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Materials Science in Additive Manufacturing Preparation and modification of porous Ti

A

B C

Figure 5. Principle and shape of space holder method. (A) Scanning electron microscopy images of two different shapes of urea NaCl and schematic
diagram of porous titanium preparation. (B) Schematic diagram of preparing porous titanium alloy using magnesium particles and magnesium powder as
pore-forming agents. (C) Preparation of porous titanium alloy using magnesium particles and magnesium powder as pore-forming agents. 49

calcium, which acts as a reducing agent. Porous titanium The advantage of the gel casting method is that it
was prepared from calcium chloride volatilization by can design the overall appearance of porous materials
continuous heating at 1273 K under 0.1 Pa. Then, porous according to the needs of the damaged parts. Yang
titanium with a porosity of 62 – 82% was prepared by et al. used acrylamide, N-methylene diacrylamide,
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leaching the reduction products with dilute hydrochloric n-tetramethylenediamine (TEMED) as catalyst,
acid, and more than 90% of the pores were open. The ammonium persulfate hydrogel system, and titanium
porosity gradually increased with calcium chloride content powder to prepare a premixed solution. The slurry was
in the raw material. poured into a non-porous mold (Figure 6), kept at 60°C for
Space scaffold technology can achieve a wide range of 2 h to cure into the required shape, and dried in vacuum
pore size adjustments and high porosity by controlling at room temperature after demolding. By changing the
the mixing ratio and is one of the most commonly used volume of the polymer network between the powder
methods for preparing porous materials. However, particles, 39 – 50% porous Ti-Mo and Ti-Nb alloy porous
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the uniformity of the mixture is not easy to control, and implants were prepared after sintering at 900 – 1050°C for
the pore-forming agent needs to be removed by heating 2 h, with Young’s modulus ranging from 5 to 18 GPa.
evaporation or soaking, which makes it easy to produce Biasetto et al. used gel casting to prepare porous
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residual pore-forming agents and engender other problems Ti6Al4V metal by mixing titanium alloy powder with
affecting the material’s biocompatibility. a surfactant to prepare suspension Doran molds for
mechanical stirring to study the effect of stirring speed
3.1.4. Gel injection molding (700 rpm and 1500 rpm) on the evolution of porous

The gel injection molding method involves mixing powder titanium porosity morphology. At 700 r/min, the porous
and adhesive, followed by injection molding and curing to titanium porosity decreased from 91.3% to 81.3% at
obtain a uniform blank. After drying, dust removal, and 700 r/min, and the porosity decreased from 88.3% to
sintering, the billets are prepared into nearly net porous 70.7% at 1500 r/min. From the results, it clear that the
titanium alloys with complex shapes. 52 increase in rotational speed decreases the bubble content

Volume 3 Issue 1 (2024) 7 https://doi.org/10.36922/msam.2753