• Corrosion Science and Technology
• /
• v.18 no.1
• /
• pp.16-23
• /
• 2019

Steels for automotive fuel tank require unique properties such as corrosion resistance for fuel, welding for joining, forming for press, and painting for exterior. Recently, automakers have been requiring excellent seam weldable steels to enhance manufacturing productivity of fuel tank. Thus, POSCO developed a new type of functional steels coated with nano-composite thin layer on Zn-Ni plating steels. The nano-composite coating solution was prepared by mechanical fine dispersion of solutions consisting of polymeric resin and nano-composite materials in aqueous media. The composite solution was coated on the plating steel surface by using roll coater and cured through induction furnace. These new developed plating steels were evaluated for quality performances such as seam and spot weldability, press formability, and corrosion resistance. These new functional steels coated with nano-composite layer exhibited excellent seam weldability and press formability. Detailed discussion of coating solution and experimental results suggest that nano-sized composite dispersion as coating layer plays a key role in enhancing the quality performance.

• Corrosion Science and Technology
• /
• v.23 no.3
• /
• pp.215-220
• /
• 2024

Recently, the demand for Zn-Ni electrogalvanized steel sheets for home appliances and automobiles is increasing. Products should have a thick plating (30 to 40 g/m²) on both side with a thin thickness (≤ 0.8 mm) and the highest surface quality. By a high current density operation, current is concentrated in the edge part of the steel sheet, resulting in large surface dent defects due to dendritic plating. This can lead to a low productivity due to low line speed operation. To solve this problem, this study aimed to identify factors influencing dendritic plating. A cylindrical electroplating device was manufactured. Effects of cut edge shape and thickness of steel plate, current density, temperature, flow rate, electrolyte concentration, and pH on dendrite generation of Zn-Ni electroplating were examined. To investigate effect of edge shape of the steel sheet, the steel sheet was manufactured using three processing methods: shearing, polishing after shearing, and laser. Relative effects thickness and cut edge processing methods of the steel plate, current density, temperature, flow rate, electrolyte concentration, and pH of plating solution on dendrite plating were investigated. To prevent dendrite plating, an edge mask was manufactured and its application effect was investigated.

• Journal of the Korean institute of surface engineering
• /
• v.9 no.3
• /
• pp.1-4
• /
• 1976

In order to get high wear-resistant gold alloy plating on electronic parts, on attempt has been made, in which Cu, Ni, and Zn EDTA salts were added in gold palting solution. The results obtained on the wear resistance are as follows: 1. The addition of 0.5g/ι or over Cu in plating solution, showed 1.5 times more wear resistance than in case of no addition. 2. The addition of 1.5g/ι or over Ni, showed 3.5 times more wear-resistance . 3. The addition of 1.5g/ι and 4.0g/ι Zn , showed 3.5 times and 6.8 times more wear resistance , respectively. 4. The addition of 1.5g/ι Ni and 1.0g/ι Zn simultaneously , showed about 10 times more wear resistance than in case of no addition.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.51 no.2
• /
• pp.82-86
• /
• 2002

A series of $Ni_xZn_yFe_{3-x-y}O_4$ films were prepared by spin-spray ferrite plating on glass substrates from aqueous solution at $90[^{\circ}C]$. The magnetic properties in terms of contents of Ni and Zn in the plated films are presented. All the films are polycrystalline with spinel structure. At x+y=0.58, the film presents preferential orientation. As composition of y in the films increases grain size and void in the films increases, while saturation magnetization and coercive force of the films decrease.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2001.11a
• /
• pp.5-5
• /
• 2001

• Journal of the Korean Magnetics Society
• /
• v.15 no.3
• /
• pp.202-206
• /
• 2005

The present investigation provides an electromagnetic radiation absorptive composition which comprises silver-coated ferrite microspheres dispersed in silicon rubber matrix for the aim of thin microwave absorber in GHz frequencies. Ni-Zn ferrite spheres with $50{\mu}m$ size in average were prepared by spray-drying and sintering at $1130^{\circ}C$. Conductive silver layer was plated on ferrite spheres by electroless plating. Conductive Ni-Zn ferrite sphere with uniform silver layer were obtained in the concentration of 10 g/L $AgNO_3$ per 20 g ferrite spheres. For this powder, electrical resistance is reduced as low as $10^{-2}\~10^{-3}\;\Omega$. The most sensitive material parameters with silver plating is real and imaginary parts of complex permittivity. The conductive Ni-Zn ferrite spheres have large values of dielectric constant. Due to this high dielectric constant of microspheres, matching thickness is reduced to as low as 2 mm at the frequency of 7 GHz, which is much thinner than conventional ferrite absorbers.

• Resources Recycling
• /
• v.10 no.3
• /
• pp.23-28
• /
• 2001

Zinc ion could be recovered from metal plating wastewater with the spent iron oxide catalyst which was used in the plant of Styrene Monomer(SM) production. The zinc was recovered more than 98.7% at higher than pH 2.0. The saturation magnetization of the spent catalyst is enough high as 59.4 emu/g to apply in the solid-liquid separation after treating the wastewater. The mechanism of zinc recovery with the iron oxide catalyst could be a electro-chemical adsorption at pH 3.0~8.5, and a precipitation as $Zn(OH)_2$ at higher than pH 8.5.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1997.10a
• /
• pp.224-227
• /
• 1997

In Ni and Zn plating, microstructure and corrosion behavior of electrodeposits with various electroplating condition were investigated. Optical microstructure, SEM images and polarization curves of electrodeposits are different with plating time and temperature.

• Journal of the Korea Convergence Society
• /
• v.9 no.11
• /
• pp.285-290
• /
• 2018

The steel has been used in modern industry, car maker and electric appliance. The steel have some problem, specially corrosion problem. To solve corrosion problem, Zn electrodeposit on steel have been adapted. Recently, The modern industry asks to increase corrosion resistance. Naturally, Increasing corrosion resistance increases the thickness of Zn electrodeposit. But increasing thickness of Zn electrodeposit has some problems. In making part, There are some crack. This crack cause to decrease corrosion resistance. To solve this problem, it is interested in Zn Based alloy electrodeposit such as Zn-Cr. Here, the influence of the electrolytic conditions on the composition of the alloy plating in the chloride bath was investigated. The results are explained by the cathode overvoltage curve of Cr and Zn. As the current density of the cathode increases, Zn content of electrodeposit decrease and Cr content of electrodeposit increase. As the temperature of the electrolyte increases, Zn content of electrodeposit decrease and Cr content of electrodeposit increase.

• Korean Journal of Materials Research
• /
• v.32 no.9
• /
• pp.361-368
• /
• 2022

The overall process, from the pre-treatment of aluminum substrates to the eco-friendly neutral electroless Ni-P plating process, was observed, compared, and analysed. To remove the surface oxide layer on the aluminum substrate and aid Ni-P plating, a zincation process was carried out. After the second zincation treatment, it was confirmed that a mostly uniform Zn layer was formed and the surface oxide of aluminum was also removed. The Ni-P electroless plating films were formed on the secondary zincated aluminum substrate using electroless plating solutions of pH 4.5 and neutral pH 7.0, respectively, while changing the plating bath temperature. When a neutral pH7.0 electroless solution was used, the Ni-P plating layer was uniformly formed even at the plating bath temperature of 50 ℃, and the plating speed was remarkably increased as the bath temperature was increased. On the other hand, when a pH 4.5 Ni-P electroless solution was used, a Ni-P plating film was not formed at a plating bath temperature of 50 ℃, and the plating speed was very slow compared to pH 7.0, although plating speed increased with increasing bath temperature. In the P contents, the P concentration of the neutral pH 7.0 Ni-P electroless plating layer was reduced by ~ 42.3 % compared to pH 4.5. Structurally, all of the Ni-P electroless plating layers formed in the pH 4.5 solution and the neutral (pH 7.0) solution had an amorphous crystal structure, as a Ni-P compound, regardless of the plating bath temperature.