Insulation layer on steel pistons

A method of manufacturing a galleryless piston comprising:

• applying a thermal barrier layer to a body portion of a piston,
• the body portion of the piston being formed of metal, the body portion including an upper wall including an undercrown surface, the undercrown surface being exposed when viewed from an underside of the piston, the upper wall including an upper combustion surface opposite the undercrown surface, the body portion including a ring belt depending from the upper wall,
• the thermal barrier coating being applied to said upper combustion surface and including a ceramic material, the ceramic material of the thermal barrier coating including at least one of ceria stabilized zirconia and a mixture of ceria stabilized zirconia and yttria stabilized zirconia in an amount of 90 to 100 wt. %, based on the total weight of said ceramic material,
• the thermal barrier coating includes a metal bond material containing a superalloy disposed between the ceramic material and the upper combustion surface,
• the thermal barrier coating gradually transitions from 100 wt. % of the metal bond material to 100 wt. % of the ceramic material based on the total weight of the thermal barrier coating,
• an uppermost portion of the thermal barrier coating is formed entirely of the ceramic material, and
• the thermal barrier layer has a thickness of less than 500 microns.