Evaluation of Corrosion Properties of Electroless NiP/Nano-SiC Composite Coatings

2011 ◽  
Vol 471-472 ◽  
pp. 203-208
Author(s):  
Arman Zarebidaki ◽  
Saeed Reza Allahkaram

Ni-P/nano- SiC composite coatings were deposited in different concentrations of SiC nano-particles in the bath. The hardness and corrosion resistance of the composite coatings with different content of SiC nano-particles were measured. Moreover, the structure of the composite coatings was investigated by means of X-ray diffraction (XRD), while their morphologies and elemental composition were analyzed using scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS). Results showed that co-deposited SiC nano-particles contributed to increase the hardness but corrosion resistance of electroless Ni-P coatings decreased due to agglomeration of nano-particles and increasing porosity of coatings.

2012 ◽  
Vol 05 ◽  
pp. 817-824 ◽  
Author(s):  
S.R. Allahkaram ◽  
A. Zarebidaki ◽  
T. Rabizadeh

SiC and SiO 2 nano-particles were co-deposited with electroless NiP coating onto API-5L-X65 steel substrates with 7g/L load of nano-particles in the bath at pH 4.6 ± 0.2 and temperature of 90 ± 2°C. The hardness and corrosion resistance of the composite coatings were measured using micro-hardness, polarization and electrochemical impedance spectroscopy techniques, respectively. Moreover, the structure of the composite coatings was investigated by means of X-ray diffraction (XRD) technique, while their morphologies and elemental compositions were analyzed using a scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS). Results showed that co-deposited nano-particles caused an increase in the hardness of the composite coatings. Corrosion tests showed that addition of nano- SiO 2 particles improved corrosion resistance of electroless Ni - P coatings in salty atmosphere but addition of nano- SiC particles decreased, due to the agglomeration of SiC nano-particles together with an increase in the porosity of the composite coatings.


2017 ◽  
pp. 1303-1326
Author(s):  
Prasanna Gadhari ◽  
Prasanta Sahoo

Electroless nickel coatings are widely popular in various industrial sectors due to their excellent tribological properties. The present study considers optimization of coating parameters along with annealing temperature to improve microhardness and corrosion resistance of Ni-P-TiO2 composite coatings. Grey relational analysis is used to find out the optimal combination of coating parameters. From the analysis, it is confirmed that annealing temperature of the coating has the most significant effect and amount of titanium particles in the coating has some significant effect on corrosion properties of the coating. The same trend is observed in case of combined study of corrosion behavior and microhardness. The surface morphology, phase transformation and the chemical composition are examined using scanning electron microscopy, X-ray diffraction analysis and energy dispersive analysis respectively. The Ni-P-TiO2 composite coating revealed nodular structure with almost uniform distribution of titanium particles and it turns in to crystalline structure after heat treatment.


2011 ◽  
Vol 306-307 ◽  
pp. 901-906 ◽  
Author(s):  
Huan Ming Chen ◽  
Ya Hong Gao ◽  
Qiong Lv ◽  
Dong Yang ◽  
Xin Xin Lin

The Ni-P-W/nano-Al2O3composite coatings were deposited on the surface of sintered NdFeB permanent magnet by electroless plating method. The morphology and the phases of Ni-P-W/nano-Al2O3composite coatings were investigated using scanning electron microscopy and X-ray diffraction respectively. The hardness and the corrosion resistance of the composite coatings were also tested. The results indicated that the composite coatings morphology appears closely nodules morphology, and the microhardness increases with increasing incorporation of Al2O3ratio. Compared with NdFeB magnet and Ni-P-W alloy coatings, the corrosion resistance of the composite coatings was superior to that of the NdFeB magnet and the alloy coating obviously.


Author(s):  
Bo Xu ◽  
Yafeng He ◽  
Xiangzhi Wang ◽  
Weimin Gan

Abstract Ceramic coatings were prepared on the surface of 7050 highstrength aluminum alloy using micro-arc oxidation in an aluminate electrolyte with added graphene. To analyze the surface morphology, roughness, phase composition, and corrosion resistance, scanning electron microscopy, X-ray diffraction, X-ray photoelectron, and electrochemical measurements were used, respectively. The addition of 9 g · L-1 of graphene to the electrolyte decreased the micro-pore size of the composite coatings and improved the density. In addition, with the addition of graphene, the roughness was the lowest, and the corrosion resistance was significantly improved.


Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2253
Author(s):  
Channagiri Mohankumar Praveen Kumar ◽  
Manjunath Patel Gowdru Chandrashekarappa ◽  
Raviraj Mahabaleshwar Kulkarni ◽  
Danil Yurievich Pimenov ◽  
Khaled Giasin

Pure Zn (Zinc) and its Zn–WO3 (Zinc–Tungsten trioxide) composite coatings were deposited on mild steel specimens by applying the electrodeposition technique. Zn–WO3 composites were prepared for the concentration of 0.5 and 1.0 g/L of particles. The influence of WO3 particles on Zn deposition, the surface morphology of composite, and texture co-efficient were analyzed using a variety of techniques, such as X-ray diffraction (XRD) and scanning electron microscopy (SEM) with Energy Dispersive X-ray analysis (EDX). Higher corrosion resistance and microhardness were observed on the Zn–WO3 composite (concentration of 1.0 g/L). The higher corrosion resistance and microhardness of 1.0 g/L Zn–WO3 nanocomposite coatings effectively protect the steel used for the manufacture of products, parts, or systems from chemical or electrochemical deterioration in industrial and marine ambient environments.


2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
N. Sridhar ◽  
K. Udaya Bhat

High phosphorus Ni-P alloy was deposited on aluminium substrate using electroless deposition route. Using zincating bath, the surface was activated before deposition. Deposition time was varied from 15 minutes to 3 hours. Deposit was characterised using scanning electron microscope with energy dispersive spectroscope, X-ray diffraction, and microhardness tester. The corrosion resistance was measured using Tafel extrapolation route. The medium was aqueous 5% HNO3 solution. The analysis showed that the deposit consisted of nodules of submicron and micron scale. The predominant phase in the deposit was nickel along with phosphides of nickel. Compared to substrate material, deposit showed higher hardness. With increase in deposition time, the deposit showed more nobleness in 5% HNO3 solution and nobleness reached a limiting value in 1 hour deposition time.


2011 ◽  
Vol 66-68 ◽  
pp. 1668-1675 ◽  
Author(s):  
Xue Tao Yuan ◽  
Zhi Qiang Hua ◽  
Lei Wang ◽  
Dong Bai Sun ◽  
Song Lin Chen

Composite coatings were prepared using electroless nickel bath containing different concentrations of Al2O3nano-particles. The analyses of coating compositions, carried out by EDS, showed that there is marginal difference between phosphorus contents of NiP and NiP/nano-Al2O3deposits. The structure of the coatings was examined by scanning electron microscopy (SEM), and X-ray diffraction (XRD). It has been found that the co-deposition of nano-Al2O3particles with Ni disturbs the NiP coating’s regular surface structure and increases its surface roughness. DC and AC electrochemical tests were carried out on such coatings in a 3.5wt.% solution of NaCl in order to evaluate their corrosion resistance. The potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests both showed that, the corrosion resistance of NiP-Al2O3coatings firstly increases and then decreases when Al2O3concentration in electroless bath is increasing, but the corrosion resistance of NiP-Al2O3composite coating is better than that of amorphous NiP coating.


Minerals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 533 ◽  
Author(s):  
Xin Zhang ◽  
Guanghui Li ◽  
Jinxiang You ◽  
Jian Wang ◽  
Jun Luo ◽  
...  

Ludwigite ore is a typical low-grade boron ore accounting for 58.5% boron resource of China, which is mainly composed of magnetite, lizardite and szaibelyite. During soda-ash roasting of ludwigite ore, the presence of lizardite hinders the selective activation of boron. In this work, lizardite and szaibelyite were prepared and their soda-ash roasting behaviors were investigated using thermogravimetric-differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), and scanning electron microscope and energy dispersive spectrometer (SEM-EDS) analyses, in order to shed light on the soda-ash activation of boron within ludwigite ore. Thermodynamics of Na2CO3-MgSiO3-Mg2SiO4-Mg2B2O5 via FactSage show that the formation of Na2MgSiO4 was preferential for the reaction between Na2CO3 and MgSiO3/Mg2SiO4. While, regarding the reaction between Na2CO3 and Mg2B2O5, the formation of NaBO2 was foremost. Raising temperature was beneficial for the soda-ash roasting of lizardite and szaibelyite. At a temperature lower than the melting of sodium carbonate (851 °C), the soda-ash roasting of szaibelyite was faster than that of lizardite. Moreover, the melting of sodium carbonate accelerated the reaction between lizardite with sodium carbonate.


2012 ◽  
Vol 501 ◽  
pp. 316-320
Author(s):  
Jian Zhang Guo ◽  
Bin Xu

In order to improve the surface property of the steel tire mold, carbon steels were processed by electroless Ni-P and Ni-P-PTFE under contrast experiment. The coatings were characterized by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrometer (EDS). The wear resistance and corrosion resistance of the coatings were explored by tribometer, salt spray cabinet and advanced electrochemical system. The experimental results showed that the Ni-P coating was amorphous structure, and the Ni-P-PTFE coating was micro-pore structure; The wear resistance of Ni-P-PTFE coating was superior to Ni-P coating; In view of the micro-pore structure, the corrosion resistance of Ni-P-PTFE coating was worse than Ni-P coating, but they were all superior to carbon steels, and the service life of the steel tire mold were improved.


2021 ◽  
Vol 325 ◽  
pp. 181-187
Author(s):  
Martin Nguyen ◽  
Radomír Sokolář

This article examines the influence of fly ash on corrosion resistance of refractory forsterite-spinel ceramics by molten iron as a corrosive medium. Fly ash in comparison with alumina were used as raw materials and sources of aluminium oxide for synthesis of forsterite-spinel refractory ceramics. Raw materials were milled, mixed in different ratios into two sets of mixtures and sintered at 1550°C for 2 hours. Samples were characterized by X-ray diffraction analysis and thermal dilatometric analysis. Crucibles were then made from the fired ceramic mixtures and fired together with iron at its melting point of 1535°C for 5 hours. The corrosion resistance was evaluated by scanning electron microscopy on the transition zones between iron and ceramics. Mixtures with increased amount of spinel had higher corrosion resistance and mixtures with fly ash were comparable to mixtures with alumina in terms of corrosion resistance and refractory properties.


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