【摘要】：為了開發(fā)高性能生物鎂合金及其涂層制備工藝,本文系統(tǒng)研究了一種新型熱擠壓工藝(iECAP)對(duì)Mg-Nd-Zn-Zr合金生物腐蝕行為的影響,以及電化學(xué)沉積工藝對(duì)鈣磷涂層的影響機(jī)理。通過調(diào)控?cái)D壓溫度研究了iECAP工藝對(duì)Mg-Nd-Zn-Zr合金在模擬體液中腐蝕行為的影響。結(jié)果表明,擠壓態(tài)合金在模擬體液中的耐蝕性優(yōu)于鑄態(tài)合金;鑄態(tài)合金經(jīng)擠壓后,腐蝕方式由局部腐蝕轉(zhuǎn)變?yōu)榫鶆蚋g;擠壓溫度從400℃升高到500℃,耐蝕性逐漸提高。經(jīng)模擬體液浸泡后,形成了主要成分為Mg(OH)_2、HA、(Ca,Mg)_3(PO_4)_2等的腐蝕產(chǎn)物層以及少量結(jié)晶狀沉淀物。通過調(diào)控電化學(xué)沉積工藝參數(shù),研究了pH值、溫度、電流密度和時(shí)間對(duì)鈣磷涂層的影響及機(jī)理。pH值由3升高到5,涂層形貌由針狀轉(zhuǎn)變?yōu)閹?再轉(zhuǎn)變?yōu)榍驙?不利于FHA形成;pH值決定電解液中OH-數(shù)量,隨pH值升高,電解液中OH-增多,有利于形核,因此pH值為3到4時(shí)針狀組織逐漸長大變?yōu)閹?當(dāng)OH-數(shù)量過多時(shí),會(huì)導(dǎo)致鈣磷離子沉淀,不利于形核,因此不利于FHA形成。沉積溫度由50℃升高到80℃,涂層形貌由針狀轉(zhuǎn)變?yōu)閹罴扒驙?FHA結(jié)晶度增強(qiáng);溫度決定體系的自由能,溫度越高,自由能越大,因此形核速率也大,FHA結(jié)晶度增強(qiáng)。電流密度由0.25mA/cm~2增大到1mA/cm~2,涂層由細(xì)小的帶狀和球狀組織組成,其中帶狀組織變得越來越細(xì)小;電流密度決定H2和OH-的生成速度,隨電流密度增加,兩者共同作用,使晶粒變得細(xì)小。時(shí)間由2h增加到8h,涂層由細(xì)小的帶狀和球狀組織組成,且涂層由致密變疏松;時(shí)間導(dǎo)致晶體生長差異,部分晶粒優(yōu)先長大,部分晶粒生長受到抑制,形成了表面疏松的涂層。綜上,pH值影響最大,溫度次之,電流密度和時(shí)間影響較小,涂層的主要成分為FHA。
[Abstract]:In order to develop high performance biological magnesium alloy and its coating preparation process, the effect of a new hot extrusion process, (iECAP), on the biocorrosion behavior of Mg-Nd-Zn-Zr alloy was systematically studied in this paper. And the influence mechanism of electrochemical deposition process on calcium-phosphorus coating. The effect of iECAP process on corrosion behavior of Mg-Nd-Zn-Zr alloy in simulated body fluid was studied by adjusting extrusion temperature. The results show that the corrosion resistance of the extruded alloy is better than that of the as-cast alloy in simulated body fluid, the corrosion mode of the as-cast alloy changes from local corrosion to uniform corrosion after extrusion, and the corrosion resistance of the as-cast alloy increases from 400 鈩，

本文編號(hào)：2305938