Evolution of Microstructure, Texture and Mechanical Properties for Multilayered Al Matrix Composites by Accumulative Roll Bonding.

Carbon nanotubes (CNTs) reinforced aluminum matrix nanocomposites were fabricated by Accumulative Roll Bonding (ARB). The surface morphologies, mechanical properties, grains texture and orientation of the Al/CNTs nanocomposites were characterized, and the mechanisms and influences of CNTs contents and ARB cycles on the mechanical performance and grain textures of Al/CNTs were investigated and revealed. The strength of the composites rose with increase of the CNTs content, and the ARB cycles showed a 26% improvement when the CNTs content varied from 0 to 1 volume percent (vol.%). The increase in the mass fraction of the carbon nanotubes made the grain distribution in the Al/CNTs nanocomposite samples more diffuse. Besides, the stable texture of the hot rolled crystal grains on the α orientation are constantly turning to {011}< 011> with the mass fraction of the reinforcing phase increased.

Additive and Photochemical Manufacturing of Copper.

In recent years, 3D printing technologies have been extensively developed, enabling rapid prototyping from a conceptual design to an actual product. However, additive manufacturing of metals in the existing technologies is still cost-intensive and time-consuming. Herein a novel platform for low-cost additive manufacturing is introduced by simultaneously combining the laser-induced forward transfer (LIFT) method with photochemical reaction. Using acrylonitrile butadiene styrene (ABS) polymer as the sacrificial layer, sufficient ejection momentum can be generated in the LIFT method. A low-cost continuous wave (CW) laser diode at 405 nm was utilized and proved to be able to transfer the photochemically synthesized copper onto the target substrate. The wavelength-dependent photochemical behaviour in the LIFT method was verified and characterized by both theoretical and experimental studies compared to 1064 nm fiber laser. The conductivity of the synthesized copper patterns could be enhanced using post electroless plating while retaining the designed pattern shapes. Prototypes of electronic circuits were accordingly built and demonstrated for powering up LEDs. Apart from pristine PDMS materials with low surface energies, the proposed method can simultaneously perform laser-induced forward transfer and photochemical synthesis of metals, starting from their metal oxide forms, onto various target substrates such as polyimide, glass and thermoplastics.

Photochemical Copper Coating on 3D Printed Thermoplastics.

3D printing using thermoplastics has become very popular in recent years, however, it is challenging to provide a metal coating on 3D objects without using specialized and expensive tools. Herein, a novel acrylic paint containing malachite for coating on 3D printed objects is introduced, which can be transformed to copper via one-step laser treatment. The malachite containing pigment can be used as a commercial acrylic paint, which can be brushed onto 3D printed objects. The material properties and photochemical transformation processes have been comprehensively studied. The underlying physics of the photochemical synthesis of copper was characterized using density functional theory calculations. After laser treatment, the surface coating of the 3D printed objects was transformed to copper, which was experimentally characterized by XRD. 3D printed prototypes, including model of the Statue of Liberty covered with a copper surface coating and a robotic hand with copper interconnections, are demonstrated using this painting method. This composite material can provide a novel solution for coating metals on 3D printed objects. The photochemical reduction analysis indicates that the copper rust in malachite form can be remotely and photo-chemically reduced to pure copper with sufficient photon energy.