Electron spectroscopy studies of surface In–Ag alloy formation on the tungsten surface

Bukaluk, A.; Trzciński, Marek; Okulewicz, K.

doi:10.1016/j.apsusc.2008.01.007

Cited by 4 publications

(6 citation statements)

References 20 publications

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“…In this process the distribution between silver and tungsten in the sintered compact is controlled by the mixing and sizes of the elemental powders which are used to produce the powder blend for pressing. This process is limited in the variety of microstructures that are available particularly when uniform distributions of submicron tungsten particles in a silver matrix are required, as recognized by Gáuchowski and Rdzawski (2008), Bhagat et al (2008) and Bukaluk et al (2008).…”

Section: Introductionmentioning

confidence: 99%

Sintering Characteristics of Iron and Cobalt Doped Silver-tungsten Metal-matrix Composites

Es-Saheb¹,

Azhar²,

Arabia³

2014

RJASET

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Silver-Tungsten composites are known as electrical contact materials used in circuit breakers and industrial relays. The performance of the contact during their service life depends upon high strength and anti-weld properties of these materials. Despite their promising industrial applications, the literature dealing with their production route is still limited. Therefore, a comprehensive study exploring the structure related properties with great emphasis on the sintering process of these materials is carried out. Therefore, in this study, the successful production of a homogeneous composite powder with controlled tungsten particle size using co-precipitation and two stage reduction techniques is followed by the compaction and sintering processes. Thus, high density compacts are produced from Fe and Co doped silver-tungsten powder using powder metallurgy technique. Various environments and sintering conditions, including N 2 atmosphere and temperatures up to 1000°C, to obtain successful compacts from both doped and un-doped powders, are investigated. The morphologies and the microstructures of the sintered compacts obtained under the different sintering conditions are characterized and assessed using Scanning Electron Microscopy (SEM). Results display excellent agreement with the published studies and no evidence was found for the activated sintering of silver-tungsten by Fe additions. Also, the homogeneity of silver-tungsten in compacts is completely lost in the Fe-doped powders. However, Co additions help to facilitate the sintering between silver and tungsten whilst retaining a high homogeneity between the silver and tungsten in the sintered product.

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Section: Introductionmentioning

confidence: 99%

Sintering Characteristics of Iron and Cobalt Doped Silver-tungsten Metal-matrix Composites

Es-Saheb¹,

Azhar²,

Arabia³

2014

RJASET

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“…A high silver content offers maximum conductivity and minimum contact resistance, while high tungsten content offers maximum resistance to arc erosion and welding tendency (Karakas, 2002;Glickman et al, 2003). So for any particular application a balance must be struck between the desirable properties of the two metals, as reported by O ӕ zkal (2002) and later by Bhagat et al (2008) and Bukaluk et al (2008). Witter and Warke (1974) investigated the welding and erosion resistance of silver-tungsten contacts and showed them to be dependent upon particle size, morphology and distribution of the phases within the composite, with finer particles potentially giving better performance.…”

Section: Introductionmentioning

confidence: 99%

“…Meanwhile, the performance of these materials as electrical contacts is investigated lately by Slade (2009) and Bukaluk et al (2008). The standard production route for these materials is either a press-sinter-infiltrate or press-sinter-repress process.…”

Section: Introductionmentioning

confidence: 99%

Homogenous Silver-Tungsten Composite Production for Electrical Contacts

Es-saheb¹

2015

RJASET

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Silver-tungsten composite materials have been widely used as medium duty electrical contacts since they offer the advantages of both refractory tungsten (welding and erosion resistance) and silver (efficient electro-thermal conductivities). Since there is no alloying between the two elements (Ag and W), the properties of the composite depends on their composition. So for any particular application, a balance must be struck between the desirable properties of the two metals. Both welding and erosion resistance properties of silver-tungsten contacts depend on particle size, morphology and distribution of both elements within the composite, with finer W particles in Ag matrix give better performance. The main objective of this study is to produce an intimately mixed silver-tungsten powder with homogeneous distribution of both phases (silver and tungsten) in the composite. Thus, to produce homogenous elemental silver-tungsten powder, the reduction behavior of each tungstate is studied at various reduction temperatures using TGA technique. Based on the results obtained from TGA, the reduction of silver tungstate carried out in two stage reduction process for producing elemental silver-tungsten powder with controlled particle size of tungsten. Also, small quantities of Fe and Co as sinter aids are introduced into tungstates by coprecipitation technique. However, the precipitated Fe and Co doped silver tungstates are reduced to yield Iron and cobalt doped silver-tungsten powders. The effect of Fe and Co on the morphology and particle size of the tungsten is studied using SEM. The reduced products will be used for subsequent sintering experiments to produce high density sintered compact for contact fabrication.

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“…Thus, the second process is often used for the production of contacts. In this process the distribution between silver and tungsten in the sintered compact is controlled by the mixing and sizes of the elemental powders which are used to produce the powder blend for pressing [3].…”

Section: Introductionmentioning

confidence: 99%

Effect of Co Additions on the Densification Behavior of the Ag-W Composite Powder Compacts at Various Sintering Temperatures

2015

International Conference Data Mining, Civil and Mechanical Engineering (ICDMCME’2015) Feb. 1-2, 2015 Bali (Indonesia)

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The Ag-W composite materials are widely used in electrical contacts due to their excellent welding and erosion resistance as well as superb thermal conductivity. However, these properties and characteristics are affected by the powder particle size, morphology and distribution of both elements within the composite. A homogeneous distribution of fine W particles in Ag matrix is needed, to achieve better performance. In this investigation, the main effort was concentrated on producing Ag-W composite powder with homogeneous structure. This involves investigating the effect of Co addition on the powder morphology using SEM. The Co addition in the silver tungstate was in the form of CoWO 4 via co-precipitation technique. First, the reduction behavior of these powders at few reduction temperatures was studied using TGA. Then, based on the TGA data obtained, two stages reduction process was employed to produce large batches of un-doped Ag-W and Co-doped Ag-W powders for subsequent sintering experiments. The temperature sets identified and adopted in the study were 250 o C-750 o C and 250 o C-850 o C. The Ag-W compacts produced from the reduced powders at these temperatures were then sintered below the melting point of silver phase to avoid any segregation between Ag and W. Finally the characteristics and densification behavior of the sintered compacts was studied and evaluated for contacts application using TEM.

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Electron spectroscopy studies of surface In–Ag alloy formation on the tungsten surface

Cited by 4 publications

References 20 publications

Sintering Characteristics of Iron and Cobalt Doped Silver-tungsten Metal-matrix Composites

Sintering Characteristics of Iron and Cobalt Doped Silver-tungsten Metal-matrix Composites

Homogenous Silver-Tungsten Composite Production for Electrical Contacts

Effect of Co Additions on the Densification Behavior of the Ag-W Composite Powder Compacts at Various Sintering Temperatures

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