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FIG. 16. Schematic view of friction induced hydroxylated-ter- minated carbon surfaces. (© Springer. Reproduced with per- mission of Kano et al.*°’ Permission to reuse must be obtained from the rightsholder.)

Figure 16 Schematic view of friction induced hydroxylated-ter- minated carbon surfaces. (© Springer. Reproduced with per- mission of Kano et al.*°’ Permission to reuse must be obtained from the rightsholder.)

Related Figures (20)

FIG. 1. Ternary phase diagram for various DLC films with respect to their sp*, sp* type bonding and hydrogen content in the structure. (© Elsevier. Reproduced with permission of Love et al.'® Permission to reuse must be obtained from the rightsholder.)
FIG. 1. Ternary phase diagram for various DLC films with respect to their sp*, sp* type bonding and hydrogen content in the structure. (© Elsevier. Reproduced with permission of Love et al.'® Permission to reuse must be obtained from the rightsholder.)
Friction coeffecient and wear rate of different types of DLC coating in different environmental condition’? uv refers to coeffecient of friction K refers to wear rate [x10~-°mm3(N m)/] Me refers to metal, such as W,Ti, Mo, Fe, V... X refers to nonmetal, such as Si, O, N, F, B... TABLE 1
Friction coeffecient and wear rate of different types of DLC coating in different environmental condition’? uv refers to coeffecient of friction K refers to wear rate [x10~-°mm3(N m)/] Me refers to metal, such as W,Ti, Mo, Fe, V... X refers to nonmetal, such as Si, O, N, F, B... TABLE 1
Different types of coating applied to engine parts
Different types of coating applied to engine parts
FIG. 2. Schematic diagram of different deposition techniques (A) ion beam deposition technique,' (B) magnetron sputtering,” (C) plasma immersion ion implantation and deposition ioint, and (D) plasma activated chemical vapor deposition.”
FIG. 2. Schematic diagram of different deposition techniques (A) ion beam deposition technique,' (B) magnetron sputtering,” (C) plasma immersion ion implantation and deposition ioint, and (D) plasma activated chemical vapor deposition.”
FIG. 4. Coefficient of friction and wear property variation with respect to temperature of the Tungsten-doped DLC coating. (© Elsevier. Reproduced with permission of Gharam et al.°* Permission to reuse must be obtained from the rightsholder.) hyd DL wil obs C. If ta-C film is annealed in vacuum, then t Phase transformation and oxidation temperature for non rogenated DLC is much higher than that for hydrogenated he structure be stable up to 727°C. If heated in air, film oxidation is erved from 450-500°C.*8 Therefore, the CoF of non hydro- genated DLC will be stable at higher temperature compared to hyd rogenated DLC. Behavior of non hydrogenated car by magnetron sputtering are reported to be therma to 300°C. Beyond 300°C, the hardness value drastically drops because of graphitization of the coating structure. CoF increases at elevated temperature testing. The increased fric- tion coefficient is due to the absence of water in the trib ocontact. 98 amorphous bon a-C is different from ta-C. DLC (a-C) film deposited ly stable up 2.4.3.1. Silicon Containing DLC. Tkeyama et al.”® inves- tigated the property of DLC coating doped with Si. Si doping releases internal stress, which results in decreased hardness. Si Some metals and non metals can be added as a dopant to enhance some coating properties mentioned in earlier section (Section 2.1). Their effects will be discussed briefly in the fol- lowing sections.
FIG. 4. Coefficient of friction and wear property variation with respect to temperature of the Tungsten-doped DLC coating. (© Elsevier. Reproduced with permission of Gharam et al.°* Permission to reuse must be obtained from the rightsholder.) hyd DL wil obs C. If ta-C film is annealed in vacuum, then t Phase transformation and oxidation temperature for non rogenated DLC is much higher than that for hydrogenated he structure be stable up to 727°C. If heated in air, film oxidation is erved from 450-500°C.*8 Therefore, the CoF of non hydro- genated DLC will be stable at higher temperature compared to hyd rogenated DLC. Behavior of non hydrogenated car by magnetron sputtering are reported to be therma to 300°C. Beyond 300°C, the hardness value drastically drops because of graphitization of the coating structure. CoF increases at elevated temperature testing. The increased fric- tion coefficient is due to the absence of water in the trib ocontact. 98 amorphous bon a-C is different from ta-C. DLC (a-C) film deposited ly stable up 2.4.3.1. Silicon Containing DLC. Tkeyama et al.”® inves- tigated the property of DLC coating doped with Si. Si doping releases internal stress, which results in decreased hardness. Si Some metals and non metals can be added as a dopant to enhance some coating properties mentioned in earlier section (Section 2.1). Their effects will be discussed briefly in the fol- lowing sections.
Different doped DLC coating changes in structure and effect in hardness
Different doped DLC coating changes in structure and effect in hardness
FIG. 5. (A) Friction coefficient change with different velocity at a normal load of 20.7N. (B) Friction coefficient change at dif- ferent load with the change of velocity. (© Elsevier. Reproduced with permission of Kim and Kim.'*° Permission to reuse must be obtained from the rightsholder.) where AT is the induced temperature rise, ft is the CoF, P is the applied normal load, v is the sliding speed, K; and K, are the thermal conductivities of the coating and the ball, respectively, a is the contact radius of t! he real contact area, and H is the measured coating hardness. According to Eq. (1), with the increase of sliding speed v and lo temperature increases; therefore, grap Graphitization results in the lowering of load lowers the graphitization temperatu ad P, contact surface hitization enhances. CoF. Increasing the re by increasing the contact stress. Further graphitization can be promoted by fric- tion-induced annealing on the local contact areas and sliding- induced strain energy.'40'*8 Kim et al.'4° showed the change in CoF at different velocities and normal load. They found the results accord- ing to Figure 5. Figure 5A shows the change of CoF at
FIG. 5. (A) Friction coefficient change with different velocity at a normal load of 20.7N. (B) Friction coefficient change at dif- ferent load with the change of velocity. (© Elsevier. Reproduced with permission of Kim and Kim.'*° Permission to reuse must be obtained from the rightsholder.) where AT is the induced temperature rise, ft is the CoF, P is the applied normal load, v is the sliding speed, K; and K, are the thermal conductivities of the coating and the ball, respectively, a is the contact radius of t! he real contact area, and H is the measured coating hardness. According to Eq. (1), with the increase of sliding speed v and lo temperature increases; therefore, grap Graphitization results in the lowering of load lowers the graphitization temperatu ad P, contact surface hitization enhances. CoF. Increasing the re by increasing the contact stress. Further graphitization can be promoted by fric- tion-induced annealing on the local contact areas and sliding- induced strain energy.'40'*8 Kim et al.'4° showed the change in CoF at different velocities and normal load. They found the results accord- ing to Figure 5. Figure 5A shows the change of CoF at
FIG. 6. Friction coefficient vs. number of passes at dry and humid condition between different pair of surfaces at a load of 9.8 and velocity 1.6 cm/s. (© Cambridge University Press. Reproduced with permission of Jia et al.'*? Permission to reuse must be obtained from the rightsholder.) Ronkainen et al.” showed the effect of counter face at differ- ent sliding velocity and normal load to the CoF. They used steel and aluminum counterpart and found in both cases CoF decreased with the increment of sliding velocity and normal load. In the case of aluminum counter face, the increase of sliding velocity results in less pronounced trend of decreasing CoF for a-C:H coating (Figure 7). Friction property varies with the type of counter face, material hardness of counter face, and roughness of surface.'*°
FIG. 6. Friction coefficient vs. number of passes at dry and humid condition between different pair of surfaces at a load of 9.8 and velocity 1.6 cm/s. (© Cambridge University Press. Reproduced with permission of Jia et al.'*? Permission to reuse must be obtained from the rightsholder.) Ronkainen et al.” showed the effect of counter face at differ- ent sliding velocity and normal load to the CoF. They used steel and aluminum counterpart and found in both cases CoF decreased with the increment of sliding velocity and normal load. In the case of aluminum counter face, the increase of sliding velocity results in less pronounced trend of decreasing CoF for a-C:H coating (Figure 7). Friction property varies with the type of counter face, material hardness of counter face, and roughness of surface.'*°
FIG. 7. The friction coefficient values at the end of the tests for (a) a-C:H coating sliding against steel (AISI 52100), (b) ta-C coating sliding against steel, (c) a-C:H coating sliding against alumina, and (d) ta-C coatings sliding against alumina in pin-on- disc tests with different sliding. (© Elsevier. Reproduced with permission of Ronkainen et al.” Permission to reuse must be obtained from the rightsholder.)
FIG. 7. The friction coefficient values at the end of the tests for (a) a-C:H coating sliding against steel (AISI 52100), (b) ta-C coating sliding against steel, (c) a-C:H coating sliding against alumina, and (d) ta-C coatings sliding against alumina in pin-on- disc tests with different sliding. (© Elsevier. Reproduced with permission of Ronkainen et al.” Permission to reuse must be obtained from the rightsholder.)
FIG. 8. Wear coefficient vs. temperature for 7 and 10 N applied normal loads. (© Elsevier. Reproduced with permis- sion of Veverkova and Hainsworth.'®! Permission to reuse must be obtained from the rightsholder.)
FIG. 8. Wear coefficient vs. temperature for 7 and 10 N applied normal loads. (© Elsevier. Reproduced with permis- sion of Veverkova and Hainsworth.'®! Permission to reuse must be obtained from the rightsholder.)
FIG. 9. Wear volume (a) and wear rate (b) of DLC coating at different load and velocity. (© Elsevier. Reproduced with permis- sion of Kim and Kim.'** Permission to reuse must be obtained from the rightsholder.) Counter face has a direct impact on the wear behavior of the DLC coating. Table 4 shows the effect of counter face on the wear behavior of the DLC coating and mating surfaces at humid and dry conditions. !*? Si3N, ball has a lower wear rate in dry condition compared to steel ball. However, when the condition is humid, the steel ball has lower wear rate com- pared to the Si3;N, ball. Thus, some kinds of tribochemical reaction favored the wear property of the steel ball in humid condition. Veverkova et al.'®! found that during the pin-on- disk test, steel versus W—DLC showed higher wear rate com- pared to W—DLC/DLC coating pair, which might be due to tri- bolayer formation in the counter faces. The formation of Hydrogen stabilizes the random covalent network of DLC coating and prevents this network from graphitization. Lubri- cant works as a coolant; when this substance is added, the con- tact temperature remains within the allowable range. Therefore, graphitization will not take place. As a result, tribo- chemical interactions of DLC and additives become dominant. Some researchers found that a-C DLC provides low CoF than a-C:H DLC in lubricated condition. Higher surface energy leads to better interaction with a-C:H DLC. Surface energy is low for a-C:H because of the difference in their molecular structure. When high temperature is generated during the slid- ing friction in contact, sp? to sp” conversion of the bond takes place. This sp- bond type represents the graphite-like
FIG. 9. Wear volume (a) and wear rate (b) of DLC coating at different load and velocity. (© Elsevier. Reproduced with permis- sion of Kim and Kim.'** Permission to reuse must be obtained from the rightsholder.) Counter face has a direct impact on the wear behavior of the DLC coating. Table 4 shows the effect of counter face on the wear behavior of the DLC coating and mating surfaces at humid and dry conditions. !*? Si3N, ball has a lower wear rate in dry condition compared to steel ball. However, when the condition is humid, the steel ball has lower wear rate com- pared to the Si3;N, ball. Thus, some kinds of tribochemical reaction favored the wear property of the steel ball in humid condition. Veverkova et al.'®! found that during the pin-on- disk test, steel versus W—DLC showed higher wear rate com- pared to W—DLC/DLC coating pair, which might be due to tri- bolayer formation in the counter faces. The formation of Hydrogen stabilizes the random covalent network of DLC coating and prevents this network from graphitization. Lubri- cant works as a coolant; when this substance is added, the con- tact temperature remains within the allowable range. Therefore, graphitization will not take place. As a result, tribo- chemical interactions of DLC and additives become dominant. Some researchers found that a-C DLC provides low CoF than a-C:H DLC in lubricated condition. Higher surface energy leads to better interaction with a-C:H DLC. Surface energy is low for a-C:H because of the difference in their molecular structure. When high temperature is generated during the slid- ing friction in contact, sp? to sp” conversion of the bond takes place. This sp- bond type represents the graphite-like
Wear rate and friction coefficient at a load of 1 Kg and 1200 m sliding distance. (© Cambridge University Press. Reproduced with permission of Jia et al.'*° Permission to reuse must be obtained from the rightsholder)
Wear rate and friction coefficient at a load of 1 Kg and 1200 m sliding distance. (© Cambridge University Press. Reproduced with permission of Jia et al.'*° Permission to reuse must be obtained from the rightsholder)
FIG. 10. (A) Wear loss and (B) coefficient of friction of selected material combinations using mineral oils with additives (A W/ EP and EP) and without additives. (© Elsevier. Modified with permission of Kalin and Vizintin.'*? Permission to reuse must be obtained from the rightsholder.)
FIG. 10. (A) Wear loss and (B) coefficient of friction of selected material combinations using mineral oils with additives (A W/ EP and EP) and without additives. (© Elsevier. Modified with permission of Kalin and Vizintin.'*? Permission to reuse must be obtained from the rightsholder.)
FIG. 11. (a) Wear loss and (b) coefficient of friction of selected material combinations with sunflower oil with additives (AW/ EP and EP) and without additives. (© Elsevier. Modified with permission of Kalin and Vizintin.'*? Permission to reuse must be obtained from the rightsholder.) EP additives are additives for lubricants, which have a function in dec reasing the wear of the parts of engine compo- nents exposed to very high pressures. Therefore, the coating to the engine components, which is exposed to high pressure might have the possibility to interact with EP additives. Thus, the study of EP additive to different types of DLC coating interaction has become important. Non doped DLC is compar- atively inert towards the additive coating interaction. How- ever, when t his material is doped with metal, some interactions take place between the DLC and the additive because metal has higher surface energy. Some studies on the tribological characteristics of steel/DLC contacts have been 186, 1 conducted. ~” 89.197 Kalin et al.!7 investigated the interaction of metal-doped (Ti, WC) DLC with EP additive in tribological and static condition. They investigated the wear and friction property of metal doped, non doped, and steel self-mated con- tact in the presence of mineral oil and additive-added mineral oil. In each case, additive-added mineral oil shows lower wear rate; however, no significant change of friction property is observed. The change of wear rate is greater for metal-doped DLC coating. Non doped hydrogenated DLC coating shows low friction in the absence of additive. However, oil additive blend shows higher friction because in the presence of addi- tive, a viscous tribofilm is formed in the non doped hydroge- nated DLC coating surface and this oil additive hinders the motion. Through this reaction, friction increases, but wear property enhances because the tribofilm protects the coating layer.'7!°°:1°8 For uncoated steel surface, maximum wear causes adhesion when tested in oil-lubricated condition. How- ever, when additive is added, adhesion is minimized. Same case is true for metal-doped DLC coating. In every case, tribo- film formation takes place; therefore, different degrees of reac- tivity are observed among different coating surfaces. Kalin 1.!°” showed that Ti-doped DLC coating have high reactiv- ity compared to WC-doped DLC and non doped hydrogenated DLC coating. They observed a difference in phosphorus/sulfur (P/S) ratio after the friction and wear test in the worn surface
FIG. 11. (a) Wear loss and (b) coefficient of friction of selected material combinations with sunflower oil with additives (AW/ EP and EP) and without additives. (© Elsevier. Modified with permission of Kalin and Vizintin.'*? Permission to reuse must be obtained from the rightsholder.) EP additives are additives for lubricants, which have a function in dec reasing the wear of the parts of engine compo- nents exposed to very high pressures. Therefore, the coating to the engine components, which is exposed to high pressure might have the possibility to interact with EP additives. Thus, the study of EP additive to different types of DLC coating interaction has become important. Non doped DLC is compar- atively inert towards the additive coating interaction. How- ever, when t his material is doped with metal, some interactions take place between the DLC and the additive because metal has higher surface energy. Some studies on the tribological characteristics of steel/DLC contacts have been 186, 1 conducted. ~” 89.197 Kalin et al.!7 investigated the interaction of metal-doped (Ti, WC) DLC with EP additive in tribological and static condition. They investigated the wear and friction property of metal doped, non doped, and steel self-mated con- tact in the presence of mineral oil and additive-added mineral oil. In each case, additive-added mineral oil shows lower wear rate; however, no significant change of friction property is observed. The change of wear rate is greater for metal-doped DLC coating. Non doped hydrogenated DLC coating shows low friction in the absence of additive. However, oil additive blend shows higher friction because in the presence of addi- tive, a viscous tribofilm is formed in the non doped hydroge- nated DLC coating surface and this oil additive hinders the motion. Through this reaction, friction increases, but wear property enhances because the tribofilm protects the coating layer.'7!°°:1°8 For uncoated steel surface, maximum wear causes adhesion when tested in oil-lubricated condition. How- ever, when additive is added, adhesion is minimized. Same case is true for metal-doped DLC coating. In every case, tribo- film formation takes place; therefore, different degrees of reac- tivity are observed among different coating surfaces. Kalin 1.!°” showed that Ti-doped DLC coating have high reactiv- ity compared to WC-doped DLC and non doped hydrogenated DLC coating. They observed a difference in phosphorus/sulfur (P/S) ratio after the friction and wear test in the worn surface
FIG. 13 (a) Typical triglyceride composition (vegetable oil) with three different types of fatty acids having different level of saturation (number of double bonds). (b) A schematic of boundary lubrication mechanism on metal surface via adsorp- tion of the polar group from oil or additive. (© Elsevier. Reproduced with permission of Kalin et al.'°° Permission to reuse must be obtained from the rightsholder.) by XPS analysis. P and S come from the additive (EP), the ratio in the additive components is 0.5 (P/S) as shown in Table 4. However, in the worn surface, the ratio is changing because of some reactivity towards the surface. Ti-doped DLC worn surface have 10 times higher P/S ratio compared to the other tested coating surfaces. Oxide formation is actually important. Ti has a higher reactivity with oxygen and forms TiO and TiO. TiO, is the most stable phase of the Ti com- pounds. Friction heating enhances TiO, formation and some
FIG. 13 (a) Typical triglyceride composition (vegetable oil) with three different types of fatty acids having different level of saturation (number of double bonds). (b) A schematic of boundary lubrication mechanism on metal surface via adsorp- tion of the polar group from oil or additive. (© Elsevier. Reproduced with permission of Kalin et al.'°° Permission to reuse must be obtained from the rightsholder.) by XPS analysis. P and S come from the additive (EP), the ratio in the additive components is 0.5 (P/S) as shown in Table 4. However, in the worn surface, the ratio is changing because of some reactivity towards the surface. Ti-doped DLC worn surface have 10 times higher P/S ratio compared to the other tested coating surfaces. Oxide formation is actually important. Ti has a higher reactivity with oxygen and forms TiO and TiO. TiO, is the most stable phase of the Ti com- pounds. Friction heating enhances TiO, formation and some
Fig. 12. Schematic presentation of the effect of polar groups and unsaturation of molecules on tribological properties in metal contacts and oxidation stability of selected oils. (© Elsevier. Reproduced with permission of Kalin et al.!°° Permission to reuse must be obtained from the rightsholder.)
Fig. 12. Schematic presentation of the effect of polar groups and unsaturation of molecules on tribological properties in metal contacts and oxidation stability of selected oils. (© Elsevier. Reproduced with permission of Kalin et al.!°° Permission to reuse must be obtained from the rightsholder.)
Classification and corresponding chemical nomenclature of analyzed additives
Classification and corresponding chemical nomenclature of analyzed additives
FIG. 15. Electrochemical process of the MoS, formation from MoDTC. (© Elsevier. Reproduced with permission of Barros Bouchet et al.'®° Permission to reuse must be obtained from the rightsholder.)
FIG. 15. Electrochemical process of the MoS, formation from MoDTC. (© Elsevier. Reproduced with permission of Barros Bouchet et al.'®° Permission to reuse must be obtained from the rightsholder.)
FIG. 14. Molecular structure: a. Moly dimer and b. Moly trimer. (© Elsevier. Reproduced with permission of Kalin et al.°°° Permission to reuse must be obtained from the rightsholder.)
FIG. 14. Molecular structure: a. Moly dimer and b. Moly trimer. (© Elsevier. Reproduced with permission of Kalin et al.°°° Permission to reuse must be obtained from the rightsholder.)
Related topics:
Condensed Matter PhysicsThin Films and CoatingsImmersion and ExperienceLubrication and FrictionDiamond Like CarbonIon ImplantationWear RateMetal DLC CoatingsHYDROGENATED AMORPHOUS-CARBON
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