Changes of valency state during electro-chemical machining

Mileham, A R; Jones, Roy; Harvey, S. J.

doi:10.1016/0141-6359(82)90094-0

Cited by 8 publications

(8 citation statements)

References 6 publications

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“…The rate of these reactions increases with the electrolysing current and, therefore, reduces the current belonging to the anodic dissolution. This can be compared with the findings obtained by Mileham and other [4], during the ECM of medium and low carbon steels in NaC1 aqueous solutions. His results show a reduction in current efficiency, which is associated with a change in the valency from Fe 2+ to Fe3+ , as either the current density is increased or the electrolyte inlet velocity is decreased.…”

Section: Effect Of Electrolysing Currentsupporting

confidence: 51%

Experimental Determination of the Parameters Affecting Productivity Characteristics of Electrochemical Machining Processes

Asfour

EL-Dardiry

Osman

1984

The International Conference on Applied Mechanics and Mechanica

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The effect of working conditions, namely gap voltage, tool ' feed-rate, electrolysing current, additives to electrolyte and metal removal rate has been investigated for the electro-.chemical drilling process(ECD). Tests were also performed ' using small additions of hydrogen. peroxide (H 202) as an oxygen supplier to the electrolysis bath. Some disadvantages, • are discussed and merits are critically evaluated. The : results are also compared with the available data in the li-:terature. Finally, the effects of various parameters are discussed in details.

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Section: Effect Of Electrolysing Currentsupporting

confidence: 51%

Experimental Determination of the Parameters Affecting Productivity Characteristics of Electrochemical Machining Processes

Asfour

EL-Dardiry

Osman

1984

The International Conference on Applied Mechanics and Mechanica

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“…This is both chemically reasonable and consistent with previous interpretations of the ECM valencies of SS. 16,17 For these and all subsequent electrolyte and steel systems, substitution of the values of k/ f 2 , f, , , V, M, n and F into Eq. 2 enabled V 0 to be calculated for each current/time transient.…”

Section: Resultsmentioning

confidence: 99%

“…Experimental data is also presented on the application of this system to the characterization of stainless steels ͑SS͒. Marked changes in the dissolution characteristics of SS 316 ͑SS316͒ have been measured 16,17 under ECM conditions ͑ϳ100 A cm Ϫ2 ͒, with a boundary along the flow path length being observed, delineating areas with different surface finishes, consistent with different dissolution mechanisms and different valencies. The position of the boundary was shown to be sensitive to electrolyte flow conditions, but these measurements were not in-line ͑and hence could not readily be used to map ECM parameters͒ and were not related to the chemistry of the ECM process.…”

mentioning

confidence: 97%

The Electrochemical Machining Characteristics of Stainless Steels

Mount¹,

Howarth²,

Clifton

2003

J. Electrochem. Soc.

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A systematic study of a variety of stainless steels ͓SS316, SS410, Jethete ͑J͒, Duplex ͑D͒, and Super Duplex ͑SD͔͒ has been performed, measuring their electrochemical machining ͑ECM͒ characteristics in chloride and nitrate electrolytes. Theoretical current/time analysis using a segmented tool was used to determine the dissolution valencies, n, and overpotentials, V 0 , along the flow path length. Electrolyte samples from the interelectrode gap, taken at intervals along the flow path, and the bulk were analyzed for conductivity, pH, and visible absorption. The results indicate that the ECM dissolution characteristics of stainless steels are controlled by the surface oxide structure, which is primarily determined by the chromium content. Typically, the high chromium steels D and SD were found to machine with high primary elemental valencies ͑consistent with n Fe ϭ 3 and n Cr ϭ 6), resulting in the production of soluble CrO 4 2Ϫ . However, for the low chromium steels J and SS410, low valency dissolution ͑consistent with n Fe ϭ 2, n Cr ϭ 3) occurred with chloride electrolyte, and this was also found for the intermediate chromium steel SS316 at low electrolyte flow and recycled electrolyte. These results have been explained by the disruption caused to the surface barrier oxide layer by chloride ions and solid ECM products, which allow low valency dissolution to take place. Significant accumulation of these products occurred when performing electrolyte recycling, which is commonly used in industry.

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“…The electrolytic oxidation of iron is predominantly ferrous (z = 2) [1,16]. However in some electrolytes, ferric (z = 3) corrosion has been shown to dominate, for example where a significant level of chloride is present [17,18]. Further electrolytic oxidation to ferrate (z = 6) has also been demonstrated and is an area of ongoing research [19,20], as ferrate species are very effective coagulants.…”

Section: Oxidation State Of Iron In Ecmentioning

confidence: 98%

Electrocoagulation of fermentation wastewater by low carbon steel (Fe) and 5005 aluminium (Al) electrodes

et al. 2010

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Successful application of electrocoagulation technology requires a thorough evaluation of electrode behaviour. This study is concerned with the treatment of fermentation wastewater, generated by molasses-fed biorefineries in large volumes and containing high concentrations of biorecalcitrant, coloured organic melanoidins that form a highly dispersed colloid. The polarisation behaviour, surface morphology and current efficiency of both hot rolled coil steel and 5005 aluminium electrodes were investigated. The steel electrodes were found to be susceptible to aggressive anodic pitting which is attributed to the high chloride content of the wastewater, while the aluminium exhibited anomalous corrosion of the anode and cathode. The redox potential of the wastewater has a significant effect on Fe 2? /Fe 3? speciation with steel electrodes and thus on the decolourising efficiency of electrocoagulation. The practical implications of the corrosion characteristics are discussed.

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Changes of valency state during electro-chemical machining

Cited by 8 publications

References 6 publications

Experimental Determination of the Parameters Affecting Productivity Characteristics of Electrochemical Machining Processes

Experimental Determination of the Parameters Affecting Productivity Characteristics of Electrochemical Machining Processes

The Electrochemical Machining Characteristics of Stainless Steels

Electrocoagulation of fermentation wastewater by low carbon steel (Fe) and 5005 aluminium (Al) electrodes

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