphology and the ultra-fine acicular laths(dual phase: γ and ε) with the slender and rectangular morphologies. As compared to the slight reduction sample, the much denser acicular laths are observed in the heavily ausformed sample. In addition, recrystallization behavior and annealing-induced γ→ε transformation have occurred in ausformed Co samples during the annealing treatment.     

Utilization of excess corn kernels for hydrogen gas biofuel production

Corn kernels are good candidates for production of various value-added products such as gas biofuel, hydrogen due to the carbohydrate-rich composition. In this study, widely grown corn, field corn kernels were dissolved in subcritical water at different temperatures to determine optimal thermal hydrolysis condition. Organic-rich hydrolysate obtained from hydrolysis process was gasified by aqueous-phase reforming (APR) for hydrogen gas production.Since hydrolysis at 200 °C resulted in significantly more total organic carbon release than other temperatures and the lowest amount of insolubilized solid residue. Different concentrations of this hydrolysate (diluted with water at different ratios) were evaluated for high yielding hydrogen gas production. Gasification performance of corn kernels was also compared with lignocellulosic biomass using corn stover as a representative biomass material.The hydrolysate with 2486 mg/L TOC concentration showed the best performance for hydrogen gas production (130 mL H₂/g corn) and left less amount of ungasified solid residue. Corn kernels produced 2.3 times more hydrogen gas compared to corn stover biomass. Thus, corn kernels are promising feed materials for APR process, and excess production of corn can be utilized for hydrogen gas production in higher yield and richer composition.     

Canada to move out of Kyoto agreement…

The Canadian government, under pressure from energy producers worried about the costs of the Kyoto climate change protocol, has given a clear sign that it might not ratify the Kyoto treaty.     

Formation of a novel nanocrystalline coating on AZ31 magnesium alloy by bias sputtering

A novel protective coating was deposited on AZ31 magnesium alloy by bias sputtering with a Ti/Al composite target in this study. It was determined by the analysis of EDS and XRD that the coating was mainly composed of Ti₃Al phase. The calculation, based on the Scherrer formula, further revealed the formation of nanocrystalline structure in the coating. SEM and AFM observations showed that the coating was compact and no obvious columnar structure occurred. In corrosion tests, it was found that the coating was more cathodic than the AZ31 substrate and had a good corrosion resistance in a 3.5 wt.% NaCl solution. Accordingly, the AZ31 substrate was protected by this obtained coating.     

激光熔覆原位生长TiB2/TiC增强铁基涂层组织及性能

目的 采用激光熔覆技术在45钢表面制备原位生长的TiB₂、TiC陶瓷相,以提高铁基涂层的耐磨性能。方法 利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和能谱仪(EDS)研究铁基复合涂层的相组织、显微组织。使用显微硬度计、磨损实验机等仪器进行显微硬度和耐磨性的测试。结果 在铁基粉末中添加Ti、B₄C后,涂层原位生长出均匀分布的TiB₂、TiC陶瓷相,其数量随着(Ti+B₄C)添加量的增加而增多。经过扫描电镜结合EDS判定TiB₂多呈矩形形貌,TiC呈球形或花瓣状。在原位生长过程中,TiB₂优先形成,而TiC多依附在TiB₂周围,以颗粒状存在。铁基复合涂层的显微硬度随着(Ti+B₄C)添加量的增加逐级增加,质量分数为30%的(Ti+B₄C)复合涂层的硬度最高(1 086HV0.2),比铁基涂层(611HV0.2)的硬度提高了约0.78倍。复合涂层的磨损性能得到明显改善,其中质量分数为...     

沉积偏压对MoN涂层结构和柴油中摩擦学性能的影响

目的 研究沉积偏压对MoN涂层微观结构、性能,以及在柴油介质中摩擦学行为的影响机制。方法 采用磁控溅射技术在304不锈钢基体上沉积MoN涂层。利用X射线衍射仪、X射线光电子能谱仪、X射线能谱仪、原子力显微镜、纳米压痕仪、薄膜应力测试仪和电化学工作站研究MoN涂层的微观结构、成分、表面粗糙度、力学性能、耐腐蚀性能。利用球−盘式摩擦实验机和激光拉曼光谱仪对MoN涂层在0号柴油中的摩擦学行为及机制进行研究。结果 随着偏压的增加,涂层的厚度和膜−基结合力均呈先增大后减小的趋势;涂层的表面粗糙度、内应力和硬度呈先升高后降低的趋势。在偏压为−120 V时,沉积的γ-Mo2N涂层组织致密、表面光滑(Sa 7.78 nm)、硬度高(18.02 GPa)、膜−基结合力高(253 mN)。随着偏压的增加,涂层的摩擦因数呈先减小后增加的趋势。在偏压为−120 V时,沉积的γ-Mo2N涂层的摩擦因数和磨损率均最小,分别为0.10和1.8×10⁻⁷ mm³/(N∙m)。拉曼光谱分析结果表明,在摩擦催化作用下,柴油在磨痕表面产生了碳基膜。此外,通过电化学腐蚀分析发现,在偏压−120 V下沉积的γ-Mo2N涂层具有优异的耐腐蚀性能。结论 MoN涂层结构、性能受到偏压的影响显著。柴油在摩擦催化作用下发生了降解,形成了碳基膜,这有利于降低MoN涂层的摩擦因数和磨损率。     

Cr12MoV钢表面激光熔覆Ni/Ni-WC梯度涂层的组织与耐磨性能

利用脉冲Nd:YAG激光器在Cr12MoV模具钢表面熔覆了Ni/Ni-WC梯度涂层,通过X射线衍射仪、扫描电镜及能谱仪、高速往复摩擦磨损试验机以及白光干涉仪研究了梯度涂层的物相组成、耐磨性能和磨损形貌。结果表明:梯度涂层Ni60A+35%WC耐磨层物相主要由γ-(Ni, Fe)固溶体、WSi₂相以及多种碳化物等硬质相组成。梯度涂层间以及涂层与基体间没有裂纹和气孔等缺陷生成,在界面处表现为良好的冶金结合。Ni60A+35%WC耐磨层平均显微硬度约为基体的1.7倍,Ni/Ni-WC耐磨涂层的磨损机理主要为疲劳磨损和磨粒磨损,基体的磨损机理主要为粘着磨损和磨粒磨损。