초록 ▼

A method for forming an investment casting core comprises cutting a patterned core precursor from refractory metal-based sheet. The cutting forms recast along the cuts. An oxide is grown on non-recast areas. The recast is substantially chemically removed but substantially leaving the oxide. The core

A method for forming an investment casting core comprises cutting a patterned core precursor from refractory metal-based sheet. The cutting forms recast along the cuts. An oxide is grown on non-recast areas. The recast is substantially chemically removed but substantially leaving the oxide. The core precursor may then be shaped.

대표청구항 ▼

What is claimed is: 1. A method for forming an investment casting core comprising: cutting a patterned core precursor from refractory metal-based sheet, the cutting forming recast along cuts; growing oxide on non-recast areas; substantially chemically removing the recast but substantially leaving t

What is claimed is: 1. A method for forming an investment casting core comprising: cutting a patterned core precursor from refractory metal-based sheet, the cutting forming recast along cuts; growing oxide on non-recast areas; substantially chemically removing the recast but substantially leaving the oxide; and shaping the core precursor. 2. The method of claim 1 wherein: the cutting comprises laser cutting. 3. The method of claim 1 wherein: the precursor comprises in major weight part molybdenum. 4. The method of claim 1 wherein: the growing comprises thermally growing. 5. The method of claim 1 wherein: the growing comprises heating in air at essentially atmospheric pressure. 6. The method of claim 1 wherein: the substantially chemically removing the recast comprises chemically milling for 25-45 seconds. 7. The method of claim 1 wherein: the substantially chemically removing the recast comprises chemically milling for 20-60 seconds. 8. The method of claim 1 wherein: the substantially chemically removing the recast comprises chemically milling for 20-30 seconds. 9. The method of claim 1 further comprising: chemically removing the oxide. 10. The method of claim 9 wherein: the chemically removing the oxide comprises cleaning with an alkaline cleaning solution. 11. The method of claim 9 wherein the chemically removing the oxide is performed after the substantially chemically removing the recast but before the shaping the core precursor. 12. The method of claim 1 further comprising: casting a nickel-or cobalt-based superalloy over the core; and chemically removing the core from the superalloy. 13. The method of claim 1 further comprising: using the core to sacrificially form cooling passageways in a turbine airfoil. 14. A method for investment casting comprising: forming, according to claim 1, an investment casting core; casting an alloy over said investment casting core; and destructively removing the investment casting. 15. The method of claim 1 wherein: the growing and substantially chemically removing facilitate the shaping by improving resistance to cracking caused by the shaping. 16. The method of claim 1 wherein: the growing is after the cutting. 17. The method of claim 16 wherein; the substantially chemically removing is after the growing; and the shaping is after the substantially chemically removing. 18. The method of claim 1 further comprising coating the core precursor after the shaping. 19. A method for forming an investment casting core comprising: cutting a patterned core precursor from refractory metal sheet, the cutting forming recast along cuts; growing oxide on non-recast areas; and removing the recast areas but substantially leaving the oxide. 20. The method of claim 19 further comprising: using the core to sacrificially form cooling passageways in a turbine airfoil. 21. A method for investment casting comprising: forming, according to claim 19, an investment casting core; casting an alloy over said investment casting core; and destructively removing the investment casting. 22. A method comprising: cutting a patterned core precursor from refractory metal sheet, the cutting forming recast along cuts; growing oxide on non-recast areas; a step for removing the recast areas but substantially leaving the oxide; and shaping the core precursor. 23. The method of claim 22 further comprising a step for removing the oxide. 24. The method of claim 22 further comprising: casting a nickel-or cobalt-based superalloy over the core; and chemically removing the core from the superalloy. 25. A method for forming an investment casting core comprising: cutting a patterned core precursor from refractory metal-based material, the cutting forming recast along cuts; preferentially removing the recast; and shaping the core precursor.