• Journal of Welding and Joining
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• v.15 no.4
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• pp.109-115
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• 1997

Laser cladding is a technique for modification of metal surface. In this laser cladding experiment a metal powder feeding system was developed for more efficient laser cladding. This system can reduce processing time and be used simpler than the conventional method. The feeding of metal powder has given a rise to the process for sequential buildup of bulk rapidly solidified materials in the form of fine powder stream to the laser cladding process. The parameters of laser cladding have been investigated using this experimental equipment. Bronze on aluminum alloy and copper on aluminum alloy were experimented by using defocused beam, powder feeding system, and gas shielding. Good cladding was achieved in the range of beam travel speed of 2.25m/min. In the case of copper/aluminum and bronze/aluminum substrate, the absorption of laser beam was too high to produce low diluted clad. In the case of copper/1050 aluminum, the optimal laser cladding condition was of laser power of 2.8kW, powder feed rate of 0.31g/s and beam travel speed of 2.25m/min. In the case of bronze/aluminum the optimal condition is of laser power of 2.5kW, powder feed rate of 0.31g/s, and beam travel speed of 2.36m/min.

• Tribology and Lubricants
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• v.10 no.3
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• pp.39-46
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• 1994

In order to investigate the effect of the ceramic reinforcements on the wear properties of aluminum bronze composites, Cu-8wt%Al aluminum bronze alloys reinforced with the Saffil alumina short fiber were produced by the powder metallurgical method and tested by a pin-ondisc wear testing machine. The wear surfaces of the pin specimens and discs, wear debris, and the cross sections of the wear specimens were observed by SEM. The wear mechanism according to various wear conditions and the change of microstructure in the composites were also discussed. In the results, the reinforcement of the composites with alumina short fiber was very effective at the higher applied load over 10N. The material transportation to the counter disc was observed in the alloy specimens without reinforcements. However, the composites reinforced with ceramic particles and fibers showed the resistance against the material transportation.

• Journal of the Korean institute of surface engineering
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• v.33 no.5
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• pp.329-338
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• 2000

In this study, as an effort to improve the brittlement of coating layer, aluminum bronze coatings formed on steel substrates by arc jet spray process were subjected to post heat treatment. After each treatment, mechanical properties such as hardness, and UTS, and microstructural characterization of the specimens were investigated. The results showed that the hardness in the coatings slightly decreased with increasing heat treatment tine and temperature. The UTS of as-sprayed coatings was 4.31kgf/$\textrm{mm}^2$ and slightly increased to 5.51kgf/$\textrm{mm}^2$ after heat treatment at $900^{\circ}C$ for 120min. On the other hand, the interdiffusion of copper and aluminum particles after heat treatment lead to decrease of the porosity density and increase the bond strength.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.276-277
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• 2006

In order to accelerate the sintering of Al-Bronze powder covered with passive oxide film, we focused on the way to add Al-Ca fluoride consisting of $AlF_3$ and $CaF_2$, examined the effect of the $CaF_2$ mixing rate in Al-Ca fluoride, the amount of the added Al-Ca fluoride and the sintering temperature on sintering properties of Al-Bronze powder and considered the mechanism of the sintering acceleration. Al-Bronze powder was sintered most effectively by adding Al-Ca fluoride with the $CaF_2$ mixing rate of 20mass%. If the amount of added fluoride was over 0.05mass% and the sintering temperature was over 1123K, the sintering acceleration of the Al-Bronze powder appears. Regarding the mechanism of the sintering acceleration, it was presumed that $Al_2O_3$ film on the surface of the Al-Bronze particles was removed in the process of the formation of gaseous AlOF by the reaction with $AlF_3$, and the reaction was accelerated further by the presence of the liquid phase which is formed in Al-Ca fluoride.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1996.04b
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• pp.13-19
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• 1996

The tribological properties of the aluminum short fiber and glass fiber reinforced tin-bronze matrix composites manufactured by vacuum hot pressing was studied. The effect of the composition and the relative density on the wear properties was examined by a reciprocal type tribo-test machine. The results were discussed by the observation of the microstructure of sintered specimen and worn surface observation using SEM and EDS. Addition of the fibers led to the wear resistance since the metal matrix was reinforced by the fibers. The reinforcement of the fiber seemed to be stronger as the distribution of the fibers was more uniform. Graphite also reduce the wear loss. The pores in the sintered composites seemed to play an important role to improve the wear resistance since the pores provide the places where the solid lubricants locate.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2011.06a
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• pp.311-311
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• 2011

• Journal of the Korean institute of surface engineering
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• v.39 no.1
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• pp.35-42
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• 2006

In this study, the fatigue properties on the cavitation damage of the flame quenched 8.8Al-bronze (8.8Al-4.5Ni-4.5Fe-Cu) as well as the current nuclear pump impeller materials (8.8Al-bronze, STS316 and SR50A) has been investigated using an ultrasonic vibratory cavitation test. For this the impact loads of cavitation bubbles generated by ultrasonic vibratory device quantitatively evaluated and simultaneously the cavitation erosion experiments have been carried out. The fatigue analysis on the cavitation damage of the materials has been made from the determined impact load distribution (e.g. impact load, bubble count) and erosion parameters (e.g. incubation period, MDPR). According to Miner's law, the determined exponents b of the F-N relation ($F^b$ N = Constant) at the incubation stage (N: the number of fracture cycle) were 5.62, 4.16, 6.25 and 8.1 for the 8.8Al-bronze, flame quenched one, STS316 and SR50A alloys. respectively. At the steady state period, the exponents b of the F-N' curve (N': the number of cycle required for $1{\mu}m$ increment of MDP) were determined as 6.32, 5, 7.14 and 7.76 for the 8.8Al-bronze, flame quenched one, STS316, and SR50A alloys, respectively.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.6
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• pp.89-94
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• 2011

The wear characteristics between nonmetal and metals have been investigated using a disc on disc system. The specimens of nonmetal are made by the nylon and teflon materials. The specimens of the metal are used as eight kinds of along their hardness. The kinds of metals are copper(Hv96), aluminum(Hv186), brass(Hv234), aluminum bronze(Hv294), stainless steel(Hv327), annealing mild steel(Hv345), mild steel(Hv372), Hard steel(Hv434). In this study, a upper and lower specimens have been used the same size and shape. Using experimental data we figured the relationship between friction coefficient of nonmetal and metals. We figured the relationship between friction temperature of nonmetal and metals. The result had been verified a wear characteristics of nonmetal and metals in the wear tests.

• Journal of the Korean Society for Heat Treatment
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• v.17 no.6
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• pp.346-355
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• 2004

The flame quenching process has been employed to modify the surfaces of commercial marine propeller material, aluminum bronze alloy (Cu-8.8Al-5Ni-5Fe), and the microstructure, hardness and wear properties of the flame-quenched layers have been studied. The thermal history was accurately monitored during the process with respect to both the designed maximum surface temperature and holding time. The XRD and EDX analyses have shown that at temperatures above $T_{\beta}$, the microstructure consisting of ${\alpha}+{\kappa}$ phases changed into the ${\alpha}+{\beta}^{\prime}$ martensite due to an eutectoid reaction of ${\alpha}+{\kappa}{\rightarrow}{\beta}$ and a martensitic transformation of ${\beta}{\rightarrow}{\beta}^{\prime}$. The ${\beta}^{\prime}$ martensite phase formed showed a face-centered cubic (FCC) crystal structure with the typical twinned structure. The hardness of the flame-quenched layer having the ${\alpha}+{\beta}^{\prime}$ structure was similar to that of the ${\alpha}+{\kappa}$ structure and depended sensitively on the size and distribution of hard ${\kappa}$ and ${\beta}^{\prime}$ phases with depth from the surface. As a result of the sliding wear test, the wear resistance of the flame-quenched layer was markedly enhanced with the formation of the ${\beta}^{\prime}$ martensite.

• Journal of Korea Foundry Society
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• v.36 no.6
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• pp.202-207
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• 2016

The effects of Fe and Si additions on the microstructures and mechanical properties of aluminum bronze have been investigated. In a bar-type specimen cast in a die mold, the addition of Fe promoted the dendritic solidification of the ${\alpha}$ phase. The hardness values increased slightly in the Fe-added specimen with heat treatment, while these values was increased significantly in the specimens with Si or with combined additions of Fe and Si. When a centrifugal casting bush with combined addition of Fe and Si was heat treated, the FeSi compound within the matrix was finely dispersed, and was observed to be the origin of cup-cone type conical dimple failure in the tensile fracture surface. The mechanical properties of the heat treated centrifugal casting bushes, whose nominal alloy compositions were (Cu-7.0Al-0.8Fe-3.0Si)wt%, exhibited tensile strength of $703-781N/mm^2$, elongation of 6.6-11.7% and hardness of Hv 222.6-249.2. These high values of strength and elongation were attributed to the strengthening of the matrix due to the combined addition of Fe and Si, and to precipitation of fine the FeSi compound.