Heat exchange method, heat exchange medium, heat exchange device, patenting method, and carbon-steel wire

Abstract

The present invention provides a novel heat exchange medium to replace lead. A carbon-steel wire 1 A heated in a heating furnace 11 is passed through a bath 12 A filled with a liquid-phase Mg—Al—Ca alloy 20 obtained by melting a Mg—Al—Ca alloy in which the main constituent elements are Mg (magnesium), Al (aluminum) and Ca (calcium). When it passes through the bath 12 A, the carbon-steel wire 1 A, which has been heated for example to about 950° C. in the heating furnace 11 , is cooled to about 550° C. The Mg—Al—Ca alloy is non-toxic and has no environmental impact as well.

What is claimed is: 
     
         1 . A heat exchange method comprising:
 bringing an object into contact with or in close proximity to a liquid-phase Mg—Al—Ca alloy obtained by melting an Mg—Al—Ca alloy in which Mg, Al and Ca are main constituent elements; and   exchanging thermal energy between said object and said liquid-phase Mg—Al—Ca alloy.   
     
     
         2 . A heat exchange method according to  claim 1 , wherein said liquid-phase Mg—Al—Ca alloy is a cooling medium for cooling said object. 
     
     
         3 . A heat exchange method according to  claim 1 , wherein said liquid-phase Mg—Al—Ca alloy is a heating medium for heating said object. 
     
     
         4 . A heat exchange method according to  claim 1 , wherein said liquid-phase Mg—Al—Ca alloy has an ignition temperature of 1000° C. or higher. 
     
     
         5 . A heat exchange method according to  claim 1 , wherein said liquid-phase Mg—Al—Ca alloy has a liquidus temperature lower than 640° C. 
     
     
         6 . A heat exchange method according to  claim 1 , wherein said liquid-phase Mg—Al—Ca alloy has a liquidus temperature lower than 550° C. 
     
     
         7 . A heat exchange method according to  claim 1 , wherein the element ratio of Ca is x×0.015 (at %) or higher, where x (at %) is the element ratio of Mg in said liquid-phase Mg—Al—Ca alloy. 
     
     
         8 . A heat exchange method according to  claim 1 , wherein the element ratio of Ca is less than x×0.1+10 (at %), where x (at %) is the element ratio of Mg in said liquid-phase Mg—Al—Ca alloy. 
     
     
         9 . A heat exchange method according to  claim 1 , wherein said object is carbon steel. 
     
     
         10 . A heat exchange medium including a liquid-phase Mg—Al—Ca alloy obtained by melting an Mg—Al—Ca alloy in which Mg, Al and Ca are the main constituent elements. 
     
     
         11 . A heat exchange apparatus having a bath filled with a liquid-phase Mg—Al—Ca alloy obtained by melting an Mg—Al—Ca alloy in which Mg, Al and Ca are main constituent elements. 
     
     
         12 . A heat exchange apparatus according to  claim 11 , wherein a thin film forms on the surface of the liquid-phase Mg—Al—Ca alloy with which said bath is filled. 
     
     
         13 . A patenting treatment comprising:
 passing heated carbon steel through a bath filled with a liquid-phase Mg—Al—Ca alloy obtained by melting an Mg—Al—Ca alloy in which Mg, Al and Ca are main constituent elements; and   cooling the heated carbon steel when it passes through the bath.   
     
     
         14 . A carbon-steel wire obtained by being subjected to a patenting treatment using a liquid-phase Mg—Al—Ca alloy, and to a drawing process. 
     
     
         15 . A carbon-steel wire according to  claim 14 , having a tensile strength higher than that of a carbon-steel wire that has been subjected to a patenting treatment using molten lead. 
     
     
         16 . A carbon-steel wire according to  claim 14 , having a processing limit higher than that of a carbon-steel wire that has been subjected to a patenting treatment using molten lead. 
     
     
         17 . A carbon-steel wire according to  claim 14 , wherein no lead adheres to the surface thereof.