查看更多>>摘要：Strict control of powder properties,especially particle size distribution(PSD),is critical in the laser powder bed fusion(LPBF)process to ensure the quality of the fabricated parts.This work shows that reducing the powder size could improve the ductility of LPBF fabricated AlSi10Mg.The tensile elongation increased from 4.1％to 8.8％when AlSi10Mg powder sizes(D50 value)decreased from 76 μm to 16 μm in the as-fabricated state.Our results showed that fine powder size stimulates epitaxial grain growth due to excessive remelting.The presence of epitaxial columnar grains makes the crack path across inner melt pools more frequent and travels from the coarse melt pool zones to the fine melt pool zones.This work suggests that powder size is a crucial factor to be considered in maintaining repeatable mechanical properties in LPBF processes,particularly when ductility and ductility-dominated properties are critical.
查看更多>>摘要：3D printed polyether-ether-ketone(PEEK)implant has become a popular clinical alternative to implants made of titanium alloy for cranial bone substitutes due to its bone-match properties,however its biological inert hin-dered the progress of clinical applications of such material.To enhance the tissue integration capability of PEEK implants and promote their long-term stability,cranial implants of gradient porous structures were designed and manufactured via fused filament fabrication(FFF)3D printing technology in both PEEK and PEEK/HA com-posites materials,then functionally evaluation of the implants on the tissue in-growth and the osteointegration mechanisms was conducted via animal tests.The 3D printed PEEK scaffold was found to have 2-5 folds of the compressive strength to those of the natural cranial bone.The in vivo studies verified that the porous PEEK/HA scaffold could effectively induce the bone ingrowth to form a stable biointegration boundary surrounding the host bone tissue after 4 weeks of implantation.Moreover,the PEEK/HA scaffold showed no significant advantages in improving the soft tissue in-growth,only making its distribution more evenly.It is also interestingly to find out that the vertically connective pores throughout the implant did not enhance the tissue binding force even though it did promote the nutrient transportation.In conclusion,the use of PEEK/HA composite material and a well-designed porous structure was proved to be an effective approach to improve the biointegration between the implant and host tissues.
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