Effect of Milling Treatment on Texture Development of Hydroxyapatite Ceramics by Slip Casting in High Magnetic Field

Abstract

Hydroxyapatite (HAP, Ca 10 (PO 4 ) 6 (OH) 2 ) is a main component of bones and teeth, and a specific crystal orientation is required for biomaterial application. In this study, the effects of the processing parameters on the orientation, such as de-agglomeration by milling procedure, applied magnetic field and sintering temperatures, were examined. Using the de-agglomerated particle by a milling procedure, it is possible to control the particle orientation, but when using heavily agglomerated particles, it was impossible to control the particle orientation by applying a high magnetic field. Highly-textured HAP can be fabricated by slip casting using a well-dispersed suspension in a high magnetic field (above 4 T) followed by sintering above 1373 K.

Difference in Bioactivity, Initial Cell Attachment and Cell Morphology Observed on the Surface of Hydroxyapatite Ceramics with Controlled Orientation

“…The prepared suspension was ground in an agate mortar using an automatic milling machine (Nitto Kagaku Co. Ltd., Type ANM1000) to disintegrate the aggregated particles. 2,3) A well-dispersed slurry of the disaggregated HAp particles was obtained by milling the suspension for more than 14.4 ks (4 h). The slurry was then poured into plaster molds and slip cast inside the bore of a superconducting magnet generating a 10 T magnetic field in order to form HAp green compacts with controlled orientation.…”

“…[1][2][3][4][5][6][7][8] It has an anisotropic crystal structure that belongs to the hexagonal system, and two types of crystal planes mainly appear on its crystal, which are aplane and c-plane. Since these two crystal planes are very different in atomic elements, numbers, and arrangements, they exhibit different nature (anisotropy).…”

“…[12][13][14] Owing to the recent developments in superconducting technology, controlling the crystal orientation using a magnetic field has been extended to nonmagnetic substances including HAp. [2][3][4][5]15,16) In this study, we have carried out an assessment to reveal the anisotropic biological features of HAp by using HAp ceramics with controlled orientation fabricated by slip casting under a magnetic field. Tanase et al 6) have recently reported the difference in the bioactivity of the two crystal planes by immersing crystal oriented HAp ceramics into the simulated body fluid, and they found that the precipitate layer formed earlier and thicker on the surface of c-plane oriented HAp ceramics than on the surface of a-plane oriented one.…”

“…Hydroxyapatite (HAp; Ca 10 (PO 4 ) 6 (OH) 2 ) is the major inorganic component of human hard tissues, [1][2][3][4][5][6] and it is a bioactive and biocompatible material widely utilized in biomedical applications. [1][2][3][4][5][6][7][8] It has an anisotropic crystal structure that belongs to the hexagonal system, and two types of crystal planes mainly appear on its crystal, which are aplane and c-plane.…”

Untitled

“…Since calcium orthophosphates are either thermally unstable (MCPM, MCPA, DCPA, DCPD, OCP, ACP, CDHA) or have a melting point at temperatures exceeding ~ 1400 °C with a partial decomposition (α-TCP, β-TCP, HA, FA, TTCP), only the first and the second consolidation approaches are used to prepare bulk bioceramics and scaffolds. The methods include uniaxial compaction [198,199], isostatic pressing (cold or hot) [200][201][202][203][204][205][206], granulation [207,208], loose packing [209], slip casting [210][211][212][213], gel casting [188,189,[214][215][216][217][218][219], pressure mold forming [220], injection molding [221], polymer replication [222][223][224][225], extrusion [226][227][228], slurry dipping and spraying [229], as well as to form ceramic sheets from slurries tape casting [124,216,230,231] doctor blade [232] and colander methods might be employed [194][195][196][197]…”