08:50-09:20 K1Magnesium single crystal for biodegradable implant

applications

Vesselin ShanovUniversity of Cincinnati USA

Non-degradalble

Too stiff

Degradable polymer

Degrade by releasing heat and toxic gases

inflamation

Polycrystalline materials

Preferential sites for intergranular corrosion attack

Signal crystal

Non-catastrophic failure

High purity

No grain boundaries

High strength

High corrosion resistance

How to control corrosion rate of pure Mg single crystal

Chemical etching

Anodization

Crucible for growing 3 Mg single crystal

2016, 20mm in diameter, 150mm in length

Fabricate Mg single crystal in the form of screw andplate

Characterization

Laue camera from photonic science LTD UK

XRD

Synchrotron XRD Argonne National Lab

X-ray Tomography MicroCT of the entire single crystalscanned for 8 hours

ICP-MS : distribution of selected metal impurities alongthe length of Mg single crystal.

Thermal annealing at 645 degree C in Ar for 14 hours.

Single crystal show high ductility of 60% due to ~20degree off the 002

More energy id needed to intiate crack propagation in Mgsingle crystal, showing high fracture ductility.

Such high plasticity in unusual in metals at room temperatureand may occur due to multiple deformation twinning

High ductility of Mg single crystal is useful forimplants in regions experiencing significant and interplay vetween bones andtissue such as Anterior Cruciate Ligament(ACL) ring and craniofacial

Single crystal show less corrosion 12.5 time than poly Mg

Proper etching form a nano thick and dense oxide film andbenefit the in vitro and in vivo biocompatibility.!!!

Rabbit ulna fracture

ACL ring in goat

Anodized MG single crystal ring fully degraded in 12weeks

09:20-09:40 O1Customizing absorbable magnesium alloys Jake Cao ETH Zurich Swiss

Conventional purity Mg (150ppm Fe)

High purity Mg (40 ppm Fe)

Mg distilliation

Nano capillarcy cell

P. Schmutz EMPA

Acta Biomater 23 (2015) 347-353

JOM 66 (2014) 566-572

EDS mapping

ZX10 Mg+Mg2Ca

Ternary intermetallics Ca3MgXZn15-X(4.6<X<12 below325 degree C)

Controlled annealing led to formation of desiredintermetallic phases and grain coarsening

Combination of grain size and intermetallics phasescontrol the degradation rate

09:40-10:00 O2Grain-boundary strengthening of MgZnCa lean alloys Martina Cihova ETH ZurichSwiss

Non-toxic

Appropriate immune response

Excellent mechanical property for 5-6wt.%Zn and0.2-0.4wt.%Ca

High Zn content proved to be detrimental for the corrosionbehavior (too fast)

Mg-xZn-0.3Ca

MgZnCa lean alloys with <1wt.% Zn

Desired : small grain size

Extruded at 300 degree 1.6 micrometer grain size

Desire of a tailored degradation rate to meetpatient-specific requirements

Pediatrics vs adults

Implantation site

Annealing between 275 -325 degree, the best choice

10:50-11:10 O4 Newdevelopments in Equal Channel Angular Pressing (ECAP) of Mg alloys

Maciej KrystianAustrian Institute of Technology GmbH

Austria

Low amounts of non-toxic alloying elements

Less Zn-rich intermetallic which acts as cathdonic

Angle 120 105 90

Cylindrical bolt 12mm-40mm

Length 120mm

Mg-Zn0.6-Ca0.5

Homogenization 350DegreeC/12h

Solution 450 degree/8h

Extrude at 325 degree C 16:1 ram speed 5mm/s

Double ECAP excellent strength and good ductility

Strain =1.6 compare with 0.6-1.0 for single ECAP

Reduction in the number of passes and thus cost reduction

10:50-11:10 O4Influence of primary forming on microstructure and corrosion of Mg-Ca-Zn

Daniela ZanderRWTH Aachen University Germany Met-5

Mg-0.6Ca1.8Zn Mg-1.2Ca-1.8Zn Mg-1.2Ca-3.6Zn

The grain size decrease with decreasing Ca and Zn content

Sand casting reveals the additional formation of CaMgSi.

Die casting process should be beneficial for thecorrosion resitance.

Lower concentrations should be beneficial for thecorrosion kenetic

11:10-11:30 O5Microstructure and properties of WE43 manufactured via SLM

Naemi Zumdick RWTHAachen University Germany Met-6

Powder extruded as control

SLM homogeneous extremely fine microstructure

No clear identification of the phases, furtherinvestigation

1 micrometer in grain size

As-cast 38.6 micrometer in grain size

WE 43 1.2 at.%Y 0.5 at.%Nd

SLM have higher corrosion rate

Impurity in SLM powders is important

High contamination lead to numerous large corrosion pits

Control of impurities and decrease the size.

Powder Y 3.48 Nd 1.62 Gd0.71Zr 0.40

SLM Y 4.17 Nd 1.82 Gd 0.79 Zr 0.42

As-cast Y 3.49 Nd 1.75, Gd 0.13 Zr 0.32

The mechanical property of SLM is good

11:30-11:50 O6Development of a novel biodegradable metallic stent based on micro-galvaniccorrosion: Strength and ductility assessment

Rosaire MongrainMcGill University Canada Met-7

Strut fracture

Severe strut fracture

Wall injury with strut thickness JACC 2003 41(8) 1283

Healing response with strut thickness

Eurointervention 2010 6 630

Current stent grain size are in the range of 20-25micrometer for 316L 30 micrometer for Co-Cr

Macro-galvanic corrosion

The micro-galvanic corrosion amalgamate concept

Micro-galvanic corrosion and cold spray for stentmanufacturing

The coated amalgamates are thermally treated forductility improvement

Using nitrogen as process gas

Using helium as processing gas

The treated amalgamates have superior mechanical propertythan bulk 316L, small grain and thin struts are possible with the amalgamates.

Mixed amalgamated 100-316L, 20Fe-80SS, 50 Fe-50SS,80Fe-20SS, 100Fe

J Thermal Spray Technology 23(4) 641-652, 2014

Cold spray provides a new approach for bioresorbablestent

11:50-11:55 SOP1 Developmentof balloon-expandable EW31 alloy stent for pediatric airway problems

Kotaro Hanada AISTJapan Japan Met-8

Mg-3%RE-1%Y

UTS 270-310MPa EL 20-25%

Weight reduction 2.8% per month

Corrosions rate < 0.1mm/year

Bending strength 3 month immersion >300MPa

Safely expanded to 3.6 mm

Enough radical force to open tracheal lumen

Good biodegradability

11:55-12:00 SOP2Degradation behaviour of biodegradable Mg staples used in stapler forgastrointestinal anastomosis

Jing Bai SoutheastUniversity China Met-9

Mg fine wire 0.2-0.3mm

Ceramic/polymer coating

Removing outer polymer coating, corrosion occur

7 days maintain supporting

90 days completely degraded

12:00-12:05 SOP3Sustained release of vancomycin from polymer coated micro-arc-oxidized (MAO)AZ31 alloy

Prashant KumtaUniversity of Pittsburgh USA Met-10

Antibiotic

Vancomycin does not impede bone growth in in vivofracture

MBC

MIC

12:05-12:10 SOP4Microstructure evolution and corrosion behavior of the biodegradable EZK1110alloy

Petra MaierUniversity of Applied Sciences Stralsund

Germany Met-11

Mg-10Dy-1Nd-1Zn-0.2Zr

Annealed at 500 degree C for 1h and 24h

LPSO phases

(Mg,Zn)3Dy

16:30-16:50 O7Fatigue performance of Resoloy® magnesium alloy wire

Adam Griebel Fort Wayne Metals USA

Nat Mater 4 2005 518-524

Mg-Li alloy

AZ31 WE43 ZM21

0.02mm wire

Resoloy (Meko)

Mg-RE-Zn-Zr

3 month 10 million cycles

Superficial femoral artery up to 6% diameter expansion

0.127mm Rosoly wire

Natural diamond dies

Oil-base lubricarw

70% cold work 500MPa

350 degree C annealing

400 ddgree C annealing

450 degree C annealing

Rotary Beam Fatigue

ASTM E2948-14

R=-1 N=7 60Hz 10000000 run out

Condition 400 degree C

Strain 0.6%

Cycles: 23,270

As drawn

Strain 0.55%

Cycles :6,275,160

16:50-17:10 O8 In vitro and in vivo corrosion cell response and biocompatibility of high strength Mg-Ca-ZrMg-Y-Ca-Zr and Mg-Y-Zn-Ca-Zr alloys for orthopaedic implant applications

Prashant KumtaUniversity of Pittsburgh USA

Y: 0-4% Ca: <0.6 Zr: 0.4-1% Zn:2%

Mg12Yzn LPSO phase

High proliferation of MSC than AZ31

In vivo

Systemic toxicity

Degradation behavior

Local response

Femoral osteotomy 15mm length 1.66mm in diameter rodsample implantation

2, 8, 14 weeks

Gas pocket was observed

Pin degrade more rapidly near the fracture site leadingto pin failure due to stress corrosion cracks

No abnormal electrolyte levels compared with reference

No significant increase in Mg Ca Zn observed in liver andkidney

Continued osteoblast activity surrounding

17:10-17:15SOP4 Preliminary research on biodegradation performances of

MgZnCaamorphous ribbon for tissue regeneration membrane application

YibinRen Chinese Academy of Sciences China

17:15-17:20 SOP5Remote laser cutting of Mg alloy with a ps-pulsed laser Agung PurnamaPolitecnico di Milano Italy

Dross generation is the most important defect

Laser micromachining

Effect of wavelength

Effect of pulse duration

Conventional vs submerged cutting

REMOTE

Ablation based cutting 355 and 532 nm

Large kerf and adaption to tube are the disadvantages.

17:20-17:25 SOP6Corrosion behaviour of newly developed biodegradable zinc alloys for medicalapplications

Sergio LoffredoLaval University Canada

Zn alloys containing Mg (0.15 0.5 1) and Al (0.5, 1)

17:25-17:30 SOP7Effect of initial powder preparation on mechanical and biodegradationproperties of newly developed Fe-Mg2Si composites for medical applications

Malgorzata Sikora-JasinskaPolitecnico di Milano Italy

1.5% Mg2Si was added into Fe matrix

Micro-galvanic effects depends on the size anddistribution of local anodes(Mg2Si) and cathodes(Fe matrix)

17:30-17:40 General discussion of SOP

17:40-18:30 Coffee break & Posters

Poster session 1 (attendees presenting a Poster or a SOPin Materials topic should be ready for discussion close to their poster)

18:30-18:50 O9Zn-based biodegradable alloys: recent achievements and novel alloy development

Maurizio VedaniPolitecnico di Milano Italy

Zn poor strength, desirable ductility, desirabledegradation rate

Solubility Mg in Zn 0.15wt% Al in Zn 1.7wt%

350 degree C 48h homogenize

250 degree C extrusion ratio 6:1

Zn-1Mg minitube

Grain size 3 micrometer

More homogenous behavior in extruded alloys

Intergrity of alloys on compression after 2 weeksimmersion in modified Hank solution

18:50-19:10 O10Importance of stable oxide film in endovascular biodegradable stents

Jaroslaw DrelichMichigan Technological University USA

In vivo corrosion rate of 99.99% Zn 20 micrometer / year

Can we control the degradation rate by manipulation ofoxide film

ZnO oxide, by 35odegree C 1h 0.3-0.7 micrometer thickoxide film

Electropolishing 0.06-0.08 micrometer thickness of oxide

Crack per area

Anodization to form 6-8 micrometer thick film

The oxide film thickness appears to be of secondaryimportance when cracks are present

Crack in the oxide film structure most likely appear aslocal corrosion sites and their increased density accelerates corrosion rateand its non-uniformity.

Therefore the surface oxide film could be engineered todelay and decrease the stent degradation rate and improve its uniformity in theearly stage of Zn material biodegradation.