The Computation of Throwing Efficiency

Pan, L. C.

doi:10.1149/1.3493759

Cited by 9 publications

(5 citation statements)

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“…This contradicts the experimental evidence, since the throwing power measurements expressed by the Heatley-Pan and the Field equations vary with linear ratios (3,6). Apparently, the linear correlation given in Eq.…”

Section: Limitation Of Linear Throwing Indexmentioning

confidence: 81%

“…Thus, the use of the linear throwing index results in a constant throwing efficiency and a constant "throwing power (BSI)" independent of linear ratios. This contradicts the experimental evidence, since the throwing power measurements expressed by the Heatley-Pan and the Field equations vary with linear ratios (3,6). Apparently, the linear correlation given in Eq.…”

Section: Limitation Of Linear Throwing Indexmentioning

confidence: 81%

“…Some of the linear and the logarithmic indexes listed are then used to calculate throwing powers in terms of Eq. [1]- [3] as functions of linear ratios. The results are compared with the values computed from the original data of metal distribution measurements.…”

Section: Logarithmic Throwing Indexmentioning

confidence: 99%

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A Logarithmic Throwing Index for the Measurement of Throwing Powers

Chin¹

1971

J. Electrochem. Soc.

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A new and simple method is presented for expressing the result of throwing power measurements of electroplating solutions in terms of a logarithmic throwing index," defined as the ratio of the logarithm of linear ratios (L) to that of the metal distribution ratio (M). Graphically it is the reciprocal of the slope of a straight line obtained when M is plotted against L on log-log coordinates. The limitation of a linear throwing index method found in the literature and the advantages of the method proposed here are discussed with published results from use of the Haring-Blum cells.In electroplating, throwing power is a measure of the extent to which a plating bath deposits a coating of uniform thickness on different parts of a cathode surface. For practical purposes, a simple and direct measurement, allowing rapid comparison of various plating solutions and operating conditions, is the use of a Haring-Blum cell (1). This device is a rectangular electrolytic cell having two metal cathodes of equal size placed vertically at either end. Between the cathodes is a flat, perforated anode having different distances from each cathode. The ratio of the anode distance from the far cathode to that from the near cathode is called the linear (or primary current distribution) ratio, L; the ratio of the rate of metal deposition on the near cathode to that on the far cathode is called the metal distribution ratio, M. The throwing power of a plating bath at a given operating condition is normally calculated from one of the following formulas:Haring-Blum equation (1) L--M Throwing power ----X 100[1] L Heatley-Pan equation (2, 3) Throwing efficiency ----Field equation (4) Throwing power (BSI) --Objection against using these equations has been raised by Jelinek and David (5) for the following reasons: first, the use of different equations would result in different numerical values for a plating bath at constant operating conditions; and second, the throwing powers computed by these equations vary appreciably with linear ratios. It is, therefore, desirable to have a single number that characterizes the throwing power of a bath over a range of linear ratios.Jelinek and David have suggested a throwing index (5) obtained by plotting the metal distribution ratio vs. linear ratio on arithmetic coordinates. A straight line passing a common point (L = 1, M = 1) is drawn through the data points, and the reciprocal of the gradient of the line is taken as the throwing index. In this way a single value is obtained for a range of linear ratios which can be used to show variations of throwing power with changes in current density, temperature, and bath compositions. Since the method implies that there is a linear relationship between the metal distribution ratio and the linear ratio, a throw-* Electrochemical Society Active Member. Key words; throwing power, throwing index, logarithmic throwing index.ing index obtained this way will be called the linear throwing index in this paper. As will be shown, the linear throwing index, however, has inherent...

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Section: Limitation Of Linear Throwing Indexmentioning

confidence: 81%

Section: Limitation Of Linear Throwing Indexmentioning

confidence: 81%

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A Logarithmic Throwing Index for the Measurement of Throwing Powers

Chin¹

1971

J. Electrochem. Soc.

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“…It has the appearance of a rainbow-a pleasant name for a troublesome phenomenon. According to Pan [99], angle cathodes with different angles and various side lengths, slotted cathodes, and slit cells are normally used to determine the covering power.…”

Section: Covering Powermentioning

confidence: 99%

Electrodeposition of Chromium

Mandich¹,

Snyder²

2010

Modern Electroplating

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Electroplated chromium deposits rank among the most important plated metals and are used almost exclusively as the final deposit on parts. Without the physical properties offered by electroplated chromium deposits, the service life of most parts would be much shorter due to wear, corrosion, and the like. Parts would have to be replaced or repaired more frequently, or they would have to be made from more expensive materials, thus wasting valuable resources.The thickness of electroplated chromium deposits falls into two classifications: decorative and functional. Decorative deposits are usually under 0.80 mm in thickness. They offer a pleasing, reflective appearance while also providing corrosion resistance, lubricity, and durability. Decorative chromium deposits are typically plated over nickel but are occasionally plated directly over the substrate of the part.Functional ''hard chrome'' deposits have a thickness customarily greater than 0.80 mm and are used for industrial, not decorative, applications. In contrast to decorative deposits, functional chromium is usually plated directly on the substrate and only occasionally over other electrodeposits, such as nickel. Industrial coatings take advantage of the special properties of chromium, including resistance to heat, hardness, wear, corrosion, and erosion, and a low coefficient of friction. Even though it has nothing to do with performance, many users want their functional chromium deposits also to be decorative in appearance. Functional deposits are also used on parts such as cutting tools and strip steel and are even thinner than decorative deposits.The most common and oldest commercial type of chromium process utilizes hexavalent chromium (Cr 6 þ ) in an aqueous solution containing one or more catalysts. The

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“…The ability of an electrolyte to provide a uniform current density distribution over a cathode surface has been the subject of numerous investigations, resulting in a large number of different criteria to determine it as the throwing power indexes of an electroplating bath. [1][2][3][4][5][6][7] Two of these attempts were presented in this series. [6][7] In both cases, however, the obtained results were expressed by relations without clear physical meaning and generally included a comparison of the actual current density distribution to the current density distribution in the case of total Ohmic control, i.e., under conditions of primary current distribution.…”

Section: Introductionmentioning

confidence: 99%

The current distribution in an electrochemical cell. Part VII. Concluding remarks

Popov¹,

Pesic

Živković³

2002

JSCS

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Anew method for the determination of the ability of an electrolyte to distribute uniformly current density in an electrochemical cell is proposed. It is based on the comparison of the current in cells in which the electrode edges touch the cell side walls with the current in cells with different electrode edge ? cell side wall distances. The effects of cell geometry process parameters and current density are discussed and illustrated using the results presented in the previous papers from this series.

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The Computation of Throwing Efficiency

Cited by 9 publications

References 0 publications

A Logarithmic Throwing Index for the Measurement of Throwing Powers

A Logarithmic Throwing Index for the Measurement of Throwing Powers

Electrodeposition of Chromium

The current distribution in an electrochemical cell. Part VII. Concluding remarks

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