US 11,992,874 B2
Process to make a ceramic filter for metal casting
Qigui Wang, Rochester Hills, MI (US); Andrew Thomas Cunningham, Royal Oak, MI (US); Zach Steffes, West Bloomfield, MI (US); Jeffrey B. Harris, Detroit, MI (US); Brennon L. White, Novi, MI (US); and Liang Wang, Rochester Hills, MI (US)
Assigned to GM GLOBAL TECHNOLOGY OPERATIONS LLC, Detroit, MI (US)
Filed by GM Global Technology Operations LLC, Detroit, MI (US)
Filed on May 4, 2021, as Appl. No. 17/307,295.
Prior Publication US 2022/0355369 A1, Nov. 10, 2022
Int. Cl. B22C 9/08 (2006.01); B01D 39/20 (2006.01); B28B 1/00 (2006.01); B33Y 10/00 (2015.01); B33Y 80/00 (2015.01)
CPC B22C 9/086 (2013.01) [B01D 39/2075 (2013.01); B01D 39/2093 (2013.01); B28B 1/001 (2013.01); B01D 2239/12 (2013.01); B33Y 10/00 (2014.12); B33Y 80/00 (2014.12)] 20 Claims
OG exemplary drawing
 
1. A method to manufacture a ceramic foam filter, comprising:
sintering a filter body to a temperature greater than a molten metal to be filtered through the filter body;
creating multiple filter body tortuous path channels extending through the filter body individually having a repeated and controlled passage geometry creating a continuously changing diameter and area of a flow path through the multiple filter body tortuous path channels causing localized increases and decreases in molten metal flow rate through the multiple filter body tortuous path channels;
creating a flow passage for individual ones of the multiple filter body tortuous path channels by adding an impact wall between opposed first and second path channel walls oriented at an angle to a flow direction of the molten metal within the flow passage, wherein the impact wall includes multiple impact wall tortuous path channels configured to permit flow of the molten metal through the impact wall; and
applying a mixture of at least one ceramic powder and at least one binder using additive manufacturing to shape the filter body including the multiple filter body tortuous path channels.