Characterization and corrosion behavior of Co and Co–P coatings electrodeposited from chloride bath

Ezhilselvi, V.; Seenivasan, H.; Bera, Parthasarathi; Anandan, C.

doi:10.1039/c4ra08226e

Cited by 31 publications

(15 citation statements)

References 43 publications

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“…In the deposited Co-P coatings, the components of the alloy were dense and uniform, for the reason that P dispersed in the cobalt metal during the formation of solid supersaturated solution. Thus, the alloy showed higher corrosion potential [10]. Furthermore, in the amorphous coatings of Co-P coatings as deposited, because there were no grain boundaries, the corrosion attacks seem to be lower [20]; thus, Co-P coatings were endowed with outstanding corrosion resistance.…”

Section: Effect Of Heat Treatment On the Corrosion Resistance Of Co-pmentioning

confidence: 94%

“…It has been demonstrated that a certain amount of surfactant in solution could result in more smooth coatings. Ezhilselv et al [10] measured the potentiodynamic polarization curve of Co-P coatings, which revealed that coatings deposited under pulse current showed better corrosion resistance than that deposited under direct current. A similar result was obtained by Kosta et al [11].…”

Section: Introductionmentioning

confidence: 99%

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Effect of Waveform and Heat Treatment Processes on the Performance of Electrodeposited Co-P Coating

Chen

Qian

2017

Coatings

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Cobalt-phosphorus (Co-P) alloy is a promising material for the replacement of traditional hard chromium alloy of high hardness. In this paper, the cobalt-phosphorus alloy layer with high phosphorus content was formed by electrodeposition in a cobalt sulfate solution system under direct current (DC), single pulse (SP) current and double pulse (DP) current, separately. Surface morphology, structure and properties of the deposited layer were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), Vickers microhardness and a neutral salt spray test, respectively. The results showed that the dense Co-P coatings could be obtained by DC, SP and DP with P content of 9.6, 8.9 and 9.1 wt %, respectively. After 30 min heat treatment at 400 • C, coatings deposited under DC, SP and DP currents transformed from an amorphous to a nanocrystalline state, while the grain size was 12-13 nm, 10-12 nm and 8-10 nm, respectively. Among all these conditions, the microhardness of coatings deposited under DP current was the highest, which was 1211 HV, while the microhardness of coatings deposited under DC current was the lowest but higher than that of hard chromium. The wear rate of Co-P coatings was 4 × 10 −6 -5 × 10 −6 mm 3 /N m with Si 3 N 4 ball as bearing material, which was lower than that of hard chromium. In coatings deposited under different currents with a thickness of ca. 40 µm, no visible corrosion area appeared after 1000 h of a neutral salt spray test. Coatings heated at 300 and 400 • C reached the corrosion grade 7 and grade 4-5, respectively after 1000 h of a neutral salt spray test, so the wear resistance of Co-P coatings was better than that of hard chromium.

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Section: Effect Of Heat Treatment On the Corrosion Resistance Of Co-pmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Effect of Waveform and Heat Treatment Processes on the Performance of Electrodeposited Co-P Coating

Chen

Qian

2017

Coatings

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“…Co-P coatings have been identied as suitable materials for replacement of environmentally-unfriendly hard chromium due to their excellent wear resistance, corrosion resistance and high thermal stability. [1][2][3][4][5] The properties of Co-P coatings are mainly inuenced by the P content and phase structures of alloy coatings. It was reported that Co-P coatings with high P content and amorphous structure exhibit excellent corrosion resistance.…”

Section: Introductionmentioning

confidence: 99%

“…Among these variables, current mode is a exible and efficient variable to modify the P content and phase structures of alloy coatings. Ezhilselvi et al 1,7 demonstrated that the Co-P coatings deposited by PC method have better corrosion resistance than those by DC method. Pulse current (PC) and pulse reverse current (PRC) are the two most common types of pulsed method.…”

Section: Introductionmentioning

confidence: 99%

Wear and corrosion resistance of Co–P coatings: the effects of current modes

Hou

Dong

et al. 2018

RSC Adv.

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“…However, the effect of alloying non‐metal like phosphorous to improve the properties of cobalt‐based alloys is a topic of recurring interest. Codeposition of phosphorous with cobalt from various bath conditions using different plating techniques has also gained equal attention owing to its improved microhardness, magnetic properties, thermal stability and high corrosion resistance of the coatings . In most of these above mentioned studies, individual effects of P codeposition and W codeposition with cobalt and their properties have been investigated.…”

Section: Introductionmentioning

confidence: 99%

Effect of P codeposition on the structure and microhardness of Co–W coatings electrodeposited from gluconate bath

Seenivasan

Bera

2016

Surface & Interface Analysis

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Effects of addition of P to Co-W coatings from gluconate bath using direct current (DC) and pulse current (PC) methods have been investigated in this study. Co-W-P coatings with different P concentrations are prepared by varying hypophosphite concentration in the bath. Current efficiency of the Co-W-P electrodeposition is lower than that for Co-W coatings. Increase in NaH 2 PO 2 concentration increases the cobalt content significantly and decreases the tungsten content drastically. Co-W-P coatings display 'cauliflower-like' morphology and roughness of the coatings increases with increasing P content. As-deposited Co-W-P deposits are amorphous while heat treatment at different temperatures has rendered them crystalline with the precipitation of stable species like, Co 3 W, Co 2 P, etc. Unlike Co-W coatings, Co-W-P shows two-step crystallization in differential scanning calorimetry (DSC) and on heat treatment, which is similar to the behavior of Co-P electrodeposited from gluconate baths. Moreover, inclusion of phosphorous and heat treatment have led to significant increase in microhardness of the Co-W-P coatings. X-ray photoelectron spectroscopy (XPS) studies provide a detailed insight into the nature of Co, W and P species in as-deposited and sputtered coatings. Microhardness of the heat-treated coatings is higher than the as-deposited counterparts and is comparable with that of hard chromium.

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Characterization and corrosion behavior of Co and Co–P coatings electrodeposited from chloride bath

Abstract: Co–P coatings with low and high phosphorous contents are electrodeposited using direct current (DC) and pulse current (PC) methods from cobalt chloride baths.

Cited by 31 publications

References 43 publications

Effect of Waveform and Heat Treatment Processes on the Performance of Electrodeposited Co-P Coating

Effect of Waveform and Heat Treatment Processes on the Performance of Electrodeposited Co-P Coating

Wear and corrosion resistance of Co–P coatings: the effects of current modes

Effect of P codeposition on the structure and microhardness of Co–W coatings electrodeposited from gluconate bath

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