Electrodeposition of molybdenum disulfide dry film lubricant coatings
A method of forming a lubricant coating, a method of coating a bearing surface with a lubricant coating, and a vehicle including a bearing including a lubricant coating. A substrate, such as a bearing, including a surface and an electrode are immersed in an electrolyte bath. The electrolyte bath includes an aqueous electrolyte solution including sodium metabisulfite (Na 2 S 2 O 5 ), sodium molybdate (Na 2 MoO 4 ·2H 2 O), a pH modifier, an anionic surfactant, and water. A first pulsed direct current is applied through the aqueous electrolyte solution using a direct current power supply and a molybdenum disulfide (MoS 2 ) layer is formed on the surface of the substrate.
1 . A method of forming a lubricant coating, comprising:
immersing a substrate including a surface and an electrode in an electrolyte bath, wherein the electrolyte bath includes an aqueous electrolyte solution including sodium metabisulfite (Na 2 S 2 O 5 ), sodium molybdate (Na 2 MoO 4 ·2H 2 O), a pH modifier, an anionic surfactant, and water;
applying a first pulsed direct current through the aqueous electrolyte solution using a direct current power supply, wherein the polarity of the first pulsed direct current causes the substrate to provide an anode and the electrode to provide a cathode; and
forming a molybdenum disulfide (MoS 2 ) layer on the surface of the substrate.
2 . The method of claim 1 , further comprising applying the first pulsed direct current at a peak current density in the range of 5 milliamps per square centimeter (mA/cm{circumflex over ( )}2) to 50 mA/cm{circumflex over ( )}2 for a time period of 5 minutes to twenty minutes, wherein the pulses cycle in the range of 1 second to 4 second and have a duty cycle in the range of 25 percent to 50 percent of the cycle.
3 . The method of claim 2 , further comprising preparing the aqueous electrolyte solution by combining the sodium metabisulfite (Na 2 S 2 O 5 ) in the range of 5 percent and 15 percent by weight of the total weight of the aqueous electrolyte solution, the sodium molybdate (Na 2 MoO 4 ·2H 2 O) in the range of 3 percent and 10 percent by weight of the total weight of the aqueous electrolyte solution, the pH modifier, and the anionic surfactant with the water.
4 . The method of claim 3 , further comprising combining the pH modifier to the aqueous electrolyte solution and adjusting the pH of the aqueous electrolyte solution to a pH in the range of 4.0 to 7.0.
5 . The method of claim 4 , further comprising combining citric acid as the pH modifier.
6 . The method of claim 5 , further comprising combining the anionic surfactant in the range of 5 percent and 15 percent by weight of the total weight of the aqueous electrolyte solution.
7 . The method of claim 2 , further comprising applying a second pulsed direct current through the aqueous electrolyte solution, wherein the polarity causes electrode to provide the anode and the substrate to provide the cathode; and forming a black oxide (Fe 3 O 4 ) layer on the surface of the substrate prior to applying the first pulsed direct current.
8 . The method of claim 7 , wherein applying the second pulsed direct current comprises applying the second pulsed direct current at a peak current density in the range of 5 milliamps per square centimeter (mA/cm{circumflex over ( )}2) to 25 mA/cm{circumflex over ( )}2 for a time period of one minute to five minutes, wherein the pulses cycle in the range of 1 second to 4 seconds and have a duty cycle in the range of 25 percent to 50 percent of the cycle.
9 . The method of claim 8 , wherein the molybdenum disulfide (MoS 2 ) layer is in the range of 0.01 micrometer and 4 micrometers in thickness and the black oxide (Fe 3 O 4 ) layer is in the range of 0.1 micrometer to 3 micrometers in thickness.
10 . The method of claim 1 , further comprising preparing the aqueous electrolyte solution by combining the sodium metabisulfite (Na 2 S 2 O 5 ) present in the range of 8 and 12 percent by weight of the total weight of the aqueous electrolyte solution, the sodium molybdate (Na 2 MoO 4 ·2H 2 O) present in the range of 3 percent and 7 percent by weight of the total weight of the aqueous electrolyte solution, citric acid as the pH modifier present in the range of 1 percent and 3 percent by weight of the total weight of the aqueous electrolyte solution, TEEPOL 601 S as the anionic surfactant present in the range of 8 percent and 12 percent by weight of the total weight of the solution, and the water.
11 . The method of claim 1 , wherein immersing the substrate comprises immersing at least one surface of a bearing.
12 . The method of claim 11 , wherein the bearing is a ball bearing.
13 . The method of claim 11 , wherein the bearing is a journal bearing.
14 . A method of coating a bearing surface with a lubricant coating, comprising:
immersing a bearing including a surface and an electrode in an electrolyte bath, wherein the electrolyte bath includes an aqueous electrolyte solution including sodium metabisulfite (Na 2 S 2 O 5 ), sodium molybdate (Na 2 MoO 4 ·2H 2 O), a pH modifier, an anionic surfactant, and water;
applying a first pulsed direct current through the aqueous electrolyte solution using a direct current power supply, wherein the polarity of the current causes the bearing to provide an anode and the electrode to provide a cathode; and
forming a molybdenum disulfide (MoS 2 ) layer on the surface of the bearing.
15 . The method of claim 14 , further comprising applying the first pulsed direct current at a peak current density in the range of 5 milliamps per square centimeter (mA/cm{circumflex over ( )}2) to 50 mA/cm{circumflex over ( )}2 for a time period of 5 minutes to twenty minutes, wherein the pulses cycle in the range of 1 second to 4 second and have a duty cycle in the range of 25 percent to 50 percent of the cycle.
16 . The method of claim 14 , further comprising applying a second pulsed direct current through the aqueous electrolyte solution, wherein the polarity causes electrode to provide the anode and the bearing to provide the cathode; and forming a black oxide (Fe 3 O 4 ) layer on the surface of the bearing prior to applying the first pulsed direct current.
17 . The method of claim 16 , wherein applying the second pulsed direct current comprises applying the second pulsed direct current at a peak current density in the range of 5 milliamps per square centimeter (mA/cm{circumflex over ( )}2) to 25 mA/cm{circumflex over ( )}2 for a time period of 1 minute to five minutes, wherein the pulses cycle in the range of 1 second to 4 seconds and have a duty cycle in the range of 25 percent to 50 percent of the cycle.
18 . The method of claim 14 , further comprising preparing the aqueous electrolyte solution by combining the sodium metabisulfite (Na 2 S 2 O 5 ) present in the range of 5 percent and 15 percent by weight of the total weight of the aqueous electrolyte solution, the sodium molybdate (Na 2 MoO 4 ·2H 2 O) present in the range of 3 percent and 10 percent by weight of the total weight of the aqueous electrolyte solution, citric acid as the pH modifier present in the range of 1 percent and 3 percent by weight of the total weight of the aqueous electrolyte solution, TEEPOL 601 S as the anionic surfactant present in the range of 5 percent and 15 percent by weight of the total weight of the solution, and the water.
19 . A method of forming a lubricant coating, comprising:
preparing an aqueous electrolyte solution by combining a sodium metabisulfite (Na 2 S 2 O 5 ) present in the range of 5 and 15 percent by weight of the total weight of the aqueous electrolyte solution, a sodium molybdate (Na 2 MoO 4 ·2H 2 O) present in the range of 3 percent and 10 percent by weight of the total weight of the aqueous electrolyte solution, citric acid present in the range of 1 percent and 3 percent by weight of the total weight of the aqueous electrolyte solution, an anionic surfactant present in the range of 5 percent and 15 percent by weight of the total weight of the solution, and water present in the range of 66 percent by weight to 80 percent by weight of the total weight of the solution, wherein the total weight of the solution is 100 percent weight;
immersing a substrate including a surface and an electrode in an electrolyte bath, including the aqueous electrolyte solution, wherein the electrode is an inert electrode material;
applying a first pulsed direct current through the aqueous electrolyte solution using a direct current power supply, wherein the polarity of the first pulsed direct current causes the substrate to provide an anode and the electrode to provide a cathode; and
forming a molybdenum disulfide (MoS 2 ) layer on the surface of the substrate.
20 . The method of claim 19 , further comprising:
applying a second pulsed direct current through the aqueous electrolyte solution, wherein the polarity causes the electrode to provide the anode and the substrate to provide the cathode;
forming a black oxide (Fe 3 O 4 ) layer on the surface of the substrate prior to applying the first pulsed direct current; and
applying the first pulsed direct current at a peak current density in the range of 5 milliamps per square centimeter (mA/cm∧2) to 50 mA/cm∧2 for a time period of 5 minutes to twenty minutes, wherein the pulses cycle in the range of 1 second to 4 second and have a duty cycle in the range of 25 percent to 50 percent of the cycle.