高岭石-C体系高温碳热反应过程.pdf

第15卷第4期
粉末治金材料科学与工程
2010年8月
Vol15 No 4
Materials Science and Engineering of Powder Metallurgy
Aug.2010
高岭石一C体系高温碳热反应过程
王朝胜,邵珊2,邹正光2,龙飞2,易茂中
(1.中南大学粉末治金国家重点实验室,长沙410083;
2.桂林理工大学有色金属及材料加工新技术教育部重点实验室,桂林541004)
摘要:以高岭石和无机碳为原料合成 Sicw/A12O3复相陶瓷粉末,借助X射线行射(XRD)、扫描电镜(SEMO等手
段对该陶瓷粉体进行测试表征,研究合成温度和保温时间对合成产物的影响,并初步探明高岭石碳热还原反应过
程和机理。结果表明:高岭石与碳在高温下反应过程由2段组成,第1段是高岭石的低温分解,第2段是高岭石
分解产物SiO2和莫来石的碳化还原。其中第2段反应又由SiO2的碳化还原和莫来石的碳化还原组成,二者是先
后发生而不是并列发生。在高岭石碳热还原过程中,气-固(VS)反应机制和問一固(S-S)反应机制均有可能发生,
SiC晶须的形成由占主导地位的反应机制决定。
关键词:高温;碳热还原;合成;SiCw/A12O2;反应机理
中图分类号:TQ050.4
文献标识码:A
文章编号:1673-0224(2010)4-317-07
High temperature carbothermal reaction mechanism of
kaolinite/carbon system
WANG Chao-sheng, SHAO Shan, ZOU Zheng-guang, LONG Fei, YI Mao-zhong
(1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
2. Key Laboratory of Nonferrous Materials and New Processing Technology of Ministry of Education
Guilin University oftechnology, Guilin 541004, China)
Abstract: Sicw/A203 ceramic composites were prepared by in-situ carbothermal synthesis using kaolinite and nano
carbon black as raw materials. Effects of synthesis temperature and holding time on the products and the reaction
mechanism were studied in the present paper. The synthesis products were caracterized by X-a difraction(XRD)and
scanning electron microscopy(EM).The in-situ abo hermal reaction of kaolinite at high temperature is composed of
two steps. The first step is kaolinite decomposition. The second step is carbothermal reactions between Sio and mullite
The carbothermal reactions between Sio2 and mullite also take place step by step, the Sio2 reduces firstly at lower
temperature to form Sic, then mullite reduces to form Sic/A1 2O In the reaction of kaolinite/C, solid-solid reaction
mechanism and solid-gas reaction mechanism exist together.
Key words: high temperature; carbothermal; synthesis; Sicw/A1 O3; reaction mechanism
碳化砫晶须是目前最为理想的陶瓷增强增韧材料相陶瓷的方法是以高纯Al2O3粉与SC晶须为原料,
之一。将SiC晶须引入氧化铝基材料中制备采用机械球磨混料再烧结,但该方法原料成本较高,
Sicw/A12O3复相陶瓷,其力学性能较单相A12O2陶瓷且由于纳米颗粒和晶须等特殊形貌的原料受混料均匀
有成倍提高,并具有比弹性模量和比强度高及热膨胀性的制约,导致复相陶瓷的性能大受影响の。以高
系数低等优点,广泛应用于切削刀具、耐磨零件、宇岭石与纳米碳黑颗粒为原料,通过原位碳化还原合成
航以及军用器件等领域剧。传统制备SiCw/A12O3复 SICWA1203复相陶瓷粉体具有解決上述问题的潜在工
基金项目:国家自然科学基金资助项目(50862002)
收稿日期:2010-03-25;修订日期:2010-05-05
通讯作者:易茂中,教授,博士。电话:0731-8830894;E-mail:yimaozhong@126.com