ИСТИНА

A new type nanocomposite of diamond like carbon (DLC) namely nanostructural coating-orientants and dynamic metallization process is developed to produce thick (DLC + aluminum, copper, zinc, nickel) coating on any metal or ceramic substrates. New type nanocomposite is considered having at present time no analogues in triboengineering. Authors have made a number of theoretical and experimental studies directed to optimal synthesis parameters finding, coatings structure and tribological characteristics analyzing and establishing correlation between the mentioned factors (the triad “synthesis parameters- structure-performances”). Nanocomposite using allows simplifying the composition of coatings-orientants and thick metal coatings by reducing amount of antifriction, antiwear, etc. It consists of a surface treatment process in which а mixture of solid metal and ceramic powders are accelerated by compressed air at pressures between 0.5 and 0.8 MPa. This supersonic blasting method includes the mixing of a metal powder with compressed air at a stagnation pressure of 1.0 MPa and acceleration of this, mixed jet in the supersonic nozzle. Last decade, the process of thick metal coating of surfaces by the supersonic jet of tine solid metal particles, called Cold Spray, was extensively investigated. The main process parameters revealed are the necessity of a critical particle velocity and the development of adiabatic shear instability at the interface followed by a particle intensive plastic deformation. Both processes consist of the acceleration of solid metal particles by a compressed gas jet. The main difference between these two processes is the particle velocities. To produce a thick coating instead of a thin one, the accelerated particles have to overcome the critical velocity. While both processes use supersonic nozzles to accelerate the particles, the practical difference is related to the stagnation pressure of the accelerating gas. The declared stagnation jet pressure is 1 -3MPa for Cold Spray [4] and 1 MPa for supersonic blasting. The investigation of the supersonic blasting process revealed the possibility lo produce thick metal coatings instead of thin ones by using a mined metal ceramic powder mixture with jet velocity lower than the critical velocity in Cold Spray. The coating deposition efficiency by new technology depends on the metal powder ceramic powder mixture ratio and is less than of Cold Spray. But because of the low requirements to the accelerating gas (compressed air at pressures of 0,5 - 0,8 MPa), it is used in various applications, particularly in repair, service and production of high cost manufacturing products.