【摘要】：基于鎂合金獨特的可降解性能和優(yōu)異的力學相容性,其在骨替代植入領域具有良好的前景,然而在生理體液中腐蝕過快降低了其臨床應用的成功率,因此提高鎂合金在植入環(huán)境中的耐腐蝕性,保持其在骨愈合前的力學性能完整性,調控其降解速率,抑制Mg2+、OH-和H2等腐蝕產(chǎn)物的過量釋放,是生物鎂合金研究的關鍵。本文采用放電等離子燒結技術,以生物ZK61鎂合金為基體,通過添加不同含量羥基磷灰石(HA)顆粒(5wt.%、10wt.%和15wt.%),制備了ZK61-HA生物復合材料。首先探究了不同燒結溫度下,ZK61塊體致密化過程以及對其組織和性能的影響規(guī)律,確定了SPS燒結ZK61的最佳溫度;然后通過SPS制備ZK61-HA復合材料,研究不同含量HA顆粒對復合材料微觀結構、力學性能和體外降解行為的影響,并對其生物相容性進行了評價,得出如下結論:在370℃、420℃、470℃和520℃燒結溫度下,制備出了晶粒細小組織均勻的ZK61鎂合金塊體。通過SPS技術制備ZK61合金的過程表現(xiàn)為軸向壓力下顆粒密集排布、塊體快速致密化和成分均勻化3個階段;隨燒結溫度升高,ZK61合金塊體致密度逐漸提高,在520℃溫度下燒結出的合金致密度最大,為99.3%;與370℃燒結出的合金相比,燒結溫度為520℃時合金的顯微硬度提高14.6%,為79.3 HV,抗壓強度提高18.8%,為304 MPa,抗彎強度也獲得最大值為94.7 MPa,同時材料的壓縮率增大,韌性提高。經(jīng)過球磨混合粉末,在520℃溫度下通過SPS燒結出了ZK61-HA復合材料,微觀結構檢測結果表明:第二相HA陶瓷顆粒均勻地分布在ZK61鎂合金基體周圍,界面結合良好,材料內部無明顯的孔洞,在SPS燒結時HA顆粒與基體合金沒有發(fā)生反應,復合材料的物相主要由Mg和HA相組成,復合材料的致密度較高,均在96%以上,隨著HA含量增加,致密度有所下降。力學性能測試發(fā)現(xiàn):增加HA顆粒提高了基體合金的力學性能,在HA含量為15wt.%時其平均顯微硬度(93.4±4.1 HV)提高16.5%,壓縮屈服強度(230 MPa)提高15.6%,抗彎模量達到最大為31.5 GPa,抗壓強度由0wt.%時的304 MPa增加到10wt.%時的429 MPa,抗彎強度在5wt.%時最大為142.7 MPa。電化學極化行為測試顯示:在SBF溶液中,HA顆粒的添加提高了基體合金的耐腐蝕性能,含量為10wt.%時自腐蝕電位最大為-1.5327 V,自腐蝕電流最小為1.83×10-4 A/cm2。浸泡行為結果發(fā)現(xiàn):隨著HA顆粒的添加,復合材料的析氫量和溶液的p H值均有所降低,其失重腐蝕速率也較ZK61基體低,ZK61-10HA復合材料的平均浸泡腐蝕速率最低為14.9 mm/y,具有較好的耐腐蝕性能。用MTT比色法對ZK61-HA復合材料的細胞毒性檢測結果發(fā)現(xiàn)L-929細胞在復合材料的浸提液中生長狀況良好,細胞毒性評級均合格。
[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，

本文編號：2304701