發(fā)布時(shí)間：2018-01-23 14:02

  本文關(guān)鍵詞： 液相沉淀法 玻璃陶瓷 形核 晶化 燒結(jié)行為 可加工性　出處：《西安工業(yè)大學(xué)》2010年碩士論文　論文類型：學(xué)位論文

【摘要】： 目前陶瓷材料作為一種新型的工程結(jié)構(gòu)材料,在宇航、汽車、冶金、化工、機(jī)械等領(lǐng)域得到了越來越廣泛的應(yīng)用�？杉庸げＡ沾刹牧弦云鋬�(yōu)異的美觀性能、可切削性能和機(jī)械力學(xué)性能等正日益受到人們的重視。但是目前國(guó)內(nèi)外常用的制備玻璃陶瓷的方法主要有熔融法、燒結(jié)法和溶膠-凝膠法,前兩種的制備方法復(fù)雜,制備出的晶粒尺寸粗大,且消耗電能,而溶膠凝膠法成本偏高,不適合工業(yè)生產(chǎn)的要求,因此玻璃陶瓷材料的制備工藝仍然是研究的重點(diǎn)。 本文在玻璃陶瓷的制備方法上做了改進(jìn),根據(jù)低溫液相均勻沉淀法的機(jī)理,制備了納米級(jí)的鈉氟金云母(NaMg3AlSi301oF2)玻璃陶瓷前驅(qū)粉體,并對(duì)前驅(qū)粉體進(jìn)行晶化熱處理,得到主晶相為鈉氟金云母的玻璃陶瓷的粉體,經(jīng)成型和燒結(jié)后得到云母基玻璃陶瓷。采用DTA/TGA、TEM、XRD、FT-IR、SEM和ESCA等手段,研究了材料的制備工藝和制備過程中的物相變化,微觀形貌和結(jié)構(gòu)的演變,探討了陶瓷成分和結(jié)構(gòu)對(duì)其各項(xiàng)性能的影響,并對(duì)鈉氟金云母玻璃陶瓷的可加工性能做了檢測(cè)。實(shí)驗(yàn)獲得的主要成果如下： 選取了幾種分別含有Na+、Mg2+、Al3+、Si4+、F-的水溶性化合物作為液相反應(yīng)的原材料,通過控制工藝參數(shù),制備出了分散性良好、大小均勻的納米級(jí)前驅(qū)粉體,一次粉體粒徑在10-20nm之間,二次顆粒大小約為100nm,顆粒呈近球狀,為典型的非晶態(tài)硅酸鹽粉體。 對(duì)前驅(qū)粉體晶化熱處理發(fā)現(xiàn),鈉氟金云母晶核結(jié)構(gòu)主要在600℃左右開始出現(xiàn),650℃左右形核速率最大,從700℃左右開始形核速率減至最小,晶化溫度為950℃時(shí),鈉氟金云母晶核生長(zhǎng)速度較大,晶化過程中伴隨著鎂橄欖石(Mg2Si04)和霞石(NaAlSi04)析出。粉體最佳的熱處理制度是650℃核化2h,950℃晶化0.5h,熱處理后粉體主要呈現(xiàn)層片狀鈉氟金云母晶相形貌,晶化度達(dá)到45%左右。實(shí)驗(yàn)發(fā)現(xiàn)核化溫度對(duì)粉體的析晶行為影響最大,然后是晶化溫度,最后是保溫時(shí)間的影響。 粉體成型采用階梯式單向加壓方式,先在大約40MPa的壓力下保壓1min,然后再加壓到100MPa,保壓2min。燒結(jié)工藝為550℃保溫2h,升溫到1120℃保溫2h。 研究發(fā)現(xiàn),燒結(jié)后玻璃陶瓷內(nèi)部主晶相為層片狀的鈉氟金云母晶相,徑長(zhǎng)約為10μm,晶化程度達(dá)到52%,相對(duì)密度達(dá)到96.8%。鈉氟金云母晶體含量在燒結(jié)過程中隨溫度的升高先增大后減少,燒結(jié)溫度過低或過高,均會(huì)出現(xiàn)小顆粒狀的鎂橄欖石和短柱狀的霞石,這兩種晶相的變化趨勢(shì)大致與鈉氟金云母晶體的變化相反。 綜合各項(xiàng)性能發(fā)現(xiàn),顯微結(jié)構(gòu)對(duì)玻璃陶瓷的性能有很顯著的影響,三點(diǎn)彎曲強(qiáng)度值隨著燒結(jié)溫度先升高后降低。鈉氟金云母玻璃陶瓷合適的燒結(jié)溫度為1120℃,此時(shí)玻璃陶瓷的晶化程度最高,片層狀云母晶體的長(zhǎng)厚比大,相互交錯(cuò)的程度高,三點(diǎn)彎曲強(qiáng)度達(dá)到了116.76MPa,硬度為3.23GPa,實(shí)驗(yàn)證實(shí)材料具有較好的可加工性能。
[Abstract]:At present, ceramic materials as a new type of engineering structural materials, in aerospace, automotive, metallurgy, chemical, mechanical and other fields have been more and more widely used. Machinable glass ceramic materials for its excellent aesthetic properties. People pay more and more attention to the machinability and mechanical properties of glass ceramics. However, the main methods used to prepare glass ceramics are melting, sintering and sol-gel methods. The former two preparation methods are complex, the grain size is coarse, and the electric energy is consumed, but the cost of sol-gel method is high, which is not suitable for industrial production. Therefore, the preparation of glass ceramic materials is still the focus of research. In this paper, the preparation method of glass ceramics has been improved, according to the mechanism of low temperature liquid phase homogeneous precipitation method. Nano-sized NaMg3AlSi301oF2 glass ceramic precursor powder was prepared, and the precursor powder was crystallized by heat treatment. The main crystalline phase of the glass ceramic powder is sodium fluorophlogopite. After forming and sintering, the mica based glass ceramics are obtained by using DTA / TGA TGA TGA TGM XRDX FT-IR. By means of SEM and ESCA, the preparation process and the changes of phase, microstructure and microstructure of the materials were studied, and the effects of ceramic composition and structure on their properties were discussed. The machinability of sodium fluorophlogopite glass ceramics is tested. The main results are as follows: Several water-soluble compounds containing Na ~ (2 +) mg _ (2) O _ (3) Al _ (3) O _ (3) Si _ (4) F _ (-) were selected as raw materials for liquid phase reaction. By controlling the process parameters, good dispersity was obtained. The size of nanometer precursor powder is uniform, the primary particle size is 10-20 nm, the secondary particle size is about 100 nm, the particle is nearly spherical, and it is a typical amorphous silicate powder. The crystallization heat treatment of precursor powder shows that the nucleation rate of sodium fluorophlogopite begins to appear at about 600 鈩，

本文編號(hào)：1457712