Fiber-Metal Laminate Manufacturing Technique
manufacturing
Fiber-Metal Laminate Manufacturing Technique (LAR-TOPS-170)
Synthesis of fiber-metal laminates by RF plasma spray deposition
Overview
NASA Langley Research Center has developed a method for the synthesis of fiber-metal laminates by radio frequency plasma spray deposition. Fiber-metal laminates (FMLs) combine the stiffness and strength of fiber-reinforced polymer matrix composites with the toughness and durability of metallic alloys and, therefore, have a range of applications. The use of radio frequency plasma spray (RFPS) deposition offers a unique approach to the fabrication of FMLs with many advantages. For example, the approach is ideal for highly reactive materials, allows for tailorable FMLs, and allows for materials that exploit the unique properties of nanoparticles in metallic structures. This new manufacturing technique will help create better FMLs for lighting strike protection and also open the door to new FML applications.
The Technology
Fiber-Metal Laminates (FMLs) are composite materials that consist of conventional fiber reinforced plastics with the addition of a metal component, typically a foil or mesh layer(s). The metal component offers the advantage of incorporating metal-like properties to the composite construction. While a range of potential advantages and applications have been discussed for FMLs, the primary application to date has been for aircraft structures, with one potential advantage being the lightning strike protection (LSP) offered by the improved electrical conductivity. As aircraft construction has moved to composite structures, there has been an increasing need for such conductive composites. Similarly, with increasing use of composites for other large structures, e.g. wind turbines, there are an increasing number of potential applications for lightning strike protection materials. Other advantages of FML are improved impact and fire resistance.
This innovation provides a method for making FML materials that incorporate nanotube reinforcement. The method involves the use of RF plasma spray to directly form and deposit nanotube materials onto fibers/fabrics, which can then be manufactured into composite structures by infiltrating the fiber with resin, and consolidating the structure via autoclave processing or via the use Vacuum Assisted Resin Transfer Molding (VARTM) composite manufacturing methods. Nanotubes incorporated into the structure in this manner can be of several types, for example boron nitride or carbon nanotubes. The objective of this innovation is to incorporate the nanotube materials in the FML in order to improve the mechanical properties.
Benefits
- Tailorable FMLs provide multi-functionality for improved structural efficiency
- Efficient manufacture of difficult-to-process materials
- Unique combinations of metal/fabric/polymer possible
Applications
- Aerospace lighting strike protection
- Blast protection
- Impact resistance
- Controlled electrical/ thermal conductivity
- Radiation shielding
Technology Details
manufacturing
LAR-TOPS-170
LAR-18063-1
Similar Results
Plasma Deposition of Metal in Composite Panels
NASA's plasma-deposition process provides the ability to tailor various properties while designing functional parts by selecting specific materials and processing parameters to meet the end goal. Specifically, the plasma process deposits metal particles that are heated as they travel axially at low velocity through an inert gas plasma. The accelerated powder particles become molten, strike the substrate fabric (uniaxial, biaxial, and multiaxial) and rapidly solidify, imparting very little heat to the substrate while forming a metal-to-fiber bond, as well as a metal-to-metal bond. The resulting metal-coated fabric is porous, so the polymer matrix can pass through the product precursor during the infusion process. The amount of metal deposited can be
controlled, as can the number of plies of fabric that are ultimately stacked to produce the preform for the polymer matrix infusion process. A variety of infusion processes can be utilized to prepare the FML, including resin transfer molding (RTM), resin film infusion (RFI), and vacuum-assisted resin transfer molding (VARTM). The tailorable aspect of the process allows for specific product design. By varying the combination of metal particle, fiber, fabric type, metal layer thickness, fabric direction, number of layers, polymer matrix resin, infusion process, and cure conditions, the characteristics of the final part can meet the needs of various applications.
Fabrication of Fiber-Metal Laminates with Non-Autoclave Processes
The FMLs resulting from the NASA process have similar properties to traditionally produced metal/composite hybrid laminates including, as compared to either the composite or metal only structures, improved load carrying capability, lighter weight, improved stiffness, improved impact resistance and damage tolerance, and improved permeation resistance. The NASA process can be applied to various FML types, including GLARE (glass, aluminum, epoxy), and TIGR (titanium, graphite). Typical manufacturing processes are costly and complex shapes are hard to produce, whereby the NASA process enables use of these kinds of laminates without an autoclave or press, thus increasing the size that can be produced and decreasing the cost.
The resin pathways in the foils enable connection between the plies that can improve the interlaminar strength of the final part. Functionally the NASA process creates resin columns in the transverse direction of the plies. NASA is working to optimize the final properties by varying the size and distribution of the pathways.
Fabricating printable electronics and biosensor chips
The plasma system consists of a glass tube with a diameter of 0.5 mm or larger, if desired. The electrodes are separated by 10 mm. Helium, argon or cold dry air can be used as a plasma gas source. An applied high voltage between the electrodes causes the gas to breakdown within the central core of the glass capillary generating atmospheric plasma. Nanostructures colloids/organic/inorganic precursors are placed in a glass container with an inlet and outlet for carrier gas and are seated on an ultrasonic nebuliser. The aerosol is then carried into the plasma stream by the carrier gas and is deposited.
The atmospheric plasma deposition system can be modified for depositing multiple materials, either simultaneously or sequentially, and for high-throughput processing by having multiple jets. Each capillary can either be connected to the container containing a single precursor material or to different containers containing different precursor materials to facilitate multiple depositions. The multi-jet plasma system can be automated and controlled individually to precisely control surface characteristics. This technique is independent of the chosen substrate, and has proven to work for many substrates, including paper, plastic, semiconductors and metals.
Atomic Number (Z)-Grade Radiation Shields from Fiber Metal Laminates
This technology is a flexible, lighter weight radiation shield made from hybrid carbon/metal fabric and based on the Z-grading method of layering metal materials of differing atomic numbers to provide radiation protection for protons, electrons, and x-rays. To create this material, a high density metal is plasma spray-coated to carbon fiber. Another metal with less density is then plasma spray-coated, followed by another, and so on, until the material with the appropriate shielding properties is formed. Resins can be added to the material to provide structural adhesion, reducing the need for mechanical bonding. This material is amenable to molding and could be used to build custom radiation shielding to protect cabling and electronics in situations where traditional metal shielding is difficult to place.
Conductive High-Toughness Oxides
Oxide coatings have been used in thermal and environmental barrier layers for coatings for hot section turbine applications, among other uses. With the PS-PVD method, Glenn researchers observed the formation of a minority phase of a metastable oxide (zirconium oxide) that is usually found only in a vapor state. They found that the high temperatures and fast deposition process of the PS-PVD system incorporated nonequilibrium phases in the coating and retained them at room temperature as well as at high temperature in the absence of oxygen. The material is vaporized and condensed on the surface via a rapid quenching, essentially "trapping" this phase in the deposited coating. The coating microstructure and composition can also be manipulated by changing the processing parameters, allowing the thickness of the coating to be tailored to a given application. Since this metastable phase is conductive, this coating can be used as (for example) an extremely sensitive (thermal or temperature) sensor. It also has very good durability and erosion resistance, making it useful as a protective and conductive coating for electronics and microelectronics. This is an early-stage technology requiring additional development, and Glenn welcomes co-development opportunities.
