Original Date: 01/27/1997
Revision Date: 01/18/2007
Best Practice : Vapor Phase Manufacturing
Lawrence Livermore National Laboratory’s (LLNL’s) Laser Directorate is developing and transferring electron- beam manufacturing technology to industry and government. This technology enables complex metal alloy shapes to be fabricated by depositing vaporized metal onto a mold or mandrel, which is later separated from the alloy part. The metal is vaporized by electron-beam heating. The process has successfully produced alloy parts with metallurgical properties that exceed those of equivalent forged parts. The Laboratory currently is up-scaling the process to handle larger part sizes. In parallel with this effort, LLNL is developing a real-time, laser-based control system to measure and control the alloy composition during vapor deposition of the part.
Additionally, LLNL’s Laser Directorate is developing laser-based vapor diagnostics and computer models to control the vapor phase manufacturing processes. Target applications include controlling processes for making titanium alloy matrix composites and oxide thermal barrier coatings which are important in the aerospace industry. For titanium matrix composites, silicon-carbon fibers are coated with titanium alloys and then consolidated into finished parts that are lightweight, strong, and stiff at high temperature. Electron beam evaporation can provide high-volume production, as long as alloy composition and the fraction of vapor capture can be precisely controlled.
LLNL sensors and computer models are being used to improve process control and capture efficiency. Laser absorption spectroscopy, which uses diode lasers, provides the basis for vapor density and composition monitoring sensors. Prototype systems are in use in industry.
One example of LLNL’s success was the development of a vapor deposition process for manufacturing precision nuclear weapon system components. The project’s objective was to provide a simpler, lower cost, and lower waste process for certain critical components. With this project, the Laboratory demonstrated the feasibility of vapor deposition of dense material in the required thickness, ability to meet composition specifications, and equal or better mechanical properties of the vapor-deposited metal compared to wrought metal. Material utilization for this process was more than 30 times better than existing processes. Figure 2-8 shows a cut-away view of the equipment for this process in operation. The success of this project led to a three-year, $6 million plan for manufacturing and certifying full-scale components. LLNL has transferred the vapor deposition process to commercial applications.
Figure 2-8. Net Shape Vapor Deposition System
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