3D nonlinear photolithography of tin oxide ceramics via femtosecond laser

As a wide band gap semiconductor material,tin oxide(SnO_(2))has been widely used in gas sensing,optoelectronics and catalysis.The complex micro and nanoscale threedimensional(3D)geometric structures endow the conventional SnO_(2)ceramics with novel properties and functionalities.Nevertheless,ceramics cannot be cast or machined easily due to their high mechanical toughness and resistance.The additive manufacturing opens a great opportunity for flexibly geometrical shaping,while the arbitrary shaping of SnO_(2)ceramics at micro and nanoscale is always a challenge.Herein,preceramic monomers which can be polymerized under ultrafast laser irradiation,were utilized to form complex and arbitrary 3D preceramic polymer structures.After calcination treatment,these green-body structures could be converted into pure high-dense SnO_(2)ceramics with uniform shrinkage,and the feature size was down to submicron.Transmission electron microscopy(TEM)analysis displays that the printed SnO_(2)ceramic nanostructures can be nanocrystallized with grain sizes of 2.5±0.4 nm.This work provides the possibility of manufacturing 3D SnO_(2)ceramic nanostructures arbitrarily with sub-100 nm resolution,thus making it promising for the applications of SnO_(2)in different fields.

Wettability between titanium-containing steels and TiN ceramic substrate

The wettability between TiN ceramic substrates and steels with various Ti contents was studied under an argon atmosphere at 1550℃ using a modified sessile drop method.An electron probe microanalyzer and thermodynamic calculations were applied to investigate the interface between the steels and the TiN substrates as well as the surface of solidified steel droplets.The measured apparent contact angles between the TiN substrates and steels were 96°,91°,and 146°,as the Ti content in the steel samples was 0.01,0.31,and 0.68 wt.%,respectively.No reaction products were found at the interface,and only physical interactions occurred.The wettability between high titanium steels(0.68 wt.%Ti)and TiN ceramic substrates should be evaluated from various perspectives,as many TiN particles existing in steel made the apparent contact angle increased significantly,deviating from the true value of contact angle.

In situ selective laser gas nitriding for composite TiN/Ti-6Al-4V fabrication via laser powder bed fusion

Laser-assisted gas nitriding of selective Ti-6Al-4V surfaces has been achieved during laser powder bed fusion fabrication by exchanging the argon build gas environment with nitrogen.Systematic variation of processing parameters allowed microdendritic Ti N surface coatings to be formed having thicknesses ranging from a few tens of microns to several hundred microns,with TiN dendrite microstructure volume fractions ranging from 0.6 to 0.75;and corresponding Vickers microindentation hardness values ranging from^7.5 GPa–9.5 GPa.Embedded TiN hard layers ranging from 50μm to 150μm thick were also fabricated in the laser-beam additively manufactured Ti-6Al-4V alloy producing prototype,hybrid,planar composites having alternating,ductile Ti-6Al-4V layers with a hardness of^4.5 GPa and a stiff,TiN layer with a hardness of^8.5 GPa.The results demonstrate prospects for fabricating novel,additively manufactured components having selective,hard,wear and corrosion resistant coatings along with periodic,planar or complex metal matrix composite regimes exhibiting superior toughness and related mechanical properties.

A sol-gel method to synthesize indium tin oxide nanoparticles

Transparent conductive indium tin oxide （ITO） nanoparticles were synthesized by a novel sol-gel method. Granulated indium and tin were dissolved in HNO3 and partially complexed with citric acid. A sol-gel process was induced when tertiary butyl alcohol was added dropwise to the above solution. ITO nanopartides with an average crystallite size of 18.5 nm and surface area of 32.6 m^2 ]g were obtained after the gel was heat-treated at 700 ℃, The ITO nanoparticles showed good sinterability, the starting sintering temperature decreased sharply to 900 ℃, and the 1400 ℃ sintered pellet had a density of 98.1% of theoretical density （TD）.