In-depth distribution of rusts on two weathering steels and a plain carbon steel exposed to atmosphere for 17 years under a bridge at a coastal
+
industrial region in Japan were studied. In the rust ...layer on all specimens, α-FeOOH, β-FeOOH, γ-FeOOH, Fe
3O
4 and so-called amorphous rust were found. Within rust layers, there were thick parts and thin parts, which were finely and complicatedly distributed on steels. Among these rust species, α-FeOOH was dominant on all specimens. α-FeOOH appeared almost homogeneously through the rust layer. Its concentration was higher on weathering steels than on plain carbon steel. β-FeOOH was found mainly at thick parts and was scarce at thin parts of rust layers. Concentration of α-FeOOH was higher and that of γ-FeOOH was lower on weathering steels than on plain carbon steel. Amorphous rust was located at the bottom of the rust layer irrespective of steel types. Concentration of magnetite was negatively correlated with concentration of β-FeOOH.
Superconducting magnetic bearings (SMBs) are usually composed of superconductors and permanent magnets (PMs). These SMBs are based on pinning forces between superconductors and PMs. In this paper, ...SMB-I composed of disk-shaped superconductor and SMB-II composed of doughnut-shaped superconductor are studied. To compare SMB-I with SMB-II, impulse responses in the vertical and horizontal directions are performed. Moreover, new types of SMB-III and SMB-IV are proposed. These SMB-III and SMB-IV are composed of superconductor and superconducting coils. To compare SMB-III with SMB-IV, impulse responses in the vertical and horizontal directions are studied. Then, natural damped vibration curves for impulse responses are observed. The damping coefficient for SMB-IV is larger than other SMB-I, SMB-II and SMB-III.
Superconducting magnetic bearings (SMBs) are usually composed of superconductors and permanent magnets (PMs). These SMBs are based on pinning forces between superconductors and PMs. In this paper, ...SMB-I composed of disk-shaped superconductor and SMB-II composed of doughnut-shaped superconductor are studied. To compare SMB-I with SMB-II, impulse responses in the vertical and horizontal directions are performed. Moreover, new types of SMB-III and SMB-IV are proposed. These SMB-III and SMB-IV are composed of superconductor and superconducting coils. To compare SMB-III with SMB-IV, impulse responses in the vertical and horizontal directions are studied. Then, natural damped vibration curves for impulse responses are observed. The damping coefficient for SMB-IV is larger than other SMB-I, SMB-II and SMB-III.
This paper is performed to apply superconducting magnetic bearings (SMBs) to a high-speed turbine rotor. First, we analyze the system by using the finite-element method and design the structure whose ...vibrations are suppressed well. Then, we have made an experimental setup using the theoretical result. The experimental setup consists of two SMBs, a permanent magnet motor and a rotor with many turbine blades. We perform some experiments using this experimental setup in a vacuum chamber. In this paper, we discuss the dynamic characteristics of the spinning rotor with many turbine blades.
Passivity of alloys containing corrosion-resistant elements were reviewed. Chromium and valve metals except aluminum form stable oxyhydroxide films even in aggressive hydrochloric acids. Molybdenum ...forms a passive MoO
2 film in the active region of stainless steels and hence decreases the active dissolution current. In the passive region of transition metals and valve metals, molybdenum is generally in the transpassive state and dissolved. However, if the outer oxyhydroxide film is stable the inner MoO
2 film is protected by the outer oxyhydroxide film and the MoO
2 film acts as the effective barrier against diffusion of matters through the film. Thus the passive current density of 30Cr–2Mo ferritic stainless steel is more than two orders of magnitude lower than that of 30Cr steel without molybdenum in 1
M HCl.
It was found that MgO supported catalysts gave liquid hydrocarbons and CO
2 selectively, from palm oil and other vegetable oil at around 703
K. The hydrocarbon product was composed of paraffins and ...olefins, whose carbon number was C
3 and C
10–C
20 hydrocarbons whose peak located at C
15. Chemical structure of the products was the mixture of straight chain and branched chain hydrocarbons. The fluid point of the product was about 253
K. Supported MgO promoted the di-carboxylation of triglyceride or free fatty acid. The products showed lower acid value and iodine value. The product was successfully used for the diesel engine.
Superconducting technique is applied to a superconducting magnetic suspension system. The suspension system is composed of a superconducting coil, a copper coil, a suspended object, a photo sensor, a ...PID controller, and power amplifiers. Persistent current in a superconducting coil and control current in a copper coil are used for suspending object and controlling object, respectively. In this paper, large-gap trial on the system is performed, and the static and dynamic characteristics of the suspended object are performed. As a result, it is found that the suspended object continues to suspend at a distance 43 mm for ≈14 s. It is found that there is a maximum limit of superconducting persistent current for the system. The details of the superconducting persistent current are discussed. This may be the first trial that superconducting persistent current is used for a magnetic suspension system.
A cryogenic motor with active magnetic bearings (AMBs) which works in liquid nitrogen is discussed in this paper. The cryogenic motor is composed of two AMBs, four displacement sensors, a permanent ...magnet (PM) motor, etc. In order to check the stability for the rotor, FFT (fast Fourier transform) analysis for the levitated rotor in the radial direction is performed. Displacement of rotor in the axial direction is studied during rotation.
The purpose of this study was to characterize the surface oxide films on a Co–Cr–Mo alloy located in various environments to estimate the reconstruction of the film in the human body. Five kinds of ...specimens were prepared according to the following methods: polishing in deionized water, autoclaving, immersion in Hanks’ solution, immersion in a cell culture medium, and incubation with cultured cells. X-ray photoelectron spectroscopy (XPS) was performed to estimate the compositions of the surface oxide film and substrate and the thickness of the film. The surface oxide was about 2.5
nm thick and contained a large amount of OH
−. Calcium phosphate was formed after immersion in the Hanks’ solution and the culture medium and incubation with the cultured cells. Cobalt was dissolved during immersion in Hanks’ solution and the cell culture medium and incubation in a cell culture. After the dissolution, the surface oxide consisted of chromium oxide (Cr
3+) containing molybdenum oxide (Mo
4+, Mo
5+, and Mo
6+). Results from angle-resolved XPS revealed that chromium and molybdenum were more widely distributed in the inner layer than in the outer layer of the oxide film. The results in this study suggest that Co–Cr–Mo alloy releases cobalt and that the surface oxide film consisting of chromium and molybdenum is reconstructed in living tissues.
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