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Aug 2014 DOI 10.14302/issn.2473-1005.jdoi-14-413
A. Ibrahim DinaCorresponding author
Demonstrator in Dental Biomaterials, Faculty of Dentistry, Mansoura UniverAsity, Mansoura, Egypt.
Objectives: This study was conducted to evaluate the effect of sport and energy drinks on conventional and resin-modified glass ionomer restorative materials regarding fracture toughness, surface roughness and fluoride release. Methods: The restorative materials used were conventional and resin-modified glass ionomers. Sport drinks used were Gatorade Perform 02 and Pocari sweat, while the energy drinks were Red Bull and Power Horse. Specimens were prepared and divided into five groups according to the immersion media (distilled water, two sport drinks and two energy drinks) for 1 and 7 days. The fracture toughness was determined using three-point bending method. Surface roughness was measured using surface profilometer. Fluoride release was determined using a conventional ion chromatograph testing unit. The data were analyzed using three-way ANOVA and Least Significant Difference test. For comparison between the two materials under each condition, t-test was used. Results: There was no significant difference in fracture toughness between sport, energy drinks and distilled water at the different time intervals except for conventional glass ionomer after 7 days. Resin-modified glass-ionomer exhibited smoother surfaces more than conventional one in sport and energy drinks after 1 day. After 7 days, both conventional and resin-modified glass ionomers showed greater surface roughness. Both conventional and resin-modified glass ionomers release more fluoride in acidic beverages than distilled water. Conclusions: The effect of sport and energy drinks on the fracture toughness may depend on the composition and acidity of drink. Fluoride release increased with the consumption of sport and energy drinks.
Apr 2020 DOI 10.14302/issn.2689-2855.jan-20-3244
Bendjemil BadisCorresponding author
DGM, FST, University of 8 Mai 1945 of Guelma, 24000 Guelma, Algeria
Nanocomposites are worn resistant materials used in cutting tool applications. The materials are composed of ultrafine powder hard phase grains surrounded by a tough binder phase carbon nanotubes (Mo2C)1-x–(TiC)x (2≤x≤4)//1Wt% SWCNTs. Composite bicarbide Mo2C-TiC was rapidly synthesised and simultaneously consolidated by field activated sintering technique (spark plasma sintering) at which the extensive volume expansion occurred as a function of the volumic fraction from 20 to 40 vol.% of TiC powders and 1 Wt.% of SWCNTs was reinforcement of the NCMC’s. The sintered powder mixture was examined by XRD patterns, the morphology of the obtained phase was observed by SEM and the phase compositions in different regions were analyzed by EDX. The composites were processed using Field Activated Sintering Technique, spark plasma sintering (SPS) at temperatures in the range of 1700-1800°C with addicting of SWCNTs. The effects of SWCNTs addition on phases morphology, microstructure hardness and fracture toughness of the nanocomposite were investigated. The best product contained 1.0 Wt% SWCNTs from (Mo2C)1-x–(TiC)x , x= 0.2 which was sintered at 1700°C, 70 MPa for 10 min, M0.8T0.2/ 1 Wt% SWCNTs exhibit a better density, highest hardness and good ductility. Relative densification was achieved 99.5 % from the theoretical and good mechanical properties like hardness and fracture toughness (KIC=5.6 Mpa m1/2) are improved. The results were confirmed using Raman scattering resonant spectroscopy.
Mar 2020 DOI 10.14302/issn.2689-2855.jan-20-3263
Bendjemil BadisCorresponding author
DGM, FST, University of 8 Mai 1945 of Guelma, 24000 Guelma, Algeria
Nanocomposites are worn resistant materials used in cutting tool applications. The materials are composed of ultrafine powder hard phase grains surrounded by a tough binder phase carbon nanotubes (Mo2C)1-x–(TiC)x (2≤x≤4)//1Wt% SWCNTs. Composite bicarbide Mo2C-TiC was rapidly synthesised and simultaneously consolidated by field activated sintering technique (spark plasma sintering) at which the extensive volume expansion occurred as a function of the volumic fraction from 20 to 40 vol.% of TiC powders and 1 Wt.% of SWCNTs was reinforcement of the NCMC’s. The sintered powder mixture was examined by XRD patterns, the morphology of the obtained phase was observed by SEM and the phase compositions in different regions were analyzed by EDX. The composites were processed using Field Activated Sintering Technique, spark plasma sintering (SPS) at temperatures in the range of 1700-1800°C with addicting of SWCNTs. The effects of SWCNTs addition on phases morphology, microstructure hardness and fracture toughness of the nanocomposite were investigated. The best product contained 1.0 Wt% SWCNTs from (Mo2C)1-x–(TiC)x , x= 0.2 which was sintered at 1700°C, 70 MPa for 10 min, M0.8T0.2/ 1 Wt% SWCNTs exhibit a better density, highest hardness and good ductility. Relative densification was achieved 99.5 % from the theoretical and good mechanical properties like hardness and fracture toughness (KIC=5.6 Mpa m1/2) are improved. The results were confirmed using Raman scattering resonant spectroscopy.
Mar 2020 DOI 10.14302/issn.2689-2855.jan-20-3243
Bendjemil BadisCorresponding author
DGM, FST, University of 8 Mai 1945 of Guelma, 24000 Guelma, Algeria
Cubic boron nitrid (cBN) bonded TiC and alloyed with single walled carbon nanotubes (SWCNTs or NC) ceramics matrix nanocomposites (CMNCs) tools were manufacturated by a field actived sparck plasma sintering processus (FASPS). The effects of cBN-TiC ratio, carbon nanotubes and optimisation of the sintering process on the microstructure, densification in addition mechanical and vibronic properties of NC-cBN-TiC nanocomposites were studied. The results showed that for the nanocomposite cBN-TiC vol. ratio of 8:2 with 0.1 wt% NC, it was found that microhardness incresses significantly with addition of carbon nanotubes exhibited the highest microhardness and fracture toughness. After sintering of the samples at 1800 °C, 10 mn, 75 MPa of cBN–TiC1-x, x=0.8 with and without addition of 0.1 wt% NC were characterized using field emission scanning electron microscopy (FESEM) and X-ray diffraction. The samples exhibited a dense polycrystalline structure. From the resonant Raman scattering we can locate the vibration frequency of the transformation cBN to hexagonal boron nitrid (hBN) and formation of secondary hard phase TiB2to consolid the (CMNCs) tools. The final product is hBN-TiC-TiB2-NC.The best product contained cBNx-TiC1-x (x=0.8)-0.1 wt % NC which was sintered at 1800 °C, 75 MPa for 10 mn. The Vickers hardness of cBN-TiC1-x (x=0.8) incresses with NC incorporation in the matrix The indentation fracture toughness was calculated to be 12.30 MPa m1/2 for cBNx-TiC1-x (x=0.8 -0.1 wt % NC ceramics matrix nanocomposite (CMNCs) tools with excellent wear resistant will be confirmed. The wear of cBN-TiC of the composites tools have shown that this is predominantly a chemical process involving the interaction of the tool with its environment and is restricted by the formation of protective layers on the exposed faces of the tool by the addition of carbon nanotubes (NC). The wear features of tools used in fine cutting tests under identical conditions will be compared and the results will be interpreted in terms of the existing models for the wear of cBN -based nanomaterials by the effects of the additives in the modified tools
Jun 2018
Kendall KevinCorresponding author
University of Birmingham, B15 2TT, UK
Graphene-Ceramic Composites (GCCs) have been little studied compared to graphene-polymer composites 1. Recent reviews 23 indicate that both mechanical and electrical property ceramic improvements can be obtained by mixing small quantities, typically 1 to 15% of graphene material with a ceramic precursor, then compacting and sintering. The greatest effect is on the electrical properties. The electrical conductivity of a material was first shown to rise by several orders of magnitude for only a 1% volume addition of graphene as in polymer composites 4 but the stiffness, strength and toughness only increased by 20-160% or so at 5% addition, a rather minor improvement compared to significant increases caused by slight ceramic process changes. Some crack bridging and pull-out mechanism was observed by electron microscopy in graphene-alumina composites, though the effects were modest. Surface friction and wear improvements of around 100% were also notable. This paper seeks to show that much higher toughness increases might be produced using the method pioneered by Clegg et al 5, where the graphite interlayers are replaced with graphene to produce improved ordered interfaces with reliable coverage and consistent interface fracture energy, enabling an increase in the fracture resistance of the ceramic by two orders of magnitude.