Corrosion behaviour of mechanically polished AA7075-T6 aluminium alloy

In the present study, the effects of mechanical polishing on the microstructure and corrosion behaviour of AA7075 aluminium alloy are investigated. It was found that a nano-grained, near-surface deformed layer, up to 400 nm thickness, is developed due to significant surface shear stress during mechanically polishing. Within the near-surface deformed layer, the alloying elements have been redistributed and the microstructure of the alloy is modified; in particular, the normal MgZn2 particles for T6 are absent. However, segregation bands, approximately 10-nm thick, containing mainly zinc, are found at the grain boundaries within the near-surface deformed layer. The presence of such segregation bands promoted localised corrosion along the grain boundaries within the near-surface deformed layer due to microgalvanic action. During anodic polarisation of mechanically polished alloy in sodium chloride solution, two breakdown potentials were observed at −750 mV and −700 mV, respectively. The first breakdown potential is associated with an increased electrochemical activity of the near-surface deformed layer, and the second breakdown potential is associated with typical pitting of the bulk alloy

Development of a regional climate model for polar region, and its application to the Greenland ice sheet

第6回極域科学シンポジウム[OM] 極域気水圏11月16日（月）　国立極地研究所１階交流アトリウ

A Basic Study on Path Teaching Method for a Mobile Robot Using a Digital Camera

This paper proposes a novel path teaching method for a mobile robot. In this method an operator takes pictures at significant points such as turning points, half way points and a destination on robot´s path by a digital camera. Then, the operator teaches the robot landmarks to recognize the images and actions for the robot to take at the significant points. The robot travels autonomously searching the landmarks and obeys the instructions when it recognizes reaching the significant points. By using this method, it is possible to teach paths for the mobile robot more easily. In this paper, outline of the proposed method and results of fundamental experiments in both indoor and outdoor environment to confirm possibility of the method are described

The direct observation of copper segregation at the broad faces of η’ and η precipitates in AA7010 aluminium alloy

High strength Al-Zn-Mg-Cu (7xxx) aluminium alloys obtain the required balance of mechanical and corrosion properties through complex heat treatments developed through empirical experiment. Understanding the influence of these heat treatments on the composition of the strengthening precipitates (η’ and η-phase) is critical to obtain a better mechanistic understanding of their effect. In this work, the composition of strengthening precipitates has been studied at the atomic scale in microstructures of commercially processed AA7010 alloy in the standard overaged temper state. Copper enrichment in the precipitates on over-aging is confirmed for both small (η’) and large (η) particles. It is demonstrated that in addition to entering the precipitates, a copper enriched layer forms at the particle/matrix interface on the broad faces of the precipitate plates. The implications of this structure for the mechanical and environmentally assisted cracking performance of the alloy are discussed

Understanding of surface segregation of Cu and Zn on nano Si precipitates to the mechanical property improvement of high pressure die casting Al9Si3CuFe alloy

To understand Si precipitation and its influence on mechanical property improvement in high pressure die casting (HPDC) Al9Si3CuFe alloy under direct ageing heat treatment, the precipitates in Al9Si3CuFe alloy containing in-situ MgAl2O4 particles is analyzed via atomic-resolution scanning transmission electron microscopy. It is shown that lath-like Si precipitates form in an average size of 50 nm in length, and a good orientation relationship of {010}<001>Al//{111}<01-1>Si is observed between Si precipitate and matrix. Interestingly, Cu and Zn are observed to segregate onto Si/Al interface, which has a coarsening resisting effect on precipitate growth. The presence of these Si precipitates is the main factor contributing to the further improvement of mechanical properties of Al9Si3CuFe alloy, which results in an increase of 70 MPa in yield strength compared to the alloy without Si precipitates

<Case Report> Management of Anesthesia during Tracheal Resection in a Patient with Tracheal Tumor

We anesthetized a 59-year-old patient with a tracheal tumor. The tumor was approximately 3.5 cm at maximal diameter, and it arose from the left posterior wall of the middle trachea, making near total tmcheal occlusion. A small suction catheter was insinuated past the tumor into the trachea so that the patient could be ventilaed. Aneshesia was maintained with 50% nitrous oxide and 1-3% enflurane administered through the catheter, before the resection of the tracheal tumor. While the trachea was opened, the anesthetic gas was administered across the operative field from two anesthesia machines attached separately to to endobronchial tubes in the main bronchi. After reconstruction of the trachea, ventilation was maintained through the nasotracheal tube. During anesthesia the PaO2 value was good. We think it is important to have close perioperative communication between the surgeon and anesthesiologist.journal articl

High-Pressure Die Casting: A Review of Progress from the EPSRC Future LiME Hub

This article provides an overview of high-pressure die casting (HPDC)-related research undertaken at the EPSRC Future LiME Hub between 2015&ndash;2022. The project aimed to identify the cause of variability in the tensile ductility of die-cast structures, and to develop novel processing techniques to address this issue. Variability in tensile ductility was related to the size of large pores and non-metallic inclusions. It was proposed that these non-metallic inclusions formed during the pyrolysis of commercial plunger lubricants in the shot sleeve, and that these large pores derived from dilatational strains introduced during semi-solid deformation. Processing parameters and die design were found to significantly influence the microstructure of die-cast products, and the subsequent variability in tensile ductility. To close, recent progress on the application of intensive melt shearing to HPDC is reviewed. Intensive melt shearing was found to induce significant grain refinement in both Al and Mg alloys due to the effective dispersion of native oxide particles, and the use of these particles as heterogeneous nucleation substrates. The presence of native oxide particles also enabled the use of novel heat treatment procedures that avoided conventional issues such as surface blistering and geometrical distortion