The affect of densification and dehydroxylation on the mechanical properties of stoichiometric hydroxyapatite bioceramics

Laasri, Said; Taha, Mohammed A.; Laghzizil, A.; Hlil, E.K.; Chevalier, Jean-Pierre

doi:10.1016/j.materresbull.2010.06.040

Cited by 38 publications

(22 citation statements)

References 23 publications

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“…Some authors extend this range up to 1200°C–1450°C . For lower temperatures, the literature only reports a partial dehydration of HA into oxyhydroxyapatite, which occurs between 800°C and 1350°C, according to the following equation

{Ca}_{10} {true({PO}_{4} true)}_{6} {true(OH true)}_{2} \leftrightarrow {Ca}_{10} {true({PO}_{4} true)}_{6} {true(OH true)}_{2 ‐ 2 y} {normalO}_{normaly} {+ yH}_{2} {normalO}_{(gas)} .

…”

Section: Thermal Behaviour Of Hamentioning

confidence: 99%

Hydroxyapatite and tricalcium phosphate composites with bioactive glass as second phase: State of the art and current applications

Bellucci

Sola

Cannillo

2015

J Biomedical Materials Res

121

102

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Calcium phosphates are among the most common biomaterials employed in orthopaedic and dental surgery. The efficacy of such systems as bone substitutes and bioactive coatings on metallic prostheses has been proved by several clinical studies. Among these materials, hydroxyapatite (HA) and tricalcium phosphate (TCP) play a prominent role in medical practice since the '80s. In the last years, numerous attempts to combine HA or TCP with bioactive glasses have been made. There are two main motivations for sintering calcium phosphates with a glassy phase: on the one hand, it is possible to tune the dissolution of the final system and to enhance its biological response through the synergistic combination of two bioactive phases; on the other hand, the glass acts as a sintering aid with the aim to increase the densification of the composite and thus its mechanical strength. In this sense, TCP and HA are penalized by their relatively poor fracture toughness and tensile strength compared to natural bone, which makes it impossible to use them in load-bearing applications. Moreover, the bioactivity index of pure calcium phosphates is typically lower with respect to that of many bioactive glasses. In this review, the state of the art and current applications of composites, based on HA or TCP with bioactive glass as second phase, are presented and discussed. A special emphasis is given to the processing and mechanical behaviour of these systems, together with their biological implications, as a function of the composition of the glass employed as second phase.

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{Ca}_{10} {true({PO}_{4} true)}_{6} {true(OH true)}_{2} \leftrightarrow {Ca}_{10} {true({PO}_{4} true)}_{6} {true(OH true)}_{2 ‐ 2 y} {normalO}_{normaly} {+ yH}_{2} {normalO}_{(gas)} .

…”

Section: Thermal Behaviour Of Hamentioning

confidence: 99%

Hydroxyapatite and tricalcium phosphate composites with bioactive glass as second phase: State of the art and current applications

Bellucci

Sola

Cannillo

2015

J Biomedical Materials Res

121

102

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“…7(b), regardless of different crystalline structure of samples, dependence of hardness with grain size is in agreement with the literature that hardness initially increases with grain size and reached a maximum value at a certain grain size limit and thereafter decreases with further increasing grain size. 10,30,31 So that the highest hardness value for H2 can be explained to the unique bimodal microstructure as well as the highest sintering density. The hardness value for H4 and H5 is nearly similar, emphasizing the potential application of MgP bioceramic as the same as CaP biomaterial.…”

Section: Microhardness and Fracture Toughnessmentioning

confidence: 99%

Microwave sintering of fine grained MgP and Mg substitutes with amorphous tricalcium phosphate: Structural, and mechanical characterization

2016

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This paper, for the first time, reports the results of microwave sintering of two emerging biomaterials, magnesium phosphate and amorphous magnesium calcium phosphate. Beneficial aspects of successful microwave sintering of calcium phosphate are well documented in the literature. The motivation for this work derives from the absence of any publication of similar nature on magnesium phosphates, which are becoming important with the rapid rise in interest in biodegradable Mg-alloys. Starting off with amorphous calcium magnesium phosphate and magnesium phosphate, the resulting microwave sintered product is a biphasic mixture of whitlockite substituted with magnesium and magnesium phosphate. The influence of the extent of Mg substitution on the mechanical properties, microstructure, and sintering behavior of tricalcium phosphate was evaluated. The results showed that the addition of Mg (up to the 50% wt/wt in relation to Ca mass) in the precursor compound of magnesium calcium phosphate improved the kinetics of the densification process and enhanced hardness values.

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“…Generally, it is hard to declare which powder characteristic plays a dominant role and governs the sintering process of HAp material, but enhanced sintering is to be expected with decreasing particle size below 50 nm. However, the processes occurring on the particle's surface, originating from its chemistry and structural ordering are still questionable and highly dependent on particular material and preparation method …”

Section: Discussionmentioning

confidence: 99%

Processing Route to Fully Dense Nanostructured HAp Bioceramics: From Powder Synthesis to Sintering

et al. 2012

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The study is devoted to the processing of hydroxyapatite (HAp) nanopowder to develop fully dense nanostructured bioceramics by pressureless sintering. The sintering behavior of stoichiometric HAp prepared by hydrothermal processing was investigated by nonisothermal, two‐step, and conventional sintering. By low‐temperature two‐step sintering (TSS), at 900°C and 850°C, with appropriate dwell time, dense bioceramics without final‐stage grain growth and average grain size of 75 nm was obtained. A concept of master sintering curve was applied, enabling control of sintering process, estimation of effective activation energy for sintering of HAp nanopowder, and qualitative understanding of sintering mechanisms. According to estimated activation energy of 412.6 kJ/mol, low sintering temperature and particles' microstructure as the dominant sintering mechanism we proposed diffuse‐viscous flow controlled by grain boundary diffusion. HAp nanoparticles comprising of different interior and boundary regions as ordered/disordered microstructure are found to be of an advantage for low‐temperature sintering.

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The affect of densification and dehydroxylation on the mechanical properties of stoichiometric hydroxyapatite bioceramics

Cited by 38 publications

References 23 publications

Hydroxyapatite and tricalcium phosphate composites with bioactive glass as second phase: State of the art and current applications

Hydroxyapatite and tricalcium phosphate composites with bioactive glass as second phase: State of the art and current applications

Microwave sintering of fine grained MgP and Mg substitutes with amorphous tricalcium phosphate: Structural, and mechanical characterization

Processing Route to Fully Dense Nanostructured HAp Bioceramics: From Powder Synthesis to Sintering

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