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Roberto Giovanardi - One of the best experts on this subject based on the ideXlab platform.
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a comparison between the Corrosion resistances of some hvof sprayed metal alloy coatings
Surface & Coatings Technology, 2008Co-Authors: Giovanni Bolelli, Luca Lusvarghi, Roberto GiovanardiAbstract:Abstract This study compares the Corrosion resistance of one Co–based alloy coating, namely Co–28Mo–17Cr–3Si (similar to Tribaloy-800), four Ni-based alloy coatings, namely Ni–17Cr–4Fe–4Si–3.5B–1C (Diamalloy-2001), Ni–20Cr–10W–9Mo–4Cu–1C–1B–1Fe (Diamalloy-4006), Ni–22Cr–9Mo–4Nb–5Fe (similar to Inconel-625), Ni–32Mo–16Cr–3Si–2Co (similar to Tribaloy-700), and a (WC-12Co)–33Ni–9Cr–3.5Fe–2Si–2B–0.5C cermet–Ni alloy blend coating. They were produced by liquid-fuelled HVOF spraying onto AISI1040 steel plates. Electrolytic hard chrome (EHC) plating was characterised as a reference material, to verify whether some HVOF coatings are suitable as an EHC replacement. The microstructure of the coatings was examined by SEM and XRD. Electrochemical polarization tests and free Corrosion tests were performed in 0.1 M HCl aqueous solution; the corrodkote test (ASTM B380-97R02) was also performed, to rank coatings qualitatively. The lowest Corrosion current densities (Icorr) were recorded for EHC and Tribaloy-700. The latter coating contained few secondary phases and little porosity; the damage was mainly due to Corrosion activation along lamellae boundaries. Diamalloy-2001 exhibited the highest Icorr and was significantly damaged after the polarization test, as its multi-phase microstructure had triggered Severe Galvanic Corrosion. During free Corrosion in 0.1 M HCl, Tribaloy-700 and Diamalloy-4006 retained rather stable polarization resistance (Rp), whereas the Rp of EHC decreased significantly. Tribaloy-700 survived 40 h of corrodkote test with no apparent damage and EHC underwent limited pitting Corrosion. All other coatings had visible Corrosion. The Inconel-625 coating failed to protect the substrate after 20 h of testing, due to inadequate processing conditions.
Giovanni Bolelli - One of the best experts on this subject based on the ideXlab platform.
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a comparison between the Corrosion resistances of some hvof sprayed metal alloy coatings
Surface & Coatings Technology, 2008Co-Authors: Giovanni Bolelli, Luca Lusvarghi, Roberto GiovanardiAbstract:Abstract This study compares the Corrosion resistance of one Co–based alloy coating, namely Co–28Mo–17Cr–3Si (similar to Tribaloy-800), four Ni-based alloy coatings, namely Ni–17Cr–4Fe–4Si–3.5B–1C (Diamalloy-2001), Ni–20Cr–10W–9Mo–4Cu–1C–1B–1Fe (Diamalloy-4006), Ni–22Cr–9Mo–4Nb–5Fe (similar to Inconel-625), Ni–32Mo–16Cr–3Si–2Co (similar to Tribaloy-700), and a (WC-12Co)–33Ni–9Cr–3.5Fe–2Si–2B–0.5C cermet–Ni alloy blend coating. They were produced by liquid-fuelled HVOF spraying onto AISI1040 steel plates. Electrolytic hard chrome (EHC) plating was characterised as a reference material, to verify whether some HVOF coatings are suitable as an EHC replacement. The microstructure of the coatings was examined by SEM and XRD. Electrochemical polarization tests and free Corrosion tests were performed in 0.1 M HCl aqueous solution; the corrodkote test (ASTM B380-97R02) was also performed, to rank coatings qualitatively. The lowest Corrosion current densities (Icorr) were recorded for EHC and Tribaloy-700. The latter coating contained few secondary phases and little porosity; the damage was mainly due to Corrosion activation along lamellae boundaries. Diamalloy-2001 exhibited the highest Icorr and was significantly damaged after the polarization test, as its multi-phase microstructure had triggered Severe Galvanic Corrosion. During free Corrosion in 0.1 M HCl, Tribaloy-700 and Diamalloy-4006 retained rather stable polarization resistance (Rp), whereas the Rp of EHC decreased significantly. Tribaloy-700 survived 40 h of corrodkote test with no apparent damage and EHC underwent limited pitting Corrosion. All other coatings had visible Corrosion. The Inconel-625 coating failed to protect the substrate after 20 h of testing, due to inadequate processing conditions.
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A comparison between Corrosion resistances of some HVOF-sprayed metal alloy coatings
'Elsevier BV', 2008Co-Authors: Giovanni Bolelli, Lusvarghi Luca, Giovanardi RobertoAbstract:This study compares the Corrosion resistance of one Co\u2013based alloy coating, namely Co\u201328Mo\u201317Cr\u20133Si (similar to Tribaloy-800), four Ni-based alloy coatings, namely Ni\u201317Cr\u20134Fe\u20134Si\u20133.5B\u20131C (Diamalloy-2001), Ni\u201320Cr\u201310W\u20139Mo\u20134Cu\u20131C\u20131B\u20131Fe (Diamalloy-4006), Ni\u201322Cr\u20139Mo\u20134Nb\u20135Fe (similar to Inconel-625), Ni\u201332Mo\u201316Cr\u20133Si\u20132Co (similar to Tribaloy-700), and a (WC-12Co)\u201333Ni\u20139Cr\u20133.5Fe\u20132Si\u20132B\u20130.5C cermet\u2013Ni alloy blend coating. They were produced by liquid-fuelled HVOF spraying onto AISI1040 steel plates. Electrolytic hard chrome (EHC) plating was characterised as a reference material, to verify whether some HVOF coatings are suitable as an EHC replacement. The microstructure of the coatings was examined by SEM and XRD. Electrochemical polarization tests and free Corrosion tests were performed in 0.1 M HCl aqueous solution; the corrodkote test (ASTM B380-97R02) was also performed, to rank coatings qualitatively.The lowest Corrosion current densities (Icorr) were recorded for EHC and Tribaloy-700. The latter coating contained few secondary phases and little porosity; the damage was mainly due to Corrosion activation along lamellae boundaries. Diamalloy-2001 exhibited the highest Icorr and was significantly damaged after the polarization test, as its multi-phase microstructure had triggered Severe Galvanic Corrosion. During free Corrosion in 0.1 M HCl, Tribaloy-700 and Diamalloy-4006 retained rather stable polarization resistance (Rp), whereas the Rp of EHC decreased significantly. Tribaloy-700 survived 40 h of corrodkote test with no apparent damage and EHC underwent limited pitting Corrosion. All other coatings had visible Corrosion. The Inconel-625 coating failed to protect the substrate after 20 h of testing, due to inadequate processing conditions
Xin Lin - One of the best experts on this subject based on the ideXlab platform.
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microstructure and Corrosion properties of alcocrfeni high entropy alloy coatings deposited on aisi 1045 steel by the electrospark process
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2013Co-Authors: Tai Man Yue, Zhong Ning Guo, Xin LinAbstract:Electrospark deposition (ESD) was employed to clad the AlCoCrFeNi high-entropy alloy (HEA) on AISI 1045 carbon steel. The relationship between the microstructure and Corrosion properties of the HEA-coated specimens was studied and compared with that of the copper-molded cast HEA material. Two major microstructural differences were found between the cast HEA material and the HEA coatings. First, the cast material comprises both columnar and equiaxed crystals with a columnar-to-equiaxed transition (CET), whereas the HEA coatings consist of an entirely columnar crystal structure. The CET phenomenon was analyzed based on Hunt’s criterion. Second, unlike the cast HEA material, there was no obvious Cr-rich interdendritic segregation and nano-sized precipitate distributed within the dendrites of the HEA coating. With regard to Corrosion properties, the Corrosion current of the HEA-coated specimen was significantly lower than for the 1045 steel and the cast HEA material. This was attributed to the ESD specimen having a relatively high Cr oxide and Al oxide content at the surface. Moreover, for the ESD specimen, the absence of Cr-rich interdendritic phase and second-phase precipitation resulted in a relatively uniform Corrosion attack, which is different from the Severe Galvanic Corrosion attack that occurred in the cast specimen.
Derek O Northwood - One of the best experts on this subject based on the ideXlab platform.
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influence of coating thickness on the Galvanic Corrosion properties of mg oxide in an engine coolant
Surface & Coatings Technology, 2009Co-Authors: P Zhang, Xueyuan Nie, Derek O NorthwoodAbstract:Magnesium is subject to Severe Galvanic Corrosion attack in a commercially available engine coolant, when in contact with stainless steel and an Al alloy. Thin oxide coatings with different coating thicknesses were produced using a Plasma Electrolytic Oxidation (PEO) process to protect Mg against the Corrosion attack. The Galvanic Corrosion properties of the PEO coatings were investigated using immersion Corrosion testing. The test results showed that the anti-Corrosion properties of the PEO coatings increased with increasing coating thickness. PEO coatings with a thickness of several micrometers effectively prevented the Galvanic Corrosion of Mg, without significantly reducing the heat conductivity of the Mg.
Luca Lusvarghi - One of the best experts on this subject based on the ideXlab platform.
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a comparison between the Corrosion resistances of some hvof sprayed metal alloy coatings
Surface & Coatings Technology, 2008Co-Authors: Giovanni Bolelli, Luca Lusvarghi, Roberto GiovanardiAbstract:Abstract This study compares the Corrosion resistance of one Co–based alloy coating, namely Co–28Mo–17Cr–3Si (similar to Tribaloy-800), four Ni-based alloy coatings, namely Ni–17Cr–4Fe–4Si–3.5B–1C (Diamalloy-2001), Ni–20Cr–10W–9Mo–4Cu–1C–1B–1Fe (Diamalloy-4006), Ni–22Cr–9Mo–4Nb–5Fe (similar to Inconel-625), Ni–32Mo–16Cr–3Si–2Co (similar to Tribaloy-700), and a (WC-12Co)–33Ni–9Cr–3.5Fe–2Si–2B–0.5C cermet–Ni alloy blend coating. They were produced by liquid-fuelled HVOF spraying onto AISI1040 steel plates. Electrolytic hard chrome (EHC) plating was characterised as a reference material, to verify whether some HVOF coatings are suitable as an EHC replacement. The microstructure of the coatings was examined by SEM and XRD. Electrochemical polarization tests and free Corrosion tests were performed in 0.1 M HCl aqueous solution; the corrodkote test (ASTM B380-97R02) was also performed, to rank coatings qualitatively. The lowest Corrosion current densities (Icorr) were recorded for EHC and Tribaloy-700. The latter coating contained few secondary phases and little porosity; the damage was mainly due to Corrosion activation along lamellae boundaries. Diamalloy-2001 exhibited the highest Icorr and was significantly damaged after the polarization test, as its multi-phase microstructure had triggered Severe Galvanic Corrosion. During free Corrosion in 0.1 M HCl, Tribaloy-700 and Diamalloy-4006 retained rather stable polarization resistance (Rp), whereas the Rp of EHC decreased significantly. Tribaloy-700 survived 40 h of corrodkote test with no apparent damage and EHC underwent limited pitting Corrosion. All other coatings had visible Corrosion. The Inconel-625 coating failed to protect the substrate after 20 h of testing, due to inadequate processing conditions.