THE PENNSYLVANIA STATE UNIVERSITY SCHREYER HONORS COLLEGE DEPARTMENT OF MECHANICAL ENGINEERING 3D Printing of Barium Titanate Using the Direct Ink Writing (DIW) Technique KARIM BARSOM SPRING 2021 A thesis submitted in partial fulfillment of the requirements for a baccalaureate degree in Mechanical Engineering with honors in Mechanical Engineering Reviewed and approved* by the following: Zoubeida Ounaies Professor of Mechanical Engineering Thesis Co-supervisor Amrita Basak Assistant Professor of Mechanical Engineering Thesis Co-supervisor Bo Cheng Associate Professor of Mechanical Engineering Honors Adviser * Electronic approvals are on file i ABSTRACT Barium titanate (BaTiO3) is a smart ceramic known for its piezoelectric and ferroelectric properties. 3D printing, also known as additive manufacturing, of BaTiO3 has crucial applications across the medical, robotics, and electronics industries. 3D printing allows engineers to consider innovative designs with increasingly complex geometries which can lead to innovations that are unimaginable today. The development of a process that produces ceramic parts with 3D printing can also enhance the reliability and reduce the cost of manufacturing small-scale electronic components. The Direct Ink Writing (DIW) process was selected for its relatively low cost of entry, ease of use, and for its use of ceramic pastes and slurries similar to those used traditionally in tape casting and slip casting ceramic manufacturing methods. To execute the DIW process, I am using a modified off-the-shelf consumer 3D printer. Understanding how the controllable parameters of the DIW process and hardware can affect the quality, precision, speed, and capabilities when printing a BaTiO3 based slurry is the first step towards optimizing the DIW process for prototyping and mass commercial applications. Through preliminary slurry solid loading tests and a parameter impact assessment looking at the flow rate, nozzle size, BaTiO3 solid loading in the slurry, print speed, and gap height, I have shown how understanding the relative impact of each parameter can inform the adjustments to each printing parameter for the desired outcome; may that be fastest print speed, greatest resolution, or some combination of outcomes. ii TABLE OF CONTENTS LIST OF FIGURES ..................................................................................................... iii LIST OF TABLES ....................................................................................................... iv ACKNOWLEDGEMENTS ......................................................................................... v Chapter 1 – Introduction .............................................................................................. 1 1.1 - Background and Motivation ......................................................................... 1 1.1.1 – Barium Titanate ................................................................................. 1 1.1.2 – 3D printing of Ceramics .................................................................... 3 1.1.3 – Traditional Ceramic Manufacturing .................................................. 7 1.1.4 – Direct Ink Writing of Ceramics ......................................................... 13 1.2 Problem Statement .......................................................................................... 19 Chapter 2 – Experimental Design ................................................................................ 21 2.1 - Barium Titanate Slurry Formulation ............................................................ 21 2.1.1 – Procedure for Slurry Production ........................................................ 22 2.1.1 – Manual Printing 3D Parts Using Prepared Slurries ........................... 23 2.1.2 - Variation of the Solid Loading ........................................................... 25 2.2 – DIW Printer Setup ....................................................................................... 26 2.3 – Testing Procedure for Parameter Assessment ............................................. 30 2.3.1 – Design of Experiments Setup ............................................................ 30 2.3.2 – 3D Model and Slicing ........................................................................ 31 2.3.3 – Setting Parameters ............................................................................. 32 2.4 – Data Collection and Analysis ...................................................................... 33 Chapter 3 – Results ...................................................................................................... 35 3.1 – Results of Slurry Processing ........................................................................ 35 3.2 – Printing Parameter Analysis Results ........................................................... 42 3.3 – DIW of a 3D Part ......................................................................................... 44 Chapter 4 – Conclusions .............................................................................................. 48 4.1 – Summary of Significant Results .................................................................. 48 4.2 – Conclusions.................................................................................................. 50 4.3 – Suggested Future Research .......................................................................... 52 Appendix A Full Test Matrix for Min-Max Test Plan ................................................ 53 Appendix B Binder Burnout and Sintering Ramp and Temperature Profiles ............ 55 iii BIBLIOGRAPHY ........................................................................................................ 56 iv LIST OF FIGURES Figure 1.1. Crystalline structure of a BaTiO3 unit cell [3]........................................... 2 Figure 1.2. (a) Selective Laser Sintering (SLS) setup (b) Selective Laser Melting (SLM) setup [14] .............................................................................................................. 5 Figure 1.3. CIM component green body, brown body, and sintered part, respectively [9]. 9 Figure 1.4. A schematic of a standard tape casting machine [10] ............................... 12 Figure 1.5. An example of a Direct Ink Writing setup [20]. ........................................ 14 Figure 1.6. Viscosity versus shear rate for a BaTiO3 slurry [29]. ................................ 15 Figure 1.7. (a) Particle size distribution of the three types of powders, the SEM images of the corresponding particles with (b) D50=7.41 μm, (c) D50=3.00 μm, (d) D50=0.35 μm [29] ................................................................................................................. 16 Figure 1.8. Samples of clay fabricated by extrusion 3D printing. a) Side view of “twisted gear lamp”, b) top view of (a), c) pyramidal test object, d) 20 mm diameter cylindrical samples, e) 10 mm diameter cylindrical samples, and f) side view of “Ashtray” [25]. ..................................................................................................... 18 Figure 2.1. SEM images of Ferro barium titanate powder: a) 15000x magnification. b) 35000x magnification ........................................................................................... 21 Figure 2.2. Processing of BaTiO3 slurry for extrusion ................................................ 22 Figure 2.3. Binder-burnout temperature profile ........................................................... 24 Figure 2.4. Sintering temperature profile ..................................................................... 24 Figure 2.5. Model of the control and extrusion setup attached to the Ender 5 Pro 3D printer .................................................................................................................... 27 Figure 2.6. Hardened stainless steel 3D printer nozzle (dimensions in mm) .............. 28 Figure 2.7. a) 3D model of the shape that is used for print testing. b) showing the line that the 3D printer will make when executing the G-code sent to it ........................... 32 Figure 2.8. Example of an image captured for each test case and used for data analysis 33 Figure 3.1. 75wt% parts printed by hand using a 5ml syringe with a 2mm diameter nozzle38 Figure 3.2. Close-up images of two of the printed parts shown in Figure 16. ............. 39 v Figure 3.3. Rectangular 3D form printed using a 5ml syringe, 2mm diameter nozzle, and 70wt% slurry ......................................................................................................... 39 Figure 3.4. Dried parts prepared for binder burnout and sintering .............................. 40 Figure 3.5. 75wt% (in blue boxes) and 70wt% parts (a) after binder burnout and (b) after sintering. (c) Crack formation in the 70wt% sample after the binder burnout step. 41 Figure 3.6. Parameter impact assessment plots. (a) Slurry wt% impact plot (b) Print speed impact plot (c) Nozzle size impact plot (d) Stepper motor step delay (flowrate) impact plot (e) Gap height impact plot ................................................................. 42 Figure 3.7. DIW of a 2cm x 2cm x 2cm cube using printing parameters influenced by the parameter impact assessment results .................................................................... 46 Figure 3.8. (a) Side profile of the printed cube (b) Top-down profile of the printed cube 47 vi LIST OF TABLES Table 1.1. Pros and cons of ceramic injection molding technology vs additive