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1、l : 2009- 07- 08; : 2009- 09- 09 :S E 1 S (90405015);S E M S (50425208)T e : , 1970M 3 ,p V , q , 1 V Y ( L ! / Z bE- mai:l chqtong 126. comSiB4 x M 1 i SiCV M 童长青1, 2null null 成来飞1null null 曾庆丰1null null 刘永胜1null null 张立同1(1null v S E L i , null 710072)(2null C ,C null 364000) null K null 采用 SEMaED
2、SaXRD分析了 SiB4微粉化学气相渗透(CVI)SiC后的组成和结构,并用热力学计算研究了 SiB4微粉在 CVISiC过程中变化的原因b结果表明:在 CVISiC过程中 SiB4微粉不发生分解,但在近表层处氧化生成 SiO2和 B2O3b用 SiB4浆料浸渍结合 CVI工艺对C/SiC基体进行自愈合改性时,难以形成均匀致密的基体b1 o M null SiB4微粉, SiC,化学气相渗透,氧化Changes ofSiB4 PowderDuring ProcessofChemicalVapor Infiltration ofSiCTong Changqing1, 2null null Ch
3、eng Laifei1null null ZengQingfeng1null null LiuYongsheng1null null Zhang Litong1(1null NationalKeyLaboratory ofThermostructureCompositeMaterials, NorthwesternPolytechnicalUniversity, Xinull annull 710072)(2null College ofChem istry& MaterialsScience, LongyanUniversity, Longyannull 364000)Abstractnul
4、l The phase composition andmicrostructure ofSiB4 powder during the process chemicalvapor infiltranulltion (CVI) ofSiCwere analyzed by EDS, SEM, XRD. Thermodynamic calculationwas carried out in order to investinullgate the changesofSiB4 powder. The resultsshow thattheSiB4 particlesdonotdecompose duri
5、ngCVISiC process, butthey are oxidized to form SiO2 andB2O3 near the externalsurface ofthe specimen. Therefore, thematrix ofC/SiC comnullpositemodified by SiB4 particles, by using CVI combiningwith slurry infiltration processes, isnothomogeneous andcompac.t The uneven oxidationmakes itdifficultto st
6、udy the oxidationmechanism ofC/SiC- SiB4composite.Key wordsnull SiB4 powder, SiC, Chemicalvapor infiltration, Oxidation1null 4 C/SiC P p 1 o 8 b 7 , C/SiC ! / i d # , P , ? Y V t J 8 ,V 7 P p 1b C/SiC 8 1 4 F ? r o , Z E 1 :B M 1i (CVI) 1 2- 5;= c x , 1 6b V 7: 2 E | SiB4 x 1 C/SiC8 W , CVISiC ! C/S
7、iC- SiB4, SiB4 x ? r 4 C/SiC b F ? b B C/SiC- SiB4 , SiB4x CVISiCV M bSi- B 1 SiB3aSiB4aSiB6aSiBn ( n=14a15a40 )bY SiB3aSiB4 + 8 , D53d- R3mbW , d 1 , s B 0 V 9 S,i 9 1 , T SiB2. 8 SiB4. 0 W , SiB3aSiB4 B ,| V U SiB4 x 8-10b6 H , s Si SiB6, s (V 1 100 1 390! ), s / , SiB4? i 11bCVISiCV a a K , - n S
8、iB4 x CVISiCV M M 1 b SEMaXRD# 9 SiB4 x CVI SiCV M b44 http: /www. yhclgy. comnull t null 2010M null 32null L | 5 g SiB4 x ( S MaTecK , B 99null5%, D50 1. 0nullm)b = 40mm , k , 5MPab| k d SiC ,b M V , CVI( LPCVI)E 1 i SiCbCVISiC : Cl3CH3Si Q , H2 ,Y V Z T | Q Q i= , Ar d 8 , Cl3CH3SiaH2aAr sY 35a350
9、# 350mL/min, 1 000! a 5 kPaaH W 80hb 0 A ? ( SEM EDS, , S4700)s k A F b X L N (XRD, , Rigaku D/max- 2400) M s , k CuKnull ,5 40 kV,5 100mA, q 4#/min, 0. 02#, 20# 80#b3null T ) 3. 1null F # V SiB4 x CVISiC- XRD T (m 1)V , SiB4 x CVISiC 1 s SiB4 SiC,V SiB4 1000! H q / ? i ,7 s Si SiB6bm 1null SiB4 x CVISiC- XRDmFig. 1null XRD ofSiB4 raw powdersbefore and afterCVISiCSiB4 x CVISiC # ? m 2U bV m 2V n , k K SiaC F m 2(b) , V ) SiB4 x O c ,7 k = c b XRDm V ,K SiCp , V i 3 bCVISiC- SiB4 x ? (m 3) 1 V , V SiB4 x CVISiCV ? 3 ,O V V b Si
