Vacuum Fusion Research Articles

Zur bestimmung von sauerstoff, wasserstoff und stickstoff in hochschmelzenden metallen: II. Ermittlung optimaler analysenbedingungen für die sauerstoffbestimmung in molybdän nach dem vakuumextraktionsverfahren

Optimum conditions have been ascertained for the determination of oxygen in molybdenum by means of vacuum extraction. Comparative determinations and analyses of test samples (containing known amounts of oxygen) yielded the following optimum conditions: 1. (a) Vacuum fusion using an Ni-Fe (80:20) bath at 1600–1700°C. 2. (b) Vacuum fusion without bath at approx. 2200°C.

1185. Analysis of gases by the vacuum fusion process: T Koizimi et al, Tetsu To Hagane, 50, 1966, 783–793.

1185. Analysis of gases by the vacuum fusion process: T Koizimi et al, Tetsu To Hagane, 50, 1966, 783–793.

LECO vacuum fusion analyzer: M J Miles and L C Covington,Metallurgie, 5,1965, 367–575 ( in French)

LECO vacuum fusion analyzer: M J Miles and L C Covington,Metallurgie, 5,1965, 367–575 ( in French)

真空溶融-質量分析法による鉄鋼中の極微量ガス分析装置の試作

A mass spectrometer was applied for vacuum fusion analysis of micro-amounts of gases in iron and steel produced by vacuum melting and vacuum casting. The gases extracted from the metal specimen in a vacuum fusion furnace were collected directly in the gas reservoir through a mercury diffusion pump, and the individual constituents were determined by the mass spectrometer (Gas Detector, ATLAS-WERKE AG.). The limits of detection for this apparatus were 0.07 μg of oxygen, 0.1 μg of nitrogen and 0.005 μg of hydrogen. The analysis took approximately 30 minutes. From the extraction curve with vacuum fusion it was proved to be extracted gases from iron and steel within 2 minutes.

Dosage de l'azote dans le vanadium par fusion reductrice sous vide

A study of the conditions for the determination of nitrogen in vanadium by vacuum fusion in a platinum bath has shown that ( a) the amount of nitrogen extracted depends on the ratio ( R) of the weights of platinum and vanadium, and ( b) the amount extracted passes through a maximum value for a particular R value depending on the temperature. With R values of ca. 2 and extraction temperatures above 1900°, results were in reasonable agreement with those obtained by the Kjeldahl method, the reproducibility being 2–3%.

Determination of oxygen and Hydrogen in tungsten and other metals by a vacuum-fusion gas-chromatographic method

A gas-chromatographic method has been developed for the analysis of gas evolved from tungsten and tungsten-base alloys in the vacuum-fusion process. The method is suitable for determining 5–3,000 p.p.m. of oxygen and 0.2–300 p.p.m. of hydrogen, and can be applied to other metals. Above 50 p.p.m. of oxygen and 3 p.p.m. of hydrogen, the values found compare favourably with those obtained by alternative methods; below these levels, no reliable alternative procedures are readily available. In the proposed method, the sample is submitted to vacuum fusion in a molten platinum bath in a graphite crucible, and an aliquot of the evolved gas is transferred by means of a specially modified Drallim valve, to a stream of high-purity helium. The components are separated on a column of molecular-sieve 5A at 100° and detected with a radioactive-type ionization detector. Calibration and operation of the system are described in detail, and the effects of variables are discussed. Evidence was obtained that hydrogen recoveries by the conventional vacuum-fusion method are sometimes slightly low, because of methane formation. An important advantage of the method is that the evolved gases are positively identified by their retention volumes.

高圧溶解法による溶鉄中の<U><B>C</B></U>-<U><B>O</B></U>平衡の測定

The oxygen content in liquid iron with 1∼3%C in equilibrium with carbon monoxide of 16, 8, 4 and 1 atm was studied at 1500°C.The results obtained are as follows:(1) The feature of dependence of K1′(=Pco⁄%C×%C) on %C varies with Pco when K1′ is calculated using the analytical value of oxygen which is determined by the vacuum fusion method. That is, when Pco=1 atm, K1′=constant in the range of carbon concentration studied. On the other hand, in the case of Pco=16 atm, K1′ increases with increasing %C.(2) It is considered that the above-mentioned feature is based on the existence of systematic errors included in the analytical values of oxygen. The error amounts to 5∼10 ppm and is considered to originate from the oxide film on the surface of the specimens.(3) After the correction for the systematic error, the value of K1′ is 1700 and 3000 at 2 and 3%C respectively, which is larger than the value of about 500 at %C→0 reported in literatures.(4) The activity coefficient of oxygen in the liquid iron f0 increases with increasing %C, corresponding to e0(C)=0.1.

Gases in aluminum alloy die-castings

It is well known that aluminum alloy die-castings contain a large amount of gases. However, there have been seldom reports on the content and composition of those gases.In this experiment, vacuum fusion method was applied to the determination of gas content in a certain aluminum alloy die-castings and hydrogen content in the gas was determined by measuring pressure difference between before and after heating a palladium tub econnected to gas analyzer.The present results showed that the die-castings contained gases of 20-30cc NTP/100g Al, and 70-80% of the total volume hydrogen whose source was found to be the lubricant for sleeve and die.

Determination of Oxygen in Titanium by Isotopic Dilution

AbstractTwo specimens of titanium which had been analyzed independently by vacuum fusion and inert-gas fusion were analyzed for oxygen by an isotope-dilution technique which employed a platinum bath and allowed the dilution to be followed with time. With graphite crucibles which had been degassed at 1850°C for 2 1/2 hours or longer, the exchange was linear with time for both the blank and analysis. Extrapolation to zero time permitted the oxygen content to be measured with a standard deviation of ±0.004 per cent for specimens of weight 0.5 gram. The results were in agreement with or slightly higher than those obtained by vacuum fusion. Suspected segregation in one of the specimens rendered an exact comparison between the methods uncertain. Resume Deux specimens de titanium, qui avaient ete analyses separement par fusion dans le vide et fusion dans un gaz inerte, ont ete analyses Quant a l' oxygene par une technique de dilution d'lsotope, utilisant un bain de platine et permettant de suivre la dilution ave...

1537. Mechanism of the reduction of oxide inclusions by carbon in liquid iron during vacuum fusion analysis

1537. Mechanism of the reduction of oxide inclusions by carbon in liquid iron during vacuum fusion analysis

1298. Vacuum fusion analysis with a mass spectrometer: ML Aspinal, Analyst, 91, 1966, 33–41

1298. Vacuum fusion analysis with a mass spectrometer: ML Aspinal, Analyst, 91, 1966, 33–41

The Determination of Oxygen in Metals with High Melting Points by the Inert Gas Fusion Method: A Silicon Fusion Technique

Abstract The determination of oxygen in metals with high melting points is important for the development of metallurgy. This paper will describe a very simplified apparatus and a procedure which gives precise results almost without a blank test. A silicon fusion technique developed by the present authors is used instead of the platinum bath method for the purpose of decomposing oxides in metals. It enables us to determine oxygen in a small quantity of a sample by the use of a highly-sensitive gas chromatograph. The amount of oxygen in the purified tantalum and niobium was determined within a standard deviation of 0.0038%. The precision established in tests of titanium samples containing 0.074% of oxygen was 0.0018%; this observed value is in good agreement with that obtained by the vacuum fusion method.

894. Sensitivity of detection of oxygen in niobium by vacuum fusion: Yu A Karpov et al, Zavodsk Lab, 31 (10), 1965, 1190–1191, (in Russian)

894. Sensitivity of detection of oxygen in niobium by vacuum fusion: Yu A Karpov et al, Zavodsk Lab, 31 (10), 1965, 1190–1191, (in Russian)

704. Gas adsorption by manganese and chromium in a vacuum fusion furnace: K Furuya and H. Kamada, Bunseki Kagaku, 14(8), 1965, 708, (in Japanese)

704. Gas adsorption by manganese and chromium in a vacuum fusion furnace: K Furuya and H. Kamada, Bunseki Kagaku, 14(8), 1965, 708, (in Japanese)

Thermodynamic principles of determining gases in metals by the method of vacuum fusion: L L Lumin, Zh Analit Khim, 20(7), 1965, 822–831, (in Russian).

Thermodynamic principles of determining gases in metals by the method of vacuum fusion: L L Lumin, Zh Analit Khim, 20(7), 1965, 822–831, (in Russian).

A comparison of neutron-activation analysis and hot extraction analysis of the oxygen content of steel

A system developed for the fast neutron-activation analysis of the oxygen content of metals has been tested comparatively with the conventional vacuum fusion and carrier-gas fusion techniques. The results of these tests indicate that neutron-activation analysis is much faster (the total analysis takes only 2 min or less), and more reliable than vacuum fusion and carrier-gas fusion methods because all oxygen present is analysed. Samples can be much larger than the 0.2–3 g commonly used for the fusion methods. Furthermore, the analysis is non-destructive—the same samples can be re-analysed as often as desired. The fast neutron-analysis system includes a 14-MeV neutron generator producing 10 11 neutrons/sec, a dual-tube pneumatic transfer system, a 5 × 5 inch NaI(T1)crystal, a single-channel analyser, two scalers, and timers and switch-gear. A sample, in a polyethylene bottle, and a Lucite reference are irradiated simultaneously, after which the sample is returned to a detector for counting the 16N gammas from the 16O(n,p) 16 N reaction. The reference is then counted in a second detector; the ratio of the sample counts to the reference counts is proportional to the oxygen content of the sample. Samples with oxygen contents from 0.002 to 0.1 % of oxygen have been analysed by neutron activation, then cut in several pieces for hot extraction analysis of the total sample.

240. High resolution mass spectrometric measurement system for a vacuum fusion apparatus: R J Conzemius and H T Svec,Anal Chim Acta, 33(2), 1965, 145–152

240. High resolution mass spectrometric measurement system for a vacuum fusion apparatus: R J Conzemius and H T Svec,Anal Chim Acta, 33(2), 1965, 145–152

The gas-chromatographic analysis of gases extracted from metals by vacuum fusion

The equipment necessary to use a micro-ionisation detector of the Lovelock type with helium carrier gas is described. Although not used at its highest sensitivity, the apparatus can measure quantitatively 1 per cent. v/v of components in a mixture of carbon monoxide, nitrogen, hydrogen and methane of total volume 5 × 10–4 cm3 at S.T.P.

The preparation and stability of uranium carbide samples for the determination of oxygen, hydrogen and nitrogen by vacuum fusion

The preparation and stability of uranium carbide samples for the determination of oxygen, hydrogen and nitrogen by vacuum fusion

A study of the macroscopic distribution of oxygen in a steel rod by neutron-activation and vacuum fusion techniques

The distribution of oxygen was determined along the length of a steel rod. Neutron-activation and vacuum fusion techniques were used alternatively, and the relevant pieces of apparatus and methods are described. The over-all average oxygen content determined by neutron-activation analysis was 129 p.p.m., in excellent agreement with 128 p.p.m. found by vacuum fusion. The results further show the continuity between the two sets of results, and also a definite inhomogeneity in the macroscopic distribution of oxygen.