KHOA HOC - CONG N G H £
-So 12/2015
Mang mong nanocomposite ma sat thap
• T h S . NCS. LE V A N AN
Trddng Dgi hgc Sdphgm Ky thu$t TP. Hd CM Minh
• P G S . T S . BUI X U A N L A M
Trddng Dgi hgc Cdng nghg TP. Ho Chi Minh
T o m tilt: Trong nghien cdu ndy, cde tinh the TIC ddtfc dda vdo nin vd dinh hinh carbon giing kim cddng bing phddng phdp phun xg magnetron, ding thdi cdc bia Ti vd C. Cde mdng mdng 1pm ddtfc phd trdn cdc tam Si cd dddng kinh 100 mm. XRD, TEM, thiit bi do dg cdng nano vd thiit bl do ma sdt ddtfc surdgng dexdc dinh ciu tnic vd cde tinh ehat cua mdng. Kit qua thf nghidm eho thiy, khi thdnh phin Ti thip hdn 8 at.%, Ti ton tgi trong mdng m0t deh vd dfnh hinh. Cde hgt nano TiC hinh thdnh khi thdnh phdn Ti td8 - 45 at.%. Khi thdnh phin Ti cao hon gid tri ndy, mdng khdng cdn Id nanocomposite md trd thdnh mdng tinh the TiC. H^ si ma sdt cOa mdng thip hdn 0,25 d dieu ki$n khdng bdi trdn khi hdm Idtfng Ti trong mang thip hdn 36 at.%.
TU khda: Mdng mdng nanocomposite.
Abstract: In this research, nanocrystals of TiC were embedded in an amorphous matrix of diamond-like carbon via magnetron co-sputtering of Ti and C targets. 1 pm thin coatings were coated on 100mm - diameter SI wafers. XRD, TEM, nanoindenter and tribometer were employed to determine the structures and properties of the coatings. Experimental results indicated that at Ti compositions of less than 8 at%, Ti exists in the coatings as an amorphous. From 8 to 45 at.%Ti, the formations of nanocomposite were confirmed. Higher than that, the coatings were almost crystalline TiC.
Low coefficients of friction of < 0,25 under non- lubtrieated condition of nanocomposites of lower than 36 at. % Ti were observed.
Keywords: Nanocomposite thin films.
1 . G i d i t h i g u
Carbon gidng kim cQdng Diamond-like carbon (DLC) da dQOc nghifen cQu tQ lau, ddc bifet la tU nhQng ndm 1990 den nay. NhQng nghidn cQu v l ddc tinh ma sdt vd m d n cQa logi vdt Hfeu nay dQOc cdng b d ngdy cang n h i l u (trung binh khodng 500 bdi bdo khoa hpc mdi ndm [1]). Carbon gifl'ng kim CQdng cd cdu true vd djnh hinh v d cd t h i xem Id
mOt "hdn hop" eua lai hoa sp^' (graphit) va sp^ (kim CQdng). Carbon gidng kim cQdng dUOc chia ra lam 2 nhdm chfnh: Co chQa (a-C:H) va khdng chQa (a-C) hydro. Ham IQOng hydro trong a-C:H cO t h i Idn ddn 6 9 % nguyfen tQ (at.%). Cac a-C eO hdm laong hydro thap hdn 1 at.%. S9 vOi a-C:H, a-C cQng hdn vd co the dQOc phu bang cdc phUdng phap vat ly nhQ phun xg magnetron, bde hdi laser, phong difen cathode trong chdn khdng [2] . Cdc tfnh chdt ma sat tfl't trong cd dieu kifen bdi trdn va khdng boi trdn cua carbon gidng kim cQdng da duoe n h i l u nghifen cQu chUng minh. Do cQng c u a a-C dao ddng trong khoang 18 - 70 GPa tuy theo phQdng phdp phu [3],
Nanocomposite dQOe htnh thanh khi cO cac hgt ngno tinh the p h d n tan trong mdt nen vO djnh hinh h o l e tinh the khde. Cac tinh chat c u a mdng nanocomposite (ehdng vd giOn tdt, dp cQng cap, ehdng mon tfl't) da dQOc nghifen cQu vd edng b d [4,5]. Vifec sQ d y n g carbon gidng kim cQdng Idm nen cQa nanocomposite duoe k^ vong se tgo ra mang mOng ed cde tinh ehdt Uu vidt d l sijf d u n g trong ky thugt.
Trong nghifen cQu nay, ehung tfli c h l tao nanocomposite vdi cac hat tinh t h i nano TiC (nc- TiC) phdn tdn trong ndn vd djnh hinh carbon gidng kim CUdng bdng phUdng phap phun xa magnetron.
Anh hudng c u a hdm iQpng Ti ddn cau true t l vl va cac tinh chdt cQa mang daoc nghifen cQu mflt cdch ehi t i l t .
2. T h i nghiOm
Mang nanocomposite vdi ndn carbon gidng kim CQdng dQdc phCi bdng phUdng phdp phun xa SLf d y n g hai de (graphite va Ti) cung mdt luc. Hfe thdng sQ d y n g Id E303A. S d dd eiia hfe thdng duoc trinh bdy trong tdi HOu [6]. Mat dd ndng luong trfen graphite Id 10,5W/cm2, mat dp ndng lUdng trfen Ti se dQOc thay doi de tgo ra cdc ham IQOng Ti khde nhau. A p sud't qua trlnh phu dQdc giQ e d dinh 6 0,6Pa va nhifet dfl trfen vat edn phu la 150°C.
Cac mdng dUdc phCi Ifen cac tdm Si [100] (dudng kinh 100mm, b l ddy 450pm, dd nham be mat R
= 2nm) vd cde dia thep M2, dUdng kinh 5 0 m m , bi day 5mm (mang phQ trfen dTa thep dUde d u n g de thQ ma sdt). Trade khi dua vdo b u d n g , cac mieng
45
KHOA H p c - C O N G N G H i
SI va thep dUOe lam sgch bdng sifeu dm trong dung djch acetone, sau d d tidp tyc duoc lam saeh trong ethanol trong vdng 15 phut Sau khi diioc dua v a o budng p h u , chung duoe nung ndng ddn 150<'C trong vong 30 phut de ddm bdo thdi hdt khf bj hap thy trfen b l mat vdt c i n p h u .
Thidt bj nhidu xg tia X (Philips PW1710 vdi ngudn phat tia X Id CuK 40 kV/30kmA (bade sdng 0,1506nm)) dUdc sQ d y n g de xde dmh ede tinh t h i trong m a n g . Kfch thudc trung binh eua cde hat tinh t h i duoc tinh toan bang cdng thQc Debye- Seherrer [7]:
/ , = _ ^ (nm)
licos(&) (1)
Trong dd: D - Kich thade trung binh efla tinh t h i theo phUdng vudng goc vdi vat the nhifeu xa (K = 0 , 9 1 , = 0,15406nm). tinh bdiig radian Id be rdng efla dfnh tgi vj tri mflt nQa c h i l u eao trdn phd nhieu xg tia X, Id gdc Bragg. Thdnh p h i n cfla mdng dapc nghifen cQu bdng t h i l t XPS sCf dyng phd kd Kratos - Axis vdi ngudn phdt ra tia X Id AlK (1486,71 eV). DO ehdn khflng trong budng phfl XPS Id 2x10-^ torr (2,66x1 O T a ) . Phd dQOc nghidn cQu trong khoang tQ 0 d i n 1100 eV. Bade nhdy Id 0,1 eV. D e khdp dudng cong, phdn m i m sQ d y n g ham Gauss/Lorentz sau khi da trQ phdn n l n Shiriey vdi quy ludt binh phQdng tdi t h i l u . D^
log! bd Idp tgp ehdt (thQdng Id oxide) bdm trfen b l mdt cfla mdng, trade khi phdn tieh, cdc ddng Ion Ar dQOe b i n phd Ifen bd mdt cua mdng d l logi bd cdc tgp ehdt. Sung ion Ar dQOe siS d y n g Id logi Kratos Macro Beam vdi dign thd d l gia tdc cac ion Id 4 KeV. DO cQng va md-dun ddn hdi dUOc xae djnh bdng thidt bj do dp cQng nano (XP) vOi mui kim CUdng Berkovich. C h i l u sau dn vdo mdng cCia m u i kim cUdng dupe ldp trinh de khdng vuot qua 10% bd ddy cua mang d l trdnh dnh hudng cCia vdt cdn phfl ddn kfe't qua do dfl cQng. Trfen mfli mau 10 vj tri ngdu nhifen daoc do dd cUng vd md-dun dan h i i . Gid trj dp cQng vd mfl-dun dan h i i efla mdu dupe Idy trung binh cua cae l l n do (sai Ifech chudn khflng qua 10%). Thi nghifem ma sdt daoc thQC hlOn bdi may thQ ma sat C S E M vdi c i u hinh
^^^ bl trQOt trfen dfa. Bi daoe i sQ d y n g trong thf nghifem
^ H>°e CO dudng kinh 6mm lam tQ X a i ^ H M f ^^^P khOng g? 100Cr6. S d I \ dd thf nghidm ma sdt daoe I "^ t h i hifen trdn H;n/7 2. r:
^ ^ Hinh 2.1: Sd do thi
^ * * - nghigm ma sdt bi trdtft trdn dfa
Tdc dO trUOt cua bi trdn bd mdt mdng la 20em/s vd duoc duy tri khdng ddi trong sudt qud trinh thQ vdi khodng each trUdt Id 1km. Nhifet dfl mdi trudng thQ Id 22°C vd do am 7 5 % .
3. Kdt qud thi nghigm vd thdo ludn 3.1. Thdnh phan hda hgc vd du trde ti vi eua mdng
Sau khi phfl xong va duoc dua ra khdi buong phfl, b l mdt cua mang thudng bi d-xy hoa tgo ndn mOt Idp oxide mdng. Vi vdy, trade khi nghifen
cQu bdng XPS be mat m a n g dQOc lam sgch bang c h u m ion ngay trong budng XPS trong v d n g J 5 phut. Luong o-xy tdn tgi trong m a n g ( < 5 % , xdm nhdp vao mdng trong qud trinh phfl) khdng dUOc tinh d i n trong eae phep tinh vfe ham luong cfla XPS. C d c dfnh C I s cho phfep xac djnh sQ tdn tgi c u a 3 pha sau day: a-C,
" TiC vd Ti kim logi. V i trf C I s eua C-C trong a-C vd C-Ti trong TIC Idn lUOt Id 284,6 eV vd 281,8 eV.
Hlnh 3.1: Pho XPS Nta,b™,b=,w>(,^i (.(jg Q -fg f.Qg mdng DLC
ed chda Ti
Hinh 3.1 cho thd'y, khi chua co Ti thi lifen k i t C-C duoc quan sat thd'y tgi 284,6 eV. Khi hdm luqng Ti tang Idn thi dfnh carbide (TiC) tgi 281,8 eV b i t ddu xuat hidn v d Idn ddn (trong khi d?nh a-C nhd ddn). Khi ham lUOng Ti dgt 3 at.% hdu nhu chua eo TiC (Ti tdn tgi trong m a n g dUdl dgng Ti nguyfen tQ). Vifee chua hinh thdnh lien kfe't Ti-C khi hdm IQOng Ti nho ed t h i gidi thfch bdi mdt dp ndng lUOng trfen dm CQC Ti be ndn khdng tgo ra ndng lUOng dfl Idn eho Ti kd't hop vdi C. TiC daoc hinh thdnh khi ham lUOng Tl dgt d d n 8 gt.%. Khi hdm luong Ti vUdt q u a 48 at.% hau nhu khflng quan sdt dadc d?nh a-C, nghTa Id todn bd C da Hfen kdt vdi Ti. Luc ndy, mdng ehfnh Id TIC.
H)nh 3.2 the hifen phd nhifeu xg tia X (XRD) efla mang DLC co chda T i . 6 3 at.% T i , mdng la vd djnh hinh, nhu da d l edp S trdn, Ti tdn tgi trong mang dudi dang Ti nguygn t f l . Trfen 8 at.% T i , sQ hinh thdnh cfla cac tinh t h i TIC dUde quan sdt thdy. Cde d?nh tgi 35,9°. 41,7" v d 60,4° 2 6 t h i hidn ede hadng nhifeu xg l l n lUOt la [111], [200]
v d [220] eua cac tinh the TiC. C a d n g dd efla cac
" dinh ndy tdng Idn khi hdm luong J l tang Ifen. Co t h i t h i y rdng, hQdng efla cdc tinh thd Id ngdu nhifen.
Hinh 3.2: Pho XRD
"'^ eua mdng DLC d chda 77 Kfeh thadc efla eae hgt tinh t h i TiC duoc tfnh bdng eflng thQc Debye-Scherrer (cflng thQc 1).
K i t qud tfnh todn duoe t h i hifen trfen d d thj Hinh 3.3. TQ hlnh ndy c d t h i thay rdng kich thadc tinh t h i TiC tdng dan khi hdm luong Ti tang. Kfch thadc TiC [111] ldn nhat; TiC [200] va TiC [220] eo kfch t h Q d c n h d hdn. Kfch thadc tinh the TiC [111] tdng ::i . ] • • : tQ 2nm ddn 17nm khi hdm I " y IQOng Ti tdng tQ 8 at.% ddn ' " / . L , ™ , 48 at.%.
1 •! y^.-^X.,„ W/nh 3.3: Kich thddc
^ r ^iE^i=^^ tinh thi TIC tinh todn ddtfc - - , - , 7 „ „ „ „ „ . , , . td phi XRD bang cdng
" " " " " " " thdc Debye-Scherrer Tis cdc kdt qua co dUOc sau khi p h d n tfch XPS va X R D , CO the thay rdng cdu true nanocomposite (cdc hgt nano TiC phdn tdn trong nen vfl dinh hinh DLC) duOc hinh thdnh khi hdm laong Ti trong khodng tQ 8 at.% ddn 45 at.% (cde hgt tmh the
lE3fi"
46
KHOA H p c - C d N G N G H l
nano TIC c d kich thadc tQ 2 nm ddn 17nm v d ed hudng ngdu nhidn).
3.2. D^ edng vd h$ si ma sdt
Hinh 3.4 the hien mdi quan hfe giQa dd cQng vd m d dun ddn hdi vdi hdm luong Ti cfla mang DLC cd chUa T l . Khi ham IQOng Ti dgt ddn mOt gid trj nhat dinh thi cdc tinh t h i nano TiC (rat cQng) daoc hlnh t h d n h . Trong trudng hop nay, dp cQng eua mdng khdng eh? phy thude vdo ham laong sp^ cd trong n l n DLC m d edn phy thuOe vao cae tinh t h i nano TiC (kfeh thadc, hudng, phdn tram t h i tfch cdc tinh thd TiC trong n l n DLC). DLC nguyfen chdt cO dO cUng 3 3 G P a , mfl-dun dan hdi 342,6GPa. Khi cd Ti d d cUng efla mdng gidm rdi sau do lai tdng do nhQng c d c h d khde nhau: Khi ham luong Ti thdp thi chua ed hoac cO rat ft eae tinh the nano TiC duoc hinh thanli, trong khi d d , hdm luong sp^ trong DLC gidm di (do cde nguyfen tfl v d ion carbon gidm ndng lUOng vi va chgm vdi nguyfen tU vd ion Ti). Khi ham luong Ti Idn hdn 16 at.% thi mOt luong ddng k l cde tinh t h i nano TiC daoc hinh thdnh ddn d i n vifec tdng dd cQng efla mang ddn 3 3 G P a khi ham IQOng Ti dgt 36 at.%. Lue ndy, ndu tidp tye tang hdm IQdng Ti thi dd cQng gidm do kfeh thudc cde hgt tinh t h i TiC Idn. NhQ vdy> cd t h i thdy rang, dO cQng cfla nanocomposite dgt dUdc gid tri tUdng dUdng vdi DLC nguydn chdt khi hdm luong Tl trong khodng 35 at.% ddn 40 a L % .
Hinh 3.4: Mii quan h$ gida hdm Idtfng Ti vdi dd cdng vd md dun ddn hii khi phO 6 thi dl$n 150V vd dp suit phu 0,6 Pa
Hinh 3.5: H$ si ma sdt cua mdng nanocomposite khi trdtft tddng dil vdi bi thdp d chi dd khdng bdi trdn
Hfe s d ma sdt efla mdng khi traot vdi bi thfep d c h d dd khdng bdi trdn, tdi 5 N , tde do trQOt 20cm/s daoc t h i hiOn trdn Hinh 3.5. Sau khodng each trUOt 1km, tdt cd cdc mdng trong thi nghidm ndy ddu bdm dinh tdt, khong ed hifen tUOng bong trde vd hO s d ma sdt ddu 6 gid trj dn djnh, khflng cd nhidu thay d i l . C d t h i thd'y d cdc hdm luong at.%
Ti nhd hdn 36 %, hfe s d ma sdt nhd hdn 0,25 (ddy Id gid tri ly tudng cho ede Qng d y n g trong ky thudt).
6 cdc ham lUOng at%Ti ldn hdn (45, 48at%), hfe sd ma sat tdng mgnh (>0,4). Didu nay dUOc gidi thfch bdi hdm lUOng carbon trong m d n g . at.%Ti edng Idn ddng nghTa vOI hdm IQOng C gidm, ma C
S6 12/2015
ddng vai trd quan trpng trong vifee gidm ma sat bdi cd ehd graphite hda ddn ddn viOc hinh thdnh Idp graphit mdng ddng vai trd Id chdt bdi trdn rdn [8].
4. Kdt luan
- Khi hdm iQOng Ti dat 8 at.% thi cde tinh the TiC duoc hinh thanh v d d 45 at.% thi hdu nhU ch?
cd cac tinh the TiC ma khflng edn pha vd dinh hinh DLC.
- Kich thudc cdc hgt tinh t h i trong khodng tQ 2nm ddn 17nm khi ham IQdng Tl tang tU 8 at.%
den 45 at. %, cac tinh t h i TIC phdn tdn trong nen vfl djnh hlnh DLC theo cae hudng khac nhau.
- DO cQng cfla mang nanoeomposfte tQdng dUdng vdi dp cQng cfla mdng DLC thudn khiet khi ham IQOng Ti trong khodng tQ 35 at. % ddn 40 at.%.
- Hfe sd ma sat cua mang thap hdn 0,25 d dieu kifen khdng bfli trdn khi ham IQOng Ti trong m a n g thdp hdn 36 at.%. 6 cdc ham IQdng at.%Ti eao hdn, hd s d ma sdt tdng nhanh vd dgt gid trj
>0,4 (Qng vdi at.% Ti > 45%) do mdng khdng edn dfl carbon de hlnh thanh Idp mang boi trdn ran giQa cde b l mat ma sat.
- Mdng nanocomposite vdi n l n DLC cho thay tidm ndng rdt Idn trong Qng d y n g ky thudt, dac bifet cho cdc ehi tife't chju ma sdt •
Tai ligu tham khdo
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[2]. Y. Catherine 1 9 9 1 , Preparation techniques for diamond-like carbon, in "Diamond and diamond like films and coatings", p.193, Plenum Press, New York.
[3]. Y. Lifshltz (1999), Diamond-like carbon - present status, Diamond and Related Materials 8 1659-1676.
[4]. J . Musil (2000), Hard and superhard nanocomposite coatings, Surface and Coatings Technology 125322-330.
[5]. S. Veprek, S. Reiprich (1995), A concept for the design of novel superhard coatings. Thin Solid Films 2 6 8 6 4 - 7 1 .
[6]. S. Zhang, X. L. Bui, Y.Q. Fu (2003), Magnetron sputtered hard a-C coatings of very high toughness. Surface and Coatings Technology 167 137-142.
[7]. M.V. Zdujic, O.B. Milosevic, L.C. Karanovlc (1992), Materials Letters, 13125-128.
[8]. Bui Xuan Ldm (2008), Mdng phij chong mdn cacbon giing kim cddng, T g p chf Phdt t r i l n Khoa hpe & Cdng nghd, TrQdng D g i hpc Qudc gia T P . H d Chi Minh, 11-10101-109.
Ngay nhdn b a i : 16/11/2015 Ngay chdp nhdn d d n g : 30/11/2015 NgUdi phdn biOn: TS. Ld Vdn Vang
PGS. T S . Nguydn Hoai Sdn
