Lime Crucible Research Articles

The Segregation of Chemical Composition in NiTi Shape Memory Alloy Melted by VIM in Lime Crucible

Binary NiTi shape memory alloy cast ingots with large scale size are produced by using vacuum induction melting (VIM) in lime crucible, the oxygen and carbon contents are less than 500ppm. Usually, oxygen was introduced into the melts by the dissolution of lime during melting, resulting in higher content of oxygen over 500ppm. VAR + VIM ingot metallurgy is prone to produce materials with a good chemical homogeneity. However, it is difficult for one single melting of NiTi by VIM in the lime crucible. So in the present paper, the segregation of chemical composition and the consistency of transformation temperature in NiTi alloys in as-casted condition along the cross-section area on edge and center, in homogeneization-treated condition, and in as-forged condition along the longitudinal-section area on head and tail, are measured and analyzed by differential scanning calorimetry (DSC), OM, SEM, and XRD, to indicate the chemical homogeneity in microscopic and macroscopic scale.

Solubilities of carbon in CaO‐Al2O3‐SiO2 slags saturated with liquid iron

By equilibrating the CaO‐Al2O3‐SiO2 slags with Fe ‐ 0.0003∼0.07% Al ‐ 0.002∼3.5% Si ‐ 0.9∼2.0% C alloys (mass contents in %) at 1873 K, the solubilities of carbon were measured as a function of Si contents in metal, using an alumina or lime crucible. The distribution ratios of carbon as a C2‐ ‐ion were found to be linearly related to Si contents with a slope of 1/2 at a given slag composition. The carbide capacity, , defined by (% C) , increased with increasing SiO2 contents at a given CaO/AlO1.5 molar ratio in the CaO‐AlO1.5SiO2 system.

Service Life of Electrically Fused Lime Crucible for Vacuum Induction Melting of Reactive Alloys

Service Life of Electrically Fused Lime Crucible for Vacuum Induction Melting of Reactive Alloys

Effect of sulfur on supersaturation in aluminum deoxidized liquid iron

The effect of sulfur addition on supersaturation observed in aluminum deoxidized liquid iron was studied at 1873 K, by using CaO‐Al2O3 slags in an alumina or lime crucible. The contents of supersaturated oxygen for a given aluminum level were not influenced by the addition of sulfur (mass contents of 1×10−5 ∼ 0.42%) in the experiments where the sample was rapidly quenched. However, in the experiments in which the sample was cooled from 1873 to 1723 K at a cooling rate of 2.7 K/min, the effect of sulfur on supersaturation was observed for mass contents of more than 0.01% sulfur. The critical supersaturation for alumina precipitation was discussed based on the variation of the interfacial energy between liquid iron and alumina.

Apparent Solidification Shrinkage of Titanium Castings Induction-Melted in Lime Crucible

Apparent Solidification Shrinkage of Titanium Castings Induction-Melted in Lime Crucible

Activities of FetO in CaO-Al2O3-SiO2-FetO (<5 pct) slags saturated with liquid iron

The activity coefficients of FetO in CaO-Al2O3 and CaO-Al2O3-SiO2 slags with 0.01 to 5 mass pct FetO were determined at 1873 K from the data obtained in the present and previous slag-metal experiments, using an alumina or lime crucible. It was found that the activity coefficients of FetO obeyed a dilute solution law and increased with increasing the content of SiO2. Based on the findings pertaining to the activity coefficient, the values for the activities of SiO2 and Al2O3 in CaO-Al2O3-SiO2 slags were assessed.

Calcium desulfurization equilibrium in liquid iron

Sulfur distribution ratios between CaO‐Al2O3 slags and liquid iron were measured at 1873 K as a function of aluminum content using an alumina or a lime crucible. Activity coefficients of CaS relative to a solid standard state were obtained as 52&2.6 and 23&1.7 for the CaO‐Al2O3 slags saturated with an Al2O3 and a CaO crucible, respectively, in the concentration range up to the CaS solubility limit. From these results, logarithm of the equilibrium constant, log KCaS, for the calcium desulfurization reaction CaS(s) = Ca + S and the first‐order interaction parameter eSCa (eSCa) were estimated to be –8.72&0.27 and –269&28 (–336&35), respectively.

Improvement of the Internal Soundness of Titanium Castings Prepared by Induction Melting in Lime Crucibles

Improvement of the Internal Soundness of Titanium Castings Prepared by Induction Melting in Lime Crucibles

CaO-Al<SUB>2</SUB>O<SUB>3</SUB>系融体-溶鉄間のAl-O平衡

Aluminium-oxygen equilibria between CaO-Al2O3 melts and liquid iron were studied in the temperature range of 1 823 to 1 923 K, using an alumina and lime crucibles. The equilibrium constant K for the reaction: 2Al+3O= Al2O3 was discussed with reference to the supersaturation for nucleation of alumina, and compared with the previous experimental and thermodynamic data. The supersaturation was observed in the experiments in which an Fe-Al alloy with low concentrations of initial oxygen was used under the condition of no stirring. Supersaturation increased with a decrease of oxygen content in liquid iron. Two types of alumina inclusions with a size of 2-5 μm and below 0.1 μm were observed by SEM.

Aluminium-Oxygen Equilibrium between CaO-Al2O3 Melts and Liquid Iron.

Aluminium-oxygen equilibria between CaO-Al2O3 melts and liquid iron were studied in the temperature range of 1 823 to 1 923 K, using an alumina and lime crucibles. The equilibrium constant K for the reaction: 2Al+3O= Al2O3 was discussed with reference to the supersaturation for nucleation of alumina, and compared with the previous experimental and thermodynamic data. The supersaturation was observed in the experiments in which an Fe-Al alloy with low concentrations of initial oxygen was used under the condition of no stirring. Supersaturation increased with a decrease of oxygen content in liquid iron. Two types of alumina inclusions with a size of 2-5 μm and below 0.1 μm were observed by SEM.

Desulphurization of Carbon-free Liquid Iron Contained in Lime Crucible with Aluminum

Desulphurization of Carbon-free Liquid Iron Contained in Lime Crucible with Aluminum

Deoxidation of Liquid Iron and Its Alloys by Calcium Contained in Lime Crucible

Deoxidation of Liquid Iron and Its Alloys by Calcium Contained in Lime Crucible

CaO坩塙による溶鉄と溶融鉄合金のカルシウム脱酸およびアルミニウム脱硫

CaO坩塙による溶鉄と溶融鉄合金のカルシウム脱酸およびアルミニウム脱硫

合金鋼の脱燐に関する研究

The dephosphorization in alloy steel was investigated for Fe-C-Cr-P alloy chiefly with high basic and fluid slags.At first, the experimental heats were made by induction melting the Fe-Cr-P alloys in lime crucibles under various oxidizing conditions. In this case, the relation between the contents of chromium and phosphorus nearly followed its equilibrium relation calculated under the condition of both a4CaO·P2O5=1 and aFeO·ECr2O3=1, and the dephosphorization in a few per cent chromium steel was not improved in this condition.Then in order to investigate the effects of CaF2 and FeO concentration in the slag and temperature on the dephosphorization, the Fe-C-Cr-P alloys were melted in MgO crucibles with CaO-CaF2-FeO slags.For dephosphorization in alloy steel, less oxidizing condition in slag is desirable to restrict the oxidation loss of alloy constituents. As a result of a series of experiments, it was found that the synthetic slag at CaO: CaF2=5: 5 could fairly promote the dephosphorization at the least concentration of iron oxide, and in the course of its process, for the medium carbon alloy steel containing several per cent chromium, the oxidation loss of carbon and chromium could be remarkably restricted.

XII. On the reversal of the lines of metallic vapours. No. VIII. (iron, titanium, chromium, and aluminium.)

In our last communication on this subject we observed (“Proc. Roy. Soc.,” vol. 29, p. 405) that iron introduced as metal, or as chloride, into the electric arc, in a lime crucible, in the way which had proved successful in the case of many other metals, gave us no reversals. We succeeded, however, in reversing some ten of the brightest lines of iron, mostly in the blue and violet, by passing an iron wire through one of the carbons, so as to keep up a constant supply of iron in the arc. Considering the great number of iron lines, and that so many of them are strongly represented amongst the Fraunhofer lines, it seemed somewhat surprising that it should be difficult to obtain a reversing layer of iron vapour in the arc inclosed as we use it in an intensely heated crucible. A like remark might be made respecting titanium, which is almost as well represented as iron in the Fraunhofer lines, but has heretofore given us no reversals. Almost the same might be said of chromium, except that the number of chromium lines is so much less than that of either of the other two metals. We have since found that most, if not all, of the strong lines of these three metals may be reversed by proper management of the atmosphere and supply of metal in the crucible. Indeed, with regard to iron we have found that the method employed with other metals was successful so far as the ultra-violet rays were concerned, though it failed for less refrangible rays. Then iron has been put into the crucible through which the arc of a Siemens’ dynamo-electric machine is passing, and then fragments of magnesium dropped in from time to time, most of the strong ultra-violet lines of iron are reversed. The magnesium seems to supply a highly reducing atmosphere, and to some extent carry with it the iron vapour. It also produces a good deal of continuous spectrum, at least in certain regions, and against this the iron lines are often depicted on the photographic plates sharply reversed. In this way we have observed the reversal of the strong iron lines about the solar lines L and M, four strong lines below N, the line O, all the strong lines from S 2 to U inclusive, and two strong groups still more refrangible.

III. On the reversal of the lines of metallic vapours. No. VI

The experiments described in the following communication were made with the electric arc, and in lime crucibles, or in crucibles of a highly calcareous sandstone, kindly supplied to us by Messrs. Johnson, Matthey, and Co., as described in our fourth communication on this subject; but for some of them we used, instead of a galvanic battery, a magneto-electric machine producing a much more powerful current and a much longer arc. The experiments with this machine were made, through the kindness of Dr. Tyndall, at the Royal Institution, and we are indebted to Messrs. Siemens both for the working of the machine and for sparing to us the services of a skilled engineer, in he person of Mr. Oscar Doermer, whose assistance was most valuable. We wish to express our thanks to all these gentlemen for the facilities they so readily granted to us.

II. On the reversal of the lines of metallic vapours. No. V

Since our last communication we have continued our experiments, using the electric arc as a source of heat, in lime and in carbon crucibles as described before. Success depends on the getting a good stream of vapour in the tubular part of the crucible. This is easily attained in the lime crucibles, which quickly reach a very high temperature, but are very soon destroyed; not so certainly in the carbon crucibles, which are good conductors of heat. The latter, however, last for a very long time.