CMC Process Overview

Introduction

• The process begins with polycrystalline silicon powder.
• This powder is melted and processed into silicon carbide fiber.
• Fibers are high-strength, corrosion-resistant, and low-density.
• Each fiber is 1/5 the diameter of a human hair.

Fiber Coating

• Finished fibers have four proprietary coatings applied.
• Enhances high strength and creep resistance.

Fiber to Tape Transformation

• Treated fibers pass through a slurry of solvents, binders, and plasticizers.
• Spooled around a wet drum to form workable tape.
• Large sheets of unidirectional fiber are created.

Cutting and Stacking

• Tape is cut by a computerized machine into specific sizes and shapes.
• Cut-out plies are stacked to desired thickness on a form or tool.
• Plies are oriented to utilize fiber strength, often alternating directions.

Autoclave Process

• Tool is placed in an autoclave.
• Low heat and high pressure mold the layered plies into a part.

Burnout and Infiltration

• Burnout process converts organic material to carbon.
• Open pores are melt infiltrated with silicone for density.
• Converts to SiC fiber and matrix part withstands 2,400 degrees.

Machining and Inspection

• GE uses industrial diamond drills and discs for machining parts.
• Components undergo a rigorous multi-point inspection and image analysis.
• Ensures physical and geometrical characteristics are met.

Final Integrity and Coating

• CT scan assesses structure integrity and identifies defects.
• Parts are coated with thermal and environmental protective layers.

Conclusion

• Over fifty steps involved in preparing a CMC part for service.
• Each part undergoes meticulous processes to ensure quality and precision.

This summary provides an overview of the CMC process, focusing on key steps from the initial melting of polycrystalline silicon powder to the final inspection and coating of parts. Each stage is crucial in ensuring the creation of high-quality, durable components.