Effect of a rigid component (tungsten alloy) on the process of formation of mixtures based on copper powder and the properties of heterogeneous unsintered compacts

Kоval

et al. 2007

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621.762The change in the content, structure, and microhardness at a depth of the scale layer, which forms on the copper-based material under focused solar radiation, is studied. The formation of a structure with an external layer of CuO, Fe 2 O 3 , NiO oxides and mixed Cu 3 WO 6 oxide (spinel type) with high microhardness H μ = 29.4 GPa is shown.The use of solar energy in recent years has intensified significantly. This is practically an inexhaustible source providing pure heating. Solar energy can be focused into a high-intensity beam to be used for different processes: welding, cutting, soldering, single-crystal growing, and remelting in both land-based and space facilities [1].The copper-based structural material 80 wt.% Cu-20 wt.% W alloy (90 wt.% W-7 wt.% Ni-3 wt.% Fe) with solid inclusions of a tungsten alloy exhibits excellent mechanical properties and corrosion resistance [2]. Should a heterogeneous powder material be used under extreme conditions, changes in its properties -caused, for example, by focused solar beams -must be revealed depending on the parameters of the external influence. Using a copper-based powder material for borehole perforation [3] assumes short-term high temperatures. However, changes in the initial properties of the powder material have been studied inadequately. The objective of this paper is to study the effect of focused solar radiation (FSR) on the phase composition and structure of the heterogeneous powder material 80 wt.% Cu-20 wt.% W alloy . MATERIALS AND TECHNIQUEThe original components were: PMS-1 electrolytic copper powder (bottle density ρ = 8.86 g/cm 3 ) with dendrite-like particles of 100 μm (GOST 4960-75) and tungsten alloy powder (90 wt.% W-7 wt.% Ni-3 wt.% Fe) with average particle size 28.6 μm (ρ = 17.1 g/cm 3 ). The heavy tungsten-based alloy, produced by co-reduction of mechanically mixed oxygen-containing components, has been extensively studied [4,5].The W-Ni-Fe alloy was produced by a powder metallurgy technique. The initial powders of tungsten anhydrite, nickel carbonate, and iron oxide were wet-mixed in a set ratio. The mixture, dried at 150°C and sifted through a 045-mesh screen, was hydrogen-reduced in two stages: at 600°C for 4 h and at 900°C for 5 h. The original components were mechanically agitated to form a heterogeneous mixture 80 wt.% Cu-20 wt.% W alloy , with a combined density of 9.91 g/cm 3 . The mixture was compacted by double-action pressing at 800 MPa.The grain-size distribution of the tungsten alloy powder was examined using SIAMS-600 image processing software (developed by SIAMS Ltd, Ekaterinburg, Russia, http://siams.com).

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Section: 762mentioning

confidence: 99%

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confidence: 99%

Effect of focused solar power on the structure and phase composition of a copper-based material

Kоval

et al. 2007

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“…The four-point bending strength of the samples was determined using a Ceramtest machine equipped with an automated data processing system (for determining elastic modulus, strength, and plasticity). A stress-strain curve has been plotted [4].…”

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Effect of warm pressing on the mechanical properties and structure of green compacts of heterogeneous copper-based powder

Shtern

et al. 2010

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The paper examines the warm pressing of copper-based powder mixtures with additions of lead, graphite, and tungsten. It is shown that the density increases by 2 to 3% in warm pressing of copperbased powders with additions of lead and graphite at 800 MPa and their bending strength and elastic modulus become almost twice as high. The tungsten content of 20 and 50% of the compact increases the bending strength. Preliminary cold pressing of the samples before warm pressing has practically no effect on material properties and, hence, does not contribute to energy saving.Cracks sometimes form when green powder materials used to produce hollow charges for perforators for oil and gas wells are pressed into a steel casing. To get rid of this drawback, the mechanical properties of materials should be improved. Warm pressing is a method of improving the strength of parts.Low temperatures (150-170ºC) are commonly used for warm pressing. It is advantageous in that it increases the density of products under lower compaction forces [1]. Simulation of warm pressing has revealed that the powder particles tend to flow radially and, thus, the density is uniform over the volume of a part [2].The paper [3] studied the effect of warm pressing on the density of samples made of iron powder with different methods involving the addition of different lubricants. It is established that the density of samples made of SС-200-36 iron powder (Höganäs Company, Sweden) increased by 0.2 g/cm 3 when 0.6% zinc stearate was introduced as a lubricant after warm pressing. However, this was not the case for pressing of samples made of PZhRZ-200-28 iron powder (State Powder Metallurgy Works, Brovary, Ukraine) when zinc stearate and animal oil were used for lubrication.Since there are only ambiguous published results and different factors during warm pressing are still to be examined, we studied the effect of pressing pattern, chemical composition, and pressure on the density, structure, and mechanical properties of composites based on copper powder.

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Production of copper powder from rolled scale and its mechanical properties

Fedorov

et al. 2010