The Research Of Flame Retardant Modification And Performance Of Solid Lubricanting Materials Used In Locomotive Wheel/Rail

In this paper solid lubricating materials were flame retarded respectively byhalogen flame retardant decabrominated diphenyethane （DBDPE）, antimonous oxide（Sb₂O₃） and halogen-free intumescent flame retardant ammonium polyphosphate（APP）. As for halogen flame retardant, we studied first the proportion ofDBDPE-Sb₂O₃by the single factor method and determined the optimal proportion.Then the total amount of the halogen flame retardant additives were analyzed.Weused orthogonal experiment methods to optimize conditions of the diatomitepurification experiment.We treated the magnesium hydroxide and aluminumhydroxide with silane coupling agent and researched their relationship with halogenflame retardants.The purified diatomite were tested by ultraviolet spectrophotometer,bulk density and water absorption.The flame retardant solid lubricating materialswere tested by limiting oxygen index（LOI）, hardness and friction performance.Thispaper also studied the mechanism of diatomite influencing LOI of the solidlubricating materials.As for intumescent flame retardant, we determined the optimal proportion ofthree components system of ammonium polyphosphate （APP）, pentaerythritol （PER）and melamine proportion （MEL）. Then microencapsulated ammonium polyphosphate（MAPP） with melamine formaldehyde resin coating layer was prepared by in situpolymerization and characterized by Fourier-transform infrared （FTIR）, transmissionphotoelectron spectroscopy （TEM）.The solid lubricating materials treated by kinds ofintumescent flame retardant were tested by LOI, hardness, impact strength andfriction performance.Main conclusions as follow:（1） The effect of halogen flame retardant is superior to that of halogen-freeflame retardants. Halogen-free flame retardant produced black smoke and meltdripping phenomenon during burning process, halogen-free flame retardants did notproduce black smoke.（2） Proportional relationship of flame retardant DBDPE-Sb₂O₃has anoptimal values，DBDPE:Sb₂O₃=3:1. When the amount of DBDPE-Sb₂O₃ reaching30w%of solid lubricating material was added into compound, LOI of theflame retardant solid lubricating materials improved to29.3%.（3） The conditions for the purification of diatomite: calcination temperature700℃, acid concentration25%, acid soak time6h.（4） When its content belows1%, diatomite can improve the LOI of flameretardant solid lubricating material system. However, diatomite contents more than1%, the LOI values of flame retardant solid lubricating materials declined. When1%diatomite was added into compound, LOI improved from29.3%to31.5%.（5） It easy to achieve smoke suppressive effect with large amount of hydroxides.But introducing a small amount of hydroxides will damage effect ofDBDPE-Sb₂O₃and severely reduce the LOI values.（6） The compatibility of APP with solid lubricating material is poor; thecross-sectional surface of flame retardant solid lubricating materials flame retarded byAPP can clearly see many white spots.（7） Through water solubility and LOI, we determined the preparation process ofMAPP by melamine: formaldehyde=1:3, coating amount for20%of the mass ofMAPP. We finally got MAPP coated completely and its flame retardant effect wasexcellent.（8） Carbon agent PER working with APP or MAPP was advantageous to theLOI of the system. We determined the best flame retardant formula for MAPP:PER=3:1by the amount of30w%.