THE MECHANISM OF FRICTION BETWEEN SURFACES WITH REGULAR MICRO GROOVES UNDER BOUNDARY LUBRICATION

The results of researches related to the influence of partially regular microrelief parameters on the adhesion component of the friction factor under boundary lubrication have been given. A special ring-on tape test rig is proposed in order to avoid errors during running-in process. Special technique is used to form sinusoidal microgrooves what helped to create a partially regular microrelief on the surface with controlled contour and nominal contact areas. Fatigue and deformation components of wear process are considered. We proved that microtexturing with proposed parameters decreases the adhesion component of friction and reduces the probability of microwelding. It has been shown that under boundary friction micro grooves are effective on precision surfaces with low roughness when lack of film and probability of seizure appear

FUNCTIONAL PLASMA-DEPOSITED COATINGS

The paper focuses on the problem of low adhesion of plasma sprayed coatings to the substrate. The subsequent laser treatment modes and their influence on the coatingsubstrate interface were studied. This allows to decrease the level of met-stability of the coating, thus decreasing its hardness down to 11–12 GPa on the surface and to about 9 GPa on depth of 400 µm. The redistribution of alloying elements through solid and liquid diffusion improves mechanical properties and rises the adhesion up to 450 MPa after remelting and up to 90–110 MPa after laser-aided thermal cycling. At the same time, remelting of coating helps to decrease its porosity down to 1%. The obtained complex of properties also allows to improve wear resistance of coatings and to decrease friction factor

GRADIENT COMPOSITE COATINGS FOR WORKING SURFACES OF BRAKING DEVICES

In this paper a study to develop a composite wear-resistant coatings for application to the working surface of linings of brake devices, which is based on a rule of a positive gradient of mechanical properties was carried out. These devices and so coatings work in conditions of rapid rise of temperature. Thermal properties of matrix and inclusions should not differ a lot. Otherwise this will cause internal cracking and deterioration of coating. With this purpose we did the analyses of thermal properties of matrix and carbide particles of coating and concluded thet a material with balanced composition based on thermal properties will have the best wear resistance It was created and tested eutectic composites based on alloy steel 12X18H9T based on thermal characteristics of all components. Wear tests indicated the best wear resistance of coating with composition: steel 12X18H9T (matrix) - 75%; fillers TiB2 - 10%, VC - 15%

Functional Plasma-Deposited Coatings

The paper focuses on the problem of low adhesion of plasma sprayed coatings to the substrate. The subsequent laser treatment modes and their influence on the coating-substrate interface were studied. This allows to decrease the level of metstability of the coating, thus decreasing its hardness down to 11-12 GPa on the surface and to about 9 GPa on depth of 400 µm. The redistribution of alloying elements through solid and liquid diffusion improves mechanical properties and rises the adhesion up to 450 MPa after remelting and up to 90-110 MPa after laser-aided thermal cycling. At he same time, remelting of coating helps to decrease its porosity down to 1%. Obtained complex of properties also allows to improve wear resistance of coatings and to decrease friction factor

Fretting-Wear Mechanism of Textured Surfaces

The wear mechanism of textured dimpled in conditions of lubricated fretting-wear is established, which, in contrast to others, takes into account possibility of removing deterioration products out of tribo-contact areas into dimples, preventing their action as abrasive material. Selection of optimal structural parameters of selectively dimpled areas allows to reduce duration of tribological couple running-in time. Depending on texture type, friction coefficient was reduced from 0.27 (for untreated furface) to 0.18, and wear loss – from 7.8 ×10–3g to 3.3 ×10–3g

Теоретичні основи та технології нанесення зносостійких евтектичних покриттів

In this work we propose a new view to natural composite materials - multicomponent eutectic alloys, which may be used for broad variety of applications - manufacturing and recovery of turbine blades, stator vanes, metallurgical furnaces, quick closing equipment, cutting tools etc. These wear resistant materials may be used for manufacturing or modification of heavy duty components, so significant part of current work is devoted to overview and development of efficient coating deposition technologies - plasma and gas spray, laser alloying and surface engineering. We also evaluate the effects of deposition processes parameters on microstructures, mechanical properties and wear resistance of coatings being investigated

Теоретичні основи та технології нанесення зносостійких евтектичних покриттів

In this work we propose a new view to natural composite materials - multicomponent eutectic alloys, which may be used for broad variety of applications - manufacturing and recovery of turbine blades, stator vanes, metallurgical furnaces, quick closing equipment, cutting tools etc. These wear resistant materials may be used for manufacturing or modification of heavy duty components, so significant part of current work is devoted to overview and development of efficient coating deposition technologies - plasma and gas spray, laser alloying and surface engineering. We also evaluate the effects of deposition processes parameters on microstructures, mechanical properties and wear resistance of coatings being investigated