Abstract
Metallic biomaterials are widely used for implants and dental and orthopedic applications due to their good mechanical properties. Among all these materials, 316L stainless steel has gained special attention, because of its good characteristics as an implantable biomaterial. However, the Young’s modulus of this metal is much higher than that of human bone (~193 GPa compared to 5–30 GPa). Thus, a stress shielding effect can occur, leading the implant to fail. In addition, due to this difference, the bond between implant and surrounding tissue is weak. Already, calcium phosphate ceramics, such as beta-tricalcium phosphate, have shown excellent osteoconductive and osteoinductive properties. However, they present low mechanical strength. For this reason, this study aimed to combine 316L stainless steel with the beta-tricalcium phosphate ceramic (β-TCP), with the objective of improving the steel’s biological performance and the ceramic’s mechanical strength. The 316L stainless steel/β-TCP biocomposites were produced using powder metallurgy and functionally graded materials (FGMs) techniques. Initially, β-TCP was obtained by solid-state reaction using powders of calcium carbonate and calcium phosphate. The forerunner materials were analyzed microstructurally. Pure 316L stainless steel and β-TCP were individually submitted to temperature tests (1000 and 1100 °C) to determine the best condition. Blended compositions used to obtain the FGMs were defined as 20% to 20%. They were homogenized in a high-energy ball mill, uniaxially pressed, sintered and analyzed microstructurally and mechanically. The results indicated that 1100 °C/2 h was the best sintering condition, for both 316L stainless steel and β-TCP. For all individual compositions and the FGM composite, the parameters used for pressing and sintering were appropriate to produce samples with good microstructural and mechanical properties. Wettability and hemocompatibility were also achieved efficiently, with no presence of contaminants. All results indicated that the production of 316L stainless steel/β-TCP FGMs through PM is viable for dental and orthopedic purposes.
Highlights
The results showed that the addition of β-TCP significantly improved the wettability of all compositions with 316L stainless steel, due to its high hydrophilic behavior
Even with the variability in the results presented, they are still very close and below 5% of hemolysis rate, which indicates the high hemocompatibility of the individual compositions and the functionally graded materials (FGMs) composite
Through mapping by EDS, it was observed that its chemical composition was homogeneously distributed throughout the composite
Summary
Biomaterials compose a wide range of materials of various types, including alloys, ceramics, glasses and biodegradable and non-degradable polymers, among others. They are used in different areas of medicine and dentistry, for the repair or replacement of damaged body parts. To be considered biocompatible and avoid compromising the patient’s health, the material must not induce cytotoxic reactions in the organism [1,2]. The biomaterials market is growing expansively, and according to the compound annual growth rate, it is estimated that in five years the numbers can vary from 5.5% to 32% in some areas [3]
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