Ceramic Nano-particle/Substrate Interface Bonding Formation Derived from Dynamic Mechanical Force at Room Temperature: HRTEM Examination

Abstract

The bonding of TiO 2 nano-particle/substrate is a critical factor influencing the performance of dyesensitized solar cells. In order to reveal the bonding properties at TiO 2 nano-particle/substrate interface, high-resolution transmission electron microscopy (HRTEM) analysis was adopted to TiO 2 coatings prepared by three different approaches. In the HRTEM analysis, the effective bonding mode is allowed to distinguish from the false image overlapping. Results show that large areas of effective bonding between nano-TiO 2 particles and the substrate surface formed in the room temperature cold sprayed coating and mechanically pressed coating, while only limited interface areas with the effective bonding were observed in the coating deposited by non-pressed method. These results confirm that both high impact pressure during the room temperature cold spraying and mechanical pressure contribute to the bonding formation at the particle/substrate interface.

MD Simulation on Collision Behavior Between Nano-Scale TiO2 Particles During Vacuum Cold Spraying

“…Those simulation results for low velocities are consistent with the experimental results that particle fragments cannot be found during depositing agglomerates by vacuum cold spraying. [18][19][20][21][22] Once the impact velocity continuously increasing, the nano-scale ceramic particle can be intensively deformed. Atoms in the fixed particle and moving particle significantly displace from their equilibrium positions when the particle initial velocity is up to 1200 m/s.…”

“…Those simulation results are consistent with the experimental results that nano-scale ceramic particles are bonded together without obvious fragmentations. [18][19][20][21][22] This phenomenon indicates that bonding formation between nano-scale ceramic particles can be realized by localized deformation without obvious fragments.…”

“…[18][19][20][21] The results obtained by HRTEM examination confirm that no particle fragmentation is found when nano-scale particles deposited onto the substrate by vacuum cold spraying. 22 Those phenomena imply that the particle fragmentation may be not the main reason for nano-scale ceramic particles bonding and deposition. By analyzing the deposition process, collision mainly occurs between nano-scale ceramic particles during the deposition of agglomeration.…”