Abstract: A transparent soluble polyimide resin was dissolved in N,N-dimethyacetamide, and a sample solution whose concentration was 10 weight percent was produced. This sample solution is put in a container CNT which is attached to an apparatus shown in FIG. 1, whereby a nanofiber structure was produced. The produced polyimide nanofiber structure acquired the excellent water resistance, air permeability and moisture permeability while maintaining the physical properties inherent in a polyimide, such as high heat resistance and insulation. Further, when a nanofiber structure is produced in a similar manner from a different polyimide resin, the nanofiber structure maintains excellent adhesiveness.

Abstract: A working tool and a cladding device are interchangeably mounted on a working head of a working apparatus. First, in a condition in which the working tool is attached to the working head, a die blank is subjected to profiling, and also a predetermined portion is cut to thereby form a beveled portion Then, the working tool on the working head is changed to a cladding device to thereby perform cladding on the beveled portion with a required material. Thereafter, the cladding device on the working head is changed again to the working tool to thereby finish the clad portion into a predetermined shape.

Abstract: The composition of a hard-facing welding material to be overlaid onto a cast iron base metal followed by a supercooling treatment for hardening must lie above a line LA in a Schaeffler's structure diagram which is represented by a Cr equivalent and a Ni equivalent. On the other hand, if the base metal is preheated, the carbon precipitation line will be at the Ni equivalent of 34 (LC1), and the Cr equivalent will thus be above 4. However, if the Cr equivalent is above 4, there will occur cracks after welding (examples in which cracks occurred are shown by square marks represented by a in FIG. 1). As a solution, the carbon precipitation line was raised up to the Ni equivalent of 38 without preheating the base metal, and the Cr equivalent of the welding material was made to be 4 or less.

Abstract: A metallic press die having an edge portion or high pressure portion for processing a workpiece therewith is made by overlaying a welding material to that portion of a base material for the metallic press die which forms the edge portion or high pressure portion, and then machining an overlaid portion into a predetermined shape of the edge portion or high pressure portion. The welding material has a hardness after welding of HRC 45 or below. After the machining step, the overlaid portion is subjected to a subzero treatment to increase the hardness of the overlaid portion. The welding material contains, as a basic composition thereof, 0.5-1.5% by weight of carbon (C), 0.2 -2.0% by weight of silicon (Si), 0.3-6.0% by weight of manganese (Mn), 0.3-10.0% by weight of chromium (Cr), 0.3-10.0% by weight of cobalt (Co), and the remaining parts of iron (Fe) inclusive of unavoidable impurities, and wherein a starting temperature of martensitic transformation is 150 .degree. C. or below.