Self generated protective atmosphere for liquid metals

Abstract

An improved method of manufacturing a cast part by sand casting, permanent mold casting, investment casting, lost foam casting, die casting, or centrifugal casting, or a powder metal material by water, gas, plasma, ultrasonic, or rotating disk atomization is provided. The method includes adding at least one additive to a melted metal material before or during the casting or atomization process. The at least one additive forms a protective gas atmosphere surrounding the melted metal material which is at least three times greater than the volume of melt to be treated. The protective atmosphere prevents introduction or re-introduction of contaminants, such as sulfur (S) and oxygen (O 2 ), into the material. The cast parts or atomized particles produced include at least one of the following advantages: less internal pores, less internal oxides, median circularity of at least 0.60, median roundness of at least 0.60 and increased sphericity of microstructural phases and/or constituents.

What is claimed is: 
     
         1 . A method of manufacturing a powder metal material, comprising the steps of:
 adding at least one additive to a melted base metal material, the at least one additive forming a protective gas atmosphere surrounding the melted base metal material which has a volume of at least three times greater than the volume of the melted base metal material to be treated; and   atomizing the melted base metal material after adding at least some of the at least one additive to produce a plurality of particles.   
     
     
         2 . The method of  claim 1 , wherein the melted base metal material is iron-based, and the at least one additive includes magnesium. 
     
     
         3 . The method of  claim 1 , wherein the atomizing step includes water atomizing, gas atomizing, plasma atomizing, ultrasonic atomization or rotating disk atomizing. 
     
     
         4 . The method of  claim 1 , wherein the melted base metal material includes at least one of aluminum (Al), copper (Cu), manganese (Mn), nickel (Ni), cobalt (Co), iron (Fe), titanium (Ti), and chromium (Cr); and the melted base metal material optionally contains at least one alloying element selected from the group consisting of silver (Ag), boron (B), barium (Ba), beryllium (Be), carbon (C), calcium (Ca), cerium (Ce), gallium (Ga), germanium (Ge) potassium (K), lanthanum (La), lithium (Li), magnesium (Mg), molybdenum (Mo), nitrogen (N), sodium (Na), niobium (Nb), phosphorus (P), sulfur (S), scandium (Sc), silicon (Si), tin (Sn), strontium (Sr), tantalum (Ta), vanadium (V), tungsten (W), yttrium (Y), zinc (Zn), and zirconium (Zr). 
     
     
         5 . The method of  claim 4 , wherein the at least one additive includes at least one of K, Na, Zn, Mg, Li, Sr, Ca, and Ba. 
     
     
         6 . The method of  claim 4 , wherein the melted base metal material is iron-based, and the at least one additive forming the protective gas atmosphere includes at least one of K, Na, Zn, Mg, Li, Sr, and Ca. 
     
     
         7 . The method of  claim 4 , wherein the melted base metal material is iron-based and includes sulfur present as an impurity; and the at least one additive includes at least one of Zn, Mg, Li, Sr, Ca, and Ba. 
     
     
         8 . The method of  claim 4 , wherein the melted base metal material is iron-based and includes at least one oxide present as an impurity; and the at least one additive includes at least one of K, Na, Zn, Mg, Li, Sr, Ca, and Ba. 
     
     
         9 . The method of  claim 4 , wherein the melted base metal material is iron-based and includes sulfur and at least one oxide present as impurities; and the at least one additive forming the protective gas atmosphere includes at least one of Zn, Mg, Li, Sr, and Ca. 
     
     
         10 . The method of  claim 4 , wherein the melted base metal material is an aluminum alloy and includes sulfur and/or at least one oxide present as impurities; the at least one additive forming the protective gas atmosphere includes at least one of K and Na; and the at least one additive includes at least one of K, Na, Mg, Li, Sr, Ca, and Ba to react with the sulfur, and/or the at least one additive includes at least one of K, Na, Mg, Li, Ca to react with the at least one oxide. 
     
     
         11 . The method of  claim 4 , wherein the melted base metal material is titanium-based and includes sulfur and/or at least one oxide present as impurities; the at least one additive forming the protective gas atmosphere includes at least one of Zn, Mg, Li, Ca and Ba; and the at least one additive includes at least one of K, Na, Zn, Mg, Li, Sr, Ca, and Ba to react with the sulfur, and/or the at least one additive includes at least one of Sr, Ca, and Ba to react with the at least one oxide. 
     
     
         12 . The method of  claim 4 , wherein the melted base metal material is a cobalt alloy and includes sulfur and/or at least one oxide present as impurities; the at least one additive forming the protective gas atmosphere includes at least one of K, Na, Li and Ca; and the at least one additive includes at least one of Na, Mg, Li, Sr, Ca, and Ba to react with the sulfur, and/or the at least one additive includes at least one of K, Na, Zn, Mg, Li, Sr, Ca, Ba to react with the at least one oxide. 
     
     
         13 . The method of  claim 4 , wherein the melted base metal material is a chromium alloy and includes sulfur and/or at least one oxide present as impurities; the at least one additive forming the protective gas atmosphere includes at least one of K, Na, Zn, Mg, Li, Sr, Ca and Ba; and the at least one additive includes at least one of K, Na, Zn, Mg, Sr, Ca, and Ba to react with the sulfur, and/or the at least one additive includes at least one of K, Na, Zn, Mg, Li, Sr, Ca, and Ba to react with the at least one oxide. 
     
     
         14 . The method of  claim 4 , wherein the melted base metal material is iron-based; and
 the at least one additive includes Mg.   
     
     
         15 . A method of manufacturing a cast part, comprising the steps of:
 adding at least one additive to a melted base metal material, the at least one additive forming a protective gas atmosphere surrounding the melted base metal material which has a volume of at least three times greater than the volume of the melted base metal material to be treated; and casting the melted metal material after adding at least some of the at least one additive.   
     
     
         16 . The method of  claim 15 , wherein the melted base metal material is iron-based, and the at least one additive includes magnesium. 
     
     
         17 . The method of  claim 15 , wherein the casting step includes sand casting, permanent mold casting, investment casting, lost foam casting, die casting, or centrifugal casting. 
     
     
         18 . The method of  claim 15 , wherein the melted base metal material includes at least one of aluminum (Al), copper (Cu), manganese (Mn), nickel (Ni), cobalt (Co), iron (Fe), titanium (Ti), and chromium (Cr); and the melted base metal material optionally contains at least one alloying element selected from the group consisting of silver (Ag), boron (B), barium (Ba), beryllium (Be), carbon (C), calcium (Ca), cerium (Ce), gallium (Ga), germanium (Ge) potassium (K), lanthanum (La), lithium (Li), magnesium (Mg), molybdenum (Mo), nitrogen (N), sodium (Na), niobium (Nb), phosphorus (P), sulfur (S), scandium (Sc), silicon (Si), tin (Sn), strontium (Sr), tantalum (Ta), vanadium (V), tungsten (W), yttrium (Y), zinc (Zn), and zirconium (Zr). 
     
     
         19 . The method of  claim 18 , wherein the at least one additive includes at least one of K, Na, Zn, Mg, Li, Sr, Ca, and Ba. 
     
     
         20 . The method of  claim 18 , wherein the melted base metal material is iron-based, and the at least one additive forming the protective gas atmosphere includes at least one of K, Na, Zn, Mg, Li, Sr, and Ca. 
     
     
         21 . The method of  claim 18 , wherein the melted base metal material is iron-based and includes sulfur present as an impurity; and the at least one additive includes at least one of Zn, Mg, Li, Sr, Ca, and Ba. 
     
     
         22 . The method of  claim 18 , wherein the melted base metal material is iron-based and includes at least one oxide present as an impurity; and the at least one additive includes at least one of K, Na, Zn, Mg, Li, Sr, Ca, and Ba. 
     
     
         23 . The method of  claim 18 , wherein the melted base metal material is iron-based and includes sulfur and at least one oxide present as impurities; and the at least one additive forming the protective gas atmosphere includes at least one of Zn, Mg, Li, Sr, and Ca. 
     
     
         24 . The method of  claim 18 , wherein the melted base metal material is an aluminum alloy and includes sulfur and/or at least one oxide present as impurities; the at least one additive forming the protective gas atmosphere includes at least one of K and Na; and the at least one additive includes at least one of K, Na, Mg, Li, Sr, Ca, and Ba to react with the sulfur, and/or the at least one additive includes at least one of K, Na, Mg, Li, Ca to react with the at least one oxide. 
     
     
         25 . The method of  claim 18 , wherein the melted base metal material is titanium-based and includes sulfur and/or at least one oxide present as impurities; the at least one additive forming the protective gas atmosphere includes at least one of Zn, Mg, Li, Ca and Ba; and the at least one additive includes at least one of K, Na, Zn, Mg, Li, Sr, Ca, and Ba to react with the sulfur, and/or the at least one additive includes at least one of Sr, Ca, and Ba to react with the at least one oxide. 
     
     
         26 . The method of  claim 18 , wherein the melted base metal material is a cobalt alloy and includes sulfur and/or at least one oxide present as impurities; the at least one additive forming the protective gas atmosphere includes at least one of K, Na, Li and Ca; and the at least one additive includes at least one of Na, Mg, Li, Sr, Ca, and Ba to react with the sulfur, and/or the at least one additive includes at least one of K, Na, Zn, Mg, Li, Sr, Ca, Ba to react with the at least one oxide. 
     
     
         27 . The method of  claim 18 , wherein the melted base metal material is a chromium alloy and includes sulfur and/or at least one oxide present as impurities; the at least one additive forming the protective gas atmosphere includes at least one of K, Na, Zn, Mg, Li, Sr, Ca and Ba;
 and the at least one additive includes at least one of K, Na, Zn, Mg, Sr, Ca, and Ba to react with the sulfur, and/or the at least one additive includes at least one of K, Na, Zn, Mg, Li, Sr, Ca, and Ba to react with the at least one oxide.   
     
     
         28 . The method of  claim 18 , wherein the melted base metal material is iron-based; and the at least one additive includes Mg.