芦玉峰
,
堵永国
,
肖加余
,
张为军
,
郑晓慧
,
周文渊
无机材料学报
doi:10.3724/SP.J.1077.2008.00315
利用烧结法制备化学计量比和高Ba含量的两组BaO-Al2O3-SiO2(BAS)系微晶玻璃, 采用等转化率法计算玻璃粉的活化能随析晶过程的变化, 利用线性回归的方法确定最概然析晶机理函数, 进而对比研究添加ZrO2和提高Ba含量对BAS系微晶玻璃析晶过程的影响. 结果表明, 4种成分的BAS系玻璃的最概然析晶机理函数均为SB(m, n)函数, 析晶过程中存在自催化的相变机制. 在化学计量比的BAS系玻璃中添加ZrO2或者提高Ba含量, 对六方钡长石的析出表现为促进作用, 并且随着温度的降低或者析晶过程的进行, 促进效果更加明显. 在高Ba含量的BAS系玻璃中添加ZrO2对六方钡长石的析出表现为抑制作用, 并且随着温度的升高抑制效果更加明显.
关键词:
微晶玻璃
,
celsian
,
crystallization
,
isoconversional method
,
Sestacute ak-Berggren function
芦玉峰
,
堵永国
,
肖加余
,
张为军
,
吴剑锋
,
杨光
,
王跃然
无机材料学报
doi:10.3724/SP.J.1077.2008.00159
用烧结法制备了化学计量比和高Ba含量的两组BaO-Al2O3-SiO2 (BAS)系微晶玻璃, 采用差示扫描量热法(DSC)和X射线衍射分析(XRD)等手段研究了ZrO2对BAS系微晶玻璃中六方钡长石析晶和六方钡长石向单斜钡长石晶型转变的影响. 研究表明, 两组BAS系玻璃的烧结温度低于850℃, 晶化温度低于900 ℃. 六方钡长石的析出为整体析晶. 不加形核剂晶型转变为整体析晶; 添加ZrO2晶型转变为表面析晶. 提高Ba含量或添加ZrO2促进六方钡长石的析出和晶粒细化. 化学计量比的BAS系微晶玻璃中添加ZrO2明显促进晶型转变. 高Ba含量的BAS系微晶玻璃中添加ZrO2表现为抑制晶型转变, 850℃保温100h不发生转变.
关键词:
微晶玻璃
,
celsian
,
low temperature sintering
,
crystallization
,
phase transformation
J.M.Yang
,
J.C.Lei
,
J.P.Li and P.Cheng Dept. Mater.Sci.and Eng. Xi'an Institute of Technology
,
Xi'an 710032
,
China
金属学报(英文版)
BAS (BaAl 2Si 2O 8) glass ceramic was prepared by a sol gel process and the SiC W/BAS composites were fabricated by hot pressing. The transformation from hexacelsian to celsian, the microstructure and mechanical properties of the composites was investigated. The results show that the transformation promoted by adding celsian seeds is retarded in the composite by the presence of SiC whisker. SiC whisker has a good effect of improving the mechanical properties of BAS glass ceramic matrix. The toughening mechanisms are crack deflection and whisker fracture. The strengthening mechanism is loading transition. The amorphous phase at SiC W/BAS matrix interface damages the fracture toughness and high temperature strength of the composites.
关键词:
glass ceramic
,
null
,
null
,
null
,
null
X.W.Yin
,
L.F.Cheng
,
L.T.Zhang
,
W.C.Zhou and Y.D.Xu State Key Laboratory of Solidification Processing
,
Northwestern Polytechnical University
,
Xi′an 710072
,
China
金属学报(英文版)
Strong, tough, and almost fully dense C fiber reinforced celsian matrix composites have been fabricated by impregnation of the fiber tows with the matrix slurry, winding on a drum, drying, stacking the prepreg tapes in the desired orientation, and hot pressing. The monoclinic celsian phase in the matrix was produced in situ, during hot pressing, from amphosous BAS. The unidirectional composites having ≈20 vol% of fibers exhibited graceful failure with extensive fiber pullout in three point bend tests at room temperature. Values of ultimate flexural strength and fracture toughness were 379MPa and 8 3MPa·m 1/2 , respectively.
关键词:
barium aluminosilicate
,
null
,
null
,
null
,
null
