Systems and methods for refining or otherwise processing tungsten alloys, including ferrotungsten powder and articles formed therefrom, and methods for detecting the presence of the same. The methods include at least one of magnetically-separating and particle-size-separating ferrotungsten or ferrotungsten-containing powder. In some embodiments, powder may be separated to remove fine particles, and optionally to separate the remaining particles into fractions containing selected particle size distributions. The powder additionally or alternatively may be separated into at least magnetic and non-magnetic fractions. In some embodiments, portions of two or more size and/or magnetism fractions are mixed to provide a ferrotungsten-containing feedstock. Selected fractions resulting from the size and magnetism separation steps may be utilized to provide a ferrotungsten-containing feedstock from which articles are produced and which may include additional components.



 

Tungsten Powder Manufacturer & Supplier: Chinatungsten Online - www.tungsten-powder.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

Determination of lead,tin and bismuth in the ferrotungsten by inductively coupled plasma atomic emission spectrometry.

A method for the determination of lead,tin and bismuth by inductively coupled plasma atomic emission spectrometry was studied.The sample was decomposed with oxalic acid and hydrogen peroxide.In the medium of ammonia at pH≥9,Pb,Sn and Bi were precipitated and separated from W in the solution.The residual tungsten in the sediment was less than 0.7% after twice precipitation with ammonia liquor.The interferences from residual tungsten could be eliminated by the background correct mode.The restraining influence from iron on the intensity of Pb,Sn could be overcome by matrix matching.The method has been applied to the determination of Pb,Sn and Bi in ferrotungsten with the recovery of 96%-102% and relative standard deviation of 1.3%-1.5%.



 

Tungsten Powder Manufacturer & Supplier: Chinatungsten Online - www.tungsten-powder.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

Determination of Ar、Sb、Bi Content in Ferrotungsten by the Method of Inductively Coupled Plasma Emission Spectrometry

The sample was dissolved with oxalic acid and hydrogen peroxide and processed with mixed acid to remove the tungsten. Determination of arsenic、antimony、bismuth in ferrotungsten by the method of ICP-AES. The results indicated that matrix effect of the tungsten for measuring element was not obvious after tungsten removal. This method was applied to the determination of synthetic ferrotungsten sample,and the results agreed well with the certified values,with recovery rate of 96.5%～102.0%and relative standard deviation of 1.2%～4.6%.



 

Tungsten Powder Manufacturer & Supplier: Chinatungsten Online - www.tungsten-powder.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

An inductively coupled plasma atomic emission spectrometric(ICP-AES) method for the determination of Cu,Mn,Si in the ferrotungsten was studed.The optimal working conditions of instrument were confirmed.The experiment factors including the method for dissolving sample,spectral line of element,and oxalic acid concentration were discussed.The sample was discomposed by oxalic acid-hydrogen peroxide.Throuth selectiong 327.396 nm,279.482 nm and 251.612 nm as the analytical lines of copper,manganese and silicon and adopting appropriate background correction points in oxalic acid medium,matrix elements W,Fe and other coexistent elements have no effect in the determination.So Cu,Mn,Si could be determined directly without separation.The detection limits for Cu,Mn,Si were 0.005 2 μg/mL,0.007 2 μg/mL,0.009 0 μg/mL respectively.This method could be employed in simultaneous determination of Cu,Mn,Si in ferrotungsten,with the RSDs of 0.47%-1.98%.



 

Tungsten Powder Manufacturer & Supplier: Chinatungsten Online - www.tungsten-powder.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

The simultaneous determination of arsenic,antimony and bismuth in ferrotungsten was studied by inductively coupled plasma atomic emission spectrometry.The sample was decomposed with oxalic acid and hydrogen peroxide.In the medium of mixed acid,tungsten was converted to tungstate precipitates and thus separated from sample solution.When residual tungsten in sample solution was less than 150 μg/mL,it did not interfere in the determination.The interference of residual tungsten could be eliminated by the background correction mode and matrix matching. The proposed method has been applied to the determination of arsenic,antimony and bismuth in ferro-tungsten,with the recoveries of 95 %-105 %,and the relative standard deviation(RSD) of 0.86 %-3.6 %.



 

Tungsten Powder Manufacturer & Supplier: Chinatungsten Online - www.tungsten-powder.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

An inductively coupled plasma atomic emission spectrometry (ICP—AES) procedure has been developed for the determination of aluminium, cobalt, chromium, copper, manganese, molybdenum, nickel, silicon, titanium and vanadium in ferrotungsten. The sample is dissolved by a combination oxalic acid and hydrogen peroxide and the decomposition is completed with a mixture of sulphuric and phosphoric acids in a PTFE vessel without application of hydrofluoric acid. In this way silicon is quantitatively converted into a solution form. No separation of elements from the matrix is required. Calibration graphs have been prepared using synthetic standard samples and verified by means of the Czechoslovak standard ferrotungsten and analysed ferrotungsten samples. For comparison, the samples were analysed by flame atomic absorption spectrometry. The silicon content was also verified by gravimetric and titrimetric methods. The results and accuracy of the method are discussed.

 

Tungsten Powder Manufacturer & Supplier: Chinatungsten Online - www.tungsten-powder.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

The following content is the other part of GTAW development on tungsten electrode.

Initially, the electrode overheated quickly and, despite tungsten's high melting temperature, particles of tungsten were transferred to the weld. To address this problem, the polarity of the electrode was changed from positive to negative, but the change made it unsuitable for welding many non-ferrous materials. Finally, the development of alternating current units made it possible to stabilize the arc and produce high quality aluminum and magnesium welds.

Developments continued during the following decades. Linde developed water-cooled torches that helped prevent overheating when welding with high currents. During the 1950s, as the process continued to gain popularity, some users turned to carbon dioxide as an alternative to the more expensive welding atmospheres consisting of argon and helium, but this proved unacceptable for welding aluminum and magnesium because it reduced weld quality, so it is rarely used with GTAW today. The use of any shielding gas containing an oxygen compound, such as carbon dioxide, quickly contaminates the tungsten electrode, making it unsuitable for the TIG process. In 1953, a new process based on GTAW was developed, called plasma arc welding. It affords greater control and improves weld quality by using a nozzle to focus the electric arc, but is largely limited to automated systems, whereas GTAW remains primarily a manual, hand-held method. Development within the GTAW process has continued as well, and today a number of variations exist. Among the most popular are the pulsed-current, manual programmed, hot-wire, dabber, and increased penetration GTAW methods. The following content is the other part of GTAW development on tungsten electrode.

The electrode overheated quickly initially and tungsten particles were transferred to the weld in spite of tungsten's high melting temperature. To deal with this problem, the electrode polarity was changed from positive to negative, but the change made it unsuitable for welding many non-ferrous materials. Finally, the development of alternating current units made it possible to stabilize the arc and produce high quality aluminum and magnesium welds.

Developments continued during the following decades. Linde developed water-cooled torches that helped prevent overheating when welding with high currents. During the 1950s, as the process continued to gain popularity, some users turned to carbon dioxide as an alternative to the more expensive welding atmospheres consisting of argon and helium, but this proved unacceptable for welding aluminum and magnesium because it reduced weld quality, so it is rarely used with GTAW today. The use of any shielding gas containing an oxygen compound, such as carbon dioxide, quickly contaminates the tungsten electrode, making it unsuitable for the TIG process. In 1953, a new process based on GTAW was developed, called plasma arc welding. It affords greater control and improves weld quality by using a nozzle to focus the electric arc, but is largely limited to automated systems, whereas GTAW remains primarily a manual, hand-held method. Development within the GTAW process has continued as well, and today a number of variations exist. Among the most popular are the pulsed-current, manual programmed, hot-wire, dabber, and increased penetration GTAW methods. 

Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn
 Tel.: 86 592 5129696; Fax: 86 592 5129797
 Email: sales@chinatungsten.com
 Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
 Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
 Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

The following content is one part of GTAW development on tungsten electrode.

Arc welding develop slowly after the discovery of short pulsed electric arc in 1800 by Humphry Davy, and of the continuous electric arc in 1802 by Vasily Petrov. C.L.Coffin had the idea of welding in an inert gas atmosphere in 1890, but even in the early 20th century, because these metals react rapidly with air and result in porous, dross - filled welds, welding non-ferrous materials(such as, aluminum and magnesium), remained difficult. Processes using flux-covered electrodes didn’t keep the weld area from contamination well. To solve the problem, bottled inert gases were applied at the eailier1930s. A few years later, a direct current, gas-shielded welding process emerged in the aircraft industry for welding magnesium.

Russell Meredith of Northrop Aircraft perfected the process in 1941. Because it used a tungsten electrode arc and helium as a shielding gas, Meredith named the process Heliarc, but it is often referred to as tungsten inert gas welding (TIG); in parts of the world where tungsten is called wolfram, it is known as WIG. The American Welding Society's official term is gas tungsten arc welding (GTAW).  Linde Air Products developed a wide range of air-cooled and water-cooled torches, gas lenses to improve shielding, and other accessories that increased the using of the process. 

Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn
 Tel.: 86 592 5129696; Fax: 86 592 5129797
 Email: sales@chinatungsten.com
 Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
 Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
 Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

With the continuous development and improvement of TIG welding (Tungsten Inert Gas), plasma welding, spraying, cutting and other technologies, people have put forward higher requirements to electrode material performance; certainly, including cerium tungsten electrode, there are several requirements of cerium tungsten electrode welding performance showing in the following:

(1) Increasing the arc performance - lower work function (that is, the need for better active substance and content);

(2) Applies to more welding atmosphere - the need for greater chemical stability;

(3) Also requires that they have a better material structure;

(4) Under high temperature conditions, it is able to put up with stream erosion;

(5) What is more, the mort important point is the one that, requiring it without radioactivity, to eliminate the radioactivity that to harm the environment and human health. The following is a comparative on cerium tungsten electrode and thorium tungsten electrode performance:

(1) Compared to the thorium tungsten electrode, cerium tungsten electrode work function material, oxidation resistance and X-ray dose and other properties are significantly improved.

(2) Cerium tungsten electrode influenced by the decrease of cathode spot reduce and the lower of cathode voltage drop, so that the arc emission current density increases, which raising the minimum arc current, the allowable current and breaking arc spacing and other properties. These parameters will increase as the increase of the content of cerium oxide in the experimental range, and during plasma cutting, its ends will be rendered 'natural sharpened' characteristics.

(3) Cerium tungsten electrode melting deep, weld width, burning rate and the reliability of repeated arc is superior to thorium tungsten electrode. During welding the ultra-thin foil devices and precious metals, the performance of 4% cerium tungsten electrode is better.

 

Tungsten Metals Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten.com.cn
 Tel.: 86 592 5129696; Fax: 86 592 5129797
 Email: sales@chinatungsten.com
 Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
 Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
 Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

A rapid analysis method of X-ray fluorescence spectrometry for determining tungsten in ferrotungsten was established with pure iron as flux and centrifugal casting method for sample preparation.The result indicated tungsten had excellent distribution uniformity in sample after melting.No significant difference existed among samples after melting.Meanwhile,test measurement and exclusion were conducted on the potential spectral overlap interference factors in the sample.National standard sample and manually prepared calibration samples were used to draw calibration curve,with linearity scope of 50.00%-85.00%.A comparison was conducted between the testing result of gravimetric method and the proposed method,and the difference was within ±0.20%.The method can meet the the routine testing requirements for fast determination of tungsten in ferrotungsten.

Tungsten Powder Manufacturer & Supplier: Chinatungsten Online - www.tungsten-powder.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn