Abstract: To provide at least one of: a powder composition from which a calcined body with similar processability can be produced without requiring the application of different forming conditions and calcination conditions for each composition; a method for producing the powder composition; a calcined body produced from the powder composition; a method for producing the calcined body; and uses thereof. A powder composition including: two or more types of zirconia in which a lanthanoid rare-earth element is dissolved; a transition metal element other than zirconium and hafnium; and a remainder composed of zirconia stabilized only by one or more selected from the group consisting of yttrium, calcium and magnesium, wherein a different lanthanoid rare-earth element is dissolved in each zirconia in which the lanthanoid rare-earth element is dissolved, and a transition metal element content is 1500 ppm or less.

Abstract: A metal tube is formed from a metal tape. The metal tape is rounded to be abutted at the both side edges, and the edge-abutted portion is welded to provide a butt-welded seam. The metal tube includes an inner iron base layer, a chrome layer provided on the base layer, and an outer chrome oxide layer provided on the chrome layer. The chrome oxide layer is preferably toughened at the outer surface to provide an appropriate frictional resistance relative to forming tools.