本文選題：鈣鈦鋯石 + 玻璃陶瓷��； 參考：《西南科技大學(xué)》2015年碩士論文

【摘要】：針對目前高放廢液硼硅酸鹽玻璃固化體存在錒系核素溶解度較低、熱力學(xué)穩(wěn)定性較差等不足,以及在玻璃熔制過程中容易出現(xiàn)分離的含硫黃色第二相(黃相)問題,通過在鋇硼硅酸鹽玻璃體系(Ba O-B2O3-Na2O-Si O2)中加入不同含量的氧化鈣(Ca O)、二氧化鈦(Ti O2)和鋯英石(Zr Si O4)(記為CTZ),采用熔融-熱處理工藝制備了含有鈣鈦鋯石晶相的鋇硼硅酸鹽玻璃陶瓷固化體。系統(tǒng)研究了CTZ含量(0~55 wt%)對鋇硼硅酸鹽玻璃陶瓷固化體的晶相組成、顯微結(jié)構(gòu)和化學(xué)穩(wěn)定性的影響;研究了鈣含量變化(Ca O:Ti O2:Zr O2=x:2:1,x=0.5~10)對鋇硼硅酸鹽玻璃陶瓷的晶相結(jié)構(gòu)和顯微結(jié)構(gòu)等的影響;采用正交試驗(yàn)法優(yōu)化了鋇硼硅酸鹽玻璃陶瓷的熱處理工藝參數(shù),并比較了一步法(核化和晶化同時(shí)進(jìn)行)和二步法(核化和晶化分開進(jìn)行)熱處理工藝對玻璃陶瓷結(jié)構(gòu)的影響;研究了鋇硼硅酸鹽玻璃陶瓷對硫元素(以Na2SO4形式引入)的最大包容量。結(jié)果表明:含CTZ的鋇硼硅酸鹽基礎(chǔ)玻璃的熔制溫度為1150~1250℃樣品的玻璃轉(zhuǎn)變溫度為615~650℃且隨著CTZ含量增加而升高。CTZ含量為35 wt%和45 wt%的樣品分別在900℃和850℃附近出現(xiàn)了明顯的放熱峰。當(dāng)CTZ含量≥35 wt%時(shí),鈣鈦鋯石晶相開始析出;CTZ含量為45 wt%時(shí),樣品中出現(xiàn)了大量均勻分布的柱狀鈣鈦鋯石晶相;CTZ含量達(dá)55 wt%時(shí),樣品致密性較差,除鈣鈦鋯石晶相外還有榍石和二氧化硅晶相析出。產(chǎn)品一致性試驗(yàn)(Product Consistency Test,PCT)結(jié)果表明,CTZ含量為45 wt%的固化體的抗浸出性能較好,42 d后Na和B的歸一化質(zhì)量損失約為0.2 g/m2,Si和Ca約為0.02 g/m2。當(dāng)Ca O:Ti O2:Zr O2=2:2:1和4:2:1時(shí),可以獲得僅含鈣鈦鋯石晶相的玻璃陶瓷。正交試驗(yàn)結(jié)果表明,核化溫度和晶化溫度對玻璃陶瓷體內(nèi)鈣鈦鋯石含量影響較大,而核化時(shí)間和晶化時(shí)間的影響相對較小。二步法和一步法熱處理工藝對玻璃陶瓷結(jié)構(gòu)無顯著影響,當(dāng)晶化溫度較高或晶化時(shí)間較長時(shí),均會(huì)出現(xiàn)榍石晶相。鋇硼硅酸鹽玻璃陶瓷能夠包容3 mo l%的Na2SO4而不出現(xiàn)分層,硫含量在0~3mol%范圍內(nèi)樣品晶相組成僅有鈣鈦鋯石,且硫含量變化對鈣鈦鋯石晶體數(shù)量和分布影響不大;當(dāng)Na2SO4含量大于3 mo l%時(shí),玻璃陶瓷結(jié)構(gòu)疏松,存在少量孔洞,樣品體內(nèi)含有鈣鈦鋯石和榍石晶相,表面形成了由硫酸鋇和硫酸鈉組成的白色分離層。樣品PCT實(shí)驗(yàn)表明,當(dāng)Na2SO4含量低于3 mol%時(shí),元素歸一化質(zhì)量損失在7 d之后基本保持穩(wěn)定:NLB和NLCa為0.01 g/m2,NLBa為0.001 g/m2,NLNa為0.1 g/m2。當(dāng)Na2SO4含量超過3 mo l%后,7 d之后NLB和NLNa隨時(shí)間增加而增加,NLBa和NLCa在28 d之后基本保持穩(wěn)定,分別為10-4 g/m2和10-2 g/m2數(shù)量級。
[Abstract]:In view of the shortcomings of low solubility of actinide nuclides and poor thermodynamic stability in the present high level waste liquid borosilicate glass solidification, the second phase (yellow phase) containing sulfur is easy to be separated in the process of glass melting. Barium borosilicate (barium borosilicate) containing calcium oxide (Cao), titanium dioxide (TIO 2) and zircon (Zr Sio 4) (denoted as CTZ) was prepared by melt heat treatment in the barium borosilicate glass system (BaO-B2O3-Na2O-SiO 2). Salt glass ceramic solidified body. The effects of CTZ content (0 ~ 55wt%) on the crystal phase composition, microstructure and chemical stability of barium borosilicate glass ceramics were systematically studied. The effect of calcium content (Cao: TIO 2: Zr O 2: x 2: 1: 1) on the crystal phase structure and microstructure of barium borosilicate glass ceramics was studied, and the heat treatment process parameters of barium borosilicate glass ceramics were optimized by orthogonal test. The effects of one-step heat treatment (nucleation and crystallization at the same time) and two-step heat treatment (nucleation and crystallization) on the structure of glass ceramics were compared. The maximum inclusion capacity of barium borosilicate glass ceramics for sulfur (introduced in the form of Na _ 2SO _ 4) was studied. The results show that the melting temperature of barium borosilicate base glass containing CTZ is 1 150 鈩，

本文編號：2072917