• Journal of the Korean institute of surface engineering
• /
• v.36 no.6
• /
• pp.437-443
• /
• 2003

The effects of additive(grain refiner, GR) on process efficiency of the Ni-Fe-P alloy electrodeposition and the material properties of the deposit were investigated. Electrochemical properties of the deposits were investigated using polarization and electrochemical impedance techniques, and the material properties of the deposits were characterized through inductively coupled plasma(ICP), spiral contractometer, XRD, SEM and TEM. When the additive was added into the electrodeposition bath, current efficiency, Ni content and corrosion resistance of the deposit increased, whereas residual stress, surface roughness and grain size of the deposit decreased.

• Electrical & Electronic Materials
• /
• v.9 no.6
• /
• pp.542-550
• /
• 1996

ZnO-based ceramic varistors containing NiO range 0.5 mol% to 4.0 mol% were fabricated by standard ceramic techniques. The influence of NiO on the microstructure and electrical behavior of ZnO varistor was investigated. As the content of NiO additive increases, average grain size decreased from 16.5.mu.m to 13.2.mu.m, and the amount of NiO existing in the grain interior and grain boundary region was approximately equal. NiO acted as an acceptor which decreases donor concentration due to the increase of Zn vacancy in the grain, and as a driver which migrates Zn interstitial in the depletion region toward the interface of grain boundary, which resulted in the decrease of interface state density. As a result, increasing the content of NiO additive, barrier height, nonlinear exponent, and varistor voltage decreased, and leakage current increased. Wholly, the physical and electrical properties of the ZnO varistor can be said to be affected by the NiO additive.

• Transactions of Materials Processing
• /
• v.33 no.1
• /
• pp.36-42
• /
• 2024

Additive manufacturing with 3XX austenitic stainless steels has been widely investigated during a decade due to its high strength, good corrosion resistance, and fair weldability. However, in recently, Ni price drastically increased due to the high demand of secondary battery for electric mobilities. Thus, it is essential to substitute the Ni with Mn for reducing stainless steels price. Meanwhile, the chemical composition changes in stainless steels not only affect to its properties but also change the optimal processing parameters during additive manufacturing. Therefore, it is necessary to optimize the processing parameters of each alloy for obtaining high-quality product using additive manufacturing. After processing optimization, mechanical properties and microstructure of the laser-powder bed fusion processed Fe-15Cr-7Ni-3Mn alloy were investigated in both room (298 K) and cryogenic (77 K) temperatures. Since the temperature reduction affects to the deformation mechanism transition, multi-scale microstructural characterization technique was conducted to reveal the deformation mechanism of each sample.

• Corrosion Science and Technology
• /
• v.3 no.3
• /
• pp.112-117
• /
• 2004

This work investigated the material properties of Ni-P-B alloy electrodeposits obtained from a Ni sulfamate bath as a function of the contents of the P and B sources($H_3PO_3$ and dimethyl amine borane complex(DMAB), respectively) with/without additives. Chemical composition, residual stress, microstructure and micro hardness were investigated using ICP(inductively coupled plasma) mass spectrometer, flexible strip, XRD, TEM and micro Vickers hardness tester, respectively. From the results of the compositional analysis, it was observed that P and B are incorporated competitively during the electrodeposition and the sulfur from the additive is codeposited into the electrodeposit. The measured residual stress value increased in the order of Ni, Ni-P, Ni-B and Ni-P-B electrodeposits indicating that boron affects the residual tensile stress greater than phosphorus. As the contents of the alloying element sources of P and B increased, crystallinity and the grain size of the electrodeposit decreased. The effect of boron on crystallinity and grain size was also relatively larger than the phosphorus. It can be explained that the boron with a smaller atomic radius contributes to the increase of residual stress in the tensile direction and the larger restraining force against the grain growth more significantly than the phosphorus with a larger atomic radius. Introduction of an additive into the bath retarded crystallization and grain growth, which may be attributed to the change of the grain growth kinetics induced by the additive adsorbed on the substrate and electrodeposit surfaces during electrodeposition.

• Journal of Magnetics
• /
• v.3 no.4
• /
• pp.116-119
• /
• 1998

Influence of small additions ($\leq$2.0 at.%) of Al, Ti, Co, and Ni on the microstructural development and the magnetic properties of melt-spun Fe-Bd-C alloys was investigated. Addition of these elements tended to stabilize the crystallization of as-spun ribbons. Especially, Al and Ti preferred to stabilize$ Fe_{17}Nd_2C_x.$ The average grain size of Fe17Nd2Cx (0.1~0.3 ${\mu}{\textrm}{m}$), obtained by a proper annealing, in the ribbon treated with 0.5 at.% additive was much smaller than that of additive-free ribbons, which would be the major source of large increase in coercivity. Among the additives, Ni was very effective to increase the coercivity whereas Co had beneficial effect on $T_c.$ By adding 0.5 at.% Ni, intrinsic coercivities of more than 1.4 T, 40~50% higher than that (~1.0T) of additive-free ribbons, can be obtained after annealing at 750~80$0^{\circ}C$.

• Korean Journal of Materials Research
• /
• v.15 no.6
• /
• pp.399-407
• /
• 2005

The effect of IN738 additive powder on microstructure and mechanical properties of the wide-gap region brazed with BNi-3 filler metal powder was investigated. The wide-gap brazing was conducted in a vacuum of $2\times10^{-5}torr\;at\;1200^{\circ}C$ with various powder mixing ratios of additive to filler powders. The microstructures of the wide-gap brazed region were analyzed by SEM and AES. The region brazed with only BNi-3 filler metal powder had a microstructure consisted of proeutectic, binary eutectic and ternary eutectic structure, while that brazed with a mixture of IN738 additive powder and BNi-3 filler metal powder had a microstructure consisted of IN738 additive powder, binary eutectic of $Ni_3B-Ni$ solid solution and (Cr, W)B. The fracture strength of the wide-gap brazed region was about 680 MPa regardless of the additive powder mixing ratios. Cracks were initiated at the (Cr, W)B and binary eutectic of $Ni_3B-Ni$ solid solution, and propagated through them in the wide-gap brazed region, which lowered the fracture strength of the region.

• Journal of the Korean institute of surface engineering
• /
• v.51 no.1
• /
• pp.62-70
• /
• 2018

Sulfamate plating solution containing a small amount of chloride bath was fabricated to study the properties of the electrodeposited Ni thin films. Effects of the changes of current density and additive concentration on current efficiency, residual stress, surface morphology and microstructure of Ni thin films electrodeposited from Ni sulfamate-chloride baths were investigated. The current efficiency was measured to be more than about 95%, independent of the changes of current density and saccharin concentration in the baths. Residual stress of Ni thin film was appeared to be the compressive stress modes in the range of $5{\sim}30mA/cm^2$ current density. Maximum compressive stress was observed at the current density of $10mA/cm^2$. Compressive stress values of Ni thin/thick films were increased to be about -85~-100 MPa with increasing saccharin concentration from 0 to 0.0195 M(4 g/L). Surface morphology was changed from smooth to nodule surface appearance with increasing the current density. Smooth surface morphology of Ni thin films electrodeposited from the baths containing saccharin was observed, independent of the saccharin concentration. Ni thin/thick films consist of FCC(111), FCC(200), FCC(220), FCC(311) and FCC(222) peaks. It was revealed that the FCC(200) peak of Ni thin films is the preferred orientation in the range of $5{\sim}30mA/cm^2$ current density. The intensity of FCC(200) peak was gradually decreased and the intensity of FCC(111) peak was increased with increasing saccharin concentration in the baths.

• Journal of Electrochemical Science and Technology
• /
• v.14 no.3
• /
• pp.272-282
• /
• 2023

Ni-rich layered oxides cathode has recently gained attention as an advanced cathode material due to their applicable energy density. However, as the Ni component in the layered site is increased, the high reactivity of Ni⁴⁺ results in parasitic reaction associated with decomposing electrolyte, which leads to a rapid decreasing the lifespan of the cell. The electrolyte additive triallyl borate (TAB) improves interfacial stability, leading to a stable cathode-electrolyte interphase (CEI) layer on the LNCM83 cathode. A multi-functionalized TAB additive can produce a uniformly distributed CEI layer via electrochemical oxidation, which implies an increase in long-term cycling performance. After 100 cycles at elevated temperature, the cell tested by 0.75 TAB retained 88.3% of its retention ratio, whereas the cell performed by TAB-free electrolyte retained 64.1% of its retention. Once the TAB additive formed CEI layers on the LNCM83 cathode, it inhibited the decomposition of carbonate-based solvents species in addition to the dissolution of transition metal components from the cathode. The addition of TAB to LNCM83 cathode material is believed to be a promising way to increase the electrochemical performance.

• Transactions of the Korean hydrogen and new energy society
• /
• v.19 no.5
• /
• pp.394-402
• /
• 2008

The Effects of Cu or Ni additives co-added with Ce/Zr mixed oxides to Fe-based oxide mediums were investigated for the purpose of the replacement of Rh, a precious metal additive, in terms of hydrogen storage(reduction by hydrogen) and release(water splitting). From the results of temperature programmed reduction(TPR), initial reduction rate of iron oxide in the mediums was greatly increased with the addition of Cu, similar to that of Rh. For isothermal redox reaction of 10 cycles, the total amounts of hydrogen evolved in water splitting steps for the mediums added with Cu or Ni were highly maintained at ca. 7 mmol/g-material, even though the oxidation rates were slightly lower than that for the medium added with Rh. This result suggests that the replacement of Rh to Cu or Ni is possible as a co-additive for Fe-based oxide mediums.

• Corrosion Science and Technology
• /
• v.2 no.4
• /
• pp.197-201
• /
• 2003

In this study, Ni-P layers were electroplated on the surface of stainless steel in order to investigate the effects of an additive and agitation on their mechanical properties and microstructure. The concentration of the additive in the plating solution increased, the pores formed in the layer decreased, while the residual stress developed in the layers during electroplating increased. Agitation of the solution during electroplating was observed to force to increase local pores in the layer, which lowers its tensile properties. Grain growth was suppressed due to very fine $Ni_3P$ precipitates formed at its grain boundaries during heat treatment at $343^{\circ}C$ for 1 hr in air.