Ribbon Material Research Articles

Power loss, flux harmonics and domain motion in amorphous ribbon and grain-oriented silicon-iron materials

The harmonic content of the flux density of wide and narrow amorphous ribbons and grain-oriented silicon-rion samples when magnetized at 50 Hz have been measured. The values of the harmonic content have been correlated to the type of material, domain wall motion, width of ribbon, power loss and heat treatment.

Magnetostriction measurements on amorphous ribbons by the Becker-Kersten method

The Becker-Kersten method of measuring magnetostriction, which involves observing the (M, B) loop of a long straight sample when it is in tension, is applied to two kinds of amorphous ribbon material both having very small negative magnetostriction.

An improved force transducer using amorphous ribbon cores

One potential use of magnetic amorphous ribbon materials is in force, stress or displacement transducers. This application relies on the high degree of stress sensitivity of magnetic properties exhibited by some amorphous materials. Mohri et al have described amorphous-core transducers composed of a two-core multivibrator circuit with a d.c. output. An improved transducer which produced an a.c. voltage output has been constructed and tested. An oscillator is used to magnetize an amorphous ribbon toroid by a primary winding via a buffer amplifier. The amplified output voltage from a secondary winding is directly proportional to the force applied to the toroid. This improved a.c. transducer system can be favourably compared to the d.c. system. The linear operating region has been improved to 350 g from 140 g for single core systems and to 400 g from 200 g for the double-core system. The repeatability and hysteresis of the two systems are comparable. Finally, this new a.c. device does not possess d.c. drift problems and is simpler to produce commercially.

The causes of the anomalous loss in amorphous ribbon materials

The total power loss under alternating flux at power frequencies and zero applied stress conditions is an important criterion for the manufacturer and user of soft magnetic materials. The total power loss may be divided into three major types, namely the static hysteresis loss, classical eddy current loss and excess eddy current loss. It has been shown that the excess eddy current loss is responsible for approximately 90% and 50% of the total power loss of wide amorphous ribbon and grain-oriented silicon-iron respectively. Therefore it is possible to make comparisons of the causes and magnitude of the excess eddy current loss in these materials. The origin of the excess eddy current loss in grain-oriented 3% silicon-iron has been attributed to many causes. The feasibility of each of the suggestions as a possible cause of the excess eddy current loss of amorphous ribbon material is considered. It is concluded that the principal cause of the excess eddy current loss in amorphous ribbons is the non-sinusoidal non-uniform and non-repetitive domain wall motion which is the source of the observed non-sinusoidal and localised variations of the flux density.

Evaluation of Metal Ribbon Reinforced/Resin Matrix Composites

Ribbon-reinforced composites possess a unique set of properties which can offer specific advantages when compared to fiber-reinforced composites. The potential for this class of composites has been demonstrated in several investigations utilizing ribbon-reinforced metal matrix systems [1–8] and ribbon-reinforced resin matrix systems [9–15]. However, the development and practical application of ribbon-reinforced composites has progressed very slowly due to the absence of a low-cost, high-performance ribbon material.

The variation of power loss and domain wall spacing with applied stress in wide amorphous ribbon material

The power loss of wide, 1.3 cm, ribbons of commercially produced Metglas 2826 (Fe <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">40</inf> Ni <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">40</inf> P <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">14</inf> B <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</inf> ) have been measured under sinusoidal flux conditions. These measurements have been performed on samples in the as-cast unpolished, annealed unpolished, as-cast polished and annealed polished condition over a frequency range from 20 to 1000 Hz at flux densities up to 0.75 T. The variation of power loss with tensile stress applied in the direction of the ribbon length over the range 0 to 25 MPa (0 to 3600 psi) has been determined. The variation of domain configuration with tensile stress for the annealed polished samples has been observed by the Kerr magneto-optic effect technique. The static hysteresis loss of the ribbons has been reduced by the application of the tensile stress but at higher frequencies the stressed samples exhibit a higher power loss. The total power loss has been divided into the major constituent losses and the high excess eddy current loss is attributed to the observed high domain wall spacing to thickness ratio. The effect of polishing the ribbons in order to observe the domains is to introduce a complex stress which increases the power loss. The power loss of the annealed samples has not been reduced by the application of the tensile stress.

Amorphous ribbon materials and their possibilities

The magnetic properties of a new type of material, the amorphous alloys, appear to have advantages over those of existing magnetic materials, e.g. lower power loss. But the new material is not yet completely acceptable. The present research and development programme is aimed principally at improving dimensional quality, increasing saturation flux density and lowering the power loss further, all of which should make the new material commercially viable in the 1980s

Variable delay lines using magnetostrictive metallic-glass film overlays

A variable surface acoustic wave (SAW) delay line was fabricated using a thin (&amp;lt;1 μm) magnetostrictive film, metallic-glass overlay. It is well known that metallic-glasses can be prepared in ribbon form by rapid quenching from the melt. However, it is difficult to prepare thin film overlays of these materials for SAW and other devices with this technique. We have succeeded in preparing film overlays of Fe-B by co-evaporation. Our measured magnetostrictions and magnetizations of these films are virtually the same as in ribbon materials. Delay measurements were made using a vector voltmeter method with a bias magnetic field applied along the direction of SAW propagation and in the two perpendicular directions. The largest delay change is in the plane and perpendicular to the direction of propagation. Although the magnetostriction constants are approximately equal to that of Ni, the changes in delay time, Δτ, in the Fe-B coated SAW delay lines are larger than for Ni coated SAW devices. Also, much lower saturation bias magnetic fields, H, are required. A figure of merit, Δτ/τH, is about 250 times larger for some of the Fe-B films than for Ni.

Epitaxial silicon solar cells on “ribbon” substrates

The ability to grow Si in ribbon form offers the potential for greatly reducing the cost of solar cells compared with the present technology that is based on cutting large-cross-section ingots with the accompanying material waste. In the recent past, the edge- defined-growth (EFG) process technology has received much attention, and progress was made in growing 1-in.-wide ribbons of significant length. However, this material is polycrystalline over most of its length. In addition, the possible inclusion of the die materials (carbon) and associated contaminants leads to difficulties in controlling the minority-carrier lifetine in the ribbon. Thus, because of lattice defects (e.g., dislocations, grain boundaries, andcontaminants), problems are anticipated in obtaining a high yield of efficient solar cells by direct diffusion into such ribbon material produced with the present technology. This paper reports on a study of means of generally improving the quality of solar cell devices obtained by using thin epitaxial layers deposited on such material. The program encompasses analytical studies aimed at relating the defects to device performance, and the fabrication of solar cells on a comparative basis (diffusio versus epitaxial growth on crystals of similar quality) to establish the improvement which is obtained. Indeed, the program described in this report demonstrated substantially improved performance with ≈50-μm-thick epitaxial layers compared with those made by direct diffusion. The difference in performance was analyzed in detail to yield significant new insight into the factors controlling the solar cell efficiency when such devices are fabricated in large- grained polycrystalline silicon ribbon.

Radioisotope thickness gage based on a stream of beta particles deflected by a magnetic field

The design and performance of a ..beta.. radiometric thickness gage are described. The ..beta.. source and detector are positioned on the same side of the sheet or ribbon material to be measured. After penetrating the material, the ..beta.. particles are directed back through the material by a magnetic field and measured by the radiation detector. (WHK)

A program controlled machine for winding closed vessels from glass reinforced plastics

The Severodonets Glass Reinforced Plastics Factory has designed and built a machine for winding undivided vessels having capacity up to 6 m 3 (length up to 4000 mm and diameter to 1400 ram) for storing acids or alkalis in the chemical industry. The vessels are wound by a wet method and braided glass fiber is used as reinforcing material. In order to obtain a hermetically tight lay-up, a machine has been developed which ensures high-grade winding of ribbon or tape materials.* The rate of production of the machine can be as much as 20 kg/h of glass reinforced plastics. When forming enclosed vessels, a mandrel is used which is easily soluble in warm water. The construction of the machine enables two forms of winding to be laid: radial winding and polar winding (from pole to pole).