M. Awaad

• PhD
• National Research Centre

Zirconia-toughened alumina (ZTA)/Al2TiO5 composites were prepared via a sol–gel route. The prepared samples were uniaxially pressed and pressurelessly sintered at 1650–1700 °C for 1 h. The microstructure, densification, and X-ray diffraction patterns of the sintered ZTA/Al2TiO5 composites were investigated, and their mechanical properties, thermal...

This study fabricates Nano cerium Zirconate and yttrium aluminium garnet (YAG)/cerium zirconate composites. The effect of adding different YAG contents (10, 20, and 30 mass %) to cerium zirconate on the sintering properties of the fabricated composite was investigated. The addition of YAG reduced the densification and increased the porosity of the...

In the present study, Al 2 TiO 5 was prepared via the sol–gel technique then sintered at 1000°C to 1300°C for 1 h. The thermal stability of the formed ceramic bodies was explored. The densification parameters, microstructure, and phase composition of the sintered Al 2 TiO 5 ceramic were examined, and the mechanical properties and thermal coefficien...

The main target of the present research was a full assessment of the toxicity effects and biocompatibility of a Ti/Al-alloy device coated with biogenic hydroxyapatite (bHA) when implanted in dogs in comparison with those of an uncoated Ti/Al-alloy device. The coating of the alloy was carried out using controlled high-velocity suspension flame spray...

The main objective of this study was to investigate the role of zirconia addition to mullite through an in-situ reaction aimed at improving both the mechanical properties and the sinterability behavior. In this work, mullite–zirconia composites were produced using a sol-gel technique. Different amounts of zirconia (0, 10, 15, and 20 wt.%) were adde...

Rhyodacite is a good source of major oxides, as these are contained in its essential mineral components, such as quartz, oligoclase, and albite. Thus, using natural rhyodacite and kaolin, dielectric self-glazing ceramic materials were prepared that exhibit excellent dielectric properties. The obtained materials were sintered at different temperatur...

The effect of doping with nano-MgO and co-doping with nano-MgO–Gd2O3 on the densification behavior, mechanical properties, and dielectric behavior of alumina was evaluated. Magnesium oxide-doped alumina nanoparticles were prepared by the sol-gel method with varying nano-MgO ratios (5, 6, and 7 mass %). Alumina samples containing 7 mass % MgO showed...

This study investigated the densification behaviour and mechanical properties of SrAl12O19/zirconia-toughened alumina (ZTA) composites prepared by two different forming methods, namely, uniaxial pressing and cold isostatic pressing (CIP). The compatibility of hexaaluminate with alumina makes them the most effective second phase, which strengthening...

This study investigated the effect of soaking time on the phase composition, physical and mechanical properties of strontium hexaaluminate/zirconia-toughened alumina (ZTA) composites prepared via the in situ technique. X-ray diffraction (XRD), scanning electron microscopy and mechanical testing techniques for flexural strength, Vickers hardness and...

In the present paper, direct foaming technique and sacrificial template method were used to prepare porous alumino-silicate bonded SiC ceramics from mixtures of silicon carbide, kaolin and calcined alumina. The direct foaming process depends on generating bubbles inside the slurry of SiC mixtures through a reaction between CaC2 and Al powder in pre...

Recently, silicate materials have received attention as materials with promising applications in the bioceramics field. A recent study aimed to investigate the effect of forsterite (Mg2SiO4) addition to biogenic hydroxyapatite, Ca10(PO4)6(OH)2, on the phase formation, physical and mechanical properties, and biocompatibility of the produced composit...

Aim: The main goal of the study is the evaluation of the toxicity effect of the implantation of Ti/Al alloy coated with HA on the wound healing as well as the biological effects and safety evaluation in dogs. Methods: fifteen cylindrical, one-stage implants of Ti/Al alloy substrate with a 32.49 µm thick plasma-sprayed HA coating were performed and...

In the present study, the preparation of strontium hexaaluminate/ZTA composites via a solid-state reaction was carried out. The effect of 10–40 mass% SrAl 12 O 19 on the microstructure, physical and mechanical properties of the SrAl 12 O 19 /ZTA composite were addressed. X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) were u...

In the present investigation, Al2O3/YAG/CeO2 composites containing equal proportions of YAG and ceria powders; (10, 15 and 20 wt%); were prepared by mechanical mixing. The prepared batches were uniaxially pressed and pressureless sintered at 1600 °C for 1 h. The particle size distribution, densification, microstructure, mechanical properties and we...

Silicon carbide was mixed with alumina and kaolin to obtain porous alumino-silicate bonded SiC ceramics. Starch was added as sacrificial template. The mixtures were processed by hand-pressing and extrusion method. The effect of firing temperature (1450 ∘C) and the addition of starch on the composition and characteristics of fired specimens were stu...

The main aim of the present study is to evaluate the impact of the nano-ZnO on the dielectric properties of alumina bodies used in high voltage insulators. In this work, Zinc oxide/alumina nanocomposites were prepared by sol–gel method. The ratios of ZnO were 5, 6 and 7 mass %. The effect of ZnO on the densification, microstructure, mechanical and...

Silicon carbide (SiC) was mixed with alumina and kaolin to obtain porous alumino-silicate bonded SiC specimens. These mixtures contain 40 to 80 mass% SiC while the alumina contents of their bonding materials are 60–80 mass%. Porous SiC specimens were prepared from mixtures of silicon carbide, calcined alumina and Klabsha kaolin using the foaming me...

The target of the recent study is to achieve a significant inexpensive and eco-friendly way for getting ZTA/HA composites, based on the nano-HA derived from the eggshell biogenic source. Combining simultaneously the porous structure; which is considered as a bone formation key, with developed mechanical properties and adequate biocompatibility, is...

Although β-spodumene/anorthite composites are interesting systems, little research work has been done to study their properties. This study aims at investigating the preparation and properties of β-spodumene/anorthite composites containing β-spodumene proportions ranging between 10 and 25 mass %. X-ray diffraction analysis (XRD), Scanning electron...

In the present study, ZTA composites containing 0–10 vol% of 5mol% YSZ (in the range 0–10 vol%) were prepared by sol-gel technique followed by powder mixing and sintering up to 1650 °C for 1 h. Microstructure of the composites was observed using scanning electron microscopy and phase compositions was detected by means of X-ray diffraction. Density...

In the present study, a multi-layer thermal barrier coating (TBC) consisting of ZrO2 and La2Zr2O7 layers was designed in order to study the effect of the sequential layering and the composition of the top layer on hot corrosion resistance against a (1:1) V2O5/Na2SO4 mixture. Accordingly, functionally graded YSZ/La2Zr2O7 thermal barrier coatings (TB...

In the present study, La2Zr2O7 was used as a coat for stainless steel alloy. Lanthanum zirconate coat was sprayed using plasma spray technique. The preparation and characterization of La2Zr2O7 coat was studied. Hot corrosion of the coat surface was conducted in (1:1) V2O5 / Na2SO4 molten mixture at 900°C for 50 and 100 h. The results showed that mo...

In the present study, the use of naturally occurring weathered feldspar for partial or total substitution of conventional potash feldspar in the batches containing fish bone ash was evaluated. Weathered feldspar, Hafafit feldfpasr and El-Tieh kaolin from Sinai, Egypt; together with fish bone ash were characterized and employed to obtain stoneware t...

The aim of this research is to investigate the characteristics and mechanical properties of Ta2O5 doped zirconia-toughened-alumina composites. Samples of partially stabilized-zirconia toughened alumina (ZTA) with 5% volumetric ZrO2 addition doped with Ta2O5 in amounts ranging between 0.12 and 0.36 vol% were prepared by sol–gel technique. The powder...

Yttria-ceria doped tetragonal zirconia / alumina, (Y,Ce–TZP / Al2O3) composites were prepared via sol-gel and powder mixing techniques. The bodies were uniaxially pressed at 220 MPa. The formed green bodies were fired at 1500°C up to 1650°C with temperature interval of 50°C and firing rate of 5°C /min. The samples were evaluated for their densifica...

The densification behavior, microstructure and mechanical properties of high-purity a-Al 2 O 3 doped with 0.25, 0.5 and 0.75 wt% Nb 2 O 5 were investigated. The batches were uniaxially pressed at 220 MPa into discs and rectangular bars and pressureless-sintered at temperature ranging between 1500º and 1650 °C for 1 h. The phase composition of the s...

The densification behavior, microstructure and mechanical properties of high-purity alpha-Al2O3 doped with 0.25, 0.5 and 0.75 wt% Nb2O5 were investigated. The batches were uniaxially pressed at 220 MPa into discs and rectangular bars and pressureless-sintered at temperature ranging between 1500 and 1650 C for 1 h. The phase composition of the sinte...

This work studied the recycling of fish bone ash by using it in stoneware tiles. Tiles containing up to 20 mass-% crushed and fired fish bone were prepared from starting materials characterized with respect to their chemical composition and X-ray diffraction and thermal properties. The effects of added fish bone ash were studied by measuring the ph...

The present article deals with the development of 3D porous scaffolds for bone grafting. They were prepared based on rapid fluid infiltration of Al 2 O 3-SiO 2 sol into a polyethylene non-woven fabric template structure. Titanium dioxide in concentration equal to 5 wt% was added to the Al 2 O 3-SiO 2 mixture to produce Al 2 O 3-SiO 2-TiO 2 composit...

This work studied the recycling of fish bone ash by using it in stoneware tiles. Tiles containing up to 20 mass-% crushed and fired fish bone were prepared from starting materials characterized with respect to their chemical composition and X-ray diffraction and thermal properties. The effects of added fish bone ash were studied by measuring the ph...

The effects of Ta2O5 addition on the densification behavior, microstructure and mechanical properties of Ta2O5- doped alumina ceramics were investigated. The Ta2O5 addition to the alumina matrix was varied from 0.25wt% to 0.75 wt%. In order to optimize the sintering temperature, the powders of each composition were uniaxially pressed at 220 MPa int...

The present article deals with the development of 3D porous scaffolds for bone grafting. They were prepared based on rapid fluid infiltration of Al2O3-SiO2 sol into a polyethylene non-woven fabric template structure. Titanium dioxide in concentration equal to 5 wt% was added to the Al2O3-SiO2 mixture to produce Al2O3-SiO2-TiO2 composite scaffolds....

Alumina composite containing 10 vol.-%YAG was processed by injection moulding. The injection moulding feedstock was prepared by milling an aqueous dispersion of submicrometre size alumina and YAG powder synthesised by aqueous sol–gel method using aluminium tri-isopropoxide and yttrium oxide as starting powders. Binder and additives were further add...

Yttria–ceria doped tetragonal zirconia (Y, Ce–TZP)/ alumina (Al2O3) composites were fabricated by cold isostatic pressing at 350 MPa and firing at 1500 °C up to 1650 °C in air. Y, Ce–TZP/Al2O3 composite powders were prepared using two routes: (1) sol–gel method and in situ preparation of the composites, (2) mechanical mixing of as received μm powde...

The effects of Ta2O5 addition on the densification behavior, microstructure and mechanical properties of Ta2O5- doped alumina ceramics were investigated. The Ta2O5 addition to the alumina matrix was varied from 0.25wt% to 0.75 wt%. In order to optimize the sintering temperature, the powders of each composition were uniaxially pressed at 220 MPa int...

Alumina–mullite–zirconia ceramic composites were prepared by reaction bonding of alumina and zircon mixtures after firing at different temperatures 1300o, 1400o and 1500 oC. Constant amount of magnesia was added as a sintering aid. The technological parameters of the sintered ceramic composites, i.e. the mechanical properties and densification para...

Alumina composites containing 5, 10 and 20 vol.% YAG were produced by a slip-casting process. Two different routes for adding the YAG phase were chosen. Either by mixing of alumina with previously produced YAG powder or by coating of an adequate amount of yttria to form YAG precipitates during the calcining step. The mechanical properties of the si...

Multilayered zirconia toughened alumina (ZTA) and c-zirconia coatings were prepared using electron beam physical vapour deposition (EB-PVD). Characterizations of the morphology and chemical composition of the deposited coatings were performed using scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD). Scratch resistance, nano-ind...

Neodymium-doped yttrium-aluminum garnet (Nd:YAG) ceramics that contained 0.025, 0.05 and 0.10 at% Nd2O3 additives and exhibited nearly the same optical properties as those of a single crystal were fabricated by means of the sol-gel technique and hot press sintering method. Transparent YAG and Nd:YAG ceramics are fabricated either by high-temperatur...

Highly porous alumina and zirconia toughened alumina (ZTA) bone scaffolds were fabricated from bioorganic nonwoven cellulosic fabric by sol-gel infiltration technique. Biomimetic processes were used to grow a bone-like calcium phosphate layer on the ceramic surface using simulated body fluids (SBF). The scaffolds, with and without coating, were cha...

Ion assisted electron beam physical vapour deposition (EB-PVD) technique was used for three zirconia toughened alumina (ZTA) batches containing 15, 25, 35, mole% ZrO2 and c-zirconia ceramic multilayer deposition on 617-Ni based alloy substrate. The ceramic batches were prepared via sol–gel technique. The thickness of the coated layers was found to...

The main target of this work is to prepare refractory magnesia- and alumina-based ceramics within the MgO-Al2O2-ZrO2-SiO2 system. These include periclase (MgO) and its composites with MgAl2O4-spinel and forsterite (MgSiO4)-zirconia (ZrO2) as well as corundum (alpha-Al2O3) and its composite with mullite (Al6Si2O13)-zirconia (ZrO2). These were proces...

Semiconductor nanostructures doped with rare earth ions is a possible way to overcome the limitation of low luminescence efficiency of rare earth ions, providing that the strong confinement of carriers in dots will enhance their recombination in the vicinity of RE ions. Undoped and Eu³⁺-doped GaN crystallites have been synthesized by the co-precipi...

A novel way of synthesizing pure tungsten carbide (WC) as well as silicon carbide (SiC) powders by in situ carbo-thermal reaction of sugar cane and tungstic acid or silicon is presented. Tungsten and silicon carbide bodies were sintered at a temperature of 1,450 °C under vacuum. The preparation process, catalytic activity, micro structure, and phas...

Five samples of glass/ceramic composites were prepared from borosilicate glasses and both nano-aluminum oxide and nano-titanium oxide. The glass composite samples contain 10, 20, 30, 40, 50wt.% of alumina and titania mixture. The ratio of Al2O3:TiO2 in the mixture was 1:1. The formation of cristobalite in the glass matrix of low firing glass/cerami...

Pure cordierite and cordierite-ZrO2-composites containing 10, 20 and 30 mass-% Y2O3 stabilized ZrO2 were prepared by dispersing ZrO2 powder in cordierite sol. The evolution of crystalline phases and the microstructure were studied using X-ray diffraction and scanning electron microscopy. It was found that increasing both ZrO2 content and firing tem...

A study was conducted to investigated the effect of yttrium aluminum garnet (YAG) content on the densification, mechanical properties, and microstructure of YAG-alumina composites. The study found yttrium aluminum garnet-alumina composites can be used as materials for optical, electronic, and structural applications. The study used YAG-Al2O3 compos...

The microstructure and properties of porous Si/silicon carbide (SiC) composites manufactured from nonwoven cellulosic fabrics have been investigated. A fibrillar reaction product with a microstructure reproducing the initial preform morphology consisting of β-SiC and unreacted Si was obtained. Improvement of strength is expected to be achieved by i...

A study was made to prepare and characterize multicomposite containing zirconia–mullite–spinel [ZrO2–Al6Si2O13–xMgAl2O4 (0.25≤x≤4)]. This multicomposite was prepared by reaction sintering of relatively pure commercial grades of zircon, alumina and magnesium carbonate. Spinel and mullite could be in situ formed, while ZrO2 evolved mainly in monoclin...

Five batches of low cement zircon- magnesia concretes were prepared using dead burned magnesite aggregate, fine zircon sand and high alumina refractory cement. The concretes were shaped and fired at 1500°C. Densification parameters were determined through bulk density (BD) and apparent porosity (AP). High temperature phases were examined by XRD. A...

A compositional study was made of in situ formed mullite-ZrO 2-SiC composites sintered at up to 1550°C. Compositions of zircon-alumina in the presence of SiC particulates are formed to fulfil the mullite stoichiometric composition. The composites fired in semi reducing atmospheres showed great densification dependence on the SiC content, while SiC...

A study was conducted to prepare and characterize in-situ mullite reinforced with ZrO2 composites using Egyptian kaolin and micron-sized ZrO2, and the addition of Al2O3 to the mixture was conducted to obtain the stoichiometric composition of mullite. Kaolin was grounded and sieved, calcination process was conducted at high temperature to prevent th...

Various methods of preparing Mullite-Zirconia composites such as by sintering mullite and zirconia powders and by reaction of alumina, silica and zirconia, were analyzed. Mullite was synthesized by the reaction of alumina with fumed silica primarily at 1350°C. The mixtures were attrition milled for 6h with distilled water using magnesium. After the...

New systems consisting of ceramic composites have been recently developed to replace conventional alumina as a substrate for high performance large scale integrated packaging. Few investigations on the ß-spodumene—alumina composites have been performed. Accordingly, the effect of ß-spodumene content on the sintering behaviour and mechanical propert...

A compositional study was made of in situ formed mullite-ZrO 2-SiC composites sintered at up to 1550°C. Compositions of zircon-alumina in the presence of SiC particulates are formed to fulfil the mullite stoichiometric composition. The composites fired in semi reducing atmospheres showed great densification dependence on the SiC content, while SiC...

The sinterability and thermal stability of pure (>99 wt-%), fine (20 ?m) zircon containing 1 wt-% of different metal oxides has been studied. Samples were fired up to 1550°C and their densification monitored. The high temperature phases were detected by XRD and the microstructural development of some selected compositions was studied by means of sc...