• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2003.05a
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• pp.31-32
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• 2003

In the Present study, the effect of galvannealing conditions on the phase distribution of the Zn-Fe intermetallic phases in the coating layer of the galvannealed steel sheets(GA) was investigated in an interstitial free steel and two kinds of high strength steels. The composition profiles of the coating layers were analyzed using AA and EDS analysis, and the distribution of the intermetallic phases was examined with the aids of X-ray diffraction. On the basis of the pole figure and OIM analyses, it was clarified that the preferred orientation of the $\zeta$ phase depended on the development of the $\gamma$-fibre texture in the substrate.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.726-731
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• 2002

Reaction synthesis is a process to form ceramics, intermetallics and their composites from elemental powder mixture. Application of this process to a surface modification techniques has a possibilities to enable the process at a lower temperature or for a shorter time, although synthesized materials are likely to include voids and unreacted elements. This paper intend to examine the effect of Si addition to the mixture of Al and Ni on the densification of synthesized Ni-Al intermetallic compounds and to evaluate the surface properties of obtained coatings. By the Si addition, exothermic reaction temperature to form Ni-Al intermetallic was lowered to be below the melting point of Al. Si soluted $Al_3$Ni$_2$, $Al_3$Ni and $Al_{6}$Ni$_3$Si were mainly formed in the coating layer when powder mixture was heated to 973K for 300s. Besides, densification was enhanced by increasing hot press pressure, Si additions and heating rate. When the composition of eutectic Al-Si reaches 78%, void ratio of sintered compact reduced to 0.4%. It is caused by higher flowability of Al-Si liquid phase generated and its infiltration into the void. Since the hardness of NiAl(Si) compound (about 600HV) formed in the coating layer is higher than that of Ni-Al compound (about 400HV), coating layer with high density and superior wear property is obtained by hot press using reaction synthesis from Al-Ni-Si powder mixture.

• Corrosion Science and Technology
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• v.23 no.4
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• pp.302-309
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• 2024

The purpose of this study was to elucidate effects of a thin (tens to hundreds of nanometers) Ni-flash coating layer on hydrogen embrittlement (HE) and liquid metal embrittlement (LME) in ultra-high-strength electrogalvanized steel with a tensile strength of more than 1 GPa. Various experimental and analytical methods, including thermal desorption spectroscopy, slow strain rate testing, resistance spot welding, X-ray diffraction, and metallographic observation, were employed. Results showed that an increase in Ni target amount for flash coating resulted in a decrease in diffusible hydrogen content during electrogalvanizing, resulting in a significant decrease in HE sensitivity. Moreover, a Ni target amount of more than 1000 mg/m² drastically reduced the occurring frequency and average depth of LME. This reduction could be primarily attributed to formation of Zn-Ni intermetallic phases during the welding process that could inhibit liquefaction of intermetallic phases in the heat-affected zone. This study provides a desirable Ni target amount for Ni-flash coating on ultra-high-strength steels conducted in a continuous galvanizing line or a high-speed batch line to achieve high resistance to both HE and LME.

• Korean Journal of Metals and Materials
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• v.50 no.1
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• pp.28-33
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• 2012

Ball-milled Ni-Al powder compacts have been synthesized by the heat of molten cast iron and have been coated on cast iron. The effects of the ball-milling time on the microstructure of the intermetallic coatings have been investigated. The experimental results showed that the ball-milled Ni-Al powder compacts were completely reacted and were successfully coated on the cast iron without re-melting the substrate. Densification of the coating layers was enhanced by increasing the ball-milling time. This might be attributed to the fact that the heat released during the intermetallic reaction was dispersed over a prolonged reaction time by the ball-milling of the elemental powders.

• Journal of the Microelectronics and Packaging Society
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• v.17 no.3
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• pp.59-63
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• 2010

Immersion Sn plating was produced on Cu foil by distributing nano-sized diamonds (ND). The ND distributed on the coating surface broke the continuity of Sn-oxide layer, therefore leading to penetrate the molten solder through the oxide and retarding the wettability degradation during a reflow process. Furthermore, the ND in the Sn coating played a role of diffusion barrier for Sn atoms and decreased the growth rate of intermetallic compound ($Cu_6Sn_5$) layer during the solid-state aging. The study confirmed the importance of ND to improve the wettability and reliability of the Sn plating. Complete dispersion of the ND within the immersion Sn plating needs to be further developed for the electronic packaging applications.

• Journal of the Korean institute of surface engineering
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• v.32 no.4
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• pp.547-554
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• 1999

The interfacial reaction, spangle and coating thickness of galvanized steel in Ni added Zn-0.18Al bath have been investigated. The size of spangle and thickness of reaction layer were observed under an optical microscope, SEM and EDS. Analysing the experimental results concerning spangle size of galvanized steel it was found that Ni addition in Zn-0.18Al bath tended to be minimized spangle size. For Zn-0.18Al bath, addition of 0.1Ni suppressed the formation of Fe-Zn intermetallic compounds but increased with Ni content above 0.1%. The coating thickness of galvanized steel was reduced with Ni addition in Zn-0.18Al bath, especially in Zn-0.18Al-0.05Ni bath. Addition of Al in Ni containing bath resulted in forming the Al-Ni intermetallic compounds such as $Al_3$Ni$_2$ and $Al_2$Ni which consist most of top precipitates.

• Journal of the Korean institute of surface engineering
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• v.29 no.4
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• pp.278-285
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• 1996

The structure of coating layer formed by hot dip Al-Cu alloy coating on Monel 1400 metal was studied. The coating layer consists of alloyed layer adjacent to the Monel 400 substrate and Al-Cu alloy. It was found that the hardness of coating increased with dipping time and heat treatment associated with the diffusion and the formation of intermetallic compound at the interface. However the thickness of coating layer was decreased at high dipping temperature due to tile higher viscosity of liquid coating alloy. Diffusion heat treatment at $600^{\circ}C$ after coating resulted in the disappearence of adhered Al(Cu) and $CuAl_2$ phases, and then they transformed into the new phases of CuAl and Al7Cu4Ni at coating layer.

• Korean Journal of Materials Research
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• v.12 no.9
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• pp.696-700
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• 2002

The Ti-aluminide intermetallic compound was formed from high purity elemental Ti and Al foils by self-propagating, high-temperature synthesis(SHS) in hot press. formation of $TiAl_3$ at the interface between Ti and Al foils was controlled by temperature, pressure, heating rate, and so on. According to the thermal analysis, it is known in this study that the heating rate is the most important factor to form the intermetallic compound by this SHS reaction. The V layer addition between Al and Ti foils increased SHS reaction temperatures. The fully dense, well-boned inter-metallic composite($TiA1/Ti_3$Al) sheets of 700 m thickness were formed by heat treatment at $1000^{\circ}C$ for 10 hours after the SHS reaction of alternatively layered 10 Ti and 9 Al foils with the V coating layer. The phases and microstructures of intermetallic composite sheets were confirmed by EPMA and XRD.

• Proceedings of the KWS Conference
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• 2005.11a
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• pp.234-236
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• 2005

• Journal of the Korean Ceramic Society
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• v.33 no.2
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• pp.155-162
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• 1996

A Taguchi methodology study of the plasma spraying thermal barrier coating (TBC) layer is presented. The experiment parameters were designed by a L8-style orthogonal arrays approach. A Taguchi analysis was conduc-ted through the results of the coating properties which were affected by plasma spraying parameters. Zirconia (partially stbilized with ytrria: PSZ) was sprayed on TiAl intermetallic compound substrates, The coating layer was characterized by thickness microstructure and porosity using SEM and Image analyzer. The coating quali-ties are discussed with respect to thermal barrier effect thermal cycling test6 and adhesion strength test. An optimum condition of plasma spraying process which are derived from the Taguchi analysis could be found for high quality TBC.