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Virtual Laboratory for Biomaterials: Processing and
CharacterisationBikramjit Basu
Department of Materials Science and Engineering,Indian Institute of Technology Kanpur, INDIA.
*E-mail: bikram@iitk.ac.in
Broad objectives:
• To design five web-based interactive experiments in the broad area ofmanufacturing/fabrication of Biomaterials.•To excite the students remotely in the emerging area of Biomaterials.•To enable sharing of highly costly equipments like spark plasma sintering as well as somestate-of-art cell culture and bacteria culture facilities with other institutions remotely.
Experiments originally proposed in the proposal: Super fast densification of Biomaterials Biological cell interaction with a material How a material can be anti-bacterial? Influence of external electric field on the cell-material interaction Inhibition of bacterial infection on implants by magnetic field
Virtual Laboratory for Nanocomposite Fabrication
and Biomaterials LaboratoryCurrent Status - experiments completed / under progress:• Video of Biomaterials fabrication using spark plasma sinteringcompleted
• All the required files on the fundamentals of Nanocompositefabrication as well as cell-material interaction in the contest of thebiomaterial application are uploaded on VLFM website maintained atIIT Kharagpur
• Planning of bacteria culture to show bactericidal /bacteriostaticproperty in magnetic field
• Cell culture experiments in electric field experiments to beperformed
Schedule of meetings with the DNCs: December, 2010 in IIT Kharagpur
Ceramics Biomaterials research
Spark Plasma Sintering (SPS) UV Spectrophotometer
Compression molding CO2 incubator
3D Printing to fabricate materials
with designed structure
Phase contrast microscope
High temperature furnaces Ultra low deep freezer
Fretting wear tester Critical point dryer
Laser surface Profilometer Pulse Electric field set up
Dynamic Elastic Modulus
analyzer
Shaking incubator
Bacterial cell incubator
Facilities developed at IIT Kanpur
Research Facilities
Spark Plasma Sintering facility
Cell Culture facility
Bacteria culture facility
Some background on Spark Plasma
Sintering
(MOVIE uploaded on website)
Spark plasma sintering (SPS)
Initial activation of powders by pulsed voltage.
Resistance sintering under pressure.
Heating rate: upto
600K/min.
Sintering temperature
lower by 200-3000C.
Holding time 0-10 min.
Total processing time:
20 min.
Benefits:
Reduced sintering
time.
Good grain to grain
bonding.
Clean grain
boundaries.
Phenomenology of SPS:- release of electrical energy through a porous powder compact
- breakdown of surface films
- Arcing at pores leading to enhanced mass transport to neck
Experimental: Spark Plasma Sintering
Heating rate : 600 – 650 K/min; Maximum pressure: 50-60 MPaDC Voltage : 5 – 10 V; Pulse frequency: 30-40 kHZVacuum: 60-70 mtorr; Sintering time: 5 minutes
SPS effect
Simultaneous application of mechanicalpressure and high power pulse source (upto 6kA).
Pulsed direct current leading to cleaning andsurface activation of powders.
Generation of electric discharge at the neckregion
In the presence of pressure and electric current, localized
necking occurs faster due to joule heating. Consequently, the
temperature raises very fast (faster than conventional sintering and
Hot pressing) and the densification is completed within few minutes.
Neck formation due to localized heating
Joule’s heating: localized
temperature increment
Groza et al., UC Davis
Three mechanisms may contribute to field assisted sintering:
activation of powder particles by pulsed current
resistance sintering
pressure application
This activation is unique and provides main difference from
more conventional resistance sintering processes (hot pressing).
The surface activation results in clean grain boundaries. The
grain boundary area shows direct grain-to-grain contact, which
is attributed to the physical activation of powder particle
surfaces during pulsed current application i.e. enhanced grain
boundary diffusion process.
SPS process
Multi-Stage Spark Plasma Sintering: Novel
technique to obtain enhanced mechanical and
triblogical properties of ceramics
Results of some Recent Experiments
Single stage SPS vs. Multi stage SPS
1 surface cleaning /activation
2 grain boundary diffusion
3 Lattice diffusion
900oC, 5 min
1100oC, 5 min
1200oC, 5 min
MSS
900oC, 5 min
1200oC, 5 min
TSS
Initial experiments to test hypotheses with α-Al2O3
1200oC, 5 min
SSS
Densification parameter vs time
• MSS: Densification is completed almost at the onset of final
stage of holding
• SSS/TSS: A relatively monotonic increase in Ψ value during
heating to sintering temperature
Ψ=(ρt-ρi) / (ρth-ρi)
ρt :instantaneous density
ρi :initial density
ρth: theoretical density
Subsurface Hardness
• SSS: Hardness decreases towards centre: non uniform densification
• MSS: Uniform hardness
15 mm
K. Madhav Reddy, Nitish Kumar and B. Basu; Scripta Materialia (in Press, 2009).
Microstructure
(i) SSS shows Porosity
(ii) TSS Bimodal distribution – (250-500nm)
(iii) MSS Unimodal distribution (iv) TEM grain size ( 200-300nm)
100nm
(iv)
Further experiments with zirconia
980oC, 5 min
1100oC, 5 min
1250oC, 5 min
MSS
980oC, 5 min
1250oC, 5 min
TSS
1250oC, 5 min
SSS
XRD Phase evolution for Zirconia Consolidated
(a) Initial Powder (b) SSS (C) TSS (d) MSS
Ψ= (ρt-ρi) /(ρth-ρi)
ρt is instantaneous density,
ρi is initial density
ρth is the theoretical density
Zirconia (ZrO2 )
Subsurface Hardness
● In SSS/TSS hardness
decreases with distance
from edge towards centre
● MSS hardness is uniform
along the pressure direction
as well transverse direction
15 mm
TEM micrograph of ZrO2
(a) SSS
(b) MSS
Grain size: 60-250 nm
Grain size 70-120nm
Sintering
Schedule
Relative
density(ρ)
Vickers
hardness
(100g)
Fracture
Toughness
( 2kg)
3-point
Flexural
Strength
SSS 98.9 13.6 0.2 5.22 0.14 619± 50
TSS 99.3 15.6±0.4 5.1±0.3 1093± 35
MSS 99.5 15.9 0.3 6.6 0.06 1350 ± 65
The summary of the research of tetragonal Zirconia
Superior and more uniform hardness/toughness/strength properties
and also better density values at identical final sintering temperatures
Uniform densification and avoid of grain growth during MSS
Biomaterials: Importance,
processing and characterization
MOVIE ON CELL CULTURE
uploaded
MOVIE ON BACTERIA CULTURE
uploaded
How to Synthesize Ca10(PO4)6(OH)2 – hydroxyapatite
powders in a laboratory?
Cell culture
Notes on protocol is provided in separate document
Cell Culture experiment
Electric-field stimulated cell adhesion
Electric Field Pulse Generator
(a) 0 V, (b) 1 V, (c) 2V, (d) 10 V
0 V 1 V 2 V 5 V 10 V 15 V 20 V 25 V0.0
2.0x103
4.0x103
6.0x103
8.0x103
1.0x104
1.2x104
1.4x104
1.6x104
1.8x104
2.0x104
2.2x104
2.4x104
2.6x104
**
*
**
*f = 100 Hz
d = 4 %
No
of
ce
lls
/cm
2
Voltage (V)
(b)
*
Influence of E-field strength on cell viability (control disc)
Optimal E-field = 0.66 V/cm
Antimicrobial property evaluation
Notes on protocol is provided in separate document
E. coli bacteria
(a) Control,
(b) HAp -20 wt. % ZnO
S. aureus bacteria
(c) Control
(d) HAp-20 wt. % ZnO
Human Osteoblast-like
cells SaOS2
(e) Control
(f) HAp -20 wt. % ZnO
An example of material with antimicrobial property:
Conventionally sintered HA–ZnO
(a)
(d)
(b)
(c)
(e)
(f)(e) (f)
(c) (d)
Basu and co-workers; J. Biomedical
Materials Research B (2010)
30
Schematic diagram of electromagnet and magnetic field set up used in our study
Magnetic field exposure cycle on bacteria suspensions
Time
2hrs. 4 hrs.
100 mT
0 mT
100 mT
0 mT
120 min
30 min
60 min
240 min
Time
2hrs. 4 hrs.
100 mT
0 mT
100 mT
0 mT
Time
2hrs. 4 hrs.
100 mT
0 mT
100 mT
0 mT
120 min
30 min
60 min
240 min
Log phase starts
Lag phase
Antibacterial efficacy of electromagnetic field
(bar = 10 µm, magnetic field strength =100mT)
Control (0 min)
Control (60 min)
HA surface (0 min)
HA surface (120 min)
Acknowledgements: Funding agencies
Department of Science and Technology (DST), India
Council of Scientific & Industrial Research (CSIR),India
Department of Biotechnology, DBT, India
IIT Kanpur CARE grant
Acknowledgements: Students, Post-doc
MaterialsA. MukhopadhyayK. Madhav Reddy
Alok Kumar
CeramicsShekhar Nath
S. BodhakN. Saha
A. R. Molla
Physics/ChemistryAshutosh K. Dubey
B. SinghS. KumarV. Raju
PolymerDr. Garima Tripathi
BiologySushma KalmodiaHemant Kumar
Acknowledgements: Students, Post-doc
Materials
A. Mukhopadhyay
K. Madhav Reddy
Alok Kumar
Ceramics
Shekhar Nath
S. Bodhak
N. Saha
A. R. Molla
Physics/Chemistry
Ashutosh K. Dubey
B. Singh
S. Kumar
Polymer
Dr. Garima Tripathi
Biology
Sushma Kalmodia
Amit Nayak
Acknowledgements: Collaborators
Materials
K. Biswas
(IIT Kanpur)
Mathematics
/Statistics
M. Banerjee
(IIT Kanpur)
In-Vivo Testing
M. Mohanty
P. V. Mohanan
(SCTIMST,
Trivandrum)
Physics
R. Gupta
(IIT Kanpur)
Materials
K. Biswas
(IIT Kanpur)
Biology
Alok Dhawan
(IITR, Lucknow)
Medical Professionals
Dr. Amit Dinda (AIIMS)
Lt. Col. Manish Mukherjee
(INMAS, DRDO)
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