Date of Award

Summer 8-19-2022

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Mechanical Engineering

Advisor

Bashir Khoda

Second Committee Member

William Gramlich

Third Committee Member

Yingchao

Abstract

Solid particle transfer is a vital process for many applications such as painting, coating, materials joining, meta-surface, bio-medical applications etc. Different solid transfer techniques including welding, spray coating, roll coating etc. are available for delivering solid particles on simple structures. However, those techniques cannot effectively deliver particles to complex structures. In this thesis work, the research objective is to develop a high throughput and economical material transfer technique for complex architecture with low volumetric flux. In first part, the particle concentration of pseudo suspension was investigated in dip coating process from density mismatching mixture. The solid particles concentration was varied from ϕ𝑝=20% to ϕ𝑝=50% and the suspension viscosity was measured through Anton Paar MCR 302 rheometer and it was observed that suspension rheology varied from Newtonian behavior in high concentration (ϕ𝑝=50%) of solid particles and coating thickness as well as surface coverage become independent of the suspension viscosity on this concentration. The binder volume fraction is also varied ranging from ϕ𝑏=2.5% to ϕ𝑏=10.5% mostly to understand the effect of binder on the particle entrainment behavior. It was observed that increasing the binder volume fraction (ϕ𝑏=6.5% to ϕ𝑏=10.5%) while the solid loading is constant (ϕ𝑝=35%), high surface coverage over 90% and uniform coating thickness can be achieved which demonstrated an optimum composition for efficient solid transfer process. Also, at zero particle regime, particle entrainment was resulted at very low capillary number below the threshold value. In second phase, the binder influence and its working mechanism was described to understand its effect of particle entrainment. To show that the particle concentration was remained constant (ϕ𝑝=10%) and binder PMMA was varied on molecular weight (15K, 120K and 350K g/mole) as well as its mass loading. Binder at liquid carrier system (LCS) forms a dilute condition at low viscosity (≀2 mPa.s) and high MW (120K and 350K g/mole) which considers the small particles entertainment for its thin polymer layer and high evaporation rate. However, at high viscosity of 15K PMMA (4 and 6 mPa.s), the LCS mixture acts as a concentrated gel-like solution and the particle accumulation follows the distribution like the bulk powder distribution. This behavior can be incorporated on particle sorting process and high-throughput material transfer for material joining process on porous structures.

Download

Share