Permanent casting methods

Copper alloys such as the brasses and bronzes can be cast by either the sand-casting or permanent mould cast methods. The alloys casts in permanent mould condition have greater corrosion resistance than the sand-cast alloys.52 This difference has been attributed to the greater porosity of the alloys in sand-cast conditions. 

Cast aluminum products are produced by s md cast, die cast, and permanent mold casting methods. The alloys and tempers used are unique to castings, and their performance differs significantly from wrought products. 

Coppers and high copper aEoys can be successhEly cast using the centrifugal, continuous, investment, permanent, plaster, and sand molding methods. 

Properties of copper—tin—lead alloys are Hsted in Table 10. The members of the tin bronze alloy group are cast using the centrifugal, continuous, permanent, plaster, and sand molding methods. Leaded tin—bronze alloys have minimum tensile strengths of 234—248 MPa (34,000—36,000 psi) as cast in sand molds, whereas the minimum tensile strengths for high leaded tin—bronze alloys are 138—207 MPa (20,000—30,000). The values are based on measurement of test bars cast in sand molds. 

Properties of copper—nickel alloys are Hsted in Table 14. The alloys in the copper—nickel group have been successfully cast using the centrifugal, investment, permanent, and sand molding methods. The minimum tensile strengths on test bars cast in sand molds are 207—310 MPa (30,000—45,000 psi). 

The current study provides a new type of edible, antimicrobial food packaging or wrapping films from food-grade natural fibers or hydrocolloid. Besides film casting, the films can also be produced by compression, extrusion blown methods. The inclusion of PEO hydrocolloid in natural fiber formulations makes films tougher and caused less permanent deformation when the films were subjected to an external force. Since the extrusion and compression were performed in mild conditions, nisin can be incorporated into films without diminishing its antimicrobial activity. 

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