The present paper describes the general view of the construction standard, which the Japan Society of Mechanical Engineers (JSME) has recently set up and published, for superconducting magnet structures to be used in nuclear fusion facilities. The present target of the standard is tokamak-type fusion energy facilities, especially the International Thermonuclear Experimental Reactor called ITER for short. The standard contains rules for structural materials including cryogenic materials, structural design considering magnetic forces, manufacture including welding and installation, nondestructive testing, pressure proof tests and leak tests of toroidal field magnet structures. The standard covers requirements for structural integrity, deformation control, and leak tightness of all the components of the superconducting magnets and their supports except for superconducting strands and electrical insulators. The standard does not cover deterioration which may occur in service as a result of corrosion, radiation effects, or instability of material. The standard consists of seven articles and twelve mandatory and non-mandatory appendices to the articles; i.e., (1) Scope, roles and responsibilities, (2) Materials, (3) Structural design, (4) Fabrication and installation, (5) Non-destructive examination, (6), Pressure and leak testing, and (7) Terms used in general requirements.
Anti-cavitation erosion performances of thermally sprayed cobalt-based alloy coatings were compared with that of aluminum bronze castings, which have been utilized as s substrate for propeller in marine vessel because of its formability, endurance against seawater, and the cavitation erosion resistance. Cobalt-based alloy coatings are fabricated by using three thermal spray processes: atmospheric plasma spray, low-pressure plasma spray and high velocity oxygen fuel flame spray. The ultrasonic vibration type cavitation erosion testing apparatus were employed for the cavitation erosion rate measurement. The cavitation erosion performances determined by the specific volume loss rate of low-pressure plasma-sprayed cobalt-based alloy and HVOF sprayed cobalt-based alloy coatings were improved five times and twice compared with that of aluminum bronze castings, respectively. The anti-cavitation erosion performance of atmospheric plasma sprayed cobalt-based alloy coating did not reach the level of aluminum bronze castings.
Blasting is a surface processing technique in which spherical or granular materials made of metals or ceramics are jetted against substrate surface using compressed air. In this process, high speed colliding of blasting materials against the substrate surface produces crush of the materials into fine particle which affect the durability of blast materials. However, there are no reliable investigations that consider influence of the durability of blast materials. This study investigated blast materials durability by examining relation between blast counts with particle distribution and changes in blast materials properties. Results from this investigation are summarized as follows: Percentage of large particle diameter decrease with increase of blast counts. On the other hand, percentage of small particle diameter increase with increase of blast counts slowly. With the increase of the blast counts, edges of blast material are mellowed. The surface roughness of the substrate remarkably increased with blast counts and afterwards, it increased slowly. Percentage of large particle diameter decrease with increase of blast counts rapidly. As a result, the removal quantity and surface roughness of substrate rapidly decreased. The arc height decrease with the increase of the blast counts.
The Ni-base self-fusing alloy layers are employed in a variety of wear resistance applications. The diode laser is more compact and the electro-optical-efficiency is higher about one order of magnitude. This is an advantage in both the small-size manufacturing field and large-size construction out door field. Another advantage is the wavelength. Due to shorter wave length most of the metals absorb diode laser (808nm) radiation more efficiently compared with CO2 laser (10600nm) enabling together with high power the use of wide beam optics. In this paper, five types of laser cladding conditions (laser power, scan speed, overlap rate, powder injection position and laser irradiation position) are examined and the structures and mechanical properties of the layers produced by each cladding condition are discussed. The Vickers hardness of laser cladding Ni-base S. F. alloy layer was increased from HV740 to 845 with increase in the layer power from 150W to 250W. Some recommended laser cladding processing conditions for a Ni-base S. F. alloy powder were scan speed of 6mm/sec, overlap rate of 60%, powder feeder nozzle angle of 60° and laser power of 200W.