Methods for Preparation of Extremely Fine Superalloy Powders and Fabrication to211 Superalloy Parts

摘要

Experiments were conducted using nickel sulfate along with different additives211u001eand either hydrazine, sodium borohydride, or sodium hypophosphite. Test results 211u001ewith hydrazine as the reducing agent did not appear to result in metal powder 211u001eformation as shown in Figure 1, thus further testing with hydrazine was 211u001esuspended. Testing using sodium borohydride and sodium hypophosphite resulted in 211u001emetal-like powders when the proper amount of reducing agent and other additives 211u001ewas present. Chemical analyses on the final powders show that a final powder of 211u001eat least 80% nickel can be produced using either sodium borohydride or sodium 211u001ehypophosphite as the reducing agent. Results also show that recoveries using 211u001eeither of these reducing agents can be greater than 90% under proper conditions. 211u001eIn most tests involving sodium hypophosphate, a small (50 mg) chip of magnesium 211u001ewas added in order to initiate the powder formation. Tests with sodium 211u001eborohydride did not require the use of the magnesium chip. Both the chemical 211u001eadditive(s) and quantity and type of reducing agent had a significant effect upon 211u001eboth the nickel powder grade and recovery. In general, nickel recovery increased 211u001eas the concentration of reducing agent increased.