Study On Preparation And Tribological Properties Of TiMoAgN Solid Lubricating Coating Materials

In cutting-edge industries such as aerospace,the operating environment of some key models of transmission components is becoming more and more demanding.Conventional lubricants or lubricating coatings have been difficult to meet the high requirements of service conditions:such as MoS2,WS2 and other layered compounds under high load conditions.Soft metals such as Ag,Pb,Zn and other self-lubricants increase the wear rate due to extrusion damage.While some high-hard compounds or oxides such as CaF2,CoO,PbO and others form abrasive wear due to embrittlement,increase the friction coefficient,and lose the lubricating effect.In addition,under high temperature conditions,rapid oxidation of some lubricants will also accelerate the failure of lubricants.Therefore,how to make lubricating materials or coatings have multiple functions such as self-lubrication,friction reduction,wear resistance and oxidation resistance is the main trend in the development of self-lubricating composite materials/coatings.This thesis proposes a Ti,Mo,Ag,N solid lubricating material system for the performance requirements of precision basic parts such as rotating seals and high-temperature bearings under load conditions.Using Ag and Ag-Mo composite solid lubricants as the lubricating phase,a TiMoAg composite material was first prepared by plasma sintering(SPS)technology.On this basis,a TiMoAgN coating lubricating material was prepared on the 316L stainless steel substrate by using multi-arc ion plating(AIP)technology,using TiN as the hard phase,and Ag,Mo and their compounds as the lubricant.In order to achieve the goal of self-lubricating with low wear rate and low coefficient of friction by relying on the synergistic effect of multiple lubricants in the material at different temperatures.In this paper,X-ray diffractometer(XRD),scanning electron microscope with energy spectrometer(SEM/EDS)and other analytical methods are used to study the effects of Ag on Ti-based composites and multi-arc target process parameters on the microstructure,mechanics,friction and wear properties of the prepared nitride coating at room temperature.The main research work is as follows:For C0Ag(90 wt%Ti+10 wt%Mo)and C15Ag(75 wt%Ti+10 wt%Mo+15 wt%Ag)two composite materials,the effect of the addition of Ag on the micro structure and properties of the composite be positive.The fine and uniform Ag elements are widely distributed at the contact interface between the Ti element-enriched phase and the Mo element-enriched phase,which improves the plastic toughness of the material while maintaining the hardness.After the micron Ag,the friction coefficient is significantly reduced by about 0.2,and the lubricating performance is excellent.The surface morphology of the wear scar looks very smooth,and a smooth lubricating film is formed in most areas.There is no lubricating film formed on the surface of C0Ag wear scars.Due to the effect of cyclic stress,some debris is formed on the surface of the wear scar due to fatigue displacement,and the presence of wear debris causes abrasive wear on the surface of the C0Ag material.Therefore,the surface of C15Ag material with 15 wt%of micron Ag can form a smooth lubricating film during the physical and chemical process of load,pressure and friction and heat generation.So C15Ag composite material has a low friction coefficient and low wear rate.For the multi-arc targets prepared by C15Ag composite materials,the nitride coatings prepared under different process parameters can contain Ag in a single substance state.And the process parameters are different,the Ag content in the coating is different.Different substrate bias,nitrogen partial pressure and other factors affect the color,.structure,composition and other properties of the coating.When the partial pressure of nitrogen increases,the color of the film will change from light yellow to grayish brown.Comparing it with TiN and 316L stainless steel substrates in order to better explain the friction and wear performance of the coating,,it is found that in the high Ag coating prepared by multi-arc ion plating technology,Ag can be precipitated on the friction surface to form a smooth lubricating film at room temperature.And the physical process of load compression and friction heat generation during the friction process can promote the process of precipitation of Ag to the friction surface to form a smooth lubricating film.The high Ag coating prepared by multi-arc ion plating technology achieves a self-lubricating effect with low friction coefficient(0.1?0.2)and low wear rate(4.61 ×10-5 mm3 ·N-1·m-1).