FATIMA ZOHRA Mezahi

سيواني أنفال

تحضير مركبات الهيدروكسي أباتيت- الفوسفات ثلاثي الكالسيوم

BOUDJEMAA MOHAMED ELAMINE

Etude de la densité et la dureté de wollastonite6r

Merzougui Malika

تأثير عناصر التطعيم (Na, Mg, Si) على الخصائص الفيزيائية و الكيميائية للهيدروكسي أباتيت المحضرة بطريقة سائل- هلام

HAMIDI CHAIMA , AZIZI ASSMAA

Synthèse de Wollastonite par voie sol-gel

Zourig Ibtissem

Effet de sodium sur la densité et dureté de l’hydroxyapatite

Sassaoui Imane

Effet du Na2O sur la synthèse de l’hydroxyapatite par voie sol-gel

Kherifi Djelal

Synthèse de l’hydroxyapatite par voie sol-gel

Oualid Zouaoui

Effet du Na2O sur la synthèse du verre 52S4 , par voie sol-gel

Attalah Malika

Etude de la bioactivité du verre 52S4 , synthétisé par voie fusion, par RMN du solide

Hadj Laroussi Asma

Edude de la bioactivité de l’hydroxyapatite dopée par le ZrO2 et Al2O3

Zouizi Fateh

Effet des additions sur la bioactivité de l’hydroxyapatite

Hydroxyapatite (HA) is a biocompatible and bioactive material used as bone-substitute materials in both orthopedics and dentistry. This work is devoted to studying the synthesis of hydroxyapatite (HA) by sol–gel route using triethyl phosphate (TEP) and calcium nitrate tetrahydrate as calcium and phosphor precursors. In order to optimize the hydrolysis of TEP, each prepared solution was aged in a closed Teflon ® container. Several factors were tested in order to improve the synthesis conditions of well-crystallized HA. The effect of aging time (4 h, 16 h, and 24 h), aging temperature (25 °C, 50 °C, 70 °C, and 90 °C) of the prepared solutions, and the type of solvents (ethanol and/or distilled water) were tested. All dried gels were calcined at 700 °C for 1 h. The obtained results showed that the crystallinity degree of hydroxyapatite increases with aging time and temperature, which must not exceed 70 °C. When the prepared solutions were aged at 90 °C, the tri-calcium phosphate (TCP) was formed as a major phase and HA was present as a very minor phase. It was remarked that the aging of sols in a closed Teflon container ® leads to an important decrease of the aging time and temperature. It was found that 24 h and 70 °C are the optimal conditions for the synthesis of well-crystallized HA. Also, it was deduced that a sufficient amount of water was needed to hydrolyze the triethyl phosphate and consequently, to obtain a well-crystallized HA.

Citation

Fatima Zohra MEZAHI , malika MERZOUGUI , Achour Dakhouche , Foudil SAHNOUNE , DJELEL Kherifi , , (2022), Improvement of the reactivity of triethyl phosphate and structural behavior of hydroxyapatite versus the synthesis conditions by sol-gel route, Chemical Papers, Vol:76, Issue:2, pages:1045-1061, springer

for 2 h. Moreover, the in vitro bioactivity of β-Ca2SiO4 was investigated by soaking the powders in a simulated body fluid (SBF) for various time periods to analyse the growth of hydroxyapatite (HA) on the surface of these powders. The synthesised powders were characterised by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), and Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) analysis. The simulated body fluid results showed that the β-Ca2SiO4 powders had good bioactivity to induce hydroxyapatite formation on their surface. The results obtained showed that (HCA) can be formed on the surface of β-Ca2SiO4 soaked in the SBF solution for 1 day, and a continuous layer of dense HCA deposits covered the surface of β-Ca2SiO4 powders after 3 days of soaking in the SBF solution. Finally, the results obtained suggest that β-Ca2SiO4 ceramics are promising candidates for bone regeneration.

Citation

Fatima Zohra MEZAHI , Siham Chehlat, Abdelhamid Harabi, Hassane Oudadesse, , (2022), In vitro hydroxyapatite forming ability od dicalcium silicate prepared from local raw materials and sintered at 1050°C, Ceramics-Silikaty, Vol:66, Issue:3, pages:274-279, academy of sciences of the czech repulic

The aim of this work is to study the effect of magnesium on the physic-chemical properties of hydroxyapatite prepared by sol-gel route. Magnesium Nitrate Hexahydrate, Calcium Nitrate tetrahydrate, and triethyl phosphate (TEP) were used as precursors for Mg, Ca, and P, respectively. Noted that the molar ratio (Ca +Mg)/P was kept constant at 1.67 when the magnesium was added (0 to 10 % (mol)) to the prepared solutions. Based on the our previous results, all solutions were aged at 70°C for 24 h, the distilled water was used as medium solvent. The same conditions were used for gelling and drying of the aged solutions. All dried gels were calcined at 700°C for 1 h and heat treated at 1100, 1200 and 1300°C for 4 h in order to study the effect of magnesium on the crystallization of doped hydroxyapatite (Ca10-xMgx (PO4)6(OH)2, crystal lattice parameters, thermal stability and morphological of hydroxyapatite. The XRD and FTIR results showed that the hydroxyapatite is the major formed phase at all temperatures without any decomposition to the tricalcium phosphate. The CaO was present as secondary phase at 700°C. But the intensity of this phase decreased with temperature. Also, a minor ratio of MgO was present in samples doped by 5% and 10% MgO. The lattice parameters of doped hydroxyapatite decreased in comparison to pure hydroxyapatite because the ion radius of magnesium is lower than that of calcium. The results of analysis of distribution size confirmed the formation of agglomerates as results of the assemblage of small grains as confirmed by SEM images. The obtained results confirmed the incorporation of the magnesium in the lattice structure of HA.

Citation

Fatima Zohra MEZAHI , malika MERZOUGUI , ,(2022), Caracterisation of doped hydroxyapatite by magnesium versus the heat treatment temperature,2nd International Seminar on Industrial Engineering and Applied Mathematics (ISIEAM’22),Skikda , Algérie

This work is devoted to study the reactivity of a quaternary glass: 52% SiO2, 30% CaO, 14% Na2O and 4% P2O5 (wt %) (named 52S4F), synthesized by the melting route. The physicochemical properties of 52S4F glasses were determined before and after immersion in simulated body fluid (SBF). The obtained results by various analysis methods, such as ICP, IR, SEM-EDS and solid state NMR, have shown that different structural modifications at the glass surface as a function of immersion time were occurred. The silica gel (SiO2) and the calcium phosphate layer (HA) were formed at the glass surfaces after the immersion in SBF. The crystallite size of HA layer is in the order of nano (as shown by SEM). NMR analysis highlights the different structural’s alterations during immersion in SBF. It shows that, after 1 day immersion time, the silica gel is formed and it has grown until 15 days. In addition, it demonstrates that after 5 days the precipitation process becomes more dominant than the dissolution process of the glass, which confirms the results of the other used methods. Finally, according to the obtained results, the quaternary glass 52S4F is a bioactive glass.

Citation

Fatima Zohra MEZAHI , ,(2019), Highlight the reactivity of 52S4F, synthesised by fusion route, by solid state NMR,4 th global conference on materials sciences (Gc-mas2019),Antalya, Turkey

Hydroxyapatite (HA: Ca10(PO4)6(OH)2) is one of the most attractive materials for human hard tissue implants because of its close physical and chemical properties to mineral part of bone and teeth1. Several works have been carried out on structural modifications and mechanical properties of HA in the presence of oxides or metallic dispersions used as reinforcing agents2–4. So, this work is devoted study the thermal stability of pure hydroxyapatite and doped hydroxyapatite (HA + 5% wt. diopside, HA + 5% wt. doloma and HA + 5% wt. silica) when they heated at 1300°C. The results show that the trace elements have a great influence on the density and the thermal stability of hydroxyapatite. The density of pure treated hydroxyapatite was near to theoretical density. A weak change was occurred in density value when the doloma was added. Or, the addition of silica and diopside has a remarkable effect on the density of hydroxyapatite. The densities of treated samples were decreased. After heat treatment at 1300°C, the XRD results show that the composition of pure hydroxyapatite has not changed. However, the addition of the doloma led to the partial decomposition of HA into -tricalcium phosphate (-TCP) as minor phase. While the addition of the diopside and silica leads to the formation of silicate hydroxyapatite "the silicocarnotite" as major phase. The FTIR results confirmed the XRD results. The IR characteristic bands of (-TCP) and the silicocarnotite were well distingued.

Citation

Fatima Zohra MEZAHI , ,(2019), Effect of additions on thermal stability of hydroxyapatite,International Conference on Chemical Physics and Materials Science (ICCPMS),ISTANBUL, TURKEY

Cordierite (Mg2Al4Si5O18) formation via sol-gel route using Tetraethyl orthosilicate TEOS, Aluminum nitrate nonahydrate Al(NO3)3.9H2O, and Magnesium nitrate hexahydrate Mg(NO3)2.6H2O as starting materials was studied by means of high-temperature by heating from room temperature up to 1350 °C. Differential thermal analysis (DTA) technique, under non-isothermal conditions is the appropriate for studying high-temperature reaction kinetics. The activation energies and kinetics parameters of cordierite formation measured by both isothermal (Johnson–Mehl–Avrami (JMA) theory using Ligero method) and non-isothermal (Ozawa, Boswell and Kissinger methods) treatments. The growth morphology parameters n (Avrami parameter which indicates the crystallization mode) and m (a numerical factor which depends on the dimensionality of crystal growth) were also determined. Powders obtained were characterized using high temperature x-ray powder diffraction (XRD), and Scanning electron microscopy (SEM). Finally, the thermodynamic parameters (ΔG#, ΔH# and ΔS#) for cordierite crystals were determined.

Citation

Fatima Zohra MEZAHI , smail LAMARA , Foudil SAHNOUNE , ,(2019), The kinetics parameters of cordierite materials synthesized via sol-gel route using Differential Thermal Analysis (DTA),6 th International Conference on computational and Experimental Science and Engineering (ICCESEN-2019),Antalya, Turquie

Hydroxyapatite (HA) is a biocompatible and bioactive material used as bone-substitute materials in both orthopedics and dentistry. This work is devoted to study the synthesis of hydroxyapatite (HA) by sol-gel route using triethyl phosphate (TEP) and calcium nitrate tetrahydrate as calcium and phosphor precursors. In order to optimize the hydrolysis of TEP, each prepared solution was aged in closed Teflon® container. Several factors were tested in order to improve the synthesis conditions of well crystallized HA. The effect of aging time (4 h, 16 h and 24 h) was tested. All dried gels were calcined at 700°C for 1 h. The obtained results showed that the crystallinity degree of hydroxyapatite increases with aging time. It was remarked that HA peaks are dominant peaks and their intensities increase in contrast to that of CaO peaks with aging time. In addition, the width of the peaks becomes narrower. So, these results are a sign of an increase in the crystallinity degree and the crystallite size with aging time.

Citation

Fatima Zohra MEZAHI , ,(2019), Effect of aging time on synthesis of hydroxyapatite by the sol-gel route,The first international conference on materials, environment, mechanical and industrial systems ICMEMIS’2019,Djelfa , Algérie

This work is devoted to study the reactivity of the quaternary glass 52S4 (52% SiO2–30% CaO–14% Na2O–4% P2O5 (wt%)), synthesized by sol-gel process versus the treatment temperature. The dried gel was heat treated at 600 and 650 °C and soaked in simulated body fluid (SBF). XRD results confirm the amorphous character of glass treated at 600 °C even though the heat treatment at 650 °C induces Na2Ca2Si3O9 formation. After soaking in SBF, SEM and EDS results show the formation of carbonated hydroxyapatite (CHA) at the glass surface for both temperatures. For the glasses treated at 600 and 650 °C, two phenomena were observed: the glass dissolution in SBF and the CHA precipitation, but the reactivity kinetics of glass was different when temperature changes. For SGDG600, the CHA began to crystallize after 16 h. For SGDG650, a glass ceramic made of a glassy matrix and of Na2Ca2Si3O9, the crystallized carbonated HA was observed after 2 h. In addition, a new crystallization at the glass surface of Na2Ca2Si3O9 was observed after 15 days.

Citation

Fatima Zohra MEZAHI , Anita Lucas - Girot, Hassane Oudadesse, Abelhamid Harabi, , (2018), Reactivity features of original sol-gel derived 52S4 glass versus heat treatment temperature, Journal of the Australian Ceramic Society, Vol:54, Issue:4, pages:609-619, springer

Hydroxyapatite (HA) Ca10 (PO4)6 (OH)2 is a very important inorganic material; first mineral constituent of bones, tooth enamel and dentin. It is very flexible in terms of composition and morphology. HA is known as a non-resorbable and surface-active bioceramic and is mainly used for many medical applications thanks to its biocompatibility and bioactivity. The aim of this work is devoted to study of the effect of the sodium addition (Na) with different molar ratio (0, 1, 5, 10, 15 and 20%) on the synthesis of hydroxyapatite by the sol-gel route. From the obtained results, it was possible to obtain well crystallized hydroxyapatite at 700 ° C; synthesized from the precursors: the calcium nitrate and tri-ethyl phosphate. Sodium nitrates were used as a source of Na. The synthesis was carried out for 3 days; one day for aging the prepared solutions; one day to obtain a gel, one day to dry the gel. The obtained results showed that the addition of sodium stabilize the hydroxyapatite synthesized by the sol-gel route. As ratio of Na increases, the intensity of the XR peaks of HA increases and that of CaO decreases. Thus, DRX has shown the apparition of a new phase (-CaNaPO4) at 1000 ° C and 1300 ° C for the large concentrations of Na (15 % and 20 %).

Citation

Fatima Zohra MEZAHI , malika MERZOUGUI , ,(2018), Sodium effect on the hydroxyapatite synthesis by the sol-gel route,International conference on Materials Science ICMS2018,Setif

Good quality ceramics costs a lot that has limited their use in developing countries. This work was devoted to prepare low-cost and good quality anorthite based ceramics. The proposed composition was 80 wt% kaolin (DD2 type) and 20 wt% calcium oxide (CaO). The choice of these raw materials was dictated by their natural abundance coupled with a modified milling system, as another interesting advantage. Previous studies have shown that a simple vibratory multidirectional milling system using bimodal distribution of highly resistant ceramic milling elements has been successfully applied for obtaining fine powders. The influence of the relatively lower sintering temperature, ranging from 800 to 1100 °C, on the porosity and the average pore size (APS) have been investigated. The APS and the porosity values of samples sintered at 950 °C were about 1 μm and 4%, respectively. The best Vickers microhardness and 3-point bending strength values for these sintered samples, using this proposed milling system, were 7.1 GPa and 203 MPa, respectively. Finally, the crystalline phase evolution during heat treatment was investigated by X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy techniques.

Citation

Fatima Zohra MEZAHI , A Harabi, S Zaiou, A Guechi, L Foughali, E Harabi, N-E Karboua, S Zouai, , (2017), Mechanical properties of anorthite based ceramics prepared from kaolin DD2 and calcite, Cerâmica, Vol:63, Issue:367, pages:311-317, Associação Brasileira de Cerâmica

In the current study, the effect of P2O5 on the mechanical properties of porous natural hydroxyapatite (NHA) derived from cortical bovine bones sintered at 1,050°C is assessed. Hydroxyapatite (HA: Ca10(PO4)6(OH)2) was synthesized using several methods and manufactured from natural materials such as coral or bone after removal of the organic matter by heating (noted NHA). The in vitro and in vivo studies showed that the natural apatite was well tolerated and has better osteoconductive properties than synthetic HA. Consequently, the NHA was manufactured from cortical bovine bone in all our studies. Nevertheless, its poor mechanical properties are one of the most serious obstacles for wider applications. So, P2O5 was added into NHA in order to enhance its initially poor mechanical strength. A careful combination between the main parameters controlling NHA elaboration such as milling techniques, compacting pressure, sintering temperature, and holding time may lead to an interesting NHA-based bioceramics. In this way, a vibratory multidirectional milling system using bimodal distribution of highly resistant ceramics has been used for obtaining submicron-sized NHA powders. To enhance the densification and lower the sintering temperature of porous NHA, different percentages of P2O5 (0.5–5.0 wt%) were added into NHA powders. The porosity ratio ranged between 36 and 41%. Using this modified milling system, the best Vickers micro-hardness and the three-point bending strength values of powders sintered at 1,050°C were 1 GPa and about 46 MPa, respectively. The latter value is significantly higher than that reported by other researchers (35 MPa) using the sol–gel method.

Citation

Fatima Zohra MEZAHI , Esma Harabi, Abdelhamid Harabi, Souheila Zouai, Nour-Eddinne Karboua, Sihem Chehlatt, , (2016), Effect of P2O5 on mechanical properties of porous natural hydroxyapatite derived from cortical bovine bones sintered at 1,050° C, Desalination and Water Treatment, Vol:57, Issue:12, pages:5297-5302, Taylor & Francis

Hydroxyapatite (HA: Ca10(PO4)6(OH)2) can be synthesized using several methods or manufactured from natural materials such as coral or bone after removal of the organic matter by heating (denoted as NHA). The in vitro and in vivo studies showed that the natural apatite was well tolerated and has better osteoconductive properties than synthetic HA. In addition, the exploitation of natural source represents an economical way of synthesizing NHA by means of sintering, rather than by sol-gel techniques. For these reasons, the NHA was manufactured from cortical bovine bones in all our studies. Moreover, there has been much eort to improve the mechanical properties of HA by introducing foreign oxides or nding out other alternative processes such as grain growth control. Indeed, encouraging lower AGS instead of exaggerated grain growth may be jugged useful for many applications. Since the works carried out on the correlation between AGS and physico-chemical properties of NHA were very limited, the present study was mainly focused on its grain growth. A carful combination between the main parameters controlling NHA production such as milling techniques, compacting pressure, sintering temperature and holding time may lead to an interesting NHA based bio-ceramics. In this way, a simple and energetically vibratory multidirectional milling system using bimodal distribution of highly resistant ceramics has been used for obtaining sub-micron sized NHA powders. For example, the AGS was ranged between 0.75 and 1.40 m (using intercept method) when NHA samples were sintered at 1250 C for 15 and 480 min, respectively.

Citation

Fatima Zohra MEZAHI , E Harabi, A Harabi, L Foughali, S Chehlatt, S Zouai, , (2015), Grain growth in sintered natural hydroxyapatite, Acta Phys. Pol. A, Vol:127, Issue:4, pages:1161-1163, PACS: 81.05.Je, 81.20.Ev

This work devoted to study the reactivity of the quaternary glass (52S4) versus the treatment temperature. The glass composition is: 52 % SiO2 -30 % CaO - Na2O - 14% 4 % P2O5 (wt%), it was synthesized by the sol-gel process. The dried gel was treated at 550 °C and 600 °C and soaked in Simulated Body Fluid (SBF) during different times (from 2 h to 30 days). XRD results confirm the amorphous aspect of treated glass. After soaking in SBF, SEM images show the formation of the carbonated hydroxyapatite (CHA) at the surface of soaked glass for both temperatures. While, the ICP results show that reactivity kinetic of glass in SBF are different when the treatment temperature changes from 550 °C to 600 °C. For glass treated at 550 °C, it only observed the migration of Ca and P from the SBF to the glass surface to form CHA after 2 h soaking in SBF. The XRD and IR results show that the new amorphous CHA phase is formed even after 30 days. As for the glass treated at 600 °C, two phenomena are observed: the glass dissolution in SBF and precipitation of CHA. This phase is amorphous at beginning and crystallizes only at 3 days. This means that the process of dissolution glass is more accelerated than the precipitation process. As the temperature increases, the surface area decreases and consequently the precipitation process slows which allows us to observe the dissolution phenomenon for glasses treated at 600 °C.

Citation

Fatima Zohra MEZAHI , A. Harabi, H. Oudadesse, A. Lucas- Girot, ,(2014), Reactivity kinetics of 52S4 glass, synthesized by sol-gel process, versus the temperature treatment,4th International Advances in Applied Physics & Materials Science Congress,Fethiye- Mugla, Turquie.

A new composition of bioactive glass, in the quaternary system SiO2–CaO–Na2O–P2O5, was synthesized using melting and sol–gel routes. The prepared glass, 52S4: (wt.%) 52% SiO2–30% CaO–14% Na2O–4% P2O5, was soaked in Simulated Body Fluid (SBF) in order to evaluate the kinetic reactivity of this glass versus the synthesis mode. The obtained results have shown that 52S4 is a bioactive glass if it is prepared either by melting or sol–gel methods. The bone-like apatite was formed at the glass surface prepared by sol–gel route after 2 h. However, the formation of this apatite was delayed to 1 day when the glass was prepared by melting method. In addition, this apatite was crystallized, after 30 days soaking in SBF, only if the glass is prepared by melting route. The glass prepared by sol–gel method was more resorbable and leads to silica gel formation up on amorphous apatite layers at any time. So, this silica gel inhibited the crystallization of amorphous apatite.

Citation

Fatima Zohra MEZAHI , Anita Lucas-Girot, Hassane Oudadesse, Hassane Oudadesse, Abdelhamid Harabi, , (2013), Reactivity kinetics of 52S4 glass in the quaternary system SiO2–CaO–Na2O–P2O5: Influence of the synthesis process: Melting versus sol–gel, Journal of Non-Crystalline Solids, Vol:361, Issue:, pages:111-118, North-Holland

In this study, the ability to form bone‐like apatite on surface of both pure natural hydroxapatite (N‐HA) and natural hydroxyapatite containing 5 wt% of ZrO2 or TiO2 or Al2O3, sintered at 1300°C for 2 h and soaked in the simulated body fluid for different times, was studied. It has been found that the presence of β‐tricalcium phosphate in N‐HA + 5 wt% ZrO2 or TiO2 has promoted the precipitation of bone‐like apatite in the Zr or Ti poorest regions. By contrast, the presence of 5 wt% of Al2O3 did not induce any apatite precipitation on N‐HA sample surfaces.

Citation

Fatima Zohra MEZAHI , Hassane Oudadesse, Abdelhamid Harabi, Yann Le Gal, , (2012), Effect of ZrO2, TiO2, and Al2O3 Additions on Process and Kinetics of Bonelike Apatite Formation on Sintered Natural Hydroxyapatite Surfaces, Revue International Journal of Applied Ceramic Technology, Vol:9, Issue:3, pages:529-540, Ceramic product devlopment and commercialization

In this study, hydoxyapatite (HA) prepared from calcined bovine bone was studied. Two methods were used for HA sintering: conventional sintering (CS) and microwave sintering (MS). HA was obtained by calcination of bovine bone at 800 C for 4 h followed by wet ball milling. Afterwards, the powder was compacted under 75 MPa and sintered for 2 h at different temperatures, from 1050 to 1200 C. It has been found that the bulk density of HA increases by increasing sintering temperature when both CS and MS were used. Nevertheless, at the same temperature and for a shorter time (15 min), the HA sintered by microwave were characterised by a density relatively higher than that of sintered by conventional furnace. For example, at 1100 C the bulk densities of samples using CS and MS were about 2.49 (for 120 min) and 2.93 (for 15 min) g/cm3, respectively. Furthermore, a near theoretical density (98.6%) was obtained when HA samples were sintered at 1200 C for 15 min only but using the proposed MS, which was much higher than that (89.7%) of HA samples sintered at the same temperature for longer holding time (120 min). Besides this, the X-ray analyses have shown that heat-treatment, using these two processes, has lead to HA decomposition into tricalcium phosphate and/or tetracalcium phosphate.

Citation

Fatima Zohra MEZAHI , Abdelhamid Harabi, Djamel Belamri, Noureddine Karboua, , (2011), Sintering of bioceramics using a modified domestic microwave oven, Journal of thermal analysis and calorimetry, Vol:104, Issue:1, pages:383-388, Springer Netherlands

New sol–gel experimental conditions were tested to prepare a new SiO2-based bioactive glass with high Na2O content. The aim of this work is to investigate the real influence of the synthesis route (sol–gel versus melting) on the glass intrinsic properties and then, later, on the glass behavior and particularly on bioactivity. The obtained glass and its melt derived counterpart were characterized from structural and morphological (porosity, specific surface area) point of view. It could be noticed that the synthesis mode has no significant influence on glass structure. Conversely, the synthesis mode greatly influences the glass texture. The sol–gel derived glass exhibits a greatly higher specific surface area and pore volume than melt derived glass. This parameter may be a key factor of glass bioactivity.

Citation

Fatima Zohra MEZAHI , Anita Lucas-Girot, Mohamed Mami, Hassane Oudadesse, Abdelhamid Harabi, Marie Le Floch, , (2011), Sol–gel synthesis of a new composition of bioactive glass in the quaternary system SiO2–CaO–Na2O–P2O5: comparison with melting method, Journal of Non-Crystalline Solids, Vol:357, Issue:18, pages:3322-3327, North-Holland

The behaviour of the natural Hydroxyapatite (N-HA) prepared from bovine bones and synthetic hydroxyapatite (S-HA) was studied. The sintering effects on the structure and on the kinetic of bioactivity of natural and synthetic hydroxyapatite were highlighted. Obtained results show some differences between these biomaterials. XRD patterns showed that the crystallographic structure of pure N-HA was not affected by the sitering at different temperatures when several modifications in S-HA were registered. To evaluate their kinetic of bioactivity, ICP-OES method was employed. The experimental results show that the kinetic of bioactivity of N-HA increases with the sintering temperature. Consequently, the new phosphate phase was formed with higher thick on the surface of granules sintered at high temperatures. However, in S-HA, the formation of bone like apatite is very sensitive to phase’s existent at any sintering temperature. The formation of TCP has favourites and activates the formation of new phase

Citation

Fatima Zohra MEZAHI , Hassane Oudadesse, Abdelhamid Harabi, Gal Y Le, Guy Cathelineau, , (2011), Sintering effects on physicochemical properties of bioactivity of natural and synthetic hydroxyapatite, Journal of the Australasian Ceramic Society, Vol:47, Issue:1, pages:23-27, Australasian Ceramic Society, c/o ANSTO Menai NSW 2234 Australia

The dissolution kinetic and structural behaviour of natural hydroxyapatite (N-HA) and synthetic hydroxyapatite (S-HA) was studied vs. sintering temperature and using ‘in vitro’ experiments. Obtained results highlight the chemical stability of N-HA. Any structural modification was observed until 1200°C. In the fact S-HA undergoes some modifications. XRD diagrams show the tricalcium phosphate (TCP) phase formation between 800 and 1100°C and tetracalcium phosphate (TetCP) phase formation at 1200°C. The ‘in vitro’ assay shows that the dissolution was occurred more in N-HA than in S-HA. The formed TCP activated the dissolution kinetic and then the precipitation phenomena when a continuous dissolution of TetCP leaded to slow down the kinetic precipitation.

Citation

Fatima Zohra MEZAHI , H Oudadesse, A Harabi, A Lucas-Girot, Y Le Gal, H Chaair, G Cathelineau, , (2009), Dissolution kinetic and structural behaviour of natural hydroxyapatite vs. thermal treatment: Comparison to synthetic hydroxyapatite, Journal of thermal analysis and calorimetry, Vol:95, Issue:1, pages:21-29, Akadémiai Kiadó, co-published with Springer Science+ Business Media BV, Formerly Kluwer Academic Publishers BV

Bioactive ceramics such as bioactive glasses, calcium carbonate and sintered hydroxyapatite are widely used in biomaterials field because of their high biocompatibility. In this study, natural hydroxyapatite (N-HA) and synthetic Hydroxyapatite (S-HA) were heat treated at 800 C and studied using “in vitro” experiments. Several physicochemical methods like: SRD, FTIR, SEM and ICP-OES were employed to evaluate the effects of the thermal treatment and to compare their behaviour after soaking in the Simulated Body Fluid SBF at different times. The formation of TCP has favours the formation of new phase. Obtained results show that the dissolution occurred more in N-HA than in S-HA and consequently the precipitation of new phosphate phase is more important in N-HA. This is due to the presence of Mg, Sr and Zn in N-HA with concentration higher to that in S-HA.

Citation

Fatima Zohra MEZAHI , Hassane Oudadesse, Abdelhamid Harabi, Nelson Heriberto A Camargo, G Cathelineau, , (2009), Physicochemical Reactivity after the In Vitro Assays of Synthetic and Natural Hydroxyapatite, Key Engineering Materials, Vol:396, Issue:, pages:261-264, Trans Tech Publications Ltd

he dissolution kinetic and structural behaviour of natural hydroxyapatite (N-HA) and synthetic Hydroxyapatite (S-HA) was studied versus sintering temperature and using “in vitro” experiments. Obtained results highlight the chemical stability of N-HA. Any structural modification was observed until 1200°C. In the fact S-HA undergo some modifications. XRD diagrams show the tricalcium phosphate (TCP) phase formation between 800 and 1100°C and tetracalcium phosphate (TetCP) phase formation at 1200°C. The “in vitro” assay show that the dissolution was occurred more in N-HA than in S-HA. The formed TCP activated the dissolution kinetic and then the precipitation phenomena. However, the dissolution of TetCP leaded to delay the kinetic precipitation.

Citation

Fatima Zohra MEZAHI , H. Oudadesse, A. Harabi, ,(2009), Bioactivity of natural hydroxyapatite versus thermal treatment, compared to synthetic hydroxyapatite,Journées Annuelles de la SF2M,Rennes, France

A new glass formulation, with themolar composition 60% SiO2–35% CaO–5% P2O5,was synthesized using the sol–gel process, for applications as biomaterial in orthopaedic or maxillo facial surgery. Pellets, made of glass powder, were uniaxially compacted and soaked in simulated body fluid (SBF) for up to 7 days at 37 8C to evaluate glass bioactivity. Ionic exchanges at the interface glass-SBF were evaluated by studying evolutions of calcium, phosphorus and silicon concentrations in SBF using ICP-OES. Changes in glass surface, and the formation of crystalline phases were analyzed using XRD, SEM, EDS and FTIR methods. Results form ICP-OES showed a high reactivity of the glass surface with a very high and continuous release of calcium, a limited glass dissolution and an uptake of phosphorous from SBF. Results from both FTIR and XRD analysis indicated that the glass surface was progressively covered by two different phases: CaCO3 as calcite and a carbonated apatite layer. The formation of these phases, following two different schemas, was observed after 2 h of immersion and confirmed after 7 days. SEM micrographs and EDS analysis demonstrated that the main phase, a carbonated apatite, was present as micro-spheroids and the secondary phase, calcite, was materialized by agglomerates which have diameters up to 10–15 mm. These results are in accordance with a bioactive feature of the glass studied.

Citation

Fatima Zohra MEZAHI , Mohamed Mami, Anita Lucas-Girot, Hassane Oudadesse, Rachida Dorbez-Sridi, Elodie Dietrich, , (2008), Investigation of the surface reactivity of a sol–gel derived glass in the ternary system SiO2–CaO–P2O5, Applied Surface Science, Vol:254, Issue:22, pages:7386-7393, North-Holland

Diopside CaMgSi2O6 is an attractive material because of its multi applications. It was prepared by sintering the mixture at different temperatures (900°C-1300°C). Starting materials were pure SiO2 and dolomite raw materials. In order to improve the properties of sintered samples, such as the density egg white (ovalbemin) has been added into diopside. Furthermore, the effect of P2O5 addition on the sintering of the prepared diopside in the range of 0.5 to 5.0 wt% was studied as a function of the sintering temperature. A density of 96.5% of theoretical has been achieved when 5.0 wt% P2O5 was added, at a sintering temperature of 1225°C, whereas the density of diopside samples, without P2O5 addition was lower than 83.0% of theoretical.

Citation

Fatima Zohra MEZAHI , S Zouai, S Achour, Abdelhamid Harabi, , (2005), A process for sintering of diopside prepared from dolomite, Materials Science Forum, Vol:492, Issue:, pages:235-240, Trans Tech Publications Ltd

In this work, the hydroxyapatite was prepared from cortical bone after calcination at 700°C during 1 hour. In order to improve mechanical properties of HA, 5 wt% of the ZrO2 (stabilized with 12.0 wt% CeO2), Al2O3 and TiO2 were added to HA powder as a reinforcing phase. All the powders were sintered at 1300°C for 2 hours. The XRD was utilized to identify the phases composition. It was found that the initial calcined powder is hydroxyapatite with the following chemical composition Ca5(PO4)3OH. In addition, the phenolphthalein test has put into evidence the existence of free CaO. For powders containing ZrO2, the XRD spectra has showed a little percent of formed b-tricalcium phosphate (b-TCP); the HA was decomposed to (b-TCP) and CaO which forms with ZrO2 the calcium zirconate (CaZrO3). Nevertheless, in powders containing TiO2, the XRD spectra showed that a partial decomposition of HA to b-TCP was occurred with formation of calcium titanium oxide (CaTiO3). However, for powders containing Al2O3, a nearly full decomposition of HA to b-TCP was occurred, the free Al2O3 was present. Finally, it has been found that HA composites containing a large amount of b-tricalcium phosphate are resorbale than HA composites containing a small amount of b-TCP and they were not well densified. The microhardness values of HA- ZrO2 composites were greater than those of HA- Al2O3 and HATiO2 composites.

Citation

Fatima Zohra MEZAHI , Abdelhamid Harabi, Souleiha Zouai, S Achour, Didier Bernache-Assollant, , (2005), Effect of stabilised ZrO2, Al2O3 and TiO2 on sintering of hydroxyapatite, Materials Science Forum, Vol:492, Issue:, pages:241-248, Trans Tech Publications Ltd

Hydroxyapatite (HAp: Ca5(PO4)3OH), has been studied for many years as an implant material because it is similar to the major constituents (mineral parts) of bone and tooth. Generally, there are two main ways of producing HAp, one is inorganic synthesis and the other is from natural bone. In this study, HAp powder was obtained by calcination of bovine bone at 800°C for 4 hours followed by ball milling. Afterwards, the powder was compacted at 75 MPa. The compacts were prepared, using both Conventionally Sintering (CS) and Micro-Wave Sintering (MS). It has been found that the relative density of samples sintered at 1250°C for 2 hours was about 92.5% which is much lower than that of samples (95.9%) sintered at the same temperature for shorter times (15 minutes), using MS.

Citation

Fatima Zohra MEZAHI , D. Belamri, S. Achour, N. Karboua, M.T Benlahrache, A. Harabi, ,(2005), Comparison between conventional and microwave sintering of bovine bone hydroxyapatite,4ème Conférence Internationale sur la Science, la Technologie et les Applications du Frittage (Sintering’ 05),Grenoble, France

In this study, hydroxyapatite (HA) was prepared from cortical bone after calcination at 700°C for 1 hour. In order to improve mechanical properties of HA, the ZrO2 (stabilised with 12.0 wt% CeO2 ) was added to HA powder as a reinforcing phase in varying proportions (1, 5, 10 and 20 wt%). All the powders were sintered at 1300°C for 2 hours. The XRD was used to identify the existing crystalline phases. It has been found that the initial calcined powder has the following chemical composition Ca5(PO4)3OH. In addition, the phenolphthalein test has put into evidence the existence of free CaO. The prepared specimens without and with ZrO2 additions (1and 5 wt%) were highly densified. The main phase present in samples containing 1 wt% ZrO2 is HA. Nevertheless, for powders containing 5, 10 and 20 wt% ZrO2, the HA was decomposed into b-tricalcium phosphate and CaO which forms with ZrO2 calcium zirconate (CaZrO3).

Citation

Fatima Zohra MEZAHI , A. Harabi, S. Achour, , (2004), Effect of stabilised ZrO2 on sintering of hydroxyapatite, Key Engineering Materials, Vol:264, Issue:, pages:2031-2034, Trans Tech Publications Ltd