【摘要】：鉀長石等硅酸鹽礦物是陶瓷生產(chǎn)的主要原料,由于硅酸鹽礦物晶格中硅氧鍵鍵能大,需要很高的溫度才能發(fā)生反應(yīng),帶來資源浪費和環(huán)境污染。而水稻生長過程中大量吸硅的現(xiàn)象表明,低分子量有機酸對打斷硅酸鹽礦物晶體結(jié)構(gòu)中的Si-O-Si鍵有一定效果,本文為了探究低分子量有機酸對硅酸鹽礦物的活化機理,并為陶瓷低溫?zé)蓭硇滤悸?利用甲酸、草酸及二者的復(fù)合酸對硅酸鹽礦物主要原料之一的鉀長石進行活化,測試活化過程中長石礦物晶格中硅、鋁的溶出量、溶出形式以及活化前后長石性質(zhì)的變化,然后將活化長石引入陶瓷坯料,用來降低陶瓷燒成溫度。另一方面,材料科學(xué)領(lǐng)域的量子化學(xué)計算正快速發(fā)展,高性能計算也給材料科學(xué)的研究帶來新思路。本文利用量子化學(xué)軟件包Gaussian模擬鉀長石的簡化結(jié)構(gòu)(HO)3-Si-O-Si-(OH)3和[(HO)3-Al-O-Si-(OH)3]-與甲酸、草酸以及水的反應(yīng),利用過渡態(tài)理論探究有機酸活化硅酸鹽礦物的機理。研究發(fā)現(xiàn),草酸對硅酸鹽礦物的活化效果遠(yuǎn)大于水,鋁硅酸鹽礦物中Al-O鍵比Si-O鍵更容易被破壞。根據(jù)反應(yīng)活化能的大小,大致確定硅酸鹽礦物的溶解機理:草酸電離出的H+首先將礦物晶格中的橋氧質(zhì)子化;然后,草酸和橋氧質(zhì)子化產(chǎn)物發(fā)生水解反應(yīng),使礦物晶格中Si-O鍵或Al-O鍵破壞。經(jīng)阿倫尼烏斯方程計算,草酸使硅酸鹽礦物晶格中Si-O鍵斷裂的反應(yīng)速率提高了3.09×1027倍,使鋁硅酸鹽礦物晶格中Al-O鍵斷裂的反應(yīng)速率提高了2.53×1012倍。經(jīng)過復(fù)合酸活化后的鉀長石中Si O2和Al2O3的含量均減少,顆粒粒徑減小了71.4%,比表面積增加了97.5%,結(jié)晶度變差。另外,將復(fù)合酸活化鉀長石作為原料引入陶瓷坯料,含量僅為3%時,在1275℃下燒成便能獲得原坯料在1325℃下燒成時的顯微結(jié)構(gòu)和性能,使燒成溫度降低50℃。
[Abstract]:Silicate minerals such as potassium feldspar are the main raw materials for ceramic production. Because of the large bond energy of silicon and oxygen in silicate mineral lattice, it needs a high temperature to react, resulting in waste of resources and environmental pollution. However, the phenomenon of large amount of silicon absorption during rice growth shows that low molecular weight organic acids can break the Si-O-Si bond in silicate mineral crystal structure. In order to explore the activation mechanism of low molecular weight organic acid on silicate minerals, The potassium feldspar, one of the main raw materials of silicate minerals, was activated by formic acid, oxalic acid and their complex acids. The dissolution of Si and Al in the crystal lattice of feldspar minerals during activation was measured. The form of dissolution and the change of feldspar properties before and after activation, and then the activated feldspar was introduced into the ceramic blank to reduce the sintering temperature of ceramics. On the other hand, quantum chemistry calculation is developing rapidly in the field of material science. In this paper, the simplified structure of potassium feldspar, (HO) _ 3-Si-O-Si-( OH) _ 3 and [(HO) _ 3-Al-O-Si- (OH) _ 3] -reacts with formic acid, oxalic acid and water are simulated by quantum chemical software package Gaussian. The mechanism of activation of silicate minerals by organic acids is explored by means of transition state theory. It is found that oxalic acid can activate silicate minerals more effectively than water, and the Al-O bond in aluminosilicate minerals is easier to be destroyed than that of Si-O bonds. According to the activation energy of the reaction, the dissolution mechanism of silicate minerals is roughly determined: h ionization of oxalic acid first protonates the bridging oxygen in the mineral lattice, and then hydrolyzes oxalic acid and bridged oxygen protonation products. The Si-O bond or Al-O bond in the mineral lattice is destroyed. Calculated by Arrhenius equation, oxalic acid increases the reaction rate of Si-O bond fracture in silicate mineral lattice by 3.09 脳 1027 times, and the rate of Al-O bond fracture in aluminosilicate mineral lattice increases by 2.53 脳 1012 times. The contents of Sio _ 2 and Al2O3 in the potassium feldspar activated by complex acid decreased, the particle size decreased by 71.4, the specific surface area increased by 97.5 and the crystallinity became worse. In addition, when the composite acid-activated potassium feldspar is introduced into the ceramic blank, the microstructure and properties of the raw material can be obtained by sintering at 1275 鈩，

本文編號：2190923