Microstructure And Properties Of FeCrMoBC Amorphous Coating Prepared By Air Plasma Spraying

Surface coating technology is often used to improve the wear resistance and corrosion resistance of component surfaces.Among them,Fe-based amorphous alloys have obvious advantages in terms of strength and hardness;at the same time,Fe-based amorphous alloys have price advantages.However,the brittleness of Fe-based amorphous and the limited critical size limit its application potential as a bulk structural member.The preparation of amorphous alloys as amorphous coatings can take advantage of its excellent properties,but it is also not subject to brittleness and preparation size.Therefore,Fe-based amorphous coatings have been used in certain industrial applications.FeCrMoBC amorphous alloy has received much attention because of its high glass forming ability,excellent thermal stability,strong resistance to crystallization,excellent wear resistan ce and corrosion resistance.However,due to the complexity of its composition,the crystallization mechanism of its high-temperature precipitation phase sequence,phase nucleation and growth mechanism is still unclear,so it is urgent to systematically st udy its crystallization kinetics.On this basis,the amorphous coating was prepared through different process parameters and the best spraying process was determined.The nano-indentation technology was used to study the indentation creep performance of th e amorphous coating,and the peak load and loading rate were analyzed for the Fe-based amorphous coating.The effect of layer creep performance;finally explore the effect of heat treatment on the structure,hardness,scratch behavior,corrosion resistance and wettability of amorphous coatings.The following main conclusions were obtained:?1?FeCrMoBC amorphous alloy exhibits excellent glass forming ability.In the non-isothermal crystallization process heated to a high temperature at a constant heating rate,the phase sequence is:?-Fe,M_{2 3}?C,B?₆,M₇C₃ and Fe Mo₂B₂?M=Fe,Cr,Mo?.The crystallization activation energy of the amorphous powder obtained by the Kissinger method is between 385 and 557 KJ/mol,which is higher than that of most iron-based amorphous alloys reported so far.Crystallization mechanism research shows that the first and fourth crystallization events are controlled by diffusion,and the second and third crystallization events are mainly controlled by grain growth.?2?The best spraying process for preparing FeCrMoBC amorphous coating by atmospheric plasma spraying technology is:spraying voltage 50 V,spraying current680 A.The amorphous coating has a dense structure with a thickness of about 300?m.The indentation creep behavior stud y shows that:the hardness and elastic modulus of the amorphous coating decrease with the increase of peak load;the higher the peak load,the lower the strain gradient under the indenter,the stronger the creep resistance;and the high load In the rate mo de,more free volume will accumulate during the loading process,causing the creep resistance of the amorphous coating to decrease.?3?The hardness of the coating increases after partial crystallization and complete crystallization after annealing.The sc ratch resistance of the coating does not show dependence on the scraping rate.The friction coefficient of the amorphous coating in the prepared state and the relaxed state is close to 0.2,while the friction coefficient of the crystallization coating is h igher.The coatings annealed at 500?showed the best corrosion resistance,and the amorphous/nanocrystalline coatings annealed at 650?had the worst corrosion resistance.The higher the wetting angle of the coating,the higher the self-corrosion potential of the coating,and the better the corresponding corrosion resistance.