This invention discloses a method for preparing a
fluorine-free heating and insulating riser, relating to the field of
casting technology. The method includes first modifying micron-nano composite aluminum
powder with a
silane coupling agent, then in-situ reducing and loading zero-valent iron-
cerium dioxide catalytic sites, followed by sequentially
coating with phenolic resin and a
potassium nitrate-
manganese dioxide composite
oxygen source, and finally forming a silica shell through interfacial
hydrolysis and condensation to obtain a core-shell structured composite heating agent. Separately, hollow
aluminosilicate microspheres are etched to create pores, then vacuum-impregnated and filled with an organic-inorganic composite
aerogel, followed by hydrophobic modification and
coating with nano-
alumina sol to obtain a composite insulating material. The heating agent is then mixed with the insulating material,
mullite powder,
corundum powder, expandable
graphite, waste glass powder, and a binder, and the mixture is vibrated, compacted, and allowed to cure to obtain the finished product. This invention solves the problems of difficult heating and poor insulation in
fluorine-free risers by constructing a multi-level core-shell heating structure and a porous, multi-level insulating structure.