Lawrence Livermore National Laboratory (LLNL), operated by the Lawrence Livermore National Security (LLNS), LLC under contract with the U.S. Department of Energy (DOE), is offering the opportunity to license and commercialize its High Velocity Laser Accelerated Deposition (HVLAD) technology for Controlled Laser-Driven Explosive Bonding- an extension of Laser Peening Technology for the Uniform and Patterned Deposition of Functional Films and Coatings with Exceptionally Strong Adhesion. This technology was selected by R&D Magazine as one of the 2012 R&D100 Award Winners.
This state-of-the-art additive manufacturing process is enabled and facilitated by LLNL's unparalled international leadership in high-performance solid-state laser technology. This process uses the world's most powerful and highest repetition rate production lasers for localized explosive bonding, thus producing a very broad range of advanced high-temperature and corrosion-resistant coatings with extreme interfacial bond strength. These interfacial bonds approach the ultimate tensile strength of the substrate.
The deposition of protective metallic films and coatings on various metallic alloy, ceramic or composite substrates is important for many industrial applications. LLNL has now demonstrated that exceptionally corrosion and wear resistant coatings can be deposited with exceptional interfacial bond strengths, approaching the ultimate strengths of the underlying substrate materials. This process is particularly interesting in that it can be conducted in manufacturing plants, aircraft hangers, and ship yards under ambient conditions (in air at room temperature). These unique coatings are made possible through controlled laser-driven explosive bonding, which uses a laser pulse to accelerate coating material towards the substrate.
This technology comprises a method of depositing coatings of dissimilar materials on a substrate. A laser pulse hits the film of deposited material covered by a thin water layer. The laser deposition on the water-material interface generates huge pressure accelerating film to the velocities a few hundred meters per second. The film hits the substrate at an oblique angle. The high velocity of impact induces the plastic flow of materials on film-substrate interface and shear flow due to the oblique incidence results in material mixing and strong coating adhesion.
The five discrete steps involved in the deposition are as follows: (Step 1) the high-performance corrosion resistant film material is advanced with a spool assembly, and bathed with water that serves as a tamper during laser pulse; (Step 2) a special laser pulse with rectangular beam cross-section is imaged onto the advancing high-performance film material bathed with a thin layer of water; (Step 3) the laser pulse generates a high temperature plasma and very large pressure shearing out a section of film accelerating it to hypersonic velocities; (Step 4) patches of ultra-hard and corrosion-resistant film are accelerated and bonded to the substrate in a controlled step-by-step process creating coating; (Step 5) the film patch hits the substrate at an oblique angle, where the high impact velocity induces plastic shear flow at the interface creating a high-strength explosive bond.
This method is compatible with LLNL's already commercialized laser peening technology, which can also be leveraged for production level implementation of this new coating process.
The advantages of LLNL's controlled laser-driven bonding include:
- Various coating materials, including refractory metal alloys, can be deposited at ambient temperature, at room temperature and in air.
- The interfacial bond formed between the coating and substrate has a strength comparable to the tensile strength of the substrate.
- The potential of creating highly textured, corrosion and wear resistant anti-skid coatings for ship and bridge decks exists.
- Compressive stresses introduced into the substrate during HVLAD make it impossible to initiate and propagate cracks, including environmentally assisted cracks, from stress corrosion cracking, corrosion fatigue, hydrogen induced cracking, or l liquid metal embrittlement.
- Deposition of refractory metals coatings such as tungsten and tungsten alloys; tantalum and tantalum alloys; niobium and niobium alloys; vanadium and vanadium alloys for ultra high-temperature high-efficiency heat exchanger applications. Some of these coatings may have application as barrier coatings for high-temperature heat exchangers and first walls in fusion reactor systems.
- Single and multi-layer coatings for protection from corrosion such as noble metals including gold, platinum, rhodium, ruthenium, palladium and silver; stainless steels and other such materials; nickel and nickel-based alloys; amorphous metal alloys; coatings for zinc galvanizing; lead and lead alloys; cadmium and cadmium alloys; chromium and chromium alloys; titanium an titanium alloys; and ceramic coatings. Some of these coatings with appropriate morphology may also have applications as reflective and anti-reflective optical coatings and surfaces for Initial Confinement Fusion targets.
- Crack healing through the directed deposition of aluminum into cracks of aluminum alloys for aircraft and ships.
- Deposition of thin films with well developed surface for promoting adhesion in subsequently deposited layers.
- Direct deposition of conductive patterned interconnects on printed circuit boards and hybrid microcircuits for the purpose of both initial fabrication and subsequent repair.
- Direct deposition of conductive patterned interconnects for the initial fabrication and subsequent repair of solid-state energy conversion and storage devices such as thermoelectric generators, Peltier coolers, and photovoltaic devices.
- Deposition of active anode materials, active cathode materials, and separators for electrochemical energy conversion and storage devices such as lithium ion batteries, solid-state batteries and solid oxide fuel cells.
- Deposition of bot n-type and p-type materials for thermoelectric energy conversion and storage such as bismuth-antimony-telluride-selenide type (BiSb)2(TeSe)3, PbTe, and SiGe alloys.
- Deposition of both n-type and p-type materials for photovoltaic energy conversion and storage such as silicon (Si), cadmium telluride (CdTe) and other similar materials.
LLNL has a patent application filed covering this technology.