(华中科技大学 材料成形与模具技术国家重点实验室，武汉 430074)
摘 要: 采用激光选区熔化工艺(SLM)制备几种不同成分的316L-nHA(纳米羟基磷灰石nHA的体积分数分别为0、5%、10%、15%)复合材料，并测试其致密度与抗拉强度；利用SEM分析其组织及断口形貌。结果表明，当nHA的含量为5%时，材料的致密度和抗拉强度与纯不锈钢的相近，扫描速度为350 mm/s时强度达到最大值634.6 MPa；当nHA含量增大至10%~15%时材料致密度和强度明显降低，强度最高只有264.4 MPa。面能谱显示nHA均匀分布在金属基体中，呈弥散型金属-HA微界面结合特征。nHA和316L热膨胀系数的差异，且nHA中富含P，导致SLM过程中产生裂纹，当nHA含量由5%增大至15%时，裂纹密度明显增大，且互相联通。当nHA含量为5%时，提高扫描速度有利于抑制裂纹产生；当nHA含量增大至10%~15%时，由于P增多，增大扫描速度对裂纹的抑制作用较小。在适当的材料配比和工艺条件下利用SLM可制备出满足承重骨修复体力学性能要求的316L-nHA复合材料，有望改善金属植入体的生物相容性。
关键字: 纳米羟基磷灰石；316L不锈钢；生物复合材料；激光选区熔化；力学性能
（State Key Laboratory of Materials Processing and Die & Mould Technology,
Huazhong University of Science and Technology, Wuhan 430074, China）
Abstract:Different compositions of 316L-nHA biocomposites (volume fractions of nano hydroxyapatite (nHA) are 0, 5%, 10% and 15%, respectively) were prepared by selective laser melting (SLM) method. The density and tensile strength of the composites were tested. And their microstructures and fracture morphologies were observed using scanning electron microscopy (SEM). The results show that at the nHA content of 5%, the density and tensile strength of composite are close to those of the pure stainless steel, and the maximum tensile strength of 634.6 MPa is achieved at a scanning speed of 350 mm/s. The tensile strength and density of composites decrease significantly when the nHA content increases to 10%-15% and the maximum tensile strength is 264.4 MPa. The surface energy spectrum shows that HA uniformly distributes in the metal matrix and the micro interface of metal-HA composite presents diffusion characteristic. Due to the difference between nHA and 316L stainless steel in thermal expansion coefficient and abundant P in HA, the cracks develop during the SLM process. When the nHA content gradually increases from 5% to 15%, the crack density increases obviously and the cracks are interconnected. When the nHA content is 5%, increasing scanning speed is helpful to reduce the crack number. When the nHA content increases from 10% to 15%, the inhibitory effect on the crack of increasing scanning speed is smaller due to the increase of P content. Under the condition of appropriate ratio of material and process, using SLM method is able to prepare 316L-nHA biocomposite satisfying the mechanical properties requirement of load-bearing bone repairing, which is expected to improve the biocompatibility of the metallic implants.
Key words: nano hydroxyapatite; 316L stainless steel; bioactive composite; selective laser melting; mechanical property
