Amorphous Al Uminum-based Alloypowder Filled Polyurethanecoating And Coating Propertiesstudy

Coatings made from polyurethanes can be applied in the aerospace,automobile and floor industries due to the outstanding thermal and chemical stabilities.Recently,much attention has been directed to low infrared emissivity coatings.The inorganic/organic composite coatings have the potential for this application.For instance,Coatings composed of polyurethane（PU）and Al flake powder filler are interesting candidates for applications in thermal control and low infrared emissivity coatings.However,the mechanical properties,especially wear resistance,are still not satisfied and can be further enhanced.To improve the abrasion resistance of the PU/Al coating,in this study,Amorphous Al-based alloy is considered ideal modified filler in organic coatings due to the high strength,low density and excellence mechanical properties.So,the topic has been done in the following.Firstly,amorphous Al-based alloy ribbons were prepared by the method of vacuum rapidly quenching and amorphous Al-based alloy ribbons were broken by ball milling.the ribbons of different compositions and processes were test by XRD and DSC,Al₈₅Ni₅Y₈Co₂ was selected to prepared the amorphous Al-based alloy ribbons at the speed of 30 m/s.The ball milling process was optimized by the test of the XRD and particle size distribution of the powder.Finally,the ball milling processes was continued for 12hours at a speed of 350 r/min with ball ratio of 50:1 in an Ar gas atmosphere.Secondly,the raw material of polyurethane coatings is selected and calculated.the isocyanate content of prepolymer was tested by titration,the reaction temperature and time of the prepolymer are determined.The CASS accelerated salt spray test was used to determine the mixing atmosphere of the double-components polyurethane.The hardness,adhesion,wear resistance,and infrared emissivity of the polyurethane coatings with different content of fillers were measured.The addition of the Al flake powder filler was optimized.The polyurethane prepolymers were stirred for 1.5 h at 80℃in a vacuum environment and the content of the filler added was 8.75 wt.%.Finally,the properties of the coatings with different amorphous Al-based alloy were studied.Microstructure of the coatings examined by scanning electron microscopy（SEM）shows a good distribution of amorphous Al-based alloy in coatings and a well bonding interface.Mechanical properties evaluated by adhesion test,hardness and wear resistance test show that the hardness was improved with the increase of content of amorphous Al-based alloy powders and the wear resistance was optimum when the amorphous Al-based alloy particles content is 57 wt.%in the filler.Corrosion test results revealed that the anti-corrosion properties increased slightly with increasing the amorphous Al-based alloy particles content up to 57 wt.%in the filler,following which it began to decrease.Results of this study can develop a new approach to control the coatings properties and provide guidance for developing the high wear resistance and low infrared emissivity coatings.