Zone Melting Apparatus Research Articles

Phase formation and microstructure of laser floating zone grown BSCCO fibers: reactivity aspects

The phase formation and microstructure of Bi 2Sr 2Ca 2Cu 3O 10+δ fibers are affected by the phase content and morphology of the starting precursor powders which modify reaction pathway and kinetics. A solid state precursor reaction process has been used to prepare (Bi, Pb)-Sr-Ca-Cu-O powders with varying phase composition. These powders were isostatically compacted and the resulting cylinders transformed into textured fibers using a laser floating zone melting apparatus. The results demonstrated that a Bi 2Sr 2Ca 2Cu 3O 10+δ precursor mixture containing Bi 2Sr 2CuO 6 and submicrometer-sized ‘CaCuO 2’ particles leads to textured fibers exhibiting high critical current density ( J c ) values.

Titanium distributions in zone melted materials measured by SIMS.

Using a zone melting apparatus the influence of the different solidification processes on the Ti distribution has been investigated in model alloys and a technical steel. The concentration profiles after the conventional zone melting process have been measured using secondary ion mass spectrometry and were used for the determination of the distribution coefficients of Ti in pure Fe-Ti- and Fe-C-Ti-alloys. The registration of lateral elemental maps helps to identify and to eliminate measuring artefacts and allows the investigation of dendritic solidification structures.

Courant critique continu supérieur à 1 000 A dans un supraconducteur texturé par fusion de zone sous champ magnétique

Texturation of YBa~CU~O~_, has been achieved in a zone melting apparatus in a magnetic field, A strong vertical thermal gradient, along which samples are pulled combined with a horizontal magnetic field of 5 teslas induces cristallite alignment with their la, b) planes Perpendicular to the magnetic field and parallel to the thermal gradient. At H= 0T and T 77 K, a dc current of 000 A passed through a multigrain sample of 13 mm~ section and 20 mm length, thus proving the quality of grain boundaries. 200 A currents also passed through in H 8 T (H L I for a large angular range between H and (a, b planes. These preliminary results are encouraging for possible practical applications of large sized textured bar samples.

The Effect of Rare Earth Elements on the Growth of Eutectic Carbides in White Cast Irons containing Chromium

The paper describes a zone melting apparatus capable of providing unidirectional solidification with a steep temperature gradient. This was used to obtain plane front solidification in specimens of...

The main features of plastic deformation of iridium single crystals

A technique for growth of massive iridium single crystals up to 55 mm in diameter and 5 kg in mass has been developed. The single crystals are subjected to plastic deformation. For deformation conditions to be appropriately chosen features of plastic behaviour of iridium single crystals have to be understood. However the data on iridium deformation available in the scientific literature are contradictory [1-3], thus not allowing them to be used in full to develop the process. On the other hand different authors have produced different tensile and compression strength values of iridium attributing them more often to the presence of impurities than to the crystallographic characteristics of plasticity. This letter is an attempt to link plastic behaviour anisotropy of iridium single crystals to the crystallographic characteristics of their deformation. Iridium single crystals were prepared in crucible less zone melting apparatus around oriented seed per one zone pass. The starting material for single crystal production was subjected to deep refining in the process of induction, oxidation melting and electron beam melting. As a result of these operations we managed to reduce gaseous impurities (oxygen, nitrogen, hydrogen and carbon) to 0.1 p.p.m. (wt), most metallic impurities (W, Mo, Nb, Zr, Cu, Gd, Y, AI, Ga, Ni, Pd, Zn, Mg, Ca) to 0.1 to 1 p.p.m. (wt), concentration levels of Pt, Rh, Fe down to 10p.p.m. (wt), and completely clear the iridium from oxide inclusions. The single crystals produced had a ratio P290/Pso = 6.1 to 6.7.

A Multi Purpose Zone Melting Apparatus

AbstractThe mechanic and electric design, the heaters and control elements as well as the ways of application of a new multiple purpose zone melting apparatus are described and the working method is demonstrated on the example of refining and growing purest KCl single crystals.

A Simple Zone Melting Apparatus For Refining Organic Compounds

Abstract A simple zone melting apparatus has been constructed for purification of low melting [<230°C] organic compounds. Six hydrocarbons were doped with benzo[e]pyrene and the purity of the refining process was monitored by high pressure liquid chromatography. In all cases presented the purity achieved was greater than one part per billion.

Improvement of Zone-melting Apparatus: A New Apparatus with a High-precision Heater-temperature-controlling Mechanism

Abstract A new zone-melting apparatus with a high-precision heater-temperature-controlling mechanism has been designed and constructed. The apparatus can control the width of several melting zones at an equal temperature and thus can obtain smooth concentration profiles after zone refining. The effect of zone refining with this apparatus was examined with fair success, using phenanthrene and naphthalene as samples.

Perfection of zone refined ice single crystals

Two techniques have been applied to ice crystals for a production of ice samples with reproducible properties. A zone melting apparatus is described. Its most important feature is the utilization of natural convection for the growth of homogeneous ice single crystals with a volume of about 3 litre and a dislocation density of 10 3 cm −2. The perfection of samples which are used in experiments can be determined in a short time from rocking curves. Defects introduced into the crystals by mechanical treatment have been detected in rocking curves as well as Lang topographs to show that these two techniques may be used complementarily.

Improvement of Zone Melting Apparatus. I. Zone Melting Apparatus with a Device to Prevent Breakage of a Sample Tube

Abstract A glass sample tube is widely used in zone melting of organic substances since it is transparent, inert to most substances and easily prepared in the laboratory. The glass tube, however, is frequently broken owing to the volume increase of the sample. A new device was worked out to prevent breakage of the sample tube, to purify the sample efficiently and to make replacement of the atmosphere inside the sample tube possible. The apparatus requires much less space than for one ever reported and consists of a sample tube with a set of stainless steel spring and Teflon plug and a new mechanism for carrying it. It was successfully used for biphenyl and p-dichlorobenzene.

A versatile vacuum induction furnace for unidirectional solidification studies

An RF zone-melting apparatus is described, working under a 1 mu Torr vacuum and suitable for the unidirectional solidification of eutectics with melting points higher than 1200 degrees C. The solidification rate can be continuously adjusted between 0.1 and 450 cm h-1. The use of an eddy-current concentrator makes easier the obtaining of large thermogradients. A gas quenching device proved suitable for further studies of the solid-liquid interface morphology.

Ring-shaped electron gun for floating zone melting apparatus and its application

Emission and focusing characteristics of an unique accelerating ring-shaped gun for a floating zone melting apparatus are presented and discussed. The ratio of the work current to the total beam current is given as a function of the accelerating voltage, filament current and the gun dimensions, and compared with the experimental data. Based on these results, an unique floating zone apparatus whose maximum output is 6.5kW, capable of refining various materials such as refractory metals, semi-conductors and ceramics, has been developed. Application examples are shown with analysis data of the purification.

電子衝撃浮遊帯域精製装置の試作およびその性能

An electron bombardment floating zone melting apparatus for the refractory metals, which was first built-up on trial in Japan (1960), is described. The operation and the performance are further described for the floating zone melting of W, Mo, Ta, Nb, Pt, Pd and Fe rods. The results obtained are as follows:(1) By using emission control, by which the bombardment current is kept constant by automatically adjusting the filament temperature and bombardment voltage in “Temperature Limited characteristics”, the floating zone melting of sintered specimens incurring a great deal of outgassing during melting was performed successfully.(2) The purifying effect of floating zone melting was confirmed by residual resistance ratio measurements and, from the ratio values, it was made clear that the zone melted rods have been purified by vacuum distillation and zone refining. Namely, in the cases of 5 mmφ W and Mo rods three zone passed at zoning rate 3 mm/min in 1×10−5 torr, the ratio values have been decreased to 1/400 for W rod and to 1/150 for Mo rod respectively against the values of starting materials.(3) By only one zoning, 5 mmφ W, Mo, Ta, Nb, Pt and Pd rods were found to be single crystals at 1∼4 mm/min without seed crystals.Moreover, 4 mmφ Nb single crystal was produced by using 〈100〉 seed crystal. Therefore, this apparatus could be used as a single crystal growing apparatus for refractory metals.

A fast method of zone melting as an aid in analytical chemistry

A new zone-melting apparatus is described which allows relatively high zone speeds up to 100 cm/h. The time required for effective separations is only a few hours so that the apparatus can be used for analytical purposes. The difference between the theoretical and actual distribution coefficients obtained is small; the distribution coefficients of unknown substances in mixtures can thus be derived from the result of zone melting, which offers a means of identification. The apparatus is fully automated and normal freezing is incorporated as a first step. A means of preventing the breakage of the glass tube containers is described. The principles of operation and possible applications are discussed.

Continuous Zone-Melting Apparatus for Organic Compounds

Continuous Zone-Melting Apparatus for Organic Compounds

Zone-melting apparatus for growing ice monocrystals

A zone-melting apparatus using an infrared heat lamp is described. Ice monocrystals can be grown from a polycrystalline charge without using a single crystal seed. The final orientation of the monocrystal will be determined by that original crystal whose a-axis shows the least deviation from the growth direction.

Zone-Melting Apparatus for Alkali Metal Cyanides and Alkali Metal Halides

A zone-melting apparatus is described that can be largely assembled from commercially available components. Details of a technique are given for zone refining alkali metal cyanides and halides in reinforced, flexible metal boats.

Zone melting apparatus for production of high purity materials

Zone melting apparatus for production of high purity materials