Self‐Crack‐Healing Behavior of Mullite/SiC Particle/SiC Whisker Multi‐Composites and Potential Use for Ceramic Springs

Abstract

To improve fracture toughness and encourage excellent self‐crack‐healing ability, mullite/SiC particle/SiC whisker multi‐composites and mullite/SiC whisker composites were hot pressed. The crack‐healing abilities and mechanical properties of these sintered composites were investigated. Based on the obtained results, the usefulness of the mullite composite as a material for springs was discussed. The part of mullite/15 vol% SiC whisker/SiC 10 vol% particle containing healed cracks retained high reliability over the whole measured temperature range. When the crack‐healing ability was endowed by SiC whiskers alone, the parts containing the healed pre‐cracks were found to have a heat‐resistance limit temperature. Mullite/15 vol% SiC whisker/10 vol% SiC particle multi‐composite had the best potential as a material for springs used at high temperatures, because it had an adequate crack‐healing ability as well as shear deformation ability almost two times stronger than that of monolithic mullite.

Generic principles of crack-healing ceramics

“…Early work focused on crack healing of surface cracks of polycrystalline UO 2 [21,22], Al 2 O 3 [23] and MgO [24]. Since then, a large number of ceramic materials were demonstrated to exhibit crack healing capability including silicon carbide [25,26], silicon nitride [27,28], single crystalline sapphire [29], alumina [15,30,31], mullite [32,33], zirconia [34], or MAS glass ceramics [35]. The temperatures to initiate healing reaction, however, were found to exceed 0.7-0.9 of the melting temperature of single crystals or equal the sintering temperature of polycrystalline ceramics.…”

Crack-Healing Ability of Structural Ceramics and Methodology to Guarantee the Reliability of Ceramic Components

“…1 (Ando et al, 2004). A multi-composite material is a material which combines nanosized SiC particles and SiC whiskers in the proportion of 25 to 30%, and has excellent self-crack-healing ability, fracture toughness, strength (Nakao et al, 2006. The proportion fraction of SiC particles to SiC whiskers is determined by taking into consideration the self-crackhealing ability and fracture toughness requirements.…”

Constante de mola de molas cerâmicas injetadas a baixa pressão

“…Molas e enrolamentos cerâmicos têm sido obtidos por usinagem de cilindros, por extrusão de misturas de cerâmicas com polímeros ou pelo processo sol-gel [1][2][3][4][5][6]. Enquanto o primeiro processo é flexível, mas de custo elevado, nos dois últimos existe a dificuldade de extrair o ligante sem deformar as molas.…”

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INTRODUÇÃONos últimos anos houve um crescente interesse na fabricação das molas cerâmicas, visando aplicações que exijam resistência à corrosão, tanto em temperatura ambiente como em alta temperatura [1][2][3][4][5][6]. Molas e enrolamentos cerâmicos têm sido obtidos por usinagem de cilindros, por extrusão de misturas de cerâmicas com polímeros ou pelo processo sol-gel [1][2][3][4][5][6].

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