Study On Quenching Mechanism Of Phosphor In Metal-based Wear Resistant Indicative Coatings

The novel Self-sensing Wear-resistant coating(Cu-14A1-X/SrAl₂O₄:Eu²⁺,Dy³⁺)not only has good wear and corrosion resistance of high aluminum bronze alloy powder,but also has excellent luminous performance phosphorescent material.This coating can quickly Monitoring the friction and wear conditions,showing an important scientific research value and broad application prospects.The composite tribological coatings with the embedded ceramic sensor materials were prepared by a vacuum-assisted sintering method,thermal spraying,cold spraying technology,electrochemical deposition method and so on.However,the SrAl₂O₄: Eu²⁺,Dy³⁺particles in the coating will quenching and reduce the indication of the coating due to the influence of the coating preparation,such as high temperature,high pressure,metal contact,alloy reaction,mechanical collision and so on.In this paper,the wear-resistant self-sensitive coatings were prepared by vacuum-assisted sintering,supersonic plasma spraying and cold spraying,the factors of affecting the quenching in the metal-based wear-resistant coating were discussed and the reasonable quenching mechanisms were proposed.The self-sensing tribological coatings were prepared at different sintering temperatures by a vacuum-assisted sintering method.The spectral observation shows that the luminous intensity of the coating increases with a certain degree of temperature.The phase structures of SrAl₂O₄ in the coatings were not changed and the crystallization performance is getting better,so the temperature in the sintered coating is not its main influencing factor.In order to study the metal contact quenching,five types of composite coatings were preparation,which formed by luminescent powders dispersed throughout different matrixes?Cu,Fe,Ni,Mn and Cu-14Al-X?.It was found that strontium aluminate was affected by high-aluminum bronze metal powder during the sintering process,which reduced the electron transition probability of the phosphor and weakened the luminescence.The metal Mn in powder has the greatest effect for quenching and the lowest is Ni.The thermal spray coating was prepared by changing the H₂ flow rate by supersonic plasma spray.With the increase of temperature,the coating luminescence performance is reduced,thermal quenching behavior inevitably appeared.XRD results indicated that the coating phase was mainly composed of Al Fe,Al Fe₃,Cu₉Al₄ and SrAl₂O₄,in addition to the luminescent impurity phases SrAl₄O₇ and Sr Fe₂O₄.With the increase of temperature,the strontium aluminate in the coating occurs melting tendency,but the surface of the coating becomes smooth and the holes were reduced.The quenching mechanism of the phosphor is due to the fact that some of the strontium aluminate particles in the coating are heated by plasma high temperature flame to obtain high thermal energy to reach the quenching critical point.These high thermal energy were released by vibration,increasing the probability of no radiation transition.The self-sensing wear-resistant coatings with different volumes of phosphorescent powder were prepared by supersonic plasma spraying and cold spraying,respectively.The deposition rate of the cold spray coating decreased with the increase of the volume fraction of the phosphor,while the thermal spraying coatings show the opposite rule.The strontium aluminate hard particles in the cold spray coating play a good shot peening and tamping effect,which makes the coating thickness increase gradually with the increase of phosphorescent particles,and the surface gradually becomes irregular.When the phosphor powder volume fraction is30%,the phosphor deposition rate of cold spray coating consistent with the thermal spray coating with volume fraction is 25%.The quenching of the phosphor in the cold spray wear-resistant coatings is mainly due to the mechanical action.Because the strontium aluminate particles in the spraying has a great speed,hard particles in will be broken after getting a lot of kinetic energy,which make the particles become smaller and defects increase.The the quenching caused by mechanical force is greater than the heat quenching.