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Surface treatment of aluminum alloy at room temperature with titanium-nitride films by dynamic mixing
644
Nuclear Instruments and Methods in Physics Research B19/20 (1987) 644-647 North-Holland, Amsterdam
SURFACE TREATMENT OF ALUMINUM ALLOY AT ROOM TEMPERATURE WITH T I T A N I U M - N I T R I D E F I L M S BY D Y N A M I C M I X I N G T. S A T O , K. O H A T A , N. A S A H I , Y. O N O , Y. O K A I), I. H A S H I M O T O 1) and K. A R I M A T S U 1) Hitachi Research Laborato~., Hitachi, Japan 319-12 t)Hitachi Kokubu Works, Hitachi, Japan 316
Titanium-nitride coating films were prepared on aluminum alloy plates at room temperature with simultaneous ion implantation and metal vapor deposition (dynamic mixing) by using a high current ion source. The films were analysed by means of Auger electron spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction. The results showed the presence of small amount of oxygen and carbon impurities due to a high current density (0.5-1.0 mA/cm2) of the nitrogen beam (energy: 20 keV). Films of 1.2 /tin thickness showed uniform composition. Titanium-nitride coated aluminum alloy (film thickness: 15 #m) was ten times harder than the untreated one. The coated plate was examined by a pin-on-disc wear tester. The results showed better wear properties.
1. Introduction Among many surface modification techniques such as sputtering, ion implantation, and ion plating, ion implantation uses the highest energy particles and the process is independent of specimen temperature. This means greater flexibility in applications to material processing. A number of studies on implantation of non-semiconductor materials, have already been done [1-9]. Some of them, such as cutting tool life improvement have seen practical implementation [2-4]. But, two main problems remain: (1) the process cost and (2) the shallow penetration depth (of the order of 0.1 /~m) of the implanted ions. These problems have limited the wide use of the process. To overcome these problems, ion implantation by a non-mass-analysed high current ion source from fusion experiments [10] was combined with a simultaneous deposition method (dynamic mixing) [11-13]. This paper describes titanium-nitride films on aluminum alloy plates (AI-11 Si alloy) prepared by nitrogen ion implantation with simultaneous titanium vapor deposition. The films were made at room temperature and analysed for composition, structure and status by Auger electron spectroscopy (AES), X-ray-induced photoelectron spectroscopy (XPS) both with argon ion sputtering, and X-ray diffraction. The hardness and wear properties of the films were also examined.
electron beam evaporator, a rotary specimen holder with water cooling and a film thickness monitor as shown in fig. 1 [13,14]. The main performances of'the machine are also indicated in fig. 1. The N ÷ and N f components of a small beam from one aperature were measured by using mass-analysing magnet. The N ÷ and N f components are of the same order of magnitude. An A I - l l Si alloy plate (diameter 10 cm; thickness 6 mm) mechanically mirror polished by a buffing wheel was used as a specimen. After cleaning in acetone the specimen was sputtered by a 20 kV nitrogen beam for surface cleaning. A 20 kV, 0.11 A nitrogen ion beam irradiated the specimen during the titanium deposition with a rate of 7 A/s. The coating speed of 2.5 # m / h , was limited by the capacity of the electron beam evaporator. The specimen was cooled by water directly to keep the specimen temperature rise below 10°C during irradiation. The basic pressure of the chamber was 3 × 10 -6 Torr and the pressure during the film preparation was 1 × 10 -4 Tort. It was difficult to measure the precise ratio of nitrogen to titanium atoms, because the ion beam was not mass analysed and the nitrogen beam contains molecular and neutral atoms. So, the above preparation conditions were determined empirically. The maximum coated film thickness was 15 #m.
2. Preparation of films
3. Results and discussion
The machine consists of a bucket-type ion source obtained by improvement and modification of the one for neutral beam injectors in fusion experiments, an
Fig. 2 shows the X-ray diffraction signal of the 15 /zm coated specimen. This measurement reveals that the film is formed by TiN crystallite of preferential 111
0168-583X/87/$03.50 © Elsevier Science Publishers B.V. (North-Holland Physics Publishing Division)
645
T. Sato et a L / Surface treatment of AI alloy
[ /
/
PURIFIED ] WATER /
I~N. . . . . ~:~uv~
COOLER 1 ~
J GAS LIII II CONTROLLER BII / /AlL / / /
Htl]1]
/
~ A I . .~K'------'~r:--~ ION BEAM '-'.:'~ ~ l l l i P
~
~
~---n" ~
~f COOLING WATER
. R ~ . ~ -
III./-", II I I I L ; it ~1~1,"~"~
AGes / / . W - / - ~ ? ~ El
VACUUM CHAMBER ~ ~GATE V A L V E ~ - - - - - ~ P ~ X . ~ . HR
~t
J
....i I f i
MONITOR
I
u
:.!:"METAL VAPOR
~----1
P~rame~er
Value
4-40kV /PLASMA/
-J-~ . . ~ . . l
Total beam current
IB~AMEXT~CT'C" 1 SUPPLY /
Electron beam evaporator High speed dc switch Vacuum pump
Max. 0.6A (Nitrogen) ¢ I 0cm 2kW 40kV 5A 150O~/s
Non mass Bnalyzed
Fig. 1. Schematicdiagram and main performance of the machine for dynamic mixing.
FILM T H I C K N E S S
T:
15ltm
>12E < n-
bers of nitrogen and titanium atoms arriving at the specimen surface per second are much larger than those in the experiment by Satou or possibly by Kant. From the XPS analysis, the fills were compounds of TiN and TIN.,(> 1).
0.5
,,(
Z
0
30
40
v
50
60 20(")
Z
70
v
80
90
100
Fig. 2. X-ray diffraction signal of the 15 /~m thickness titanium-nitride film. reflection on the aluminum alloy plate at room temperature. Fig. 3 shows the results of the electron probe microanalysis (EPMA) of the same specimen. This figure shows the titanium and nitrogen compound film with 15/zm thickness formed on the aluminum alloy. The analysis by AES is shown in fig. 4. Ti + N (387 eV, 379 eV) and Ti (418 eV) peaks are almost constant, indicating that the titanium and nitrogen elements are uniformly distributed along the depth. This figure also indicates that the film contains a much smaller amount of carbon and oxygen impurities than those by Satou [11] or Kant [8], who showed that the TiN film prepared by dynamic mixing had a considerable amount of carbon and oxygen impurities. Our machine made a TiN film about ten times faster than the one used by Satou [11]. This means the possibility of reducing the carbon and oxygen contamination in the TiN fill because the num-
TiN
FILM
ALUMINUM
ALLOY
Fig. 3. Electron probe microanalysis results of the section of the film. V. I0N BEAM MIXING
646
7'. Saw et aL / Surface treatment o]"AI alloy
FILM THICKNESS D
90
>"
80
re
70
MICROHARDNESS ( K g / r n m 2)
1.2,ttm T i N ( BULK )
E AI
1500 z t3 n-
50
~ 40 I-Z :~
w
30
20
-1- 1000 o n,(2_
o Ti °Ti
'~=P'~%"
/o J~.
• AI + O
]
'Si '~
LU
_..
g
500
o
10 n,"
100 200
400
600
800
1000
o~.
tO
1200
5 10 FILM THICKNESS (~m)
ETCHING TIME (min)
Fig.
120
tO
~r e 60 ~
2000
A L UMINUM A L L O Y (A/-tlSi)
4.
Intensity variations of peaks due to Auger electron spectroscopy.
T E ~ DISTORTION ME LOAD
SPEO,MEN P'N ROTATING D I ~ , ¢ 1 0 c r n , ~
FZ LU O ~--L
15
Fig. 5. Vickers microhardness of the films.
SPEED : 7.3rq/sec LOAD : 5 kg LUBRICANT : 60ml/min PIN : AZ-16Si
SPEED : 0.75rrl/sec LUBRICANT: 60mZ/min PIN:AI-16Si
0"1r _J
(~) 0 . 0 5 1 - ° " ' ~ " 4 1 " . -
-~--e m U/
1 LOAD (kg)
(a) Pin-on-disc wear tester
2
(b) Friction coefficient measurement
10 20 30 SLIDING DISTANCE (kin) (c) Test results
Fig. 6. Wear tests by a pin-on-disc ~vear tester and the results (O: untreated, e: TiN coated).
Fig. 5 shows the Vickers microhardness dependence on the film thickness and the indentor load. For loads smaller than 50 g, the hardness of the 15/~m thickness film specimen was of about 1000-1500 k g / m m 2, almost ten times harder than the bulk aluminum alloy. The 4 # m film coated specimen (Specimen A) and the untreated specimen (Specimen B) were examined by a pin-on-disc wear tester shown in fig. 6(a). A refrigerating oil was used as lubricant. The contact of the pin has 5.5 mm radius and 8 mm width. The friction coefficient and wear test results are shown in figs. 6(b) and 6(c). Photos of the specimens after testing are shown in fig. 7. The TiN coated specimen shows no wear under a light load, but the untreated specimen has severe wearing. The scratch test by a Rockwell diamond cone was also applied to determine the adhesive strength of the film [15]. The critical load of the 15 #m thickness film was 20 N, and the film failure came from the deformation of the aluminum alloy, which means strong adhesion of the film to the specimen.
'. I;:lql.q"l~["{lll'"ll"llmlllllrl"rll.lll.l~lliltmll.rpIlllrJrlll.~lml.~llll .lima,.Ill. lira,I.~lll~,q.~ll.llll~J i~. i..piii i ii '1 Irl ~lI'"1 .q,I, 3 4 5 6 7 8 S 19(3 1 2 3 4 5 6 7 B ' g ': ; 1 u~] [ ~,hHI{ .I.4., ~;; k.*,h, I h.d,u~;;.&. h . &,I.,~l., ~, ,~.I, .*H J,JHfr . hdl.I ;nl...IA..l..I ,,I. h, ll=h,l,.,I,l,~ I I ,
Specimen A (TiN coated)
Specimen B (Unt teated)
Fig. 7. Photographs of specimens after wear tests.
T. Sato et al. / S u r f a c e treatment of AI alloy
4. Conclusions T i t a n i u m - n i t r i d e coating films were made on alumin u m alloy ( A l - 1 1 S i ) plates at room temperature by simultaneous ion implantation and metal vapor deposition ( d y n a m i c mixing). The Vickers microhardness of the 15 /zm film was 1000-1500 k g / m m 2 which is ten times larger t h a n the one of the base a l u m i n u m alloy. The titanium-nitride film coated a l u m i n u m alloy plate showed better wear properties than the untreated one.
References [1] N.E.W. Hartley, W.E. Swindlehurst, G. Dearnaley, and J.F. Turner, J. Mater. Sci. 8 (1973) 900. [2] G. Dearnaley, Thin Solid Films 107 (1983) 315. [3] J.J. Au and P. Sioshansi, Proc. Materials Research Society Symp., vol. 27 (North-Holland, New York, 1984) p. 679.
647
[4] 3.K. Hirvonen, see ref. [3], p. 621. [5] F.A. Smidt, NRL Memorandum Report 5393 (1984). [6] J.S. Colligon, A.E. Hill, and H. Kheyrandish, Vacuum 34 (1984) 843. [7] R.A. Kant and B.D. Sartwell, see ref. [3], p. 525. [8] R.A. Kant, B.D. Sartwel], I.L. Singer, and R.G. Vardiman, Nucl. Instr. and Meth. B7/8 (1985) 915. [9] M. Satou and F. Fujimoto, Jpn. J. Appl. Phys. 22 (1983) L171. [10] T.S. Green, Proc. 10th Symp. on Fusion Technology (Pergamon Press, Oxford, 1978) p. 903. [11] M. Satou, Y. Andoh, K. Ogata, Y. Suzuki, K. Matsuda, and F. Fujimoto, Jpn. J. Appl. Phys. 24 (1985) 656. [12] Y. Andoh, Y. Suzuki, K. Matsuda, M. Satou, and F. Fujimoto, Nucl. Instr. and Meth. B6 (1985) 111. [13] T. Sato, K. Ohata, N. Asahi, Y. Ono, Y. Oka, and I. Hashimoto, J. Vac. Sci. Technol., to be published. [14] T. Sato, H. Nishimura, and T. Uede, Proc. Int. Ion Engineering Congress (Kyoto Univ., Kyoto, 1983) p. 493. [15] H.E. Hintermann and P. Laeng, Proc. Int. Conf. on Recent Developments in Specialty Steels and Hard Materials (Pretoria, 1982) p. 407.
V. ION BEAM MIXING
Nuclear Instruments and Methods in Physics Research B19/20 (1987) 644-647 North-Holland, Amsterdam
SURFACE TREATMENT OF ALUMINUM ALLOY AT ROOM TEMPERATURE WITH T I T A N I U M - N I T R I D E F I L M S BY D Y N A M I C M I X I N G T. S A T O , K. O H A T A , N. A S A H I , Y. O N O , Y. O K A I), I. H A S H I M O T O 1) and K. A R I M A T S U 1) Hitachi Research Laborato~., Hitachi, Japan 319-12 t)Hitachi Kokubu Works, Hitachi, Japan 316
Titanium-nitride coating films were prepared on aluminum alloy plates at room temperature with simultaneous ion implantation and metal vapor deposition (dynamic mixing) by using a high current ion source. The films were analysed by means of Auger electron spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction. The results showed the presence of small amount of oxygen and carbon impurities due to a high current density (0.5-1.0 mA/cm2) of the nitrogen beam (energy: 20 keV). Films of 1.2 /tin thickness showed uniform composition. Titanium-nitride coated aluminum alloy (film thickness: 15 #m) was ten times harder than the untreated one. The coated plate was examined by a pin-on-disc wear tester. The results showed better wear properties.
1. Introduction Among many surface modification techniques such as sputtering, ion implantation, and ion plating, ion implantation uses the highest energy particles and the process is independent of specimen temperature. This means greater flexibility in applications to material processing. A number of studies on implantation of non-semiconductor materials, have already been done [1-9]. Some of them, such as cutting tool life improvement have seen practical implementation [2-4]. But, two main problems remain: (1) the process cost and (2) the shallow penetration depth (of the order of 0.1 /~m) of the implanted ions. These problems have limited the wide use of the process. To overcome these problems, ion implantation by a non-mass-analysed high current ion source from fusion experiments [10] was combined with a simultaneous deposition method (dynamic mixing) [11-13]. This paper describes titanium-nitride films on aluminum alloy plates (AI-11 Si alloy) prepared by nitrogen ion implantation with simultaneous titanium vapor deposition. The films were made at room temperature and analysed for composition, structure and status by Auger electron spectroscopy (AES), X-ray-induced photoelectron spectroscopy (XPS) both with argon ion sputtering, and X-ray diffraction. The hardness and wear properties of the films were also examined.
electron beam evaporator, a rotary specimen holder with water cooling and a film thickness monitor as shown in fig. 1 [13,14]. The main performances of'the machine are also indicated in fig. 1. The N ÷ and N f components of a small beam from one aperature were measured by using mass-analysing magnet. The N ÷ and N f components are of the same order of magnitude. An A I - l l Si alloy plate (diameter 10 cm; thickness 6 mm) mechanically mirror polished by a buffing wheel was used as a specimen. After cleaning in acetone the specimen was sputtered by a 20 kV nitrogen beam for surface cleaning. A 20 kV, 0.11 A nitrogen ion beam irradiated the specimen during the titanium deposition with a rate of 7 A/s. The coating speed of 2.5 # m / h , was limited by the capacity of the electron beam evaporator. The specimen was cooled by water directly to keep the specimen temperature rise below 10°C during irradiation. The basic pressure of the chamber was 3 × 10 -6 Torr and the pressure during the film preparation was 1 × 10 -4 Tort. It was difficult to measure the precise ratio of nitrogen to titanium atoms, because the ion beam was not mass analysed and the nitrogen beam contains molecular and neutral atoms. So, the above preparation conditions were determined empirically. The maximum coated film thickness was 15 #m.
2. Preparation of films
3. Results and discussion
The machine consists of a bucket-type ion source obtained by improvement and modification of the one for neutral beam injectors in fusion experiments, an
Fig. 2 shows the X-ray diffraction signal of the 15 /zm coated specimen. This measurement reveals that the film is formed by TiN crystallite of preferential 111
0168-583X/87/$03.50 © Elsevier Science Publishers B.V. (North-Holland Physics Publishing Division)
645
T. Sato et a L / Surface treatment of AI alloy
[ /
/
PURIFIED ] WATER /
I~N. . . . . ~:~uv~
COOLER 1 ~
J GAS LIII II CONTROLLER BII / /AlL / / /
Htl]1]
/
~ A I . .~K'------'~r:--~ ION BEAM '-'.:'~ ~ l l l i P
~
~
~---n" ~
~f COOLING WATER
. R ~ . ~ -
III./-", II I I I L ; it ~1~1,"~"~
AGes / / . W - / - ~ ? ~ El
VACUUM CHAMBER ~ ~GATE V A L V E ~ - - - - - ~ P ~ X . ~ . HR
~t
J
....i I f i
MONITOR
I
u
:.!:"METAL VAPOR
~----1
P~rame~er
Value
4-40kV /PLASMA/
-J-~ . . ~ . . l
Total beam current
IB~AMEXT~CT'C" 1 SUPPLY /
Electron beam evaporator High speed dc switch Vacuum pump
Max. 0.6A (Nitrogen) ¢ I 0cm 2kW 40kV 5A 150O~/s
Non mass Bnalyzed
Fig. 1. Schematicdiagram and main performance of the machine for dynamic mixing.
FILM T H I C K N E S S
T:
15ltm
>12E < n-
bers of nitrogen and titanium atoms arriving at the specimen surface per second are much larger than those in the experiment by Satou or possibly by Kant. From the XPS analysis, the fills were compounds of TiN and TIN.,(> 1).
0.5
,,(
Z
0
30
40
v
50
60 20(")
Z
70
v
80
90
100
Fig. 2. X-ray diffraction signal of the 15 /~m thickness titanium-nitride film. reflection on the aluminum alloy plate at room temperature. Fig. 3 shows the results of the electron probe microanalysis (EPMA) of the same specimen. This figure shows the titanium and nitrogen compound film with 15/zm thickness formed on the aluminum alloy. The analysis by AES is shown in fig. 4. Ti + N (387 eV, 379 eV) and Ti (418 eV) peaks are almost constant, indicating that the titanium and nitrogen elements are uniformly distributed along the depth. This figure also indicates that the film contains a much smaller amount of carbon and oxygen impurities than those by Satou [11] or Kant [8], who showed that the TiN film prepared by dynamic mixing had a considerable amount of carbon and oxygen impurities. Our machine made a TiN film about ten times faster than the one used by Satou [11]. This means the possibility of reducing the carbon and oxygen contamination in the TiN fill because the num-
TiN
FILM
ALUMINUM
ALLOY
Fig. 3. Electron probe microanalysis results of the section of the film. V. I0N BEAM MIXING
646
7'. Saw et aL / Surface treatment o]"AI alloy
FILM THICKNESS D
90
>"
80
re
70
MICROHARDNESS ( K g / r n m 2)
1.2,ttm T i N ( BULK )
E AI
1500 z t3 n-
50
~ 40 I-Z :~
w
30
20
-1- 1000 o n,(2_
o Ti °Ti
'~=P'~%"
/o J~.
• AI + O
]
'Si '~
LU
_..
g
500
o
10 n,"
100 200
400
600
800
1000
o~.
tO
1200
5 10 FILM THICKNESS (~m)
ETCHING TIME (min)
Fig.
120
tO
~r e 60 ~
2000
A L UMINUM A L L O Y (A/-tlSi)
4.
Intensity variations of peaks due to Auger electron spectroscopy.
T E ~ DISTORTION ME LOAD
SPEO,MEN P'N ROTATING D I ~ , ¢ 1 0 c r n , ~
FZ LU O ~--L
15
Fig. 5. Vickers microhardness of the films.
SPEED : 7.3rq/sec LOAD : 5 kg LUBRICANT : 60ml/min PIN : AZ-16Si
SPEED : 0.75rrl/sec LUBRICANT: 60mZ/min PIN:AI-16Si
0"1r _J
(~) 0 . 0 5 1 - ° " ' ~ " 4 1 " . -
-~--e m U/
1 LOAD (kg)
(a) Pin-on-disc wear tester
2
(b) Friction coefficient measurement
10 20 30 SLIDING DISTANCE (kin) (c) Test results
Fig. 6. Wear tests by a pin-on-disc ~vear tester and the results (O: untreated, e: TiN coated).
Fig. 5 shows the Vickers microhardness dependence on the film thickness and the indentor load. For loads smaller than 50 g, the hardness of the 15/~m thickness film specimen was of about 1000-1500 k g / m m 2, almost ten times harder than the bulk aluminum alloy. The 4 # m film coated specimen (Specimen A) and the untreated specimen (Specimen B) were examined by a pin-on-disc wear tester shown in fig. 6(a). A refrigerating oil was used as lubricant. The contact of the pin has 5.5 mm radius and 8 mm width. The friction coefficient and wear test results are shown in figs. 6(b) and 6(c). Photos of the specimens after testing are shown in fig. 7. The TiN coated specimen shows no wear under a light load, but the untreated specimen has severe wearing. The scratch test by a Rockwell diamond cone was also applied to determine the adhesive strength of the film [15]. The critical load of the 15 #m thickness film was 20 N, and the film failure came from the deformation of the aluminum alloy, which means strong adhesion of the film to the specimen.
'. I;:lql.q"l~["{lll'"ll"llmlllllrl"rll.lll.l~lliltmll.rpIlllrJrlll.~lml.~llll .lima,.Ill. lira,I.~lll~,q.~ll.llll~J i~. i..piii i ii '1 Irl ~lI'"1 .q,I, 3 4 5 6 7 8 S 19(3 1 2 3 4 5 6 7 B ' g ': ; 1 u~] [ ~,hHI{ .I.4., ~;; k.*,h, I h.d,u~;;.&. h . &,I.,~l., ~, ,~.I, .*H J,JHfr . hdl.I ;nl...IA..l..I ,,I. h, ll=h,l,.,I,l,~ I I ,
Specimen A (TiN coated)
Specimen B (Unt teated)
Fig. 7. Photographs of specimens after wear tests.
T. Sato et al. / S u r f a c e treatment of AI alloy
4. Conclusions T i t a n i u m - n i t r i d e coating films were made on alumin u m alloy ( A l - 1 1 S i ) plates at room temperature by simultaneous ion implantation and metal vapor deposition ( d y n a m i c mixing). The Vickers microhardness of the 15 /zm film was 1000-1500 k g / m m 2 which is ten times larger t h a n the one of the base a l u m i n u m alloy. The titanium-nitride film coated a l u m i n u m alloy plate showed better wear properties than the untreated one.
References [1] N.E.W. Hartley, W.E. Swindlehurst, G. Dearnaley, and J.F. Turner, J. Mater. Sci. 8 (1973) 900. [2] G. Dearnaley, Thin Solid Films 107 (1983) 315. [3] J.J. Au and P. Sioshansi, Proc. Materials Research Society Symp., vol. 27 (North-Holland, New York, 1984) p. 679.
647
[4] 3.K. Hirvonen, see ref. [3], p. 621. [5] F.A. Smidt, NRL Memorandum Report 5393 (1984). [6] J.S. Colligon, A.E. Hill, and H. Kheyrandish, Vacuum 34 (1984) 843. [7] R.A. Kant and B.D. Sartwell, see ref. [3], p. 525. [8] R.A. Kant, B.D. Sartwel], I.L. Singer, and R.G. Vardiman, Nucl. Instr. and Meth. B7/8 (1985) 915. [9] M. Satou and F. Fujimoto, Jpn. J. Appl. Phys. 22 (1983) L171. [10] T.S. Green, Proc. 10th Symp. on Fusion Technology (Pergamon Press, Oxford, 1978) p. 903. [11] M. Satou, Y. Andoh, K. Ogata, Y. Suzuki, K. Matsuda, and F. Fujimoto, Jpn. J. Appl. Phys. 24 (1985) 656. [12] Y. Andoh, Y. Suzuki, K. Matsuda, M. Satou, and F. Fujimoto, Nucl. Instr. and Meth. B6 (1985) 111. [13] T. Sato, K. Ohata, N. Asahi, Y. Ono, Y. Oka, and I. Hashimoto, J. Vac. Sci. Technol., to be published. [14] T. Sato, H. Nishimura, and T. Uede, Proc. Int. Ion Engineering Congress (Kyoto Univ., Kyoto, 1983) p. 493. [15] H.E. Hintermann and P. Laeng, Proc. Int. Conf. on Recent Developments in Specialty Steels and Hard Materials (Pretoria, 1982) p. 407.
V. ION BEAM MIXING