Preparation and characterisation of aluminium pigments coated with silica for corrosion protection

Aluminium pigments with a layer of silica were prepared by a sol–gel method using tetraethoxysilane as precursor and ethylenediamine as catalyst. Under the optimum conditions, the corrosion protection factor can reach 99.3% and average grain almost remains the same size after coating, indicating that the coated aluminium pigments have excellent chemical stability and good dispersibility. FTIR and EDS analyses demonstrate that a layer of silica coating has been formed on the flaky aluminium particle. SEM, AFM and BET analyses show that a smooth and dense silica coating layer has been formed.

Research highlights
► Water and ethylenediamine have great influence on the silica coating process.
► Little aggregate was found between aluminium particles during coating process.
► A layer of smooth and dense silica coating has formed on aluminium particle.
► Silica coating promotes the corrosion protection.