Fugitive pattern for casting
View Patent ↗A fugitive pattern for making a shell mold for investment casting a metal or alloy comprises a substantially random interpolymer and a low molecular weight polymer in proportions to provide a fugitive pattern having a combination of properties suitable for use in making the shell molds.
1. Combination of a fugitive pattern having a shape of an article to be cast from a metal or alloy and a shell mold invested on the pattern, wherein said pattern comprises a pattern material comprising A) a substantially random interpolymer prepared by polymerizing one or more α-olefin monomers with one or more vinyl or vinylidene monomers and B) a low molecular weight polymer other than said interpolymer.
2. The combination of claim 1 having an injection molded shape of said article.
3. The combination of claim 1 wherein said pattern has a shape of a gas turbine blade or vane.
4. The combination of claim 1 where said pattern has a melt flow rate of 350 or greater by ASTM D1238.
5. The combination of claim 1 wherein the pattern has reduced dimensional variation as an I-beam pattern shape as compared to a wax pattern as an I-beam pattern shape.
6. The combination of claim 1 wherein the pattern has higher strength as compared to a wax pattern.
7. The combination of claim 1 wherein the pattern has higher toughness as expressed by less brittleness as compared to a wax pattern.
8. The combination of claim 1 wherein the pattern has a lower shrink as compared to a wax pattern and a polystyrene pattern.
9. The combination claim 1 wherein said interpolymer comprises ethylene/styrene interpolymer.
10. The combination of claim 9 wherein said low molecular weight polymer comprises low molecular weight polystyrene.
11. The combination of claim 1 further including a thermoplastic polymer other than said interpolymer and said low molecular weight polystyrene.
12. Combination of a fugitive pattern having a shape of an article to be cast from a metal or alloy and a shell mold invested on the pattern, wherein said pattern comprises a pattern material comprising A) a substantially random interpolymer and B) a low molecular weight polystyrene.
13. Combination of a fugitive pattern having a shape of an article to be cast from a metal or alloy and a shell mold invested on the pattern, wherein said pattern comprises a pattern material comprising A) ethylene/styrene interpolymer and B) a low molecular weight polystyrene.
14. The combination of claim 13 wherein said ethylene/styrene interpolymer is present in an amount of 10% to 95% by weight of said pattern material and said low molecular weight polystyrene is present in an amount of 5% to 60% by weight of said pattern material.
15. The combination of claim 14 wherein said ethylene/styrene interpolymer is present in an amount of 30% to 80% by weight of said pattern material and said low molecular weight polystyrene is present in an amount of 10% to 50% by weight of said pattern material.
16. The combination of claim 15 wherein said ethylene/styrene interpolymer is present in an amount of 50% to 70% by weight of said pattern material and said low molecular weight polystyrene is present in an amount of 20% to 50% by weight of said pattern material.
17. The combination of claim 16 wherein said ethylene/styrene interpolymer is present in an amount of about 60% by weight of said pattern material and said low molecular weight polystyrene is present in an amount of about 40% by weight of said pattern material.
18. The combination of claim 13 wherein the low molecular weight polystyrene has a molecular weight (Mn)<10,000.
19. The combination of claim 18 wherein the average molecular weight is <5,000.
20. The combination of claim 19 wherein the average molecular weight is <2,000.