• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1993.11a
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• pp.58-58
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• 1993

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2003.10a
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• pp.10-10
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• 2003

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2003.10a
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• pp.126-126
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• 2003

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1994.04c
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• pp.12-13
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• 1994

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1995.11a
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• pp.15-15
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• 1995

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.542-542
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• 2006

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.513.2-513.2
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• 2006

• Korean Journal of Materials Research
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• v.21 no.1
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• pp.67-71
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• 2011

La doped CuO-ZnO-$Al_2O_3$ powders are prepared by sol-gel method with aluminum isopropoxide and primary distilled water as precursor and solvent. In this synthesized process, the obtained metal oxides caused the precursor such as copper (II) nitrate hydrate and zinc (II) nitrate hexahydrate were added. To improve the surface areas of La doped CuO-ZnO-$Al_2O_3$ powder, sorbitan (z)-mono-9-octadecenoate (Span 80) was added. The synthesized powder was calcined at various temperatures. The dopant was found to affect the surface area and particle size of the mixed oxide, in conjunction with the calcined temperature. The structural analysis and textual properties of the synthesized powder were measured with an X-ray Diffractometer (XRD), a Field-Emission Scanning Electron Microscope (FE-SEM), Bruner-Emmett-Teller surface analysis (BET), Thermogravimetry-Differential Thermal analysis (TG/DTA), $^{27}Al$ solid state Nuclear Magnetic Resonance (NMR) and transform infrared microspectroscopy (FT-IR). An increase of surface area with Span 80 was observed on La doped CuO-ZnO-$Al_2O_3$ powders from $25m^2$/g to $41m^2$/g.

• Proceedings of the KWS Conference
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• 1996.10a
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• pp.3-15
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• 1996

The formation of a thicker hard alloyed layer have been investigated on the surface of aluminum cast alloy (AC2B) by PTA overlaying process with Cr, Cu and Ni motel powders under the condition of overlaying current 125-200A. overlaying speed 150 mm/min and different powder feeding rate 5-20 g/min. In addition the characteristics of hardening and wear resistance of alloyed layer here been examined in relation to the microstructure of alloyed layer. Main results obtained were summarized as follows: 1) There was an optimum overlaying condition to get a good alloyed layer with smooth surface. This good layer became easy to be formed as increasing overlaying current and decreasing powder feeding rate under a constant overlaying speed. 2) Cu powder was the most superior one in metal powders used due to a wide optimum overlaying condition range, uniform hardness distribution of Hv250-350, good oar resistance and freedom from cracking in alloyed layer with fine hyper-eutectic structure. 3) On the contrary, irregular hardness distribution was usually obtained in Cr ar Ni alloyed layers of which hardness was increased as Cr or Ni contents and reached to maximum hardness of about Hv400-850 at about 60wt%cr or 40wt%Ni in alloyed layer. 4) Cracking occurred in Cr or Ni alloyed layers with higher hardness than Hv250-300 at mere than 20-25wt% of Cr or Ni contents in alloyed layer. Porosity was observed in all alloyed layers but decreased by usage of spherical powder with smooth surface.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.4
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• pp.172-177
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• 2002

The CuZnAl alloys have some advantages against other shape memory alloys, such as the widely variable transformation temperature, the low cost and easy fabrication. The alloys have been produced mostly by metallurgical methods. Thereby a tendency to large grain sizes is observed, which causes brittle properties of the materials. In order to avoid these deficiencies a special powder metallurgical process, SPS(spark plasma sintering), is applied in the present investigation. The starting materials were the pure (99.9 %) Cu, Zn and Al element powders with different particle size. The relatively fine grained and homogeneous Cu-24.78Zn-9.11Al (at.%) and Cu-13.22Zn-17.24Al (at.%) shape memory alloys were obtained using the powders with size of 75-150 $\mu$m. The average grain size is about 70 $\mu$m and the phases at room temperature are the austenitic and martensitic phase respectively.