Deok-Yong Park

Characterization of plasma electrolytic oxide formed on AZ91 Mg alloy in KMnO4 electrolyte

The aim of this work is to investigate microstructure, corrosion resistance characteristics and nanohardness of the oxide layer on AZ91 Mg alloy by applying different voltage with KMnO4 contained solution. There are lots of closed pores that are filled with another oxide compound compared with the typical surface morphology with pore coated until 350 V of coating voltage. The thickness of oxide layer increases with increasing coating voltage. The oxide layer formed on AZ91 Mg alloy in electrolyte with potassium permanganate consists of MgO and Mn2O3. Corrosion potential of the oxide layer on AZ91 Mg alloy obtained at different plasma electrolytic oxidation(PEO) reaction stages increases with increasing coating voltage. The corrosion resistance of AZ91 Mg alloy depends on the existence of the manganese oxide in the oxide layer. The inner barrier layer composed of the MgO and Mn2O3 may serve as diffusion barrier to enhance the corrosion resistance and may partially explain the excellent anti-corrosion performance in corrosion test. Nanohardness values increase with increasing coating voltage. The increase in the nanohardness may be due to the effect of manganese oxide in the oxide layer on AZ91 Mg alloy coated from electrolyte containing KMnO4.

The Effects of Current Density on the Grain Size of Electroplated Thick Film Nickel(Ni) by Using Ni Metal Powder Dissolved Chloride Bath

Nanocrystalline nickel (Ni) tick films were synthesized by direct current electrodeposition at current density from 1 to and pH

Effect of Deposition Conditions on Properties of Cu Thin Films Electrodeposited from Pyrophosphate Baths

Effects of current density, electrodeposition temperature and solution pH on properties of Cu thin films electrodeposited from pyrophosphate bath were investigated. Current efficiency was decreased with increasing current density and increased with increasing temperature. But solution pH slightly influenced on current efficiency and current efficiency was measured to be above 90% at both room temperature and . Residual stress of Cu thin film electrodeposited at room temperature was decreased with increasing current density, while current density reaches to 60 or more, stress became close to zero. Cu thin films electrodeposited at exhibited the residual stress range of 0~40 MPa. At room temperature, dendritic surface morphology was observed above the current density of 30 and at , above the current density of 100 . Cu thin films electrodeposited from bath solution with room temperature and mainly consisted of (111) peaks. Specially, Cu thin film electrodeposited at 30 and exhibited strong preferred orientation of (111) peaks.

Study of Stress Changes in Nanocrystalline Ni Thin Films Eletrodeposited from Chloride Baths

Nanocrystalline Ni thin films were electodeposited from chloride baths to investigate the influences of additive concentration, current density and solution pH on residual (or internal) stress, surface morphology, and microstructure of the films. It was observed that residual stress in Ni thin film was changed from tensile stress mode (about 150 MPa) to compressive stress mode (about -100 MPa) with increasing saccharin concentration as an additive. Microstructure of Ni thin films was changed with/without saccharin in baths. Ni thin films electrodeposited from saccharinfree bath mainly consisted of both FCC(111) and FCC(200) phases. However, Ni thin film electrodeposited from the baths containing saccharin exhibited FCC(111), FCC(200) and FCC (311) phases [sometimes, FCC (220)]. Current density influenced residual stress of Ni thin films. It was measured to be the lowest compressive stress value (about-100 MPa) in range of current density of . Solution pH also influenced residual stress of Ni thin film. Addition of saccharin in baths affected grain size of Ni thin films. Grain sizes of Ni thin films were measured to be about 60 nm without saccharin and 24~38 nm with more than 0.0005M saccharin concentration. Surface of Ni thin films was changed from nodular to smooth surface morphology with addition of saccharin.

Study of Stress Changes in Nanocrystalline CoW Thin/Thick Film Alloys Eletrodeposited from Citrate Baths

Nanocrystalline CoW thin/thick film alloys were electodeposited from citrate baths to investigate the influences of metal ion concentration, current density and solution pH on chemical composition, current efficiency, residual stress, surface morphology, and microstructure of the film. Deposit W (tungsten) content in CoW thin/thick film increased with increasing W ion concentration, current density, and solution pH in the plating bath. It was observed that residual stress in CoW thin/thick film decreased with increasing W ion concentration and solution pH. CoW thin film exhibited mixed phases of hop Co [(100) and (002)] and hcp [(002) and (201)] at W ion concentration with 0.02 to 0.08 M. The microstructure of CoW thin film at W ion concentration of 0.1 to 0.2 M was close to amorphous phase. The dominant phases were found to be hop Co (002) and hop [(200), (002) and (201)] at the current densities of 5, 10, 25, and CoW thin film at the current densities of 50 and was close to amorphous phase. At solution pH 8.7, CoW thin film exhibited hcp Co (002) and hop [(200), (002) and (201)]. Below solution pH 8.7, CoW thin film exhibited amorphous microstructure. The optimum electrodeposition conditions for CoW thin/thick film were found to be W ion concentration of 0.08 M, current density of , and solution pH 8.7.

Effects of Electrodeposition Conditions on Properties of Ni Thin Films Electrodeposited from Baths Fabricated by Dissolving Metal Ni Powders

Korea Atomic Energy Research Institute, Daejeon, 305-353, Korea(Received June 16, 2015 ; revised June 25, 2015 ; accepted June 29, 2015)AbstractChloride plating solution was fabricated by dissolving metal Ni powders in solution with HCl and de-ionized water. Effects of deposition conditions on the properties of Ni films electrodeposited from chloridebaths were studied. Current efficiency of Ni films electrodeposited from the baths containing saccharin wasdecreased with increasing the current density. Residual stress of Ni thin films ware measured to be about230 ~ 435 MPa in the range of current density of 10 ~ 25 mA/cm

Influence of Chemical Composition of Pyrophosphate Copper Baths on Properties of Electrodeposited Cu Films

전기도금공정을 이용하여 상온에서 제조된 Cu박막의 특성에 미치는 피로인산구리용액의 화학성분(

Supercapacitive properties of polyaniline/Nafion/hydrous RuO2 composite electrodes

Cu^{2+}

Corrosion resistance of oxide layers formed on AZ91 Mg alloy in KMnO4 electrolyte by plasma electrolytic oxidation

농도,

Electrodeposition of FeCoNi thin films for magnetic-MEMS devices

K_4P_2O_7