CompositesWorld
Issue link: https://cw.epubxp.com/i/830100
JUNE 2017 36 CompositesWorld INSIDE MANUFACTURING then lift up into position. After the loaded floor is set inside the furnace, the insulated door is closed and the furnace is brought to operational temperature. As the furnace reaches 1093°C, the ceramic matrix fuses and residual organic materials burn off. After the parts are removed from the sintering furnace and cooled, they are transferred to a Fooke GmbH (Borken, Germany) 5-axis CNC milling machine for milling, grinding and drilling counterbores, using specially designed cutting tools. e next step is quality control: First the outside surfaces are measured, using a Romer CMM (coordinate measurement machine) from Hexagon Metrology Inc. (Cobham, Surrey, UK) to confirm surface dimension and shape. Next, they are subjected to nondestructive inspection (NDI) on site, using infrared flash thermography equipment. e automated inspec- tion system includes a robot and various other articulating devices that enable the forward-looking infrared camera (FLIR) to maintain a direct line of sight on the complex part and scan 100% of each part's surfaces to detect porosity and delamination. In flash thermography, a heat source, such as a brief pulse of light, is used to heat a sample's surface while an infrared camera records changes in the surface temperature. As the sample cools, its surface temperature is affected by internal flaws, including disbonds, voids or inclusions, which obstruct the flow of heat into the sample. Lastly, metal details and ceramic parts are assembled using mechanical fasteners, and then the finished units are packed for shipment to GE, which does the final assembly. Hynes notes that fastener technology for engine parts is intel- lectual property typically closely protected by OEMs because of the different coefficient of thermal expansion (CTE) of materials found in engine assemblies. Although oxide CMC resists high tempera- tures in operation, its CTE is similar to that of aluminum. e thermal mismatch between oxide components that are attached to nickel alloys is, therefore, a significant design consideration. Markets and applications In 2015, with the GE contract well under way, CHI concurrently began developing its own Ox-Ox CMC matrix materials designated AXC-610 and AXC-720. Hynes says CHI is currently using these materials in two other applications: one in aerospace, and the other in an industrial application. FIG. 3 Two-fold challenge: Heat and shape The GE Passport 20 engine, showing its metal outer bypass duct (a), and its Ox-Ox CMC components: the core cowl (b), the mixer (c) and the centerbody (d). Source | CHI a a b c d Read this article online | short.compositesworld.com/CMCsHOT Read more online about this subject in "Aeroengine composites, part I: the CMC invasion" | short.compositesworld.com/Jet1-CMCs Read more online about the development jet- engine-capable resin technology in "Resins for the hot zone, Part 1, polyimides" | short.compositesworld.com/HotZoneP1 FIG. 2 Focused on high-temperature composites A high-temperature materials pioneer since its inception in 1974, Composite Horizons dedicated this entire 3,252m 2 building to CMC component manufacturing. Source | CHI