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Showing 5 results for Tungsten

H. Razavizadeh, Ershad-Langroudi A.,
Volume 1, Issue 1 (3-2004)

A new process for recovering scheelite ores comprises producing a concentrate from the ore, then leaching the concentrate with H_2SO_4 in the presence of H_3PO_4 and Na Cl at atmosphericpressure are discussed. Finely purification of the product will be described. The amounts of dissolution of tungsten in acid depend on the parameters such as time, temperature, type and concentration of acid and stilt as well as solid-liquid reaction. These factors were optimized for the result and described in details.
S. M. Zahraee,, M. T. Salehi,, H. Arabi, M. Tamizifar,
Volume 4, Issue 3 (12-2007)

Abstract: The objective of this research was to develop a tungsten heavy alloy (WHA) having a microstructure and properties good enough to penetrate hard rolled steels as deep as possible. In addition this alloy should not have environmental problems as depleted uranium (DU) materials. For this purpose a wide spread literature survey was performed and on the base of information obtained in this survey, three compositions of WHA were chosen for investigation in this research. The alloys namely 90W-7Ni-3Fe, 90W-9Ni-Mn and 90W-8Ni-2Mn were selected and after producing these alloys through powder metallurgy technique, their thermal conductivity, compression flow properties and microstructures were studied. The results of these investigations indicated that W-Ni-Mn alloys had better flow properties and lower thermal conductivities relative to W-Ni-Fe alloy. In addition Mn helped to obtain a finer microstructure in WHA. Worth mentioning that a finer microstructure as well as lower thermal conductivity in this type of alloys increased the penetration depth due to formation of adiabatic shear bands (ASB) during impact.
A. Ataei, M. Jalaly, M. Tamizifar,
Volume 14, Issue 1 (3-2017)

The boronizing of a tungsten heavy alloy containing Ni and Fe as the major alloying elements were performed in the present study to increase its surface hardening. Pack cementation method was employed as a well-known, successful solid-state process for boronizing. The coating treatment was accomplished at different temperatures of 1000, 1050 and 1100°C for 6 and 9 hours. The formation of tungsten boride phase was confirmed, although a silicide layer covered the surface of the specimen as the outer layer. The mechanism of the formation of a multilayered surface was explained. The maximum thickness of reaction zone and surface hardness achieved in the current work were 300 µm and 2470 HV, respectively.

B.y.r. Surnam, B.s. Audit, A. Soopee,
Volume 14, Issue 3 (9-2017)

In this study the use titanium and tungsten as alternatives to the noble metals in the jewellery industry was investigated. The degradation of titanium and tungsten were compared to that of gold, used as reference. Alternate immersion tests were performed in 3.5% sodium chloride and artificial perspiration. The metals’ abrasion resistance with respect to textile fabrics was determined.

In general, there is around 30% difference in pit density for titanium and tungsten as compared to that of gold. Pit depth and pit diameter showed a similar trend. From the abrasive test performed, it was observed that titanium and tungsten had insignificant changes in the surface reflectivity with time. Hence, it was deduced that titanium and tungsten products would have longer maintenance intervals than that of gold. New tools and techniques, however, would be required by jewellers to work with titanium and tungsten.  

P.k. Jayashree, Sh. Raviraj, S.s. Sharma, G. Shankar,
Volume 15, Issue 2 (6-2018)

CoHErrelation between weldability and improvement in properties is a key issue in materials science research. The objective of this work is to optimize the process parameters viz., aging temperature, aging time, solutionizing time, to enhance the hardness of Al6061 alloy. Hence, the present paper deals with hardness study of Tungsten Inert Gas welded 6061 aluminium alloy after age hardening under three different aging temperatures, aging time and solutionizing time using Taguchi’s L9 Orthogonal array. Finally, a second order model has been generated for hardness using Response Surface Methodology with 20 runs for full design. The predicted and experimental results are in good agreement.

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