Pulse plated CoP alloy as substitute for hard chromium electrodeposits

Kosta, I.; Imaz, N.; Cinca, N.; García-Lecina, Eva; Sarret, M.; Müller, C.

doi:10.1179/0020296712z.00000000047

Cited by 9 publications

(9 citation statements)

References 11 publications

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“…It can be ascribed to the fact that pulse current could provide much higher overpotential under the same average current, which could cause a higher nucleation rate than the velocity of grain growth, so it produced more crystal nucleuses. Consequently, the grains were refined [7].…”

Section: Surface Morphology Of Co-p Coatingsmentioning

confidence: 99%

“…The effect on wear resistance of abrasive wear and improvement of hardness offset each other, resulting in the unchangeable wear rate of the coatings. The wear rate of Co-P coatings deposited under different currents was higher than that of hard chromium (8 × 10 −6 -11 × 10 -6 mm 3 /N m, with Al 2 O 3 ball as bearing material) [1,7], and a little higher than that of Co-P coatings deposited by Kosta [7] and Facchini [1] (5 × 10 −6 -6 × 10 -6 mm 3 /N m, with Al 2 O 3 ball as bearing material).…”

Section: Currentmentioning

confidence: 99%

“…In order to solve this problem, researchers are looking for promising materials such as Ni-P, Ni-Co-P, and Co-P to replace hard chromium [2][3][4][5][6]. Among which, cobalt-phosphorus (Co-P) alloy coatings have received much attention due to their high hardness, good wear resistance, low friction coefficient and high thermal stability [1,7]. Therefore, Co-P alloy coatings are becoming a promising alternative to hard chromium coatings [8].…”

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: Surface Morphology Of Co-p Coatingsmentioning

confidence: 99%

Section: Currentmentioning

confidence: 99%

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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“…Recently, electrodeposited cobalt and its alloy coatings, especially Co–W and Co–P coatings, have been studied extensively for their amorphous nature, increased hardness, higher thermal stability and enhanced wear and corrosion resistance. These coatings are also considered as potential replacement for conventional hard chromium which poses health and environmental threat.…”

Section: Introductionmentioning

confidence: 99%

“…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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Structure, microhardness and corrosion behaviour of nanostructured CoP coatings obtained by direct current and pulse plating

Kosta¹,

Sarret²,

Müller³

2013

Electrochimica Acta

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Pulse plated CoP alloy as substitute for hard chromium electrodeposits

Cited by 9 publications

References 11 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

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

Structure, microhardness and corrosion behaviour of nanostructured CoP coatings obtained by direct current and pulse plating

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