Foundry casting elements and methods of forming the same, the methods including: forming an aqueous slurry including an inorganic binder precursor, shaping the slurry using a pattern, curing the shaped slurry using a low temperature solidification process to form a casting element, and removing the pattern from the casting element.

Provided is a joining structure between metal and resin which has improved junction strength. A joining joint has a hand-drum shape having a constricted portion constricted between both of the bottom surfaces by forming a groove-shaped recess in a circumferential direction of a substantially cylindrical side surface made of metal. Upper and lower end portions of the side surface and the recess form a rough concavo-convex shape, and the side surface including the recess becomes a junction surface. On the junction surface, a fine concavo-convex shape with arithmetic average roughness Ra of 10 to 300 m is formed. By forming the rough concavo-convex shape and the fine concavo-convex shape on the junction surface, the joining joint makes strong joining to resin.