本文選題：AlN + 直接氮化法�。� 參考：《五邑大學》2016年碩士論文

【摘要】：氮化鋁(AlN)是一種類金剛石結(jié)構(gòu)的綜合性能良好的新型氮化物陶瓷材料,在各產(chǎn)業(yè)中具有廣泛的應用。一般來說,優(yōu)質(zhì)的Al N粉末才能制備出性能優(yōu)越的Al N陶瓷。本文以低成本制備優(yōu)質(zhì)Al N粉末為宗旨,在傳統(tǒng)的直接氮化法基礎上添加鎂粉和氯化銨為反應助劑,通過三步流程制得純度高、粒徑細小、抗水解能力強的Al N粉末。實驗按照以下三步流程進行:第一步制備Al N粉末,研究不同反應參數(shù)下的鋁粉氮化情況;第二步對未反應完全的氮化產(chǎn)物進行酸洗提純;第三步研究Al N粉末的水解性和抗水解工藝。實驗中,鋁粉和兩種添加劑按照一定的比例均勻混合,然后置于密封性良好的管式電阻爐中,通氮氣升溫,升溫階段氮氣流量30sccm,升溫速度5℃/min;升溫到預定保溫溫度800℃~1000℃時氮氣流量調(diào)高到60sccm;保溫時間1~4h,保溫結(jié)束后在20sccm的流動氮氣保護氣氛下冷卻到室溫,產(chǎn)物研磨后即可得到Al N粉末樣品。初探實驗中發(fā)現(xiàn),同時添加鎂粉和氯化銨做為添加劑,得到的氮化產(chǎn)物為疏松團聚物,易于粉碎,并且通過XRD分析發(fā)現(xiàn)鋁粉完全氮化,無殘余添加劑存在。這主要是由于鎂粉活性大于鋁粉,氮化過程中會先和氮反應生成氮化鎂,而氮化鎂穩(wěn)定性差,700℃升華,800℃分解,會在熔融的鋁粉中形成大量孔洞,減少結(jié)塊,提高氮化率。氯化銨熱穩(wěn)定性差,337.8℃時會分解為NH3和HCl,兩種氣體從熔融的鋁中逸出,形成多孔洞,加速氮在鋁粉內(nèi)的擴散。氮化產(chǎn)物的XRD分析顯示無鎂粉和氯化銨峰存在,說明兩種添加劑均為低殘留的添加劑。氮化產(chǎn)物的SEM分析發(fā)現(xiàn)產(chǎn)物中有縱橫交錯的少量晶須存在,調(diào)節(jié)不同的工藝參數(shù)可得到不同的晶須生長形貌,EDS分析顯示晶須為Al N。調(diào)整反應參數(shù)的實驗結(jié)果顯示,Al/Mg/NH4Cl質(zhì)量比為9:2:4,保溫時間為3h,保溫溫度為1000℃時,反應物能夠完全氮化,產(chǎn)物的N元素具有最高的含量33.4%,Al N晶須形貌均勻。對產(chǎn)物進行粉碎處理,手工研磨2h平均粒徑可達9.5um,用球磨機球磨1h粉末粒徑可達3um,說明氮化產(chǎn)物具有易于粉碎的特點。實驗中未完全氮化的粉末(氮化溫度小于1000℃)采用酸洗方法提純,對提純后的粉末進行XRD分析,無雜質(zhì)峰出現(xiàn),說明酸洗可用于提純未完全氮化的產(chǎn)物。水解試驗發(fā)現(xiàn),用磷酸提純的Al N樣品有比硫酸和鹽酸提純的Al N樣品更高的抗水解性。用磷酸對Al N粉末浸泡24h,發(fā)現(xiàn)水解180h溶液仍保持酸性,說明粉末具有了極高的抗水解性�？芍�,用磷酸不僅有提純作用,還能用來對Al N進行抗水解處理。對Al N粉末進行氧化熱退火處理,結(jié)果顯示在900℃保溫1h的Al N粉末具有一定的抗水解性,但是效果沒有磷酸浸泡處理的好。
[Abstract]:Aluminum nitride (AlN) is a new type of nitride ceramic material with good comprehensive properties, which has been widely used in various industries. Generally speaking, Al N ceramics with superior properties can be prepared by high quality Al N powders. The aim of this paper is to prepare high quality Al N powder at low cost. Magnesium powder and ammonium chloride are added as reaction aids on the basis of traditional direct nitridation method. Al N powder with high purity, fine particle size and strong hydrolysis resistance is prepared by three steps process. The experiment was carried out in the following three steps: the first step was to prepare Al N powder to study the nitridation of aluminum powder under different reaction parameters, the second step was to purify the nitrided product without reaction completely. The third step is to study the hydrolysis and anti-hydrolysis process of Al N powder. In the experiment, the aluminum powder and the two additives are evenly mixed in a certain proportion, then placed in a well sealed tube resistance furnace, and the nitrogen gas is heated. At the heating stage, the nitrogen flow rate is 30sccm, the heating rate is 5 鈩，

本文編號：2078147