Investigation of the wear properties of duplex Ni-P/Ni-Mo BN(h) composite coatings

Among the many metal alloy coatings, nickel alloys have a growing appeal in both scientific and industrial fields due to their high hardness and wear resistance. Current Ni-P coatings have a long plating bath life and high plating speed. Molybdenum alloys; Due to molybdenum's high melting point and high hardness at high temperatures, it is widely used in high temperature applications where wear resistance is required. Molybdenum cannot be obtained from aqueous solutions in the form of flow coating, but can be deposited with iron group metals such as nickel. One of the most important parameters affecting the coating property in electrodeposition is the type of current applied. During the application of electrodeposition; direct current, pulse current and pulse reverse current methods can be used. Since high current or high potential can be applied for a short time in pulse and pulse reverse coatings, and even the direction of these parameters can be reversed, these techniques lead to the formation of crystals that can be hybrid in character and exhibit better properties.Hexagonal BN (BN(h)) has an important place in potential engineering applications due to its high hardness, excellent lubricity, programmability in high temperature and corrosive environments. Due to the oxidation resistance of BN at high temperatures, BN nano sheets are a potential reinforcing element for nickel matrix composite coatings that can continue to be applied at high temperatures. İn this thesis, duplex Ni-P / Ni-Mo-BN (h) coatings will be applied to steel supports using direct current, pulse current and pulse reverse current methods. BN(h) will be produced in the form of 2D nano sheets by metallothermic reduction method by means of molten salt. Duplex coatings provide an advantage over a single layer for certain applications where the individual coating does not provide the necessary physical / mechanical properties. Ni-P coatings are chosen as inner layers because of their good adhesion to steel. Ni-Mo-BN(h) coating was chosen as the outer layer due to its high wear resistance. Ni-P and Ni-P / Ni-Mo-BN (h) coatings will be deposited by pulse reverse methods to protect the steel surface against abrasion at high temperatures.