Densification and Superplasticity of Hydroxyapatite Ceramics

Influence of .BETA.-tricalcium phosphate dispersion on mechanical properties of hydroxyapatite ceramics

“…As for the HAp ceramics, superplastic deformation has been already reported by Wakai et al, 7) and Tago et al. 8) The HAp/β-TCP composites showed large deformation at high temperature without the remarkable change in grain size and shape. It is conceivable from the result that the grain structure in the composites is more stable during high-temperature deformation than the HAp ceramics and grain boundary sliding is continued during the deformation, because the presence of second phase grains can retard grain growth.…”

“…For fully understanding the influence, further studies are required in the HAp/β-TCP composites. Concerning high-temperature deformation behavior, Wakai et al 7) and Tago et al 8) performed tensile tests at high temperatures in the HAp ceramics, and demonstrated their superplasticity. However, as far as the authors know, there have been no reports on the composites.…”

Calcium phosphate based ceramic with a resorbable phase and low sintering temperature

“…If cold hydrostatic compaction is used at the formation stage, then the calcination temperature can be lowered to 1100°C [10]. Another method of lowering the calcination temperature of ceramic is to introduce into the initial batch low-melting additives, for example, salts or components that form eutectic melts with the main components [11].…”

Superplastic Deformation in Carbonate Apatite Ceramics under Constant Compressive Loading for Near-net-shape Production of Bioresorbable Bone Substitutes

“…Although there is no physical definition for determining superplasticity on the basis of elongation, metals are regarded as being superplastic when the elongation is approximately 300％, while brittle ceramics are regarded as being superplastic when the elongation exceeds 100％ 18) . The occurrence of superplasticity and the mechanism of superplastic deformation have been reported for several ceramic materials, such as zirconia 12) , silicon nitride 13) , and HAP 9,10) . In these ceramics, it is thought that crystal grains undergo grain boundary sliding by closely adhering to each other, and that superplastic deformation is caused by rearrangement and growth of the grains [16][17][18][19][20] .…”

“…However, the near-net-shape production of CAP ceramics without degrading their physical properties is difficult due to their brittle character and low fracture toughness 8) . It has been previously reported that sintered HAP ceramics 9,10) showed marked plastic deformation, the so-called superplastic deformation, at around 1050℃ under appropriate loading conditions similar to other ceramics [11][12][13][14] . Recently, in a study 15) aimed at developing CAP-bearing titanium implants, one of the present authors found that CAP particles also showed marked plastic deformation at 750℃.…”