【摘要】：金屬鎂及其合金由于優(yōu)異的生物相容性,與自然骨相近的密度和力學(xué)性能,在眾多材料中脫穎而出成為最具潛力的可降解金屬骨移植材料。但是由于其腐蝕速率過(guò)快,往往在植入初期就無(wú)法保證自身結(jié)構(gòu)的完整性,限制了該材料的臨床應(yīng)用。合金化和表面改性是兩種較為有效的降低鎂合金腐蝕速率的方法,研究者對(duì)此做了大量研究,雖取得了一定進(jìn)展卻仍不盡如人意。近年來(lái),鎂基大塊非晶合金的出現(xiàn)為尋求合適腐蝕速率的鎂基可降解金屬醫(yī)用材料打開(kāi)了一扇新的大門。它們的單相結(jié)構(gòu)、化學(xué)均勻性和無(wú)晶界等特點(diǎn)可以有效減弱電偶腐蝕效應(yīng),使其耐蝕性優(yōu)于同成分的晶態(tài)合金。本文設(shè)計(jì)并制備了MgZnCa和MgZnCaSi兩種體系的塊體非晶合金,并結(jié)合微弧氧化技術(shù)對(duì)其表面進(jìn)行了改性處理,以改善非晶合金表面的生物活性和進(jìn)一步提高其耐蝕性能。通過(guò)銅模噴鑄法成功制備出臨界鑄造尺寸為5 mm的Mg_(65.2)Zn_(28.8)Ca_6非晶合金,以硅酸鈉(Na_2SiO_3·9H_2O),四硼酸鈉(Na2B4O7·10H2O)和氫氧化鈉(NaOH)為電解液,采用恒壓模式對(duì)非晶合金進(jìn)行微弧氧化處理。測(cè)試發(fā)現(xiàn):涂層由MgO,CaO,MgSiO_3和Zn_2SiO_4相構(gòu)成。涂層表面多孔內(nèi)部致密并未發(fā)現(xiàn)有因熱應(yīng)力造成的微裂紋生成。與未經(jīng)處理的非晶合金樣品相比,涂層使基體的耐蝕性明顯提高,腐蝕電位和極化電阻分別增加了101 mV和3.246×10~5Ω。模擬體液浸泡實(shí)驗(yàn)發(fā)現(xiàn)羥基基磷灰石(HA)可以在多孔的涂層表面快速而自發(fā)的形成,證實(shí)了該涂層具有優(yōu)良的生物活性。在MgZnCa三元非晶合金體系的基礎(chǔ)上添加微量的Si元素,設(shè)計(jì)并制備出四元非晶合金體系Mg_(66)Zn_(29-x)Ca_5Si_x(at.%,x=0,0.25,0.5,0.75,1)。測(cè)試發(fā)現(xiàn):當(dāng)Si含量為0.5%時(shí),合金的耐蝕性能有所提升,同時(shí)玻璃形成能力,室溫壓縮強(qiáng)度俱佳。為進(jìn)一步改善鎂基非晶合金表面的生物活性,我們采用甘油磷酸鈣(Ca-Gp),氫氧化鈉(NaOH),磷酸二氫鈣(Ca(H_2PO_4)2·H_2O),氟化氫銨(NH_4HF_2)和乙二胺四乙酸二鈉(EDTA-2Na)組成的弱堿性電解液體系,在Mg_(66)Zn_(28.5)Ca_5Si_(0.5)非晶合金表面制備了含Ca、P的微弧氧化陶瓷涂層。使用控制變量法,研究了微弧氧化電壓、時(shí)間以及電解液中的NaOH濃度對(duì)膜層結(jié)構(gòu)以及性能的影響。電化學(xué)測(cè)試表明,Ca、P涂層的腐蝕電流密度只有基體的六分之一,極化電阻提升了一個(gè)數(shù)量級(jí)。之前制備的含硅涂層可以將極化電阻提升兩個(gè)數(shù)量級(jí),顯然Ca、P涂層的耐蝕性不如含Si涂層,但其誘導(dǎo)生成的羥基磷灰石數(shù)量和結(jié)晶性均優(yōu)于含Si涂層,顯示出優(yōu)異的生物活性。
[Abstract]:Due to their excellent biocompatibility, density and mechanical properties similar to those of natural bone, magnesium and its alloys have become the most promising biodegradable bone graft materials. However, due to its rapid corrosion rate, the integrity of its own structure can not be guaranteed at the early stage of implantation, which limits the clinical application of the material. Alloying and surface modification are two effective methods to reduce the corrosion rate of magnesium alloys. In recent years, the appearance of Mg-based bulk amorphous alloys has opened a new door for magnesium based degradable metal medical materials with appropriate corrosion rate. Their single phase structure, chemical homogeneity and grain boundary characteristics can effectively weaken the galvanic corrosion effect and make their corrosion resistance better than that of the same composition crystalline alloys. In this paper, bulk amorphous alloys of MgZnCa and MgZnCaSi systems were designed and prepared. The surface of amorphous alloys was modified by micro-arc oxidation in order to improve the surface bioactivity and corrosion resistance of amorphous alloys. Mg _ (65.2) Zn _ (28.8) Ca_6 amorphous alloy with critical casting size of 5 mm was successfully prepared by copper mold spray casting. The amorphous alloy was treated by microarc oxidation in constant pressure mode with sodium silicate (Na_2SiO_3 9H_2O), sodium tetraborate (Na2B4O7 10H2O) and sodium hydroxide (NaOH) as electrolyte. It is found that the coating consists of MgO / Cao / MgSiOS _ 3 and Zn_2SiO_4 phase. No microcracks due to thermal stress were found in the porous interior of the coating surface. Compared with the untreated amorphous alloy samples, the corrosion resistance of the coating is obviously improved, the corrosion potential and polarization resistance are increased by 101mV and 3.246 脳 10 ~ (5) 惟, respectively. Simulated body fluid immersion experiments showed that hydroxyapatite (HA) could form on the surface of porous coating rapidly and spontaneously, which proved that the coating had excellent biological activity. A quaternary amorphous alloy system mg _ (66) Zn _ (29-x) Ca_5Si_x (at 0.250.50.55) was designed and prepared on the basis of adding trace Si on the basis of MgZnCa ternary amorphous alloy system, and a quaternary amorphous alloy system mg _ (66) Zn _ (29-x) Ca_5Si_x was designed and prepared. It is found that the corrosion resistance of the alloy is improved when Si content is 0.5 and the glass forming ability and compression strength at room temperature are all good. In order to further improve the surface biological activity of Mg-based amorphous alloys, a weakly basic electrolyte system composed of calcium glycerophosphate (Ca-Gp), sodium hydroxide (NaOH), calcium dihydrogen phosphate (Ca (H_2PO_4) 2H 2O), ammonium hydroxide (NH_4HF_2) and ethylenediamine tetraacetate disodium (EDTA-2Na) was used. Microarc oxidation ceramic coatings containing CaOP were prepared on Mg66 Zn28.5 Ca5Si0.5 amorphous alloy. The effects of microarc oxidation voltage, time and concentration of NaOH in electrolyte on the structure and properties of the film were studied by the method of controlling variables. Electrochemical measurements show that the corrosion current density of the coating is only 1/6 of that of the substrate, and the polarization resistance is increased by an order of magnitude. The silicon coating prepared before can increase the polarization resistance by two orders of magnitude. Obviously, the corrosion resistance of CaOP coating is not as good as that of Si-containing coating, but the amount of hydroxyapatite induced by the coating is better than that of Si-containing coating, which shows excellent bioactivity.
【學(xué)位授予單位】：深圳大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TG139.8;TG174.4

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本文編號(hào)：2172090