Electrospray pinning of nanograined depositions
A method and apparatus for fabrication of objects retaining nano-scale characteristics. A composition is provided comprising grain growth inhibitor particles in solution with a binding agent in a molten phase. An electric field and a magnetic field are generated with a combined extraction electrode. The composition is electrosprayed from a nozzle with the electric field to form a stream of droplets. The electric field drives the droplets toward a moving stage holding an object comprising successive deposition layers. The magnetic field limits dispersion of the stream of droplets. The stage is moved laterally as the stream of droplets impacts the object to form a current deposition layer of the object. The stage is moved vertically as necessary to maintain a target stand-off distance between the nozzle and a previous deposition layer of the object, based on profile data of the previous deposition layer.
1. An apparatus for fabrication of objects retaining nano-scale characteristics comprising;
a material reservoir configured to hold a molten material, wherein at least a portion of the molten material includes a composition of grain growth inhibitor particles in a solution with a binding agent;
a nozzle coupled to the material reservoir;
a moving stage configured to move relative to the nozzle in three orthogonal dimensions;
an object holder, part of the moving stage, configured to hold an object comprising successive deposition layers;
an extractor electrode coupled to the nozzle, the extractor electrode configured to generate an electrical field, the electric field configured to extract the molten material from the nozzle to form a stream of droplets of nanoparticle size, the electric field configured to drive the droplets to the moving stage, wherein the extractor electrode is configured to generate a magnetic field, the magnetic field configured to limit dispersion of the stream of droplets;
a profilometer configured to obtain profile data of the object; and
a main control unit configured to control movement of the moving stage in response to the obtained profile data of the object, including moving the moving stage laterally with respect to the nozzle as the stream of droplets impacts the moving stage to form a current deposition layer of the object and moving the moving stage vertically with respect to the nozzle to maintain a target stand-off distance between the nozzle and a previous deposition layer of the object, based on profile data of the previous deposition layer.
2. The apparatus of claim 1 , further comprising:
an enclosure coupled to and penetrated by the nozzle, the enclosure defining an enclosure cavity between the enclosure and the moving stage; and
an enclosure floating frame slidingly coupled to the enclosure, the enclosure floating frame configured to provide a seal between the enclosure and the moving stage.
3. The apparatus of claim 2 , further comprising:
a gas inlet configured to add a heated gas into the enclosure cavity.
4. The apparatus of claim 1 , further comprising:
a cooling chuck, part of the moving stage, coupled to the object holder, the cooling chuck configured to cool the object holder.
5. The apparatus of claim 1 , wherein the main control unit is further configured to adjust a flow rate of the molten material through the nozzle to correct deposition errors, based on the profile data of the previous deposition layer.
6. The apparatus of claim 1 , further comprising:
a radiation source configured to heat the stream of droplets.
7. The apparatus of claim 1 , further comprising:
a heater configured to provide heat to the stream of droplets.
8. The apparatus of claim 1 , wherein the main control unit is further configured to control electrical conditions associated with the electric field.