scholarly journals A Comparative Study on Crack-Healing Ability of Al2O3/SiC Structural Ceramic Composites Synthesized by Microwave Sintering and Conventional Electrical Sintering

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Madhan Mohankumar ◽  
A. N. Shankar ◽  
T. S. Karthik ◽  
R. Saravanakumar ◽  
Hemakesavulu Oruganti ◽  
...  
Keyword(s):  
Bending Strength ◽  
Microwave Sintering ◽  
Ceramic Composites ◽  
Bending Test ◽  
Crack Healing ◽  
Structural Ceramic ◽  
X Ray ◽  
Sem Micrographs ◽  
Before And After ◽  
Sio2 Phase

This study was conducted to assess and compare the crack-healing ability of conventional electrical sintered and microwave sintered Al2O3/x wt. % SiC (x = 5, 10, 15, and 20) structural ceramic composites. The crack-healing ability of both conventional electrical sintered and microwave sintered specimens was studied by introducing a crack of ∼100 µm length by Vickers’s indentation and conducting a heat treatment at 1200°C for dwell time of 1 h in air. The flexural or bending strength of sintered, cracked, and crack-healed specimens was determined by three-point bending test, and the phase variations by X-ray diffraction and SEM micrographs before and after crack-healing of both the sintering methods were studied and compared. The results show that almost all the specimens recovered their strength after crack-healing, but the strength of microwave sintered Al2O3/SiC structural ceramic composites has been shown to be better than that of conventional electrical sintered Al2O3/SiC structural ceramic composites. The microwave sintered crack-healed Al2O3/10 wt. % SiC specimen shows higher flexural strength of 794 MPa, which was 105% when compared with conventional electrical sintered Al2O3/10 wt. % SiC and crack-healed Al2O3/10 wt. % SiC specimen. It was found by X-ray diffractogram that before crack-healing, all the conventional electrical sintered samples have SiO2 phase which reduce the crack-healing ability and microwave sintered samples with 15 and 20 wt. % SiC show lesser SiO2 phase and 5 and 10 wt. % SiC samples have no SiO2 phase before crack-healing. However, after crack-healing treatment, all the samples have distinct SiO2 phase along with Al2O3 and SiC phases. Microwave sintered Al2O3/10 wt. % SiC specimen cracks were fully healed which was evident in SEM micrographs.

Elastic Wave Signal Characteristics of SiC Ceramics with Crack Healing Ability by Wavelet Analysis

2005 ◽  
Vol 297-300 ◽  
pp. 2046-2051 ◽  
Author(s):  
Jin Wook Kim ◽  
B.W. Park ◽  
Seok Hwan Ahn ◽  
Ki Woo Nam
Keyword(s):  
Elastic Wave ◽  
Bending Strength ◽  
Spectral Characteristics ◽  
Compressive Load ◽  
Limited Range ◽  
Bending Test ◽  
Crack Healing ◽  
Sic Ceramics ◽  
Signal Characteristics ◽  
Ae Signals

This paper reports for signal characteristics of before-and-after healing treatment SiC ceramics with crack healing ability. The elastic wave signals generated during the compress load by a Vickers indenter on the brittle materials were recorded in real time, and the waveforms of the individual signals were examined and classified based on their spectral characteristics. The compress loads were applied with the range from 9.8N to 294N. In a bulk SiC specimen, the AE signals occurred only when the load was compressive loading and unloading. But, in the after crack healing specimen of 294N only, even though the external compressive load was stopped and kept on holding constant load states, the AE signals occurred irregularly and continuously. The results of the WT and frequency analysis showed that these existed as the property of frequency in the limited range between 100kHz and about 200kHz. Three-point bending test was performed for the cracked and healed SiC specimens. Consequently the bending strength of the crack healed specimens was recovered completely, but most of the samples with the crack healed showed that the properties of the dominant frequency were comparatively lower than that of the bulk SiC samples. The classification of the wave signals can be used to develop algorithms for autonomous health monitoring systems of brittle material structures.

scholarly journals EFFECT OF IMMERSION TIME TO MECHANICAL STRENGTH OF POLYVINYL ALCOHOL– HYDROXY APATITE COMPOSITE AS BIODEGRADABLE BONE PLATE

2013 ◽  
Vol 17 (4) ◽  
pp. 310-313
Author(s):  
Mochammad Taha Ma’ruf ◽  
Widowati Siswomihardjo ◽  
Marsetyawan Heparis Nur Ekanda Soesatyo ◽  
Alva Edy Tontowi
Keyword(s):  
Polyvinyl Alcohol ◽  
Mechanical Strength ◽  
Immersion Time ◽  
Bending Strength ◽  
Bone Plate ◽  
Bending Test ◽  
Hydroxy Apatite ◽  
Before And After ◽  
Titanium Substitution ◽  
Biodegradation Test

Polymer based material such as Poly-L-Lactic-Acid (PLLA) have been used for titanium substitution. However, the last research indicates that it was not an ideal material as bone fracture fixation device. It is a challenge to develop other materials as biodegradable bone plate for titanium substitution, such as polyvinyl alcohol (PVA). In this study, polyvinyl alcohol has composited with Hydroxy apatite (HA) and reinforced with catgut fiber. The aim of this study was to know the effect of immersion time to mechanical strength of PVA– HA composite with catgut reinforced as biodegradable bone plate after biodegradation test for 30 and 60 days. Specimens were prepared for tensile and bending strength tests, immersed in phosphate buffered saline (PBS) solution with pH 7.4 at 370C. Specimens were weighed before and after biodegradation test, tensile and bending test were done after removed for 30 and 60 days. The result showed that PVAHA composite reinforced with catgut fiber has stable mechanical strength after 30 and 60 days biodegradation process. The mechanical strength decreased in 30 and 60 days in all intervention groups, but it still has adequate mechanical strength as biodegradable bone plate. In conclusion, PVA-HA composite reinforced with catgut fiber can be developed as biodegradable bone plate replace titanium and other commercial bone plate.

Pultruded glass fiber- and pultruded carbon fiber-reinforced chemically bonded phosphate ceramics

2011 ◽  
Vol 45 (23) ◽  
pp. 2391-2399 ◽  
Author(s):  
H.A. Colorado ◽  
H.T. Hahn ◽  
C. Hiel
Keyword(s):  
Carbon Fiber ◽  
Glass Fiber ◽  
Bending Strength ◽  
Bending Test ◽  
Fiber Reinforced ◽  
X Ray ◽  
The Matrix ◽  
Carbon Fiber Reinforced ◽  
Micro Tomography ◽  
Electron Microscopes

The main goal of this article is to present the pultrusion process for glass fiber- and carbon fiber-reinforced chemically bonded phosphate ceramics (CBPCs). Samples were fabricated with 15% of fibers by volume. An improvement (with respect to the matrix) of 29 times for the bending strength of CBPCs pultruded graphite fibers composites and 17 times for CBPCs pultruded glass fiber composites is shown. Bending strength was obtained with the three-point bending test. The CBPCs were fabricated by mixing special formulations of both wollastonite powder and phosphoric acid, through resonant acoustic mixing. The microstructure was analyzed with optical and scanning electron microscopes. X-ray compositional maps were obtained for the cross-section of pultruded samples with SEM-EDS. Pultruded sample response at high temperature and thermal shock were also analyzed. The structural characterization of samples was conducted by using X-ray micro tomography.

Fracture Stress Analysis in Ceramic Composites of Alumina Matrix with Zirconia 3Y-TZP Nanograins for Mechanical Shielding of Satellites

2016 ◽  
Vol 869 ◽  
pp. 64-68
Author(s):  
Eron Fernandes da Silva ◽  
Daniel Alessander Nono ◽  
Sergio Luiz Mineiro ◽  
Francisco Piorino Neto ◽  
Maria do Carmo de Andrade Nono
Keyword(s):  
Fracture Stress ◽  
Ceramic Composite ◽  
Space Debris ◽  
Tetragonal Zirconia ◽  
Ceramic Composites ◽  
Bending Test ◽  
Alumina Matrix ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mechanical Bending

This paper presents the analysis results of fracture stress values for ceramic composites of alumina matrix mixed with nanoparticulate zirconia (3Y-TZP) ((tetragonal zirconia polycrystalline doped with 3 mol% yttria), which will be used in parts of the Brazilian satellites to act as mechanical shield for micrometeoroid and space debris impacts. The ceramic composites were obtained by mixing dispersed suspensions of alumina powders and 18.5 wt % of nanoparticulate zirconia, compacted with isostatic pressure and sintered at 1550 °C. After sintering, the ceramic composite was analyzed by SEM, X-ray diffraction and subjected to 4 points mechanical bending test. The microstructure analyses were performed and rupture stress values with Weibull distribution. The results were compared to previous works obtained after mechanical mixture of same powders. The results analyses showed that the greater homogeneity distribution of zirconia nanograins on alumina matrix contributes to increased fracture stress values.

Evaluation of Impact Bending Strength of Ceramic Composites at Ultra-High Temperatures from 1500-2000 °C in Air

2013 ◽  
Vol 591 ◽  
pp. 145-149 ◽  
Author(s):  
De Tian Wan ◽  
Yi Wang Bao ◽  
Hua Zhao ◽  
Yuan Tian
Keyword(s):  
High Temperatures ◽  
Bending Strength ◽  
Impact Load ◽  
Ceramic Composites ◽  
Test Method ◽  
Bending Test ◽  
Dynamic Force ◽  
Maximal Load ◽  
Impact Bending ◽  
The Impact

In this work, a new and novel test method was developed to determine the impact bending strength of ceramic composites at ultra-high temperature from 1500-2000 °C in air. Three-point impact bending test was carried out through a SiC pressure head with a dynamic force sensor fixed on a slider and movable along a guide rail. The impact load was adjusted by different saving energy and the impact speed was lower than 0.5 m/s. The center of the sample was heated up to about 1500-2000°C by oxygen-assisted spray combustion. An impact load was put on the specimen and the impact force was recorded automatically. The impact bending strength can be calculated from the maximal load and the sample size. To check the availability and reliability for this method, several ceramics including SiC, ZrB2/SiC and C/C fiber reinforced composite without coating, were used as the testing samples. The results indicate that this method is a good and feasible method for evaluating the mechanical properties of the ceramic composite at ultra-high temperatures.

Estimation of Residual Stress Change due to Cyclic Loading by Classical Elastoplasticity Model and Subloading Surface Model

2016 ◽  
Vol 725 ◽  
pp. 281-286 ◽  
Author(s):  
Ryota Higuchi ◽  
Kazuo Okamura
Keyword(s):  
Residual Stress ◽  
Cyclic Loading ◽  
Stress Measurement ◽  
Kinematic Hardening ◽  
Bending Test ◽  
Surface Model ◽  
Material Function ◽  
X Ray ◽  
Before And After ◽  
Good Agreement

The subloading surface model has been formulated and applied to the prediction of cyclic loading behavior. The material function prescribing elastic-plastic transition in the original subloading surface model has been extended so as to describe the inverse and reloading behavior and the strain accumulation in cyclic loading more accurately for steel. In the present paper, the extended subloading surface model was applied to the prediction of the change of the residual stress due to cyclic loading. The four-point cyclic bending test was performed for the specimen that had initial residual stress. The distributions of the residual stress before and after cyclic loading were measured by the X-ray stress measurement method. The simulation to the experiment was performed by the extended subloading surface model. The stress distribution after cyclic loading simulated by the extended subloading surface model was in good agreement with measured one, and was more accurate than that by the nonlinear isotropic/kinematic hardening model.

Evaluation of Freezing Methods by Low Temperature X-Ray Diffraction

1977 ◽  
Vol 35 ◽  
pp. 330-333
Author(s):  
T. Gulik-Krzywicki ◽  
M.J. Costello
Keyword(s):  
Biological Materials ◽  
Molecular Organization ◽  
X Ray Diffraction ◽  
Glass Capillary ◽  
X Ray ◽  
Rate Dependent ◽  
Before And After ◽  
Freeze Etching ◽  
Diffraction Patterns ◽  
Set Up

Freeze-etching electron microscopy is currently one of the best methods for studying molecular organization of biological materials. Its application, however, is still limited by our imprecise knowledge about the perturbations of the original organization which may occur during quenching and fracturing of the samples and during the replication of fractured surfaces. Although it is well known that the preservation of the molecular organization of biological materials is critically dependent on the rate of freezing of the samples, little information is presently available concerning the nature and the extent of freezing-rate dependent perturbations of the original organizations. In order to obtain this information, we have developed a method based on the comparison of x-ray diffraction patterns of samples before and after freezing, prior to fracturing and replication.Our experimental set-up is shown in Fig. 1. The sample to be quenched is placed on its holder which is then mounted on a small metal holder (O) fixed on a glass capillary (p), whose position is controlled by a micromanipulator.

The Precipitation of Si in AlCuSi Thin Films

1973 ◽  
Vol 31 ◽  
pp. 34-35 ◽  
Author(s):  
R. M. Anderson
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Heat Treatment ◽  
Solid Solution ◽  
Integrated Circuit ◽  
Copper Film ◽  
Solution Concentration ◽  
X Ray ◽  
Silicon Thin Films ◽  
Before And After

Aluminum-copper-silicon thin films have been considered as an interconnection metallurgy for integrated circuit applications. Various schemes have been proposed to incorporate small percent-ages of silicon into films that typically contain two to five percent copper. We undertook a study of the total effect of silicon on the aluminum copper film as revealed by transmission electron microscopy, scanning electron microscopy, x-ray diffraction and ion microprobe techniques as a function of the various deposition methods.X-ray investigations noted a change in solid solution concentration as a function of Si content before and after heat-treatment. The amount of solid solution in the Al increased with heat-treatment for films with ≥2% silicon and decreased for films <2% silicon.

A New Polyethylene Corrosion Protecting Coating with Ion Selectivity

2011 ◽  
Vol 314-316 ◽  
pp. 273-278
Author(s):  
Yu Hua Dong ◽  
Ke Ren ◽  
Qiong Zhou
Keyword(s):  
Ion Selectivity ◽  
Nano Particles ◽  
Ammonium Bromide ◽  
Linear Low Density Polyethylene ◽  
X Ray Diffraction ◽  
Sulfosalicylic Acid ◽  
X Ray ◽  
Chemically Modified ◽  
Before And After ◽  
Industrial Standards

Linear low density polyethylene (LLDPE) was chemically modified with grafting maleic anhydride (MAH) monomer on its backbone by melting blending. Nano-particles SiO2 was modified by cationic surfactant hexadecyl trimethyl ammonium bromide (CTAB) and anionic surfactant sulfosalicylic acid (SSA) and added to PE coating respectively. Measurement of membrane potential showed that the coating containing modified SiO2 nano-particles had characteristic of ion selectivity. The properties of the different coatings were investigated according to relative industrial standards. Experimental results indicated that PE coating with ion selectivity had better performances, such as adhesion strength, cathodic disbonding and anti-corrosion, than those of coating without ion selectivity. Crystal structure of the coatings before and after alkali corrosion was characterized by Fourier transform infrared spectra (FTIR) and X-ray diffraction (XRD). Structure of the coating without ion selectivity was damaged by NaOH alkali solution, causing mechanical properties being decreased. And the structure of the ion selective coatings was not affected.

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