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Article
Publication date: 5 March 2010

Crack‐healing behaviour of ZrO2/SiC composite ceramics

Keiji Houjou, Kotoji Ando and Koji Takahashi

Zirconia ceramics exhibit high strength and fracture toughness. The purpose of this paper is to research a possibility of crack healing in zirconia ceramics.

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Abstract

Purpose

Zirconia ceramics exhibit high strength and fracture toughness. The purpose of this paper is to research a possibility of crack healing in zirconia ceramics.

Design/methodology/approach

ZrO2/SiC composite ceramics are sintered and subjected to three‐point bending. A surface crack of 100 μm in diameter is formed on each specimen. The cracks are healed and the specimens are tested under bending.

Findings

The paper finds that ZrO2/SiC composite ceramic material had a high crack‐healing ability at a considerably low temperature. For example, a crack of 100 μm in diameter is healed even at 600°C.

Research limitations/implications

The paper provides a low temperature healing and a new mechanism of crack healing.

Originality/value

The paper shows the healing temperature and the minimum time required to heal showed a good proportional relation on the Arrhenius plot at temperatures of 600‐800°C. Moreover, the crack healing is caused by SiO2 cristobalite produced during the healing.

Details

International Journal of Structural Integrity, vol. 1 no. 1
Type: Research Article
DOI: https://doi.org/10.1108/17579861011023810
ISSN: 1757-9864

Keywords

  • Ceramics
  • Composite materials
  • Zirconium
  • Silicon inorganic compounds
  • Mechanical properties of materials

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Article
Publication date: 2 March 2012

Crack‐healing behavior of ZrO2/SiC composite ceramics and strength properties of crack‐healing specimens

Keiji Houjou and Koji Takahashi

The purpose of this paper is to study the crack‐healing mechanism of ZrO2/SiC composite ceramics which have a high crack‐healing ability at low temperature.

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Abstract

Purpose

The purpose of this paper is to study the crack‐healing mechanism of ZrO2/SiC composite ceramics which have a high crack‐healing ability at low temperature.

Design/methodology/approach

The effects of dispersed SiC and the environment on crack‐healing behaviour were investigated. The fatigue strength of crack‐healed specimens was also investigated.

Findings

The main conclusions are that for crack‐healing of ZrO2 ceramics, it is necessary to have both a SiC composite and an oxidative environment; and when ZrO2/SiC composite ceramics are heat‐treated in air, a phase transformation attributable to the SiC composite results in crack‐healing and improvement of fracture toughness and bending strength.

Originality/value

An appropriate heat treatment for ZrO2/SiC composite caused not only crack‐healing but also the improvement of fracture toughness, and created a multiplier effect on crack‐healing, bending strength and fracture toughness.

Details

International Journal of Structural Integrity, vol. 3 no. 1
Type: Research Article
DOI: https://doi.org/10.1108/17579861211209984
ISSN: 1757-9864

Keywords

  • Composite materials
  • Ceramics
  • Heat treatment
  • ZrO2 ceramics
  • SiC composite
  • Crack healing
  • Fracture toughness
  • Transformation toughening

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Book part
Publication date: 12 February 2013

Hybrid Habitus: Toward a Post-Colonial Theory of Practice

Claire Laurier Decoteau

Sociologists have tended to construct theories of identity based on unitary notions of social location which avoid conceptualizing disjunction and contradiction and which…

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Abstract

Sociologists have tended to construct theories of identity based on unitary notions of social location which avoid conceptualizing disjunction and contradiction and which therefore fail to capture certain characteristics of the postcolonial condition. This paper engages in a postcolonial re-reading of sociological theories of practice (in particular, Pierre Bourdieu's notion of habitus). It does so through an analysis of the historical development of the field of health and healing in South Africa. From the beginning of the colonial enterprise, biomedicine resisted amalgamation with other forms of healing and insisted on a monotherapeutic ideology and practice whereas indigenous healing accommodated not only biomedicine, but invited pluralism within and across cultural and ethnic differences. As such, a bifurcated and parallel system of healing emerged, whereby Black South Africans practiced pluralism and white South Africans utilized biomedicine in isolation. This disjuncture became acrimonious in the post-apartheid era as the state attempted to forge a united health system and battle the AIDS epidemic. Despite the historical and contemporary bifurcations within the field of health and healing, people living with AIDS continue to subscribe to a hybrid health ideology. There is, therefore, a structural disjuncture between the realities of consumption within the field of health and healing and the logic of the field as it is articulated in the symbolic struggle raging in the field of power. The field of health and healing is characterized, therefore, by a simultaneous bifurcation and hybridity – which is reflected in HIV-infected South Africans’ beliefs and practices. In order to make sense of this puzzling disjuncture and its impact on subjects’ trajectories of action, this paper draws insight from Pierre Bourdieu's theory of habitus and Homi Bhabha's conceptualization of hybridity – transforming each of them through their synthesis and application to the postcolonial context.

Details

Postcolonial Sociology
Type: Book
DOI: https://doi.org/10.1108/S0198-8719(2013)0000024016
ISBN: 978-1-78190-603-3

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Article
Publication date: 2 January 2018

Multi-stimuli triggered self-healing of the conductive shape memory polymer composites

Hongsheng Luo, Xingdong Zhou, Yuncheng Xu, Huaquan Wang, Yongtao Yao, Guobin Yi and Zhifeng Hao

This paper aims to exploit shape-memory polymers as self-healable materials. The underlying mechanism involved the thermal transitions as well as the enrichment of the…

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Abstract

Purpose

This paper aims to exploit shape-memory polymers as self-healable materials. The underlying mechanism involved the thermal transitions as well as the enrichment of the healing reagents and the closure of the crack surfaces due to shape recovery. The multi-stimuli-triggered shape memory composite was capable of self-healing under not only direct thermal but also electrical stimulations.

Design/methodology/approach

The shape memory epoxy polymer composites comprising the AgNWs and poly (ε-caprolactone) were fabricated by dry transfer process. The morphologies of the composites were investigated by the optical microscope and scanning electron microscopy (SEM). The electrical conduction and the Joule heating effect were measured. Furthermore, the healing efficiency under the different stimuli was calculated, whose dependence on the compositions was also discussed.

Findings

The AgNWs network maintained most of the pathways for the electrons transportation after the dry transfer process, leading to a superior conduction and flexibility. Consequently, the composites could trigger the healing within several minutes, as applied with relatively low voltages. It was found that the composites having more the AgNWs content had better electrically triggered performance, while 50 per cent poly (ε-caprolactone) content endowed the materials with max healing efficiency under thermal or electrical stimuli.

Research limitations/implications

The findings may greatly benefit the application of the intelligent polymers in the fields of the multifunctional flexible electronics.

Originality/value

Most studies have by far emphasized on the direct thermal triggered cases. Herein, a novel, flexible and conductive shape memory-based composite, which was capable of self-healing under the thermal or electrical stimulations, has been proposed.

Details

Pigment & Resin Technology, vol. 47 no. 1
Type: Research Article
DOI: https://doi.org/10.1108/PRT-03-2017-0032
ISSN: 0369-9420

Keywords

  • Conductive
  • Multi-stimuli
  • Polymeric composites
  • Self-healing
  • Shape memory materials

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Article
Publication date: 3 December 2018

Mechanical behavior of aeronautical composites containing self-healing microcapsules

Panagiota Polydoropoulou, Christos Vasilios Katsiropoulos, Andreas Loukopoulos and Spiros Pantelakis

Over the last decades, self-healing materials based on polymers are attracting increasing interest due to their potential for detecting and “autonomically” healing damage…

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Abstract

Purpose

Over the last decades, self-healing materials based on polymers are attracting increasing interest due to their potential for detecting and “autonomically” healing damage. The use of embedded self-healing microcapsules represents one of the most popular self-healing concepts. Yet, extensive investigations are still needed to convince on the efficiency of the above concept. The paper aims to discuss these issues.

Design/methodology/approach

In the present work, the effect of embedded self-healing microcapsules on the ILSS behavior of carbon fiber reinforced composite materials has been studied. Moreover, the self-healing efficiency has been assessed. The results of the mechanical tests were discussed supported by scanning electron microscope (SEM) as well as by Attenuated Total Reflection–Fourier-transform infrared spectroscopy (ATR–FTIR) analyses.

Findings

The results indicate a general trend of a degraded mechanical behavior of the enhanced materials, as the microcapsules exhibit a non-uniform dispersion and form agglomerations which act as internal defects. A remarkable value of the self-healing efficiency has been found for materials with limited damage, e.g. matrix micro-cracks. However, for significant damage, in terms of large matrix cracks and delaminations as well as fiber breakages, the self-healing efficiency is limited.

Originality/value

The results obtained by SEM analysis as well as by ATR–FTIR spectroscopy constitute a strong indication that the self-healing mechanism has been activated. However, further investigation should be conducted in order to provide definite evidence.

Details

International Journal of Structural Integrity, vol. 9 no. 6
Type: Research Article
DOI: https://doi.org/10.1108/IJSI-12-2017-0075
ISSN: 1757-9864

Keywords

  • SEM
  • Composite materials
  • ATR
  • FTIR
  • ILSS behaviour
  • Self-healing efficiency
  • Self-healing microcapsules

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Article
Publication date: 6 March 2017

The self-healing evaluation of microcapsule-based epoxy coatings applied on AA6061 Al alloy in 3.5% NaCl solution

Mehdi Shahidi Zandi and Majdeh Hasanzadeh

The aim of this work is to investigate the self-healing performance of epoxy coatings containing microcapsules. The microcapsule-based coatings were applied on AA6061 Al…

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Abstract

Purpose

The aim of this work is to investigate the self-healing performance of epoxy coatings containing microcapsules. The microcapsule-based coatings were applied on AA6061 Al alloy and immersed in 3.5 per cent NaCl solution.

Design/methodology/approach

Microcapsules with urea–formaldehyde as the shell and linseed oil as the healing agent were prepared by in situ polymerization in an oil-in-water emulsion. For the sake of an optimum self-healing system, some coating samples were prepared by using different microcapsule concentrations: 0, 5, 10 and 20 Wt.%. The scratch-filling efficiency as the theoretical estimate of the self-healing performance was calculated for the coating samples with different microcapsule concentrations. The scratch-sealing efficiency (SSE) as a particularly crucial parameter in the self-healing evaluation of coatings was measured by both electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN) techniques.

Findings

According to EIS and EN results, the coating samples containing 5 and 10 per cent microcapsules provided the insignificant self-healing performance, while the coating sample containing 20 per cent microcapsules exhibited the acceptable self-healing performance to AA6061 alloy in the NaCl solution. The measured SSE values confirmed the good agreement of EN data with electrochemical parameters obtained from the EIS technique.

Originality/value

This work is an attempt to evaluate the self-healing performance of microcapsule-based epoxy coatings applied on AA6061 Al alloy in sea water.

Details

Anti-Corrosion Methods and Materials, vol. 64 no. 2
Type: Research Article
DOI: https://doi.org/10.1108/ACMM-01-2016-1640
ISSN: 0003-5599

Keywords

  • Electrochemical impedance spectroscopy (EIS)
  • Electrochemical noise (EN)
  • Microcapsule
  • Scratch-sealing efficiency (SSE)
  • Self-healing coating

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Article
Publication date: 9 November 2015

Health tourism: Needs for healing experience and intentions for transformation in wellness resorts in Korea

Jae Yeon Yang, Soyon Paek, Taegoo (Terry) Kim and Tae Hee Lee

The purpose of this study is to explore the effect of tourists’ needs for healing experience (NHE) on behavioral intentions for transformation (BIT) with healing…

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Abstract

Purpose

The purpose of this study is to explore the effect of tourists’ needs for healing experience (NHE) on behavioral intentions for transformation (BIT) with healing involvement (HI) as a mediator. Using the two sub-constructs of BIT in the tourism industry (i.e. selection of healing tour products and transformational intention of healing tour behavior), this study evaluates BIT.

Design/methodology/approach

The survey was administered to visitors in healing resorts/centers in Korea; 383 completed surveys were used to investigate the hypothesized relationships of this study using regression analysis.

Findings

The study results confirmed the hypothesized relationships: the positive effects of NHE on BIT and the significant mediating role of HI in the relationships between NHE and BIT.

Practical implications

The relationships among NHE, HI and BIT can improve the understanding and practices of healing experience and the development of healing products in the tourism industry. This study offers a meaningful and extended perspective on customers’ experience and product development by interpreting customers’ desires and needs.

Originality/value

This study explores the under-researched subject of NHE and HI from a transformative economic perspective. The study is among the first to examine the structural relationships among NHE, HI and BIT. The uniqueness of the study is highlighted by the use of two sub-dimensions of the BIT industry (i.e. selection of healing tour products and transformational intention of healing tour behavior) in a tourism context.

Details

International Journal of Contemporary Hospitality Management, vol. 27 no. 8
Type: Research Article
DOI: https://doi.org/10.1108/IJCHM-11-2013-0505
ISSN: 0959-6119

Keywords

  • Korea
  • Motivation
  • Tourism development
  • Health
  • Consumer behavior
  • Health tourism
  • Behavioral intentions
  • Experience economy
  • Experience marketing
  • Healing involvement
  • Healing tour behavior
  • Wellness resorts

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Article
Publication date: 3 October 2016

Self-repairing CFRPs targeted towards structural aerospace applications

Marialuigia Raimondo, Felice De Nicola, Ruggero Volponi, Wolfgang Binder, Philipp Michael, Salvatore Russo and Liberata Guadagno

The purpose of this paper is to describe the first experiments to manufacture self-healing carbon fiber reinforced panels (CFRPs) for the realization of structural…

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Abstract

Purpose

The purpose of this paper is to describe the first experiments to manufacture self-healing carbon fiber reinforced panels (CFRPs) for the realization of structural aeronautic components in order to address their vulnerability to impact damage in the real service conditions.

Design/methodology/approach

The developed self-healing system is based on ring-opening metathesis polymerizations reaction of microencapsulated 5-ethylidene-2-norbornene/dicyclopentadiene cyclic olefins using Hoveyda-Grubbs’ first generation catalyst as initiator. In this work, the self-healing resin is infused into a carbon fiber dry preform using an unconventional bulk film infusion technique that has allowed to minimize the filtration effects via a better compaction and reduced resin flow paths. Infrared spectroscopy provides a useful way to identify metathesis products and therefore catalyst activity in the self-healing panel after damage. The damage resistance of the manufactured CFRPs is evaluated through hail and drop tests.

Findings

The self-healing manufactured panels show, after damage, catalyst activity with metathesis product formation, as evidenced by an infrared peak at 966 cm−1. The damage response of CFRPs, detected in accord to the requirements of hail impact for the design of a fuselage in composite material, is very good. The results are very encouraging and can constitute a solid basis for bringing this new technology to the self-healable fiber reinforced resins for aerospace applications.

Originality/value

In this paper, autonomically healing CFRPs with damage resistance and self-healing function are proposed. In the development of self-healing aeronautic materials it is critical that self-healing activity functions in adverse weather conditions and at low working temperatures which can reach values as low as −50°C.

Details

International Journal of Structural Integrity, vol. 7 no. 5
Type: Research Article
DOI: https://doi.org/10.1108/IJSI-11-2015-0053
ISSN: 1757-9864

Keywords

  • Self-healing
  • Fibre reinforced composites
  • Resin film infiltration (RFI)
  • Ring-opening metathesis
  • Thermosetting resin

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Article
Publication date: 22 May 2020

Dry sliding wear performance on self-healing Al6061 composites

Nitin Kumar Gupta, Gananath Doulat Thakre and Manoj Kumar

The purpose of this study is to investigate the tribological performance of the developed self-healing Al6061 composite and to optimize the operating conditions for…

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Abstract

Purpose

The purpose of this study is to investigate the tribological performance of the developed self-healing Al6061 composite and to optimize the operating conditions for enhanced tribo-performance of the developed material.

Design/methodology/approach

A unique procedure has been adopted to convert the sand casted Al6061 into self-healing material by piercing a low melting point solder material with and without MoS2. Taguchi-based L9 orthogonal array has been used to optimize the number of experiments and analyze the influence of operating parameters such as speed, sliding distance and load on material wear.

Findings

The results reveal that the paper shows the self-healing and self-repair is possible in metal through piercing low melting point alloy. Then, the load has a significant influence over other input parameters in predicting the wear behavior of developed material. Moreover, addition of MoS2 does not affect the tribo-performance of the developed material. The study concludes that the developed self-healing Al6061 has huge potential to be used in mechanical industry.

Research limitations/implications

The concept of self-healing in metals are very challenging task due to very slow diffusion rate of atoms at room temperature. Therefore, researchers are encouraged to explore the other new techniques to create self-healing in metals.

Practical implications

The self-healing materials had shown huge potential to be used in mechanical industry. The current investigation established a structural fabrication and testing procedure to understand the effects of various parameters on wear. The conclusion from the experimentation and optimization helps researchers to developed and create self-healing in metals.

Originality/value

The previous research works were not focused on the study of tribological property of self-healing metal composite. With the best of author’s knowledge, no one has reported tribological study, as well as optimization of parameters such as speed, load and sliding distance on wear in self-healing metals composite.

Details

Journal of Engineering, Design and Technology , vol. 18 no. 5
Type: Research Article
DOI: https://doi.org/10.1108/JEDT-03-2020-0078
ISSN: 1726-0531

Keywords

  • Optimization
  • Tribology
  • Taguchi method
  • Self-healing
  • Al6061
  • Metal composite

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Article
Publication date: 7 March 2016

The effect of polyurethane-isophorone microcapsules on self-healing properties of an automotive clearcoat

Pooneh Kardar

– The purpose of this work was to prepare a catalyst-free microcapsules as self-healing agent in an automotive clearcoat to improve the scratch resistance of coatings.

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Abstract

Purpose

The purpose of this work was to prepare a catalyst-free microcapsules as self-healing agent in an automotive clearcoat to improve the scratch resistance of coatings.

Design/methodology/approach

In this research, microcapsule with isophorone diisocyanate (IDPI) core and polyurethane shell were prepared and used in self-healing coatings. Microcapsules synthesised were characterised by thermal gravimeter and infrared spectra. The microcapsules were dispersed in an acrylic-melamine clearcoat, and the scratch resistance was evaluated.

Findings

The triplex product and the formed polyurethane bonds were confirmed by thermal gravimeter and infrared spectra. In addition, smooth spherical particles with a diameter of 1.5 to 1.7 micronmeters were observed by a scanning electron microscope. The microcapsules dispersed in an acrylic-melamine clearcoat increased the scratch resistance of coatings. Also, the self-healing feature of those coatings was proved.

Research limitations/implications

The size of microcapsules can affect its dispersion in the clearcoat and consequently affect the properties of the cured films.

Practical implications

The self-healing coatings are interested for many industries such as building and automotive industries. The reported data can be used by the formulators working in the R & D departments.

Social implications

Self-healing systems are considered as one of the smart coatings. Therefore, the developing of its knowledge can help to extend its usage to different applications.

Originality/value

The application of microcapsules in the coating as healing agents is a great challenge, which has been hardly investigated so far. In the current research, the effect of polyurethane-IDPI microcapsules in an automotive clearcoat as a self-healing coating was investigated.

Details

Pigment & Resin Technology, vol. 45 no. 2
Type: Research Article
DOI: https://doi.org/10.1108/PRT-03-2015-0033
ISSN: 0369-9420

Keywords

  • Coatings
  • Improvement
  • Mechanical properties
  • Polyurethane
  • Self-healing
  • Microcapsulation
  • Scratch resistance
  • Isophorone diisocyanate

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