1

A new approach to ceramics additive manufacturing: NanoParticle Jetting™

North Carolina State University:Yongduk Oh, Vivek Bharambe, Jacob J. Adams

Youngstown State University: Bhargavi Mummareddy, John Martin, Jeremy McKnight, Martin A. Abraham, Jason M. Walker, Kirk Rogers,Brett Conner, Pedro Cortes, Eric MacDonald

Save the dates! Two conferences.

• Pan American Research in AM Workshop

• September 24th to 26th, 2019

• Santiago, Chile

• Pontificia Universidad de Chile

• Sponsor - Office of Naval Research Global

• Web portal coming soon for abstracts.Paradigma 2019

• Technological Innovations in Metals Engineering (TIME 2020)

• June 3-4, 2020

• Youngstown, Ohio (2018 Conference was in Haifa, Israel)• Technion, Israel Institute of Technology

• Youngstown State University

• TMS2

Youngstown AM Ecosystem

3

YSU Additive Manufacturing CapabilitiesAM Category System Metal Polymer Ceramics

Powder Bed Fusion 3D Systems ProX 320 X

EOS M290 (May 2018) (America Makes) X

3D Systems sPro60 (America Makes) X

Binder Jetting ExOne S-Max X (Sand)

ExOne M-Flex and Innovent+ X X

ZCorp 310 X

Directed Energy Deposition Hybrid Manufacturing Technologies AMBIT X X

Material Jetting XJET Carmel 1400 (YBI) X

3D Systems 2500W X (Wax)

Material Extrusion Fortus 250mc X

Fortus 400mc (America Makes) X

Markforged Mark Two X

Desktops (Lulzbot, Hyrel, Markforged, etc.) X X

Vat Photopolymerization Formlabs Form 2, 3D Systems ProJet 1200 X X

Sheet Lamination MCor Iris Paper

NPJ Basics

BuildNano

ParticlesJetting

SupportNano

ParticlesJetting

NPJ Basics

Print Head Droplet touches Tray Evaporation

Jetting process

7

Systems Dimensions (Carmel 1400): cm: 310 w x 212 h x 185 d; in: 122.0 w x 83.5 h x 72.8 dBuild Tray/Plate Size: mm: 500 x 280 (1,400 cm2); in: 19.7 x 11.0 (217 in2)Theoretical height: mm: 200; in: 7.9

Stochastic Nano Particles

8

XJET Nano Particles

9Materials

• Ceramics: 3YSZ Alumina, SiC, Tungsten Carbide, Other • Metals: 316L Titanium, Tool Steels, Aluminum, Other

Intricate detail, fine features

10

11

Process Flowpath for 3YSZ

PRINT

SUPPORT REMOVAL THEN DRY

SINTER

FINAL PARTS

Sintering procedure used here:• Parts sintered in a programmable Blazir dental zirconia box furnace in air• A ramp rate of 3 °C to a target temp of 1450 °C and hold for 180 minutes

Physical properties

13

• Crystallography (XRD): • Tetragonal and monoclinic zirconia (ZrO2) and yttria (Y2O3), with an average

crystalline space of 5.2 A०

• 53% of the system was found to be made of monoclinic ZrO2, and the remaining 47% of tetragonal ZrO2 and Y2O3

• Chemistry:• XRF showed an

elemental composition of 91% ZrO2and 9% Y2O3 (by mass). Agrees with EDS and XRD.

• Density: 5.71 g/cc Archimedes method

Shrinkage: Part-to-Part

• Feature sizes ranged from 2.5 to 45 mm on more than 125 unique features measured.

• Observed shrinkage (due to sintering) had an average of 18.0% with a standard deviation of 0.98%, as shown by the histogram

14

Shrinkage: Feature-to-Feature

15

Sintering: unsupported overhangs

• Overhangs that are supported during the build process are washed out prior to sintering

• These overhangs are then unsupported through sintering

• I-beams designed for measuring: • The beam thickness is 1.21 mm

• The beam width is 19.05 mm

• No drooping measured for I-beams up to 0.5W/T=7.87

16

Cavity resonator

17

For measurement, a vector network analyzer (E5071C, Keysight Technologies) was used.

The resonant frequencies of a rectangular cavity with dimensions (𝑎 × 𝑏 × 𝑐) completely

filled with a material of permittivity 𝜖𝑟 are:

𝑓𝑟,𝑚𝑛𝑝 =𝑐0

2𝜋 𝜖𝑟(𝑚𝜋/𝑎)2 + (𝑛𝜋/𝑏)2 + (𝑝𝜋/𝑐)2

where m, n, p are integers relating to the number of spatial oscillations of the mode in

each direction and c0 is the speed of light in a vacuum.

Finding permittivity

18

Resonant frequencies, 𝜔 , of the low order modes (𝑝 = 0 ) must satisfy the

transcendental dispersion relation [1]:

𝛽𝑦0

𝜖0𝑡𝑎𝑛(𝛽𝑦0(𝑐 − ℎ)) = −

𝛽𝑦𝑑

𝜖𝑟𝜖0𝑡𝑎𝑛(𝛽𝑦𝑑ℎ) (1)

where

𝛽𝑦0 = 𝜔2𝜇0𝜖0 − (𝑚𝜋/𝑎)2 + (𝑛𝜋/𝑏)2 and 𝛽𝑦𝑑 = 𝜔2𝜇0𝜖𝑟𝜖0 − (𝑚𝜋/𝑎)2 + (𝑛𝜋/𝑏)2 and ℎ

is the height of the dielectric filling.

Approach: Measure the part dimensions accurately. Measure the resonant

frequencies. Find the unknown permittivity 𝜖𝑟 by numerically solving (1)

[1]. Balanis CA. Advanced engineering electromagnetics. John

Wiley & Sons; 1999.

Dielectric loss tangent

19

• Q factor of the cavity in terms of dielectric and conductor losses while

assuming coupling losses are negligible as per [2]

𝑄−1 =𝑅𝑠

𝐺+ 𝑡𝑎𝑛(𝛿𝑒) (2)

where Rs = surface resistance of the metal cavity, G = modal shape factor

(calculated), 𝑡𝑎𝑛 𝛿𝑒 = the loss tangent of the filling medium.

Approach:

• Evaluate the behavior at the first three transverse magnetic (𝑇𝑀𝑚𝑛𝑝𝑧 ) modes,

TM110, TM310, TM130, with a ZrO2 sample in place and when empty.

• Remove the parasitic impedance introduced by the coaxial feed by simulating

its response in HFSS (Ansys, Inc.) and de-embedding it from the measured

data.

[2] Krupka J. Frequency domain complex permittivity measurements at microwave

frequencies. Meas Sci Technol. IOP Publishing; 2006;17: R55.

doi:10.1088/0957-0233/17/6/R01

Measured resonant frequencies

• The resonant frequencies of each mode are reduced by a factor of roughly 4.5 when the ZrO2 is inserted, suggesting a high dielectric constant.

• Additionally, the relative widths of the resonant peaks are similar, suggesting the loss tangent of the ZrO2 is small

20

Air Zirconia

Measured dielectric constant and loss tangent

21

The dielectric constant is 23The loss tangent is 0.0013

Application: Dielectric Resonator Antennas (DRAs)

• Why zirconia AM for DRAs?• DRA require high permittivity contrast with air in order to effectively couple

energy into a radiation mode while also requiring low loss tangent to increase efficiency

• DRAs typically consist only of a shaped dielectric, making a single-step additive manufacturing process well-suited for building such antennas.

22

Demonstrations: XJET zirconia spiral antennas

Emily Heckman

Roberto Aga

Summary

• New material jetting based method for additive manufacturing of ceramics. Ideal for fine features and detail.

• Initial ceramic material is zirconia soon to be followed by alumina

• Shrinkage found to be ~18% on average but is a function of direction and geometry

• Unsupported I-beam structures found not to deform during sintering. This has been shown up to 0.5W/T=7.87

• The dielectric constant and loss tangent are found to be 23 and 0.0013, respectively, at microwave frequencies

• Great promise for antenna applications

24

Acknowledgements

• Avi Cohen from XJET

• The Friedman Endowment for Manufacturing at Youngstown State University for supporting this project

• NCSU was supported in part by the U.S. Army Research Office under Grant W911NF-17-1-0216

• Jobs Ohio support to the Youngstown Business Incubator

25

Contact Info:

26

Dr. Brett P. ConnerYoungstown State University

bpconner@ysu.edu

If you are interested in having XJET parts printed:Ms. Stephanie Gaffney

Youngstown Business Incubatorsgaffney@ybi.org

Dr. Jacob AdamsNorth Carolina State University

jjadams2@ncsu.edu

Brett Connerbpconner@ysu.edu

27