研究目的
To investigate the inter-particle bonding formation of nano-sized TiO2 ceramic particles induced by high velocity collision and to clarify their bonding mechanisms.
研究成果
The study discovered a novel plastic deformation mechanism of nano-scale ceramic particle bonding formation derived by high velocity collision via MD simulation and TEM microstructural characterization. Simulation results demonstrate that the bonding formation of nano-sized TiO2 particles can be attributed to the displacement and lattice distortion in localized impact region of particle boundaries. TEM microstructure results prove simulation results and indicate effective chemical bonding formations between nano-particles at low temperature by high velocity collision. Quantitative results show that the high temperature is beneficial to the particle bonding formation. The asperity around nano-sized ceramic particles surface contributed to the displacement and lattice distortion in localized impact region under the high impact compressive pressure. The study opens up a promising prospect of fabricating functional equipment with nano-scale ceramic particles with high velocity collision at ambient temperature.
研究不足
The study focuses on nano-sized TiO2 particles and their bonding mechanisms under high velocity collision. The findings may not be directly applicable to other ceramic materials or different particle sizes. The experimental verification was limited to TEM microstructure characterization, and further mechanical property testing could provide more comprehensive insights.
1：Experimental Design and Method Selection:
Molecular dynamics (MD) simulation was applied to investigate the particle interface deformation during the collision process of TiO2 nanoparticles by the Buckingham-type potential. The model consisted of two TiO2 particles, a fixed particle and a moving particle. Before colliding, these two spherical particles were equilibrated at different temperatures rescaling for 30 ps with a time step of
2：5 fs. Then, quality of equilibration and energy conservation was tested by integration in the micro-canonical ensemble (NVE) for additional 10 ps. Collision simulations were carried out for 40 ps in the micro-canonical ensemble (NVE) under the condition of these two particles of an initial temperature of 300 K and the moving particle of an initial velocity of 600 m/s. Sample Selection and Data Sources:
TiO2 nano-powders (P25, 25 nm, Degussa, Germany) with ambient temperature and 350oC were deposited to form TiO2 coating onto an F-doped SnO2-glass (FTO, TEC-15, LOF) substrate using a lab-developed vacuum cold spray system. For comparison, a screen-printed TiO2 coating was prepared and sintered at 500oC for 30 mins.
3：List of Experimental Equipment and Materials:
Transmission electron microscopy (TEM) (JEM-2100F, JEOL, Japan) was used for microstructure characterization.
4：Experimental Procedures and Operational Workflow:
Microstructures of particle/particle bonding for both the vacuum-cold-sprayed and screen-printed TiO2 coatings were characterized by TEM.
5：Data Analysis Methods:
The bonding ratio of bonded particles was defined and statistically estimated from TEM images.
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