A couple ways you could try: one is by spinning coating (create a TiO2 suspension and spin coat it on the surface of carbon steel; two is by dipping the carbon steel into the TiO2 suspension multiple times (depending on how thick of the layer you want). Hope this helps.

Personally I believe that the powder is of little use to you unless you can incorporate it as say part of a powder coating (an epoxy based would provide best temperature resistance too) and apply it to the steel substrate in the normal (electrostatic spray) manner.  Indeed a normal white colored powder coating (as applied to fridges, cookers etc) would provide you with corrosion resistance at a much lower cost than that of expensive (pure) TiO2. Your powder is a fused collection of post- and sub-micron aggregates and no free, independent particles of 25 nm exist.  See:.

Nov 11th, 2008. Dispersion and nanotechnology  http://tinyurl.com/hpywsge

and: November 3rd, 2015 Adhesion and cohesion  http://tinyurl.com/zwb2wlh

In order to provide a sol-gel type solution suitable for dip or spin coating you need the TiO2 in solubilized form - the isopropoxide is extensively utilized - followed by your coating process and then a subsequent firing or sintering process to produce the thin film.