Temperature-dependent micro crack healing process

1998 ◽  
Vol 4 (6) ◽  
pp. 1219-1222
Author(s):  
Kazuhiro Kitamura ◽  
Igor L. Maksimov ◽  
Kazumi Nishioka
Keyword(s):  
Healing Process ◽  
Crack Healing ◽  
Temperature Dependent

scholarly journals Tracking capsule activation and crack healing in a microcapsule-based self-healing polymer

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
S. A. McDonald ◽  
S. B. Coban ◽  
N. R. Sottos ◽  
P. J. Withers
Keyword(s):  
Healing Process ◽  
Polymeric Materials ◽  
Time Lapse ◽  
Repair Process ◽  
Three Dimensions ◽  
Crack Plane ◽  
Self Healing ◽  
Crack Healing ◽  
Healing Agent ◽  
First Time

AbstractStructural polymeric materials incorporating a microencapsulated liquid healing agent demonstrate the ability to autonomously heal cracks. Understanding how an advancing crack interacts with the microcapsules is critical to optimizing performance through tailoring the size, distribution and density of these capsules. For the first time, time-lapse synchrotron X-ray phase contrast computed tomography (CT) has been used to observe in three-dimensions (3D) the dynamic process of crack growth, microcapsule rupture and progressive release of solvent into a crack as it propagates and widens, providing unique insights into the activation and repair process. In this epoxy self-healing material, 150 µm diameter microcapsules within 400 µm of the crack plane are found to rupture and contribute to the healing process, their discharge quantified as a function of crack propagation and distance from the crack plane. Significantly, continued release of solvent takes place to repair the crack as it grows and progressively widens.

scholarly journals Formation mechanism of bubbles in the crack healing process of fused silica using a CO2 laser

2021 ◽  
Vol 29 (20) ◽  
pp. 32089
Author(s):  
Zican Yang ◽  
Jian Cheng ◽  
Mingjun Chen ◽  
Linjie Zhao ◽  
Yaguo Li ◽  
...  
Keyword(s):  
Formation Mechanism ◽  
Co2 Laser ◽  
Healing Process ◽  
Fused Silica ◽  
Crack Healing

Electronic Binding Energy Changes of Elements in Al2O3-MgAlON Composite during the Crack Healing Process

2011 ◽  
Vol 287-290 ◽  
pp. 205-208
Author(s):  
Dao Yuan Yang ◽  
Hui Yu Yuan ◽  
Fen Ling Qian ◽  
Guang Hui Wei ◽  
Kai Zhu ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Binding Energy ◽  
Raw Materials ◽  
Healing Process ◽  
Sample Surface ◽  
Chemical State ◽  
Crack Healing ◽  
Hot Press ◽  
Before And After ◽  
Hot Press Sintering

Using Al, MgO and Al2O3 as raw materials, Al2O3-MgAlON composite was synthesized in N2 atmosphere by hot-press sintering at 900°C. Cracks prepared on the sample surface were healed at 1200°C×6hrs. Phase composition and element chemical state of sample were studied before and after healing. The results showed that: after healing process Al and MgO phase disappeare, and AlN and MgAlON phase appear, all kinds of elements in Al2O3-MgAlON material change their chemical state after the healing treatment, the changed electronic binding energy is Al 0.05ev, Mg 0.08ev, O 2.58ev or N 1.02ev respectively, and the chemical composition and crystal structure of MgAlON phase also change, all these change are helpful for crack healing process of Al2O3-MgAlON material.

scholarly journals Durability of self-healing concrete

2019 ◽  
Vol 289 ◽  
pp. 01003 ◽  
Author(s):  
Nele De Belie ◽  
Bjorn Van Belleghem ◽  
Yusuf Çağatay Erşan ◽  
Kim Van Tittelboom
Keyword(s):  
Corrosion Behaviour ◽  
Healing Process ◽  
Chloride Ingress ◽  
Self Healing ◽  
Crack Healing ◽  
Nacl Solution ◽  
Visual Damage ◽  
Chloride Profiles ◽  
Cracked Specimens ◽  
Concrete Matrix

Application of self-healing concrete reduces the need for expensive maintenance and repair actions. However, the durability of self-healing concrete has only been scarcely investigated. Here, recent results are presented regarding the resistance of self-healing concrete to chloride ingress. For self-healing concrete with macro-encapsulated polyurethane, chloride profiles and electron probe microanalysis indicated that this mechanism was efficient to reduce the chloride penetration into the crack and from the crack into the concrete matrix [1]. Furthermore, the corrosion behaviour of reinforced concrete specimens subjected to cyclic exposure with a NaCl solution was studied [2]. The electrochemical measurements indicated that autonomous crack healing could significantly reduce the corrosion in the propagation stage. No visual damage could be detected on the rebars after 44 weeks of exposure. On the contrary, cracked specimens without integrated self-healing mechanism, reached a state of active corrosion after 10 weeks of exposure and after 26 weeks clear pitting damage was observed on the rebars. While self-healing by encapsulated polyurethane is complete after one day, bacteria-based products take several weeks to heal a 300 µm crack. Bacterial granules containing denitrifying cultures released nitrite as an intermediate metabolic product which protected the reinforcement during the crack healing process [3].

Dynamics of Crack Healing and its Molecular Dynamics Simulation of Al2O3-MgAlON Composite

2010 ◽  
Vol 105-106 ◽  
pp. 137-141 ◽  
Author(s):  
Dao Yuan Yang ◽  
Hui Yu Yuan ◽  
Fen Ling Qian ◽  
Juan Wu ◽  
Kai Zhu ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Healing Process ◽  
Diffusion Constant ◽  
Sample Surface ◽  
Complete Healing ◽  
Dynamics Simulation ◽  
Diffusion Activation Energy ◽  
Crack Healing ◽  
Healing Temperature

After preparing samples (3mm long×4mm wide×36mm high) of Al2O3-MgAlON composites and sintered at 1500°C for 2 h in N2 atmosphere, samples’ cracks were carved by a Vickers hardometer’s pressing head on the center of the sample surface (4 mm×36 mm). Subsequently, the cracks were healed at 1000°C-1550°C for 6 h respectively. Effects of healing temperature on sample’s strength, crack healing dynamics and its molecular dynamics simulation were investigated. The results suggested that: the optimum range of cracks healing temperature was 1300°C-1550°C, and the healing process accelerated at 1300°C, meanwhile, the strength of samples increased significantly. Cracks completely healing finished at 1550°C. The dynamics equation of crack healing was lnν = -Q/kT+lnC. Through characterizing the crack healing rate with the recovering rate of sample’s strength, the diffusion activation energy Q = 4.264 × 10-30 J•K-1 and diffusion constant C=7.359 were claimed. The result of the molecular dynamics simulation suggested that cracks healing process was caused by diffusion could be divided into five stages: passivation of crack tips, formation of salient island, crack shrinkage, generation of secondary crack, and complete healing.

A method to study the crack healing process of glassformers

2008 ◽  
Vol 92 (1) ◽  
pp. 011918 ◽  
Author(s):  
W. H. Wu ◽  
J. L. Zhang ◽  
H. W. Zhou ◽  
Y. N. Huang ◽  
L. Zhang ◽  
...  
Keyword(s):  
Healing Process ◽  
Crack Healing

Obtaining the glass transition temperature by measuring the crack healing process of glassformers

2008 ◽  
Vol 92 (13) ◽  
pp. 131906 ◽  
Author(s):  
J. L. Zhang ◽  
W. H. Wu ◽  
H. W. Zhou ◽  
X. Z. Guo ◽  
Y. N. Huang
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Healing Process ◽  
Crack Healing

Effect of crack healing process on fatigue property of Si_3N_4/SiC ceramics at high temperature

2002 ◽  
Vol 2002.6 (0) ◽  
pp. 183-184
Author(s):  
Keiji HOUJOU ◽  
Kotoji ANDO ◽  
Koji TAKAHASI ◽  
Shigemi SATO
Keyword(s):  
High Temperature ◽  
Healing Process ◽  
Fatigue Property ◽  
Crack Healing ◽  
Sic Ceramics

Dislocation Arrays in Sapphire using Femtosecond Laser Irradiation

2009 ◽  
Vol 1228 ◽  
Author(s):  
Chiwon Moon ◽  
Shingo Kanehira ◽  
Kiyotaka Miura ◽  
Eita Tochigi ◽  
Naoya Shibata ◽  
...  
Keyword(s):  
Femtosecond Laser ◽  
Laser Irradiation ◽  
Crack Formation ◽  
Focal Point ◽  
Healing Process ◽  
Femtosecond Laser Irradiation ◽  
Crack Healing ◽  
Dislocation Arrays ◽  
Crystallographic Planes ◽  
Surface Fracture Energy

AbstractWe investigated the formation mechanism and thermal behaviors of defects which were induced at a microscopic area inside (1120) sapphire. We used a femtosecond laser having a pulse width, wavelength, and repetition rate of 238 fs, 780 nm, and 1 kHz, respectively. Cracks were formed at the focal point along the {1102} and the {1100} planes by laser irradiation. The preferential crack formation on these planes was attributed to the different surface fracture energy between the crystallographic planes of sapphire. The cracks transformed into the array of discrete pores by the subsequent heat treatment above 1300 °C, which was due to the diffusive crack healing process. In addition, dislocations were also introduced at the interface between closed cracks.

Thermally-induced Crack Healing in Poly(Methyl Methacrylate)

2002 ◽  
Vol 17 (6) ◽  
pp. 1335-1340 ◽  
Author(s):  
Jane-Sang Shen ◽  
Julie P. Harmon ◽  
Sanboh Lee
Keyword(s):  
Activation Energy ◽  
Methyl Methacrylate ◽  
Crack Closure ◽  
Healing Process ◽  
Fourth Power ◽  
Surface Cracks ◽  
Crack Healing ◽  
Closure Rate ◽  
Thermally Induced ◽  
Poly Methyl Methacrylate

A microscopic theory of thermally induced crack healing in poly(methyl methacrylate) is presented. Both laser-induced cylindrical cracks and knife-induced surface cracks were analyzed. For a given temperature, the crack closure rate was constant for both types of cracks. However, the crack closure rate was lower for samples with cylindrical cracks than for those with surface cracks. The former exhibited higher activation energy for crack closure than the latter, because the knife-induced cracks had sharper crack tips. Fracture stress was proportional to surface crack healing time to the one-fourth power for thermal healing at a given temperature. Based on the reptation model of polymer chains, the activation energy of chain diffusion was calculated. The healing process was monitored via fractography and crack closure was confirmed. The results were compared with solvent healing and thermal healing in the literature.

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