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SHS 화학로법에 의해 합성된 WC 분말과 상용 WC 분말을 이용한 $WC-Co-Al_2O_3$ 세라믹 복합체의 제조 및 그 기계적 특성에 관한 연구
이강렬,조덕호,이형복,박성,Lee, K.R.,Cho, D.H.,Lee, H.B.,Park, S. 한국세라믹학회 1995 한국세라믹학회지 Vol.32 No.12
WC-10wt%Co-Al2O3 ceramic composites, using both the SHS (Self-propagating High Temperature Synthesis) synthesized WC powder method and commercial WC powder, were prepared by varing WC-Co/Al2O3 vol% ratio and sintering temperature (1350℃∼1650℃) for 1 hr in Ar atmosphere. Mechanical characterization has been investigated by Instron meterial testing system and Vicker's hardness test. Compositional and structural chracterizations were carried out by energy-dispersive analysis of X-ray (EDAX) data and scanning electron microscope (SEM). Electrical characterization was carried out by the electrical resistivity measurement using 4-point probe method. As sintering period increased and Al2O3 contents decreased in WC-10wt%Co-Al2O3 ceramic composite, shrinkage and relative density increased, resulting in maximum values at 1600℃. Also the major matrix phase changed with increasing Al2O3 content from 0 to 100 vol%. It was also identified by SEM, EDAX, and electrical resistivity measurement. Based on the results of analysis of flexural strength, toughness and hardness, the mechanical properties of WC-10wt%Co-Al2O3 ceramic composites using the SHS synthesized WC powder were better than those WC-10wt%Co-Al2O3 ceramic composites using commercial WC powder because WC-10wt%Co-Al2O3 ceramic composites using the SHS synthesized WC powder were sintered very well due to small initial particle size. By the addition of 40 vol% Al2O3 [60(WC=10wt%Co)-40Al2O3], it was possible to obtain a proper candidate as a superalloy.
pH가 자발 착화 연소법에 의해 합성된 La Sr CrO 분말의 성질에 미치는 영향
이강렬,박 성,신형철 明知大學校 産業技術硏究所 1996 産業技術硏究所論文集 Vol.15 No.-
There is an ample interest on the characteristics of the La0.84Sr0.16CrO3 Powders with various pHs conditions in the precursor solution for the GNP. In this paper the variations of the crystallinity and particle size of the La0.84Sr0.16CrO3 powders are investigated with various pHs in the precursor solutions for the GNP. It is thought that the higher crystallinity and the finer particle sizes of the powders with the increases of the pH are ascribed to the homogeneous combustion by the increasing complexation of the Sr-nitrate with the caboxylic ion group of the glycine regardless of the small decomplexation of the Cr-nitrate with the amine ion group of the glycine..