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Batch treatment of industrial components using plasma immersion ion implantation and deposition
Surface & Coatings Technology 201 (2007) 6585 – 6588 www.elsevier.com/locate/surfcoat
Batch treatment of industrial components using plasma immersion ion implantation and deposition L.P. Wang ⁎, Y.H. Wang, Y.H. Yu, H.X. Liu, X.F. Wang, B.Y. Tang State Key Laboratory of Advanced Welding Production and Technology, Harbin Institute of Technology, Harbin 150001, China Available online 3 November 2006
Abstract Surface modifications of industrial components, such as the balls, inner and outer rings of bearings, are very difficult to perform for their sophisticated shapes. Plasma immersion ion implantation and deposition (PIIID) offers an effective way for surface treatment of such components. However, implantation doses of these components are not uniform in a conventional PIIID process. To obtain uniform surface modifications, we designed a rotating target holder. Using the target holder and proper process parameters, the PIIID batch treatment of sophisticated-shape components has become easy work. In the PIIID batch treatments of balls, outer and inner surfaces of cylinder-like components, the dose uniformity can be evidently improved by using sample rotation, short width high frequency implantation pulse, and middle-frequency and -voltage glow discharge, respectively. The practical test results reveal that the life of these components can be improved significantly by this novel PIIID batch treatment. © 2006 Elsevier B.V. All rights reserved. Keywords: PIIID; Batch treatment; Industrial components
1. Introduction Some sophisticated-shape industrial components, such as the bearing, tools and cylinder-like components, are subjected to high-cycle contact usages, wear and fatigue damages that often take place on the surfaces of these components. Surface modification techniques, such as nitriding and carbonization, are usually utilized to increase their wear and fatigue resistance [1–3]. However, such treatments must be achieved at high temperature, the properties of the heat-treated bearing steel, such as GCr15 and AISI 440C steels [4,5], will be softened when the temperature exceeds halves of their melting points. For titanium alloy, high temperature will lead to tremendous brittleness because of the hydrogen absorption. In addition, an extra machining process must be carried out to reduce the dimension variation derived from the high temperature. Plasma immersion ion implantation and deposition (PIIID) offers many advantages for surface modification, such as low temperature treatment, none line-of-sight restriction and potential ⁎ Corresponding author. Tel.: +86 451 86418728; fax: +86 451 86416186. E-mail address: [email protected] (L.P. Wang). 0257-8972/$ - see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.surfcoat.2006.09.094
for sophisticated-shape components. However, the dose uniformity of these components is not reasonable in conventional PIIID conditions, especially in the batch treatment [6–10]. In order to obtain commercial applications of the PIIID technique, we had successfully developed several novel methods to improve the dose uniformity. 2. Experimental The vacuum chamber used in our experiments has the radius of 0.5 m and the height of 1.2 m. Radio-frequency (RF) glow discharge was used to generate gaseous plasma, and its power was set to 600 W. One pulsed cathodic arc plasma source was used to obtain metallic or carbon plasma, and the deposition rate can reach about 3 Å/s. In addition, two high-voltage power sources can be utilized in our experiments. One power source can generate a 5–40 kV pulsed bias, and its repetition frequency can be adjusted from 1 to 500 Hz. Another one can generate a 1– 10 kV pulsed bias, and its frequency can reach 10 kHz. In addition, we used a rotating target holder for the batch treatment of these industrial components. Revolution and rotating of many sophisticated-shape components can be acquired by this
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L.P. Wang et al. / Surface & Coatings Technology 201 (2007) 6585–6588
rotating target. Using the proper process window and rotating target holder, batch treatments of these components can be finished conveniently. 3. Results and discussion 3.1. The surface of a ball-shape component A particle-in-cell (PIC) model was used to simulate the PIIID process of a ball. During the simulation, the implantation voltage, pulse width, ball radius and plasma density are − 20 kV, 6 μs, 4.8 × 109/cm3, and 16 mm, respectively. The simulation results reveal that the implantation dose of the ball is really ununiform. As shown in Fig. 1a, the dose at the point near the holder is evidently smaller than the upper surface. In order to improve the uniformity, we also calculated the dose distribution along the ball surface when the ball is rotating. Fig. 1b shows the dose distribution along the circumference perpendicular to the rotating plane. The simulation result reveals that the rotating of the ball can improve the dose distribution significantly. In addition, along the circumference of rotation, the implantation dose is uniform obviously.
Fig. 2. The revolving principle of a ball: (1) Fixed plate, (2) Rotated plate.
According to the simulation results, in order to improve the dose uniformity, the ball must be rotated during the treatment. However, since the PIIID process employs a high voltage pulse, in order to prevent arcing, an intimate contact between the ball and target holder must be promised. Fig. 2 exhibits the revolving principle of a ball using the rotating target holder, which is mainly composed of two plates: the rotated and fixed. In the fixed plate, many holes are drilled, whose radiuses are smaller than that of the balls to be treated. In order to obtain the PIIID batch treatment of balls, the balls are put into the holes of the fixed plate. When the radius of the hole is proper, balls can drop to contact the rotated plate intimately under natural gravity. When the rotated plate revolves, the ball will gyrate around its center by the friction force between the ball and the rotated plate. The gyrating speed can be controlled through adjusting the revolving speed of the rotated plate as well as the distance between the ball and the center of the rotated plate. Fig. 3 shows the nitrogen-implanted balls with different diameters using the rotated target holder. It is found that the surface color due to nitrogen implantation in each ball is uniform. 3.2. The outer surfaces of a cylinder-like component During the PIIID process of a cylinder-like component, when the sheath shape is similar to the outer surface of the component, a uniform surface modification layer can be achieved. In order to get high shape conformability, the sheath evolution during the PIIID process of the inner ring of a bearing was calculated. The simulation results reveal that the uniformity can be improved when the ion
Fig. 1. Dose distributions along the circumference perpendicular to the rotating plane: (a) without rotation, (b) with rotation.
Fig. 3. PIIID Batch treated balls with different diameters.
L.P. Wang et al. / Surface & Coatings Technology 201 (2007) 6585–6588
density is increased and the pulse width is reduced. Therefore, we can use a high plasma density and small pulse width for the PIIID process of the outer surface of a cylinder-like component. In order to acquire the PIIID batch treatment of the inner rings of bearings, many inner rings are assembled intimately along the axis. Since the metallic plasma produced by a vacuum arc plasma source has a large dream velocity and results in lineof-sight restriction, the inner ring must be rotated during the treatment. Consequently, the uniformity of the track along the rotating circumstance will be improved through the revolving. Using this technique, we can treat 20 or more inner rings in one time, thus the efficiency is increased greatly. When the metallic and gaseous plasma are generated simultaneously in the vacuum chamber, single or composite films will be synthesized on the outer surface of the cylinder-like component. The surface modification layer acquired by PIIID should be varied according to the substrate. For instance, diamond-likecarbon (DLC) film deposited on 9Cr18 steel can achieve high quality wear resistance, while deposited on the titanium alloy (TC4) indicate unreasonable characteristic. However, TiN + Ti (CN) + DLC film synthesized on TC4 alloy exhibits a high wear resistance. Fig. 4 appears tribological properties of DLC and
6587
Fig. 5. Comparison of special TC4 shafts treated by PIIID and untreated specimens.
TiN + Ti(CN) + DLC films deposited on TC4 samples. It is found that the cut-through number of the TiN + Ti(CN) + DLC film is evidently larger than that of the DLC film. Fig. 5 depicts the PIIID batch treated outer surfaces of special TC4 shafts. It is found the TiN + Ti(CN) + DLC film is very uniform, and the practical test reveal that the surface modification layer can meet the operational requirements. 3.3. The inner surface of a cylinder-shape component Because conventional PIIID processes of the inner surface of a cylinder-shape component exist in sheath overlapping in a short time, the impact energy and retained dose will be affected greatly. Flow dynamic simulation results reveal that the dose uniformity of the inner surface of a bearing is only 40% in a conventional nitrogen PIII process. Furthermore, uniform film deposition on the inner surface is difficult because the metal plasma has a large dream velocity. Consequently, the PIIID batch treatment for the component with inner surface is very difficult to perform in conventional conditions. Recently, we used grid-enhanced inner surface PIIID [11] to treat the outer rings of bearings as shown in Fig. 6. A stainless grid
Fig. 4. The tribological properties of (a) DLC and (b)TiN+Ti(CN)+DLC films on TC4 samples.
Fig. 6. Experimental configuration of grid-enhanced inner surface PIIID.
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L.P. Wang et al. / Surface & Coatings Technology 201 (2007) 6585–6588
In addition, middle-frequency and -voltage glow discharge PIIID was also used to treat the inner surface of a cylinder-shape component. During this process, a middle-voltage (4–8 kV), middle-frequency (6–10 kHz) bias is applied on the component, and glow discharge will occur in the cylinder-like component. When C2H2 is introduced to the vacuum chamber, C2H2 plasma will be generated. Consequently, the thickness of 3 μm DLC film can be synthesized on the inner surface through this method. The cut-through number of the DLC film deposited on GCr15 steel is larger than 10,000 cycles, which exhibits a high wear resistance. Fig. 7 exhibits the treated outer rings of bearings using gridenhanced inner surface and middle-frequency and -voltage glow discharge PIIID processes, it is found that a uniform surface modification layer can be obtained by either of these two methods. 4. Conclusions Using the rotated target holder and proper PIIID process parameters, the batch treatment of balls and the outer surfaces of cylinder-shape components can be obtained easily. In addition, with grid-enhanced inner surface or middle-frequency and -voltage glow discharge PIIID techniques, the batch treatment of the inner surfaces of cylinder-shape components can be easily achieved. Acknowledgements This work is supported by the development program for outstanding young teachers in Harbin Institute of Technology. References
Fig. 7. The out rings of the bearing using (a) grid-enhanced and (b) middlefrequency and -voltage glow discharge PIIID techniques.
and titanium rod were put into the center of the cylinder. The grid was grounded, the cylinder was biased by a high negative voltage, and the titanium rod was connected to a RF power supply. Therefore, plasma will be generated between the grid and the center rod. Because of the self-bias effect of RF glow discharge, the rod was biased by about −1000 V. Consequently, atoms in the rod will be sputtered off and deposited onto the inner surface. The test result shows that the film thickness on the inner surface is uniform. When we put many cylinder-shape components together, it will form a long cylinder. Therefore, the batch treatment of these components can be achieved using grid-enhanced inner surface PIIID.
[1] A. Yoshida, M. Fujii, Tribol. Int. 35 (2002) 837. [2] J.D. Costa, J.M. Ferreira, A.L. Ramalho, Theor. Appl. Fract. Mech. 35 (2001) 69. [3] K.T. Rie, Surf. Coat. Technol. 112 (1999) 56. [4] R.C. Dommarco, P.C. Bastias, H.A. Dall'O, G.T. Hahn, C.A. Rubin, Wear 221 (1998) 69. [5] R.C. Dommarco, P.C. Bastias, G.T. Hahn, C.A. Rubin, Wear 252 (2002) 430. [6] P.K. Chu, S. Qin, C. Chan, N.W. Cheung, L.A. Larson, Mater. Sci. Eng., R Rep. 17 (1996) 207. [7] J.R. Conrad, J.L. Radtke, R.A. Dodd, F.F Worzala, N.C. Tran, J. Appl. Phys. 62 (1987) 4591. [8] L.P. Wang, B.Y. Tang, X.B. Tian, Y.X. Leng, Q.Y. Zhang, P.K. Chu, J. Mater. Sci. Technol. 17 (2001) 29. [9] L.P. Wang, B.Y. Tang, N. Huang, X.B. Tian, P.K. Chu, Mater. Sci. Eng., A Struct. Mater.: Prop. Microstruct. Process. 308 (2001) 176. [10] M. Keidar, I.G. Brown, J. Vac. Sci. Technol., B 17 (1999) 2648. [11] B. Liu, C. Liu, D. Cheng, G. Zhang, H. He, S. Yang, Nucl. Instrum. Methods Phys. Res., B Beam Interact. Mater. Atoms 184 (2001) 644.
Batch treatment of industrial components using plasma immersion ion implantation and deposition L.P. Wang ⁎, Y.H. Wang, Y.H. Yu, H.X. Liu, X.F. Wang, B.Y. Tang State Key Laboratory of Advanced Welding Production and Technology, Harbin Institute of Technology, Harbin 150001, China Available online 3 November 2006
Abstract Surface modifications of industrial components, such as the balls, inner and outer rings of bearings, are very difficult to perform for their sophisticated shapes. Plasma immersion ion implantation and deposition (PIIID) offers an effective way for surface treatment of such components. However, implantation doses of these components are not uniform in a conventional PIIID process. To obtain uniform surface modifications, we designed a rotating target holder. Using the target holder and proper process parameters, the PIIID batch treatment of sophisticated-shape components has become easy work. In the PIIID batch treatments of balls, outer and inner surfaces of cylinder-like components, the dose uniformity can be evidently improved by using sample rotation, short width high frequency implantation pulse, and middle-frequency and -voltage glow discharge, respectively. The practical test results reveal that the life of these components can be improved significantly by this novel PIIID batch treatment. © 2006 Elsevier B.V. All rights reserved. Keywords: PIIID; Batch treatment; Industrial components
1. Introduction Some sophisticated-shape industrial components, such as the bearing, tools and cylinder-like components, are subjected to high-cycle contact usages, wear and fatigue damages that often take place on the surfaces of these components. Surface modification techniques, such as nitriding and carbonization, are usually utilized to increase their wear and fatigue resistance [1–3]. However, such treatments must be achieved at high temperature, the properties of the heat-treated bearing steel, such as GCr15 and AISI 440C steels [4,5], will be softened when the temperature exceeds halves of their melting points. For titanium alloy, high temperature will lead to tremendous brittleness because of the hydrogen absorption. In addition, an extra machining process must be carried out to reduce the dimension variation derived from the high temperature. Plasma immersion ion implantation and deposition (PIIID) offers many advantages for surface modification, such as low temperature treatment, none line-of-sight restriction and potential ⁎ Corresponding author. Tel.: +86 451 86418728; fax: +86 451 86416186. E-mail address: [email protected] (L.P. Wang). 0257-8972/$ - see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.surfcoat.2006.09.094
for sophisticated-shape components. However, the dose uniformity of these components is not reasonable in conventional PIIID conditions, especially in the batch treatment [6–10]. In order to obtain commercial applications of the PIIID technique, we had successfully developed several novel methods to improve the dose uniformity. 2. Experimental The vacuum chamber used in our experiments has the radius of 0.5 m and the height of 1.2 m. Radio-frequency (RF) glow discharge was used to generate gaseous plasma, and its power was set to 600 W. One pulsed cathodic arc plasma source was used to obtain metallic or carbon plasma, and the deposition rate can reach about 3 Å/s. In addition, two high-voltage power sources can be utilized in our experiments. One power source can generate a 5–40 kV pulsed bias, and its repetition frequency can be adjusted from 1 to 500 Hz. Another one can generate a 1– 10 kV pulsed bias, and its frequency can reach 10 kHz. In addition, we used a rotating target holder for the batch treatment of these industrial components. Revolution and rotating of many sophisticated-shape components can be acquired by this
6586
L.P. Wang et al. / Surface & Coatings Technology 201 (2007) 6585–6588
rotating target. Using the proper process window and rotating target holder, batch treatments of these components can be finished conveniently. 3. Results and discussion 3.1. The surface of a ball-shape component A particle-in-cell (PIC) model was used to simulate the PIIID process of a ball. During the simulation, the implantation voltage, pulse width, ball radius and plasma density are − 20 kV, 6 μs, 4.8 × 109/cm3, and 16 mm, respectively. The simulation results reveal that the implantation dose of the ball is really ununiform. As shown in Fig. 1a, the dose at the point near the holder is evidently smaller than the upper surface. In order to improve the uniformity, we also calculated the dose distribution along the ball surface when the ball is rotating. Fig. 1b shows the dose distribution along the circumference perpendicular to the rotating plane. The simulation result reveals that the rotating of the ball can improve the dose distribution significantly. In addition, along the circumference of rotation, the implantation dose is uniform obviously.
Fig. 2. The revolving principle of a ball: (1) Fixed plate, (2) Rotated plate.
According to the simulation results, in order to improve the dose uniformity, the ball must be rotated during the treatment. However, since the PIIID process employs a high voltage pulse, in order to prevent arcing, an intimate contact between the ball and target holder must be promised. Fig. 2 exhibits the revolving principle of a ball using the rotating target holder, which is mainly composed of two plates: the rotated and fixed. In the fixed plate, many holes are drilled, whose radiuses are smaller than that of the balls to be treated. In order to obtain the PIIID batch treatment of balls, the balls are put into the holes of the fixed plate. When the radius of the hole is proper, balls can drop to contact the rotated plate intimately under natural gravity. When the rotated plate revolves, the ball will gyrate around its center by the friction force between the ball and the rotated plate. The gyrating speed can be controlled through adjusting the revolving speed of the rotated plate as well as the distance between the ball and the center of the rotated plate. Fig. 3 shows the nitrogen-implanted balls with different diameters using the rotated target holder. It is found that the surface color due to nitrogen implantation in each ball is uniform. 3.2. The outer surfaces of a cylinder-like component During the PIIID process of a cylinder-like component, when the sheath shape is similar to the outer surface of the component, a uniform surface modification layer can be achieved. In order to get high shape conformability, the sheath evolution during the PIIID process of the inner ring of a bearing was calculated. The simulation results reveal that the uniformity can be improved when the ion
Fig. 1. Dose distributions along the circumference perpendicular to the rotating plane: (a) without rotation, (b) with rotation.
Fig. 3. PIIID Batch treated balls with different diameters.
L.P. Wang et al. / Surface & Coatings Technology 201 (2007) 6585–6588
density is increased and the pulse width is reduced. Therefore, we can use a high plasma density and small pulse width for the PIIID process of the outer surface of a cylinder-like component. In order to acquire the PIIID batch treatment of the inner rings of bearings, many inner rings are assembled intimately along the axis. Since the metallic plasma produced by a vacuum arc plasma source has a large dream velocity and results in lineof-sight restriction, the inner ring must be rotated during the treatment. Consequently, the uniformity of the track along the rotating circumstance will be improved through the revolving. Using this technique, we can treat 20 or more inner rings in one time, thus the efficiency is increased greatly. When the metallic and gaseous plasma are generated simultaneously in the vacuum chamber, single or composite films will be synthesized on the outer surface of the cylinder-like component. The surface modification layer acquired by PIIID should be varied according to the substrate. For instance, diamond-likecarbon (DLC) film deposited on 9Cr18 steel can achieve high quality wear resistance, while deposited on the titanium alloy (TC4) indicate unreasonable characteristic. However, TiN + Ti (CN) + DLC film synthesized on TC4 alloy exhibits a high wear resistance. Fig. 4 appears tribological properties of DLC and
6587
Fig. 5. Comparison of special TC4 shafts treated by PIIID and untreated specimens.
TiN + Ti(CN) + DLC films deposited on TC4 samples. It is found that the cut-through number of the TiN + Ti(CN) + DLC film is evidently larger than that of the DLC film. Fig. 5 depicts the PIIID batch treated outer surfaces of special TC4 shafts. It is found the TiN + Ti(CN) + DLC film is very uniform, and the practical test reveal that the surface modification layer can meet the operational requirements. 3.3. The inner surface of a cylinder-shape component Because conventional PIIID processes of the inner surface of a cylinder-shape component exist in sheath overlapping in a short time, the impact energy and retained dose will be affected greatly. Flow dynamic simulation results reveal that the dose uniformity of the inner surface of a bearing is only 40% in a conventional nitrogen PIII process. Furthermore, uniform film deposition on the inner surface is difficult because the metal plasma has a large dream velocity. Consequently, the PIIID batch treatment for the component with inner surface is very difficult to perform in conventional conditions. Recently, we used grid-enhanced inner surface PIIID [11] to treat the outer rings of bearings as shown in Fig. 6. A stainless grid
Fig. 4. The tribological properties of (a) DLC and (b)TiN+Ti(CN)+DLC films on TC4 samples.
Fig. 6. Experimental configuration of grid-enhanced inner surface PIIID.
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L.P. Wang et al. / Surface & Coatings Technology 201 (2007) 6585–6588
In addition, middle-frequency and -voltage glow discharge PIIID was also used to treat the inner surface of a cylinder-shape component. During this process, a middle-voltage (4–8 kV), middle-frequency (6–10 kHz) bias is applied on the component, and glow discharge will occur in the cylinder-like component. When C2H2 is introduced to the vacuum chamber, C2H2 plasma will be generated. Consequently, the thickness of 3 μm DLC film can be synthesized on the inner surface through this method. The cut-through number of the DLC film deposited on GCr15 steel is larger than 10,000 cycles, which exhibits a high wear resistance. Fig. 7 exhibits the treated outer rings of bearings using gridenhanced inner surface and middle-frequency and -voltage glow discharge PIIID processes, it is found that a uniform surface modification layer can be obtained by either of these two methods. 4. Conclusions Using the rotated target holder and proper PIIID process parameters, the batch treatment of balls and the outer surfaces of cylinder-shape components can be obtained easily. In addition, with grid-enhanced inner surface or middle-frequency and -voltage glow discharge PIIID techniques, the batch treatment of the inner surfaces of cylinder-shape components can be easily achieved. Acknowledgements This work is supported by the development program for outstanding young teachers in Harbin Institute of Technology. References
Fig. 7. The out rings of the bearing using (a) grid-enhanced and (b) middlefrequency and -voltage glow discharge PIIID techniques.
and titanium rod were put into the center of the cylinder. The grid was grounded, the cylinder was biased by a high negative voltage, and the titanium rod was connected to a RF power supply. Therefore, plasma will be generated between the grid and the center rod. Because of the self-bias effect of RF glow discharge, the rod was biased by about −1000 V. Consequently, atoms in the rod will be sputtered off and deposited onto the inner surface. The test result shows that the film thickness on the inner surface is uniform. When we put many cylinder-shape components together, it will form a long cylinder. Therefore, the batch treatment of these components can be achieved using grid-enhanced inner surface PIIID.
[1] A. Yoshida, M. Fujii, Tribol. Int. 35 (2002) 837. [2] J.D. Costa, J.M. Ferreira, A.L. Ramalho, Theor. Appl. Fract. Mech. 35 (2001) 69. [3] K.T. Rie, Surf. Coat. Technol. 112 (1999) 56. [4] R.C. Dommarco, P.C. Bastias, H.A. Dall'O, G.T. Hahn, C.A. Rubin, Wear 221 (1998) 69. [5] R.C. Dommarco, P.C. Bastias, G.T. Hahn, C.A. Rubin, Wear 252 (2002) 430. [6] P.K. Chu, S. Qin, C. Chan, N.W. Cheung, L.A. Larson, Mater. Sci. Eng., R Rep. 17 (1996) 207. [7] J.R. Conrad, J.L. Radtke, R.A. Dodd, F.F Worzala, N.C. Tran, J. Appl. Phys. 62 (1987) 4591. [8] L.P. Wang, B.Y. Tang, X.B. Tian, Y.X. Leng, Q.Y. Zhang, P.K. Chu, J. Mater. Sci. Technol. 17 (2001) 29. [9] L.P. Wang, B.Y. Tang, N. Huang, X.B. Tian, P.K. Chu, Mater. Sci. Eng., A Struct. Mater.: Prop. Microstruct. Process. 308 (2001) 176. [10] M. Keidar, I.G. Brown, J. Vac. Sci. Technol., B 17 (1999) 2648. [11] B. Liu, C. Liu, D. Cheng, G. Zhang, H. He, S. Yang, Nucl. Instrum. Methods Phys. Res., B Beam Interact. Mater. Atoms 184 (2001) 644.