Processing and Characterization of MMC Beads Based on Zirconia and TRIP Steel
- PDF / 1,405,837 Bytes
- 9 Pages / 593.972 x 792 pts Page_size
- 99 Downloads / 177 Views
INTRODUCTION
METAL-matrix composites (MMC) have gained particular interest in the past 20 years since they offer the unique combination of high ductility and strength of metal and excellent wear resistance and hardness of ceramics. Especially the development of honeycomb structures has been in focus of the research for failure tolerant components.[1] These components are characterized by their excellent crashworthiness, which can be expressed in terms of specific energy absorption (SEA) per unit mass or SEA per unit volume. Conventionally, iron-based MMCs are fabricated by pressureless infiltration,[2] gas pressure infiltration, hot-isostatic pressing, or extrusion.[3] Andersen et al.[4] presented the generation of metallic hollow beads by coating styrofoam beads with a metallic suspension. Wang et al.[5] describe the gelcasting process of silicon carbide based on gelation of sodium alginate, and Zhou et al.[6] of concentrated aqueous silicon carbide suspension. The present study introduces a novel processing method for MMC based on a metal-ceramic suspension containing sodium alginate, which jells in contact with Ca2+-ions as solidifying agent in a solution (gel-casting process). Depending on the processing conditions, full and hollow composite beads as well as random bead structures can be obtained. The present paper has an emphasis on the processing and characterization of full composite beads, based on metastable austenitic stainless steel powder and magnesia partially stabilized zirconia. Both materials exhibit a MARIE OPPELT, CLAUDIA WENZEL, and HARRY BEREK, Research Assistants, and CHRISTOS G. ANEZIRIS, Professor, are with the Department of Ceramic, Glass and Construction Materials, Technische Universita¨t Bergakademie Freiberg, Agricolastr. 17, 09599 Freiberg, Germany. Contact e-mail: [email protected] Manuscript submitted February 4, 2014. Article published online August 12, 2014. 2000—VOLUME 45B, DECEMBER 2014
martensitic phase transformation. Metastable austenitic steels show a distinctive TRansformation-Induced Plasticity effect (TRIP). On mechanical load, a deformationinduced phase transformation from austenite to martensite is initiated, which is accompanied by an increase in plasticity as well as strength. The martensitic tetragonal to monoclinic phase transformation in partially stabilized zirconia is stress induced and appears with a volume increase of 3 to 5 pct. Therefore, it is expected that the combination of the starting materials leads to advantageous mechanical properties. In the present paper, the results of the optimized processing route and the characterization of different compositions are explored. The decomposition behavior of sodium alginate and the sintering parameters of the composite beads in inert atmosphere were studied. Microstructural characterization was performed with the aid of EBSD-phase analysis. Finally, the physical and mechanical properties of the composites were investigated.
II.
EXPERIMENTAL
Composite beads of varying composition were prepared from austeni
Data Loading...
