Treatment of melt for atomization technology

Abstract

An improved method of manufacturing a powder metal material by water, gas, plasma, or rotating disk atomization is provided. The method includes adding at least one additive to a melted metal material before or during the 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 atomized particles produced include at least one of the following advantages: median circularity of at least 0.60, median roundness of at least 0.60, less internal pores, less internal oxides, and an increased sphericity of the 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 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 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 median circularity of the particles is at least 0.60. 
     
     
         3 . The method of  claim 1 , wherein the median roundness of the particles is at least 0.60. 
     
     
         4 . The method of  claim 1  further including the step of heat treating the particles after the atomization step to form microstructural constituents or phases, the microstructural constituents or phases have a median circularity of at least 0.60 and a median roundness of at least 0.60. 
     
     
         5 . The method of  claim 4 , wherein the metal material is an iron-based material, the at least one additive includes magnesium, the microstructural constituents or phases are graphite precipitates and/or carbides and/or nitrides, and the phases and/or constituents have a median circularity of at least 0.60 and a median roundness of at least 0.60. 
     
     
         6 . The method of  claim 1 , wherein the atomizing step includes water atomizing, gas atomizing, plasma atomizing, or rotating disk atomizing. 
     
     
         7 . The method of  claim 6 , wherein the atomizing step includes water atomizing, and the water atomizing step includes applying water at a pressure of 2 MPa to 150 MPa and above to the melted metal material. 
     
     
         8 . The method of  claim 1 , wherein the 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 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). 
     
     
         9 . The method of  claim 8 , wherein the at least one additive added to the base metal material includes at least one of: K, Na, Zn, Mg, Li, Sr, Ca, and Ba. 
     
     
         10 . The method of  claim 8 , wherein the base metal material is an iron-based material, and the at least one additive forming the protective gas atmosphere includes at least one of: K, Na, Zn, Mg, Li, Sr, and Ca. 
     
     
         11 . The method of  claim 8 , wherein the 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 to react with the sulfur. 
     
     
         12 . The method of  claim 8 , wherein the 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 to react with the at least one oxide. 
     
     
         13 . The method of  claim 8 , wherein the base metal material is iron-based and includes sulfur and 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, Sr, and Ca; and the at least one additive also reacts with the sulfur and the at least one oxide. 
     
     
         14 . The method of  claim 8 , wherein the 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. 
     
     
         15 . The method of  claim 8 , wherein the base metal material is titanium-based and includes sulfur and/or 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, 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. 
     
     
         16 . The method of  claim 8 , wherein the 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. 
     
     
         17 . The method of  claim 8 , wherein the 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. 
     
     
         18 . The method of  claim 8 , wherein the at least one additive includes Mg. 
     
     
         19 . A water atomized powder metal material, comprising:
 a plurality of atomized particles formed from a base metal material and at least one additive, wherein the atomized particles have a median circularity of least 0.60 and a median roundness of at least 0.60.   
     
     
         20 . The powder metal material of  claim 19 , wherein the 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 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). 
     
     
         21 . The method of  claim 20 , wherein the at least one additive includes at least one of: K, Na, Zn, Mg, Li, Sr, Ca, and Ba. 
     
     
         22 . A water atomized powder metal material, comprising:
 a plurality of atomized particles formed from a base metal material and at least one additive, wherein the atomized particles include microstructural constituents or phases, and at microstructural constituents or phases have a median circularity of at least 0.60 and a median roundness of at least 0.60.   
     
     
         23 . The powder metal material of  claim 22 , wherein the 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 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). 
     
     
         24 . The method of  claim 23 , wherein the at least one additive includes at least one of:
 K, Na, Zn, Mg, Li, Sr, Ca, and Ba.   
     
     
         25 . The powder metal material of  claim 23 , wherein the base metal material is an iron-based material, the at least one additive includes Mg, the microstructural constituents or phases are graphite precipitates, and the graphite precipitates have a have a median circularity of 0.60 and a median roundness of 0.60.