A study of the stability of pyrolytic carbon-coated Fe/SiO2 composites in HNO3 and the effect of pyrolysis temperatures on their magnetic properties

Fe/SiO2 composites prepared by a sol–gel combined hydrogen reduction method were coated with carbon by the pyrolysis of acetylene. Scanning electron microscopy (SEM) showed that the as-prepared sample consists of only carbon-coated Fe/SiO2 particles without the presence of one-dimensional carbon or any other unwanted carbon formation. The stability of the Fe/SiO2 composites under a HNO3 solution at room temperature was greatly enhanced after they were coated with carbon. The effect of pyrolysis temperatures was also studied.