Preparation And Properties Of Fe-based Amorphous Metallic Coatings With High Wear Resistance

Fe-based amorphous alloy,with high hardness and strength,excellent wear and corrosion resistance,is a kind of new metal material with a promising application prospect.However the limited critical amorphous dimensions and poor plasticity are main obstacles for its application as structural material.This problem can be solved by depositing the Fe-based amorphous metallic coating on the tough substrate.The coating retain the excellent wear and corrosion resistance,and can be used in many fields such as earth excavation,drilling,oil and gas production,refining,nuclear power generation and shipping.High velocity air-fuel(HVAF)process with high deposition efficiency is able to prepare thickness-controllable coatings which have high density,hardness and bonding strength and contain low oxides content.HVAF is a kind of effective method to prepare Fe-based amorphous metallic coatings.In this paper,Fe49Cr17.8MO7.2Mn1.8W1.6B15.4C4.6Si2.5 alloy with good glass forming ability was selected.The alloy was fabricated into high wear resistant amorphous metallic coatings by HVAF process.X-ray diffraction,scanning electron microscope,different scanning calorimetry,confocal laser scanning microscope,microhardness tester,3d X-ray topography imaging system,Electrochemical System,friction-abrasion testing machine were used to systematically study the microstructure of atomized powder and coating,and the corrosion and wear resistance of coating.The main conclusions are as follows:(1)The size of the amorphous powder prepared by ultrasonic gas atomization concentrate on 20?40?m,while the oxygen content is 0.046%,the flowabilty is 19.9s/50g.(2)The Fe-based amorphous metallic coating is structurally homogeneous.The oxygen content is as low as 0.68%,while the content of the amorphous phase is up to 84.4%.The hardness is 1080HV and the roughness is 7.681?m.(3)Fe-based amorphous coating exhibits excellent corrosion resistance.In 3.5 wt%NaCl solution,it has an excellent resistance to pitting,with a transpassive potential of IV.The passive region is wide,and the passive current density is 1x10-5A/cm2.(4)Fe-based amorphous coating shows excellent wear resistance.Under the condition of dry sliding friction,coating make up friction pairs with GCr15 and Al2O3 ball respectively.The friction coefficient decrease with the increase of the load.Coupling with GCr15 ball,the wear volume of substrate is 2-3 times as much as coating.The wear mechanism of coating change from abrasive wear to adhesive wear,accompanied by oxidation wear.Coupling with Al2O3 ball,the wear volume of coating is half of substrate.The wear mechanism is the compound of abrasive wear and oxidation wear.Roughness does not affect the steady-state friction coefficient of the coating.The wear volume of the original coating is 8/3 times of the coating that is surface polished.Their wear mechanism is fatigue wear.