Meso-nozzle fabrication for refractory metals using thermal-property mismatch

There are many works focused on making meso-nozzle in metals or polymers for applications like bubble making or spraying. None of them reported successful achievement in fabricating deep holes in metals. A novel method to fabricate a meso-nozzle in metal is proposed in this paper. The method to make a suitable size holes uses refractory metal powders such as Mo and very fine glass fibers of 100 μm in diameter. It utilizes the mismatch in thermal properties between the powder and the fiber. Sintering at a temperature between their melting points causes glass to evaporate leaving a targeted shape of hole and densify the metal powder. Green compacts were prepared at various compressive loads and then subjected to sintering at temperatures below the melting points of the metal powder. The resulted hole exhibited straightness and a circular cross-section along the length. The inspection of the sintered part confirmed that the method is promising to fabricate deep meso-nozzles in metals.