Space-holder engineered porous NiTi shape memory alloys with improved pore characteristics and mechanical properties

Li, D.S.; Zhang, Y.P.; Ma, Xiaoqian; Zhang, X.P.

doi:10.1016/j.jallcom.2008.06.043

Cited by 59 publications

(46 citation statements)

References 20 publications

(23 reference statements)

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“…There are several manufacturing processes for the latter, among which are highlighted: the electron beam melting process [16], creep expansion of argon-filled pores [17], directional aqueous freeze casting [18], rapid prototyping techniques [19], laser-engineered net shaping [20], electric current activated/assisted sintering techniques [21,22], conventional powder metallurgy [23] and space-holder techniques [24]. In this last process, most of the space-holders (ammonium bicarbonate [25][26][27][28], carbamide [29] and PVA [30]) are completely evaporated at low temperatures, whilst others (e.g., sodium chloride [31][32][33][34][35]) are removed by a dissolution process, generally in water.…”

Section: Introductionmentioning

confidence: 99%

Processing, characterization and biological testing of porous titanium obtained by space-holder technique

et al. 2012

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The high Young's modulus of titanium with respect to that one of the bone is the main cause of the stressshielding phenomenon, which promotes bone resorption around implants. Development of implants with a low Young's modulus has gained increased importance during the last decade, and the manufacturing of porous titanium is one of the routes to reduce this problem. In this work, porous samples of commercially pure titanium grade IV obtained by powder metallurgy with ammonium bicarbonate (NH 4 HCO 3 ) as space-holder were studied. Evaluations of porosity and mechanical properties were used to determine the influence of compaction pressure for a fixed NH 4 HCO 3 content. Measurements by ultrasound tests gave Young's modulus results that were low enough to reduce stress shielding, whilst retaining suitable mechanical strength. Biological tests on porous cp Ti showed good adhesion of osteoblasts inside the pores, which is an indicator of potential improvement of osteointegration.

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Section: Introductionmentioning

confidence: 99%

Processing, characterization and biological testing of porous titanium obtained by space-holder technique

et al. 2012

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“…Temporary space-holders used for NiTi include ammonium bicarbonate [44][45][46], polymethyl methacrylate [40] and magnesium [47]. Removal of these space-holders occurs by thermal decomposition or evaporation and can thus be integrated into the sintering processing stage.…”

Section: Introductionmentioning

confidence: 99%

Shape-memory NiTi with two-dimensional networks of micro-channels

Neurohr

Dunand

2011

Acta Biomaterialia

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“…The diffusion rate of Mo atoms in Ti particles is much slower than that of the self-diffusivity of Ti [45], which is susceptible to the unbalanced mass transfer and the formation of Kirkendall pores [25]. The formation mechanism of the large pore is a geometrical heredity effect of space-holder NH 4 HCO 3 particles [46]. During the sintering process, the NH 4 HCO 3 particles will decompose into the gases of NH 3 , CO 2 and H 2 O, which leave the green compacts and furnace together with the continuous argon gas flow.…”

Section: Resultsmentioning

confidence: 99%

Preparation and bioactive surface modification of the microwave sintered porous Ti-15Mo alloys for biomedical application

Zhang

Bao

et al. 2017

Sci. China Mater.

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Biomedical porous Ti-15Mo alloys were prepared by microwave sintering using ammonium hydrogen carbonate (NH 4 HCO 3 ) as the space holder agent to adjust the porosity and mechanical properties. The porous Ti-15Mo alloys are dominated by β-Ti phase with a little α-Ti phase, and the proportion of α and β phase has no significant difference as the NH 4 HCO 3 content increases. The porosities and the average pore sizes of the porous Ti-15Mo alloys increase with increase of the contents of NH 4 HCO 3 , while all of the compressive strength, elastic modulus and bending strength decrease. However, the compressive strength, bending strength and the elastic modulus are higher or close to those of natural bone. The surface of the porous Ti-15Mo alloy was further modified by hydrothermal treatment, after which Na 2 Ti 6 O 13 layers with needle and flake-like clusters were formed on the outer and inner surface of the porous Ti-15Mo alloy. The hydrothermally treated porous Ti-15Mo alloy is completely covered by the Ca-deficient apatite layers after immersed in SBF solution for 14 d, indicating that it possesses high apatiteforming ability and bioactivity. These results demonstrate that the hydrothermally treated microwave sintered porous Ti15Mo alloys could be a promising candidate as the bone implant.

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Space-holder engineered porous NiTi shape memory alloys with improved pore characteristics and mechanical properties

Cited by 59 publications

References 20 publications

Processing, characterization and biological testing of porous titanium obtained by space-holder technique

Processing, characterization and biological testing of porous titanium obtained by space-holder technique

Shape-memory NiTi with two-dimensional networks of micro-channels

Preparation and bioactive surface modification of the microwave sintered porous Ti-15Mo alloys for biomedical application

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