放电等离子烧结ZK61-HA生物复合材料的组织及性能研究

发布时间：2018-11-01 18:14

【摘要】：基于镁合金独特的可降解性能和优异的力学相容性,其在骨替代植入领域具有良好的前景,然而在生理体液中腐蚀过快降低了其临床应用的成功率,因此提高镁合金在植入环境中的耐腐蚀性,保持其在骨愈合前的力学性能完整性,调控其降解速率,抑制Mg2+、OH-和H2等腐蚀产物的过量释放,是生物镁合金研究的关键。本文采用放电等离子烧结技术,以生物ZK61镁合金为基体,通过添加不同含量羟基磷灰石(HA)颗粒(5wt.%、10wt.%和15wt.%),制备了ZK61-HA生物复合材料。首先探究了不同烧结温度下,ZK61块体致密化过程以及对其组织和性能的影响规律,确定了SPS烧结ZK61的最佳温度;然后通过SPS制备ZK61-HA复合材料,研究不同含量HA颗粒对复合材料微观结构、力学性能和体外降解行为的影响,并对其生物相容性进行了评价,得出如下结论:在370℃、420℃、470℃和520℃烧结温度下,制备出了晶粒细小组织均匀的ZK61镁合金块体。通过SPS技术制备ZK61合金的过程表现为轴向压力下颗粒密集排布、块体快速致密化和成分均匀化3个阶段;随烧结温度升高,ZK61合金块体致密度逐渐提高,在520℃温度下烧结出的合金致密度最大,为99.3%;与370℃烧结出的合金相比,烧结温度为520℃时合金的显微硬度提高14.6%,为79.3 HV,抗压强度提高18.8%,为304 MPa,抗弯强度也获得最大值为94.7 MPa,同时材料的压缩率增大,韧性提高。经过球磨混合粉末,在520℃温度下通过SPS烧结出了ZK61-HA复合材料,微观结构检测结果表明:第二相HA陶瓷颗粒均匀地分布在ZK61镁合金基体周围,界面结合良好,材料内部无明显的孔洞,在SPS烧结时HA颗粒与基体合金没有发生反应,复合材料的物相主要由Mg和HA相组成,复合材料的致密度较高,均在96%以上,随着HA含量增加,致密度有所下降。力学性能测试发现:增加HA颗粒提高了基体合金的力学性能,在HA含量为15wt.%时其平均显微硬度(93.4±4.1 HV)提高16.5%,压缩屈服强度(230 MPa)提高15.6%,抗弯模量达到最大为31.5 GPa,抗压强度由0wt.%时的304 MPa增加到10wt.%时的429 MPa,抗弯强度在5wt.%时最大为142.7 MPa。电化学极化行为测试显示:在SBF溶液中,HA颗粒的添加提高了基体合金的耐腐蚀性能,含量为10wt.%时自腐蚀电位最大为-1.5327 V,自腐蚀电流最小为1.83×10-4 A/cm2。浸泡行为结果发现:随着HA颗粒的添加,复合材料的析氢量和溶液的p H值均有所降低,其失重腐蚀速率也较ZK61基体低,ZK61-10HA复合材料的平均浸泡腐蚀速率最低为14.9 mm/y,具有较好的耐腐蚀性能。用MTT比色法对ZK61-HA复合材料的细胞毒性检测结果发现L-929细胞在复合材料的浸提液中生长状况良好,细胞毒性评级均合格。
[Abstract]:Because of its unique degradability and excellent mechanical compatibility, magnesium alloy has a good prospect in the field of bone substitute implantation. However, the corrosion rate in physiological body fluid decreases the success rate of clinical application. Therefore, it is the key to improve the corrosion resistance of magnesium alloys in implanted environment, to maintain the integrity of mechanical properties before bone healing, to regulate the degradation rate and to inhibit the excessive release of corrosion products such as Mg2, OH- and H2. In this paper, the biological composite material of ZK61 was prepared by using spark plasma sintering (SPS) technique and adding different content of hydroxyapatite (HA) particles (5wt.10wt.% and 15wt.%). Firstly, the densification process of ZK61 bulk and its effect on microstructure and properties at different sintering temperatures were investigated, and the optimum sintering temperature of SPS sintered ZK61 was determined. Then, ZK61-HA composites were prepared by SPS. The effects of different content of HA particles on microstructure, mechanical properties and degradation behavior in vitro were studied. The biocompatibility of the composites was evaluated as follows: at 370 鈩，

本文编号：2304701