• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.6
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• pp.1807-1818
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• 1991

The frictional characteristic of Zn-Ni electrogalvanized steel sheet was investigated by experimental procedures. To clarify the effect of surface property on the frictional characteristic of Zn-Ni coated steel sheet, Micro-hardness test, SEM analysis and X-ray diffraction analysis were carried out. Coefficients of friction for various stamping lubricant and Ni content in coated layer were measured by a draw bead friction test. The results show that frictional characteristic is very sensitive to Ni content of coated layer and depends on stamping lubricant. For Ni content less than about 11%, selection of proper lubricant is necessary to obtain low coefficient of friction in Zn-Ni coated steel sheet such as in case of cold rolled steel sheet.

• Bulletin of the Korean Chemical Society
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• v.33 no.4
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• pp.1177-1182
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• 2012

The corrosion resistance of 316L stainless steel coated with NiO-YSZ (Ni added yttria stabilized zirconia) was examined in a proton exchange membrane fuel cell (PEMFC) environment. The NiO-YSZ coating was carried out using a sol-gel dip coating method, and the corrosion resistance and interfacial contact resistance (ICR) were determined by the composition and morphology of the NiO-YSZ film. The corrosion resistance increased with increasing Ni content in the NiO-YSZ film, but rapid corrosion was observed when the YSZ film contained more than 15 wt % Ni due to surface cracks. The polarization resistance was improved by several orders of magnitude when 316L stainless steel was coated with a 15 wt % NiO-YSZ film compared to bare 316L. The ICR of the NiO-YSZ film was decreased to that of bare 316L when the YSZ film contained 25 wt % NiO, suggesting the possible application of NiO-YSZ coated stainless steel for a bipolar plate.

• Journal of the Korean institute of surface engineering
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• v.36 no.5
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• pp.398-405
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• 2003

The stainless steel wire requires good corrosion resistance and mechanical properties, such as drawing ability, combined with a high resistance to corrosion. For increasing drawing ability of stainless steel, Ni coating methods have been used in this study. However, there is no information on the electrochemical corrosion behavior of drawed wires after Ni coating. To investigate corrosion resistance and mechanical property of drawed wire, the characteristics of Ni coated wires have been determined by tensile strength tester, hardness tester, field emission scanning microscope, energy dispersive x-ray analysis and potentiodynamic method in 0.1 M HCl. The drawed stainless steel wires showed the strain-induced martensitic structure, whereas non-drawed stainless steel wire showed annealing twin in the matrix of austenitic structure. The hardness and tensile strength of drawed stainless steel wire were higer than that of non-drawed stainless steel wire. Electrochemical measurements showed that, in the case of drawed stainless steel o ire after Ni coating, the corrosion resistance and pitting potential increased compared with non-coated and drawed stainless steel wire due to decrease in the surface roughness.

• Laser Solutions
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• v.4 no.3
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• pp.30-39
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• 2001

This work was tamed out to apply a laser welding technique in joining between a Zn coated low carbon steel plate(SECC) and a free cutting carbon steel shaft(SUM24L) with or without W coating. Experiments were carried out and analysed by applying the FD(factorial design)method to obtain the optimum Laser welding condition. Optical microscopy, SEM, TEM and XRD analyses were performed in order to observe the microstructures in the fusion zone and the HAZ. Mechanical properties of the welded specimens were examined by microhardness test, tensile test and twist test. There was no flawed Zn in the fusion zone by EDS analysis. This means that during the welding process, Zn gas could be eliminated by appropriate shielding gas flow rate and butt welding gap. Ni coating itself did not influence on the tensile strength and hardness. However, twist bending strength and the weld depth of the Ni-coated free cutting carbon steel were lower as compared with those of the uncoated free cutting carbon steel. It was attributed to a lower absorbance of laser beam to the shin Ni surface. According to the results of the factorial design tests, the twist bending strength of welded specimens was primarily affected by pulse width, laser power, frequency and speed.

• Transactions of Materials Processing
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• v.21 no.5
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• pp.330-335
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• 2012

Roll formed steel bolts are electrodeposited with Zn-Ni to protect themselves from corrosion. However, white storage stain or white rust(corrosion) is found on Zn-Ni electrodeposited surface of steel bolts when they are exposed to moisture. In this paper a new process is introduced to protect Zn-Ni electrodeposited steel bolt from white storage stain or white rust for a long time under the salt spray test and high humidity test conditions. The better corrosion resistance could be gotten by the additional process of Ni-P electroless deposition and heat treatment to conventional manufacturing method of Zn-Ni coated steel bolt. The corrosion resistance of Zn-Al powder slurry coated steel bolt showed better than that of Zn-Ni electrodeposited one.

• Journal of Welding and Joining
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• v.14 no.3
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• pp.41-47
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• 1996

The spot weldability of coated steels for automobile has been investigated. Coated steels of SPC-Zn DC, SPC Zn-Ni SC, SPC Zn-Ni DC, SPC Zn-Fe DC and OCCS were welded under different conditions of welding current, force and time. Coating thickness at the welded surface was reduced as increased welding current. Tensile shear strength(TSS) and cross tensile strength (CTS) were increased up to expulsion began, then dropped as increased current. Optimum conditions of welding force and time were different, however 200~250kgf and 15~20cycle were optimum for coated SPC (Steel Plate Cold). Weldability lobes were measured for each coated steel and they showed narrow range of working welding current. The organic composite coated steel (OCCS) had the highest current to get $\sqrt5{t}$ nugget size and narrowest working welding current range.

• Transactions of Materials Processing
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• v.28 no.2
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• pp.71-76
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• 2019

Corrosion resistance is one of the essential properties required in steel bolts. The various types of coatings are used to improve the corrosion resistance of steel bolts. But, roll formed, subsequently Zn alloy electrodeposited and top coated steel bolt easily takes place the white storage stain or white rust under high humidity condition. To investigate the corrosion resistance of roll formed and subsequently the various types of coated steel bolts, their polarization curves were measured by potentio-dynamic tester in this study. Based on the measured polarization curves, the more times of chromate and top coating on roll formed steel bolt, the higher corrosion resistance was shown. The roll formed steel bolt, which was Zn-Ni electro-deposited, two times chromated, one time inorganic top coated, one time organic top coated and annealed, showed the best corrosion resistance.

• Transactions of Materials Processing
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• v.28 no.2
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• pp.77-82
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• 2019

Corrosion occurs well on surface of roll formed and Zn alloy subsequently electro-deposited on steel bolt under wet condition. In this study, variations in corrosion resistance were investigated through the measurement of polarization curves on steel bolts which were roll formed and subsequently coated with various types of coating methods. According to the measured polarization curve, Ni-P electroless deposits on roll formed steel increased the resistance to corrosion. The corrosion resistance of Zn alloy powder coated steel bolt was found to be better than that of Zn-Ni electro-deposited sample.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1992.03a
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• pp.71-82
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• 1992

The frictional characteristics of Zn-Ni coated steel sheets were investigated by draw bead test and strip draw test. In strip draw test, the frictional characteristics were evaluated by the drawing force ratio (Tc/Ts) for half coating-stripped specimens. It is clarified that the drawing force ratio obtained by strip draw test is a convenient parameter compared to coefficient of friction obtained by draw bead test to evaluate the frictional characteristics of Zn-Ni coated steel sheets.

• Journal of Welding and Joining
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• v.31 no.4
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• pp.7-12
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• 2013

The dissimilar welding between magnesium alloy and steel sheet was required in automobile industry to increase the strength of the dissimilar joints. Laser brazing is one of the good joining processes for Mgsteel dissimilar joint. In this study, the effect of coating materials was evaluated on the laser brazing for the dissimilar joint between AZ31 and coated steels such as Zn, Sn and Ni. Diode direct laser was used to braze the lap-edge joint with Mg600 filler wire and Superior #21 flux. The wettability was best on Zn coated steel. The interlayer was formed at the interface between brazement and steel for all coating materials. The strengths of brazed specimen were 146.5N/mm, 204.6N/mm and 101.6N/mm for Zn, Sn and Ni coated steel respectively.