Search

The effect of machine shape on the swimming properties of a spiral-type magnetic micro-machine was examined by using a finite volume method. The optimum design of the blade shape was obtained by using the results of the simulation. According to the optimum design, the micro-machine was fabricated by stereolithography. The swimming properties of the machine agreed well with the analyzed results.

A small flying machine based upon a new mechanism was realized. The flying machine driven by magnetic torque had hard magnetic films as wings and a soft magnetic wire as a body, respectively. The wing has two hinges, which create different drag during up and down strokes, and produced lifting force. Shape magnetic anisotropy of the body stabilized the attitude. The flying machine flew without power supply cables and guides when an alternating magnetic field of more than 400 Oe around 12 Hz was applied.

The magnetic properties of alumite film in which Co-Fe alloy is electrodeposited are investigated with regard to the alloy composition and the geometric structure of the magnetic films. The Co-Fe particles electro-deposited in the alumite film are single-phase alloy particles. The Co-Fe alloy electrodeposited films with small pore diameter (150 AA) have a large maximum magnetic energy product (BH/sub max/) of about 1.44 MGOe due to the high coercive force, high saturation magnetization, and good squareness of the M-H curve. The magnetic properties of the Co-Fe electrodeposited alumite film of the composition of 34 at.% Co were as follows: H/sub c/=2700 Oe and M/sub r//M/sub s/=0.90. It is concluded that the Co-Fe alloy electrodeposited film shows good potential for perpendicular magnetic recording media of magnetic rotary encoders. >

Co and Co-Fe were electrodeposited in pores of anodic oxidized alumite films. It is shown that the magnetic anisotropy energy and the perpendicular coercive force of Co electrodeposited alumite films can be controlled widely by changing the pH and the temperature of the Co solutions without changing the particle diameter. It is shown that, by properly selecting the composition of the electrodeposited alloys, the saturation magnetization and the coercive force of the magnetic alumite films can be controlled. At a composition of 50 at.% Co-Fe, the perpendicular coercive H/sub c/( perpendicular to ) reaches a maximum value of 2700 Oe and the saturation magnetization is as high as 382 emu/cm/sup 3/ for the packing density P=0.2. Therefore, with this composition, the magnetic alumite film can be used for recording media. >

Tertiary recrystallized grain-oriented silicon steel sheets with thicknesses from 80 mu m to 20 mu m were developed. Such ultrathin sheets were produced with appropriate cold rolling and annealing. The magnetic induction B/sub 8/ of the sheet was above 1.95 T and the coercive force H/sub c/ was below 7 A/m. The AC iron loss of the sheet depended on the sheet thickness and was minimized for a 30- mu m-thick sheet having W13/50=0.33 W/kg. This value is about 3/5 of that of the best-grade conventional silicon steel sheet. The loss was reduced further by W13/50=0.17 W/kg when a tensile stress of 4 kg/mm/sup 2/ was applied to the sheet. This loss is comparable to that of a Fe-Si-B amorphous sheet. Moreover, 5 mu m thick grain-oriented sheets can be obtained by applying cold rolling to the tertiary recrystallized sheets with a thickness of 20 mu m and then annealing them. >

Tertiary recrystallization was observed after cold-rolling and annealing of conventional silicon steels. The magnetic induction B/sub 8/ at 800 AA/m of tertiary recrystallized sheets about 75- mu m thick is as high as 1.97 T. Magnetic domain width in these sheets is greater than 1 mm; hence domain-refining techniques such as mechanical scratching and chemical etching are employed in order to reduce the iron loss. The iron loss of the sheet mechanically scratched under the application of a tensile stress of 4 kg/mm/sup 2/ is W17/50=0.42 W/kg and W13/50=0.19 W/kg. However, this domain-refining effect disappears after annealing for 30 min at 800 degrees C. On the other hand, domain refining by the chemical etching is effective against iron loss even if the sheets are annealed; the loss of a sheet 71- mu m thick under the application of a tensile stress of 4 kg/mm/sup 2/ is W17/50=0.35 W/kg and W13/50=0.17 W/kg. The iron loss of a chemically etched sheet with a thickness of 31 mu m is W17/50=0.21 W/kg and W13/50=0.13 W/kg. >