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Grain Growth in Sintered Natural Hydroxyapatite

100%

Hababi E., Harabi A., Foughali L., Chehlatt S., Zouai S., Mezahi F.

Acta Physica Polonica A

2015

vol. 127

issue 4

1161-1163

Hydroxyapatite (HA: Ca_{10}(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 effort to improve the mechanical properties of HA by introducing foreign oxides or finding 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 μm (using intercept method) when NHA samples were sintered at 1250°C for 15 and 480 min, respectively.

Porous Ceramic Supports for Membranes Prepared from Kaolin (DD3) and Calcite Mixtures

84%

Harabi A., Boudaira B., Bouzerara F., Foughali L., Zenikheri F., Guechi A., Ghouil B., Condom S.

Acta Physica Polonica A

2015

vol. 127

issue 4

1164-1166

The supports for microfiltration (MF) and ultrafiltration (UF) were prepared with local kaolin (Djebel Debagh: type 3: DD3) and calcium carbonate (CaCO₃) mixtures. The choice of these materials is based on their natural abundance (low price). In this work, the tubular ceramic supports were prepared by the extrusion method. The sintering was carried out for 2 hours, at temperatures laying between 1150 and 1300°C. They are then characterized by various techniques: mercury porosimetry, scanning electron microscopy and x-ray diffraction. The obtained results revealed that the main phase formed during the sintering step was anorthite with a minor phase of mullite. Moreover, it has been found that supports sintered at temperatures less than 1300°C had interesting characteristics; an average pore size ranged between 3.91-8.56 μm, a porosity ratio of 42.0-50.4%, a flexural strength ≈67-77 MPa and the pore size distribution is bimodal type. According to their average pore sizes, they may be used either as supports for MF or UF membranes.

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2 Acta Physica Polonica A

2 2015

2 Foughali L.

2 Harabi A.

1 Boudaira B.

1 Bouzerara F.

1 Chehlatt S.

1 Condom S.

1 Ghouil B.

1 Guechi A.

1 Hababi E.

1 Mezahi F.

1 Zenikheri F.

1 Zouai S.

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Grain Growth in Sintered Natural Hydroxyapatite

Porous Ceramic Supports for Membranes Prepared from Kaolin (DD3) and Calcite Mixtures