Study On The Preparation And Friction Properties Of CrAlNx Coating On The Surface Of Rolls

The roll is the core component of the tube press.The bending dimension of the metal tube is controlled by two rolls.The dimensional accuracy of the metal tube is controlled by the wear resistance and surface quality of the roll,which has high requirements on the accuracy of the roll size and the seam welding performance.Rolls are prone to breakage,wear,spalling,corrosion,fatigue cracks,winding rolls,sticky rolls,etc.during the working process.Exfoliation,wear and corrosion are typical failure modes.In this paper,the surface of the roll of 45 steel is coated with CrAINx coating by vacuum ion plating.The production process of CrAINx coating was optimized,and the structure,friction and corrosion properties of CrAINx coating were studied.The surface morphology,cross-section structure and coating thickness of the coating were tested by means of scanning electron microscopy(SEM),energy dispersive spectrometer(EDS)and X-ray diffraction(XRD).And the element distribution and compound composition of the surface and cross section of the coating were studied in detail.The tribological properties of CrAINx eoatings under different friction pairs,different loads and different speeds were studied by friction and wear experiments.The corrosion resistance of CrAINx coatings was investigated by electrochemical experiments.The results show that the experimentally prepared CrAINx coating has a background vacuum of 1E10-3Pa,a working vacuum of 1E10-1Pa,and a target current of 160A,Under the conditions of voltage 600V,argon flow rate 700sccm,nitrogen flow rate 500sccm and bias voltage of 65V,SEM test results show that the coating surface is smooth and flat,and the coating is tightly combined with the roll material,no void and curl interface.Under the conditions of GCr15 and Si3N4,the friction coefficient of CrAINx coating decreases with the increase of speed and load.Under the same sliding speed and normal loading conditions,the friction coefficient of CrAINx coating when Si3N4 is equipped with auxiliary parts is smaller than the friction coefficient of GCr15 when it is friction pair.The wear rate of CrAINx coating increases with the increase of loading load.Under the condition of GCrls friction pair,the increase of wear rate increases first and then decreases with the increase of load.Under the condition of Si3N4 with accessory,the increase of wear rate increases with load.With the increase of sliding speed,the wear rate of CrAINx coating increases under the condition of GCr15 with auxiliary parts,and the wear rate of CrAINx coating decreases under the condition of Si3N4 with auxiliary parts.With the increase of sliding speed,the wear rate of CrAINx coating increases under the condition of GCrls with auxiliary parts,and the wear rate of CrAlNx coating decreases under the condition of Si3N4 with accessory parts.The wear mode of CrAINx coating mainly shows the mixed form of adhesive wear and abrasive wear.Due to the good miscibility of the metal friction pair,the adhesion tendency is large,the adhesive wear is easy,and the tearing debris is adhered to form the three-body abrasive grain.It also causes abrasive wear and friction coefficient.Under the condition of Si3N4 with auxiliary parts,due to its high thermodynamic stability and good corrosion resistance,the adhesion tendency is small.The wear pattern of CrAINx coating is mainly represented by abrasive wear.The equilibrium potential,self-corrosion potential and corrosion current of the CrAINx coating are improved.The corrosion resistance of the coating is further improved.