• Journal of the Korean Ceramic Society
• /
• v.36 no.5
• /
• pp.539-546
• /
• 1999

Absorbent polymer-cement composites were fabricated by the semi-powder mixing OPC(ordinary Portland cement) with an absorbent polymer. The effects of absorbent polymer on the mechanical properties and the hydration characteristics were observed and the polymer-cement interaction also discussed. Absorbent polymer-cement composites showed the value of total porosity of 8vol% the value of 28 days flexural strength was up to 280 Kgf/cm2 in the case of absorbent polymer-cement composite at 1 wt% absorbent polymer content and microstructure of absorbent polymer-cement composite has been observed more dense than that of OPC paste. Accordingly the permeability of compositewas improved and so the moisture resistance was also increased. Adding polymer did not retard the hydration of OPC. It was considered from the results of IR(infrared) analysis that the functional group of absorbent polymer would be changed from unidentate to bidentate during by the hydration of cement minerals.

• Journal of the Korean Ceramic Society
• /
• v.53 no.5
• /
• pp.548-556
• /
• 2016

Recently, porous alumina-based ceramics have been extensively applied in the semi-conductor and display industries, because of their high mechanical strength, high chemical resistance, and high thermal resistance. However, the high electrical resistance of alumina-based ceramics has a negative effect in many applications due to the generation of static electricity. The low electrical resistance and high air permeability are key aspects in using porous alumina-based ceramics as vacuum chucks in the semi-conductor industry. In this study, we tailored the pore structure of porous alumina-based ceramics by adjusting the mixing ratio of the starting alumina, which has different particle sizes. And the electrical resistance was controlled by using chemical additives. The characteristics of the specimens were studied using scanning electron microscopy, mercury porosimetry, capillary flow porosimetry, a universal testing machine, X-ray diffraction, and a high-resistance meter.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09a
• /
• pp.644-645
• /
• 2006

TiC-and Ti(C,N)-based cermets are excellent in semi-and final finishing of work piece during cutting operations. Typical microstructure of the cermets is a core/rim structure. The undissolved Ti(C,N) cores contribute to their high hardness while the rim phases, (Ti,M1,M2)(C,N)-type solid solutions, play great roles in enhancing the toughness. In this paper, various ultrafine pre-mixed MeC-Ni powders were synthesized and the powders were sintered or hot pressed after mixing in order to control the size and volume fractions of core and rim phases in the system. This paper will present the factors determining the microstructure along with mechanical properties.