Innovative High-Pressure Fabrication Processes for Porous Biomaterials-A Review

Abstract

Biomaterials and their clinical application have become well known in recent years and progress in their manufacturing processes are essential steps in their technological advancement. Great advances have been made in the field of biomaterials, including ceramics, glasses, polymers, composites, glass-ceramics and metal alloys. Dense and porous ceramics have been widely used for various biomedical applications. Current applications of bioceramics include bone grafts, spinal fusion, bone repairs, bone fillers, maxillofacial reconstruction, etc. One of the common impediments in the bioceramics and metallic porous implants for biomedical applications are their lack of mechanical strength. High-pressure processing can be a viable solution in obtaining porous biomaterials. Many properties such as mechanical properties, non-toxicity, surface modification, degradation rate, biocompatibility, corrosion rate and scaffold design are taken into consideration. The current review focuses on different manufacturing processes used for bioceramics, polymers and metals and their alloys in porous forms. Recent advances in the manufacturing technologies of porous ceramics by freeze isostatic pressure and hydrothermal processing are discussed in detail. Pressure as a parameter can be helpful in obtaining porous forms for biomaterials with increased mechanical strength.

Keywords: bioceramics; biodegradable polymers; freeze isostatic pressure; high pressure processing; metallic implants; porous biomaterials.

Figure 1

P-T diagram of water and their corresponding densities [78].

Figure 2

Freeze isostatic pressure equipment at ICMCB.

Figure 3

Tomography (internal diameter cut view, diameter: 10 mm) of the sample consolidated by freeze isostatic pressure (FIP) showing a non-uniform distribution of pores and inhomogeneous repartition of solvent (presence of agglomerates).

Figure 4

Tomography (internal diameter cut view, diameter = 10 mm) of the sample consolidated by FIP showing an uniform distribution of pores by increasing the content of solvent.

Figure 5

Porosity as a function of various parameter of FIP process.

Figure 6

Porosity of AE SiO₂ by hydrothermal dissolution.

Figure 7

Porosity as a function of temperature in hydrothermal sintering.

Figure 8

Microstructure of porous Cu samples obtained by hydrothermal sintering.

Figure 9

Variation of porosity with respect to initial applied pressure in Cu porous samples by hydrothermal sintering.