Presentation Title

Ceramic Composites Produced by a Directed Metal Oxidation Process

Faculty Mentor

Dr. Vilupanur Ravi, Chemical and Materials Engineering, Cal Poly Pomona

Start Date

17-11-2018 9:00 AM

End Date

17-11-2018 9:15 AM

Location

C164

Session

Oral 1

Type of Presentation

Oral Talk

Subject Area

engineering_computer_science

Abstract

Ceramic matrix composites (CMCs) couple the wear resistance of ceramics and the ductility of metals. They also can provide an alternative to the difficult issue of shape formation confronting all-ceramic components if they can be formed to near net shape. Directed Metal Oxidation is a method of fabricating CMCs to near net shape. The process can be engineered to produce a wide range of geometries of alumina matrix/aluminum composites with minimum machining and also allows for further reinforcement of the composite through the addition of constituents such as silicon carbide. In applications, e.g., pump impellers and housing, where a combination of erosion, wear and corrosion resistance are required, the CMCs could be an ideal choice. Plates of SiC-reinforced Al2O3/Al composites were fabricated from an Al-Si-Mg alloy using the Directed Metal Oxidation process. Coupons were prepared for a series of tests to characterize the microstructure, hardness and corrosion behavior of this ceramic matrix composite material. Microstructural characterization of the composite was accomplished through scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS) and optical microscopy. Vickers microhardness tests were conducted on the different phases of the composite and a microhardness profile along the direction of composite growth was obtained. Electrochemical tests were performed according to ASTM G59-97 using a 3.5 wt.% NaCl aqueous solution against a saturated calomel reference electrode and a platinum mesh counter electrode.

Summary of research results to be presented

Microscopy show the formation of a ceramic-ceramic composite structure along with residual metal. The Vickers microhardness showed that the SiC phase had the higher hardness value {2385 ± 145 HV (N=14)} in comparison to the Al2O3/Al matrix {(867 ± 352 HV} phase. The coupon reinforced with 120 grit SiC had a higher value of corrosion potential, Ecorr, indicating that the material was more stable (“noble”) (-434 mV Vs SCE as compared to -668 mV Vs SCE). The 240 grit SiC-reinforced coupon had a lower corrosion current, icorr, (6.1 µA/cm2 Vs 13.4 µA/cm2) which corresponds to a lower rate of corrosion and a higher resistance to polarization relative to the 120 grit SiC (9790 Ω-cm2 Vs 3317 Ω-cm2).

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Nov 17th, 9:00 AM Nov 17th, 9:15 AM

Ceramic Composites Produced by a Directed Metal Oxidation Process

C164

Ceramic matrix composites (CMCs) couple the wear resistance of ceramics and the ductility of metals. They also can provide an alternative to the difficult issue of shape formation confronting all-ceramic components if they can be formed to near net shape. Directed Metal Oxidation is a method of fabricating CMCs to near net shape. The process can be engineered to produce a wide range of geometries of alumina matrix/aluminum composites with minimum machining and also allows for further reinforcement of the composite through the addition of constituents such as silicon carbide. In applications, e.g., pump impellers and housing, where a combination of erosion, wear and corrosion resistance are required, the CMCs could be an ideal choice. Plates of SiC-reinforced Al2O3/Al composites were fabricated from an Al-Si-Mg alloy using the Directed Metal Oxidation process. Coupons were prepared for a series of tests to characterize the microstructure, hardness and corrosion behavior of this ceramic matrix composite material. Microstructural characterization of the composite was accomplished through scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS) and optical microscopy. Vickers microhardness tests were conducted on the different phases of the composite and a microhardness profile along the direction of composite growth was obtained. Electrochemical tests were performed according to ASTM G59-97 using a 3.5 wt.% NaCl aqueous solution against a saturated calomel reference electrode and a platinum mesh counter electrode.