Transcript Bonding Experiments for Cryogenic Detectors

Bonding Experiments for
Cryogenic Detectors
R. Douglas1, K. Haughian1, A. A. van Veggel1, L.
Cunningham1, G. Hammond1, G. Hofmann2, J.
Hough1, A. Khalaidovski3, J. Komma2, I. Martin1, P.
Murray1, R. Nawrodt2, S. Rowan1, Y. Sakakibara3, T.
Suzuki3, K. Yamamoto3
Thursday 5th December 2013
1University
of Glasgow;
ELiTES Meeting, Tokyo
2Friedrich-Schiller-Universität
Jena;
3University
of Tokyo
Talk outline
•
•
•
•
•
Hydroxide catalysis bonding
Sapphire bonding at the IGR
Sapphire bonding at the ICRR
Indium bonding
Summary
Hydroxide catalysis bonding
• Thermal noise of the test masses and suspensions in GW detectors is an
important limit to detector sensitivity.
Steel wires
Penultimate mass
Attachment or ‘ear’
Steel wire break-off
prism
Silica fibres
Fibres
Weld horns
Ear
End/input test mass
Ear
• Hydroxide catalysis bonding can be used (GEO, aLIGO, aVirgo) to form quasimonolithic suspensions of fused silica
• One possible way to reduce thermal noise is to cool test masses and
suspensions (of appropriate materials): Sapphire (KAGRA) and Silicon (ET) are
candidate materials for cooled use.
• Studies of the properties of hydroxide catalysis bonds formed between
sapphire and silicon (breaking strength, thickness, thermal conductivity etc)
are required to assess feasibility for use in cooled crystalline suspensions
The hydroxide catalysis bonding
procedure
Chemistry of bonding of
OH ions from the
bonding solution
fused silica:
fill any open bonds
OH ions form weak
Aqueous alkaline hydroxide bonds with surface Si on the surface
atoms
Bonding
solution placed between
solution with
OH OH OH OH
lots of free
surfaces to be jointed
OH ions
• Hydration and etching
Si
O
Si
Si
• Polymerisation
Si
O
O
O
Bonds between the Si
Bulk Silica
• Dehydration
-
Silicate molecule
breaking away from
the bulk and into the
bonding solution
-
Bonding solution with
lots of free OH ions Si(OH) -5
OH
OH
OH Si
Si
O
OH
Si
O
O
O
-
Bulk Silica
atoms and the bulkweaken
due to the extra OH- ions
bonding to the Si atom
Similar chemistry for jointing other oxide surfaces
Small volumes of solution used (~0.4ml/cm2)
Several stringent requirements which must be
fulfilled if bonds are to be successful
• Surface must be very clean
• Surfaces must have good match of global figure
(typically flat to l/10)
OH
SiO2 Si
H
H2O
OH
OH H O Si
i
OH
OH
H
H
H2O
OH
OH H O Si
OH
H2O
OH
OH H O Si
OH
SiO2
OH H
Bond
Once made bonds are allowed to cure
for four weeks to reach their
maximum strength
Both tensile and shear strength of interest
Tensile
strength
A 4-point-bending test is
applied to break the bonds.
This allows a value of tensile
strength to be calculated.
Shear
strength
Experiments to test shear
strength designed both at
the ICRR and Glasgow
Sapphire bonding
• Sapphire has a hexagonal crystal structure:
• We are interested in the a-axis, the c-axis and
the m-axis
Sapphire axes in KAGRA
• The mirrors will have
an orientation such
that the sapphire cplane in the mirror will
be perpendicular to the
c-plane of the fibre
• Thus investigating the
properties of bonds
between c-plane and aplane sapphire and cplane to m-plane
sapphire is of interest
Hydroxide catalysis bonding of
sapphire
Areas for investigation:
•
•
•
•
•
How does bond strength depend on type of solution used?
Strength of bonds at cryogenic temperatures
Effect of thermal cycling on bond strength
Can we re-bond if something breaks?
How strong will bonds be if different crystalline axes are bonded
together?
• Can we bond if surfaces jointed have flatness poorer than l/10?
• Will increasing the volume of bonding solution used help in bonding
surfaces with flatness poorer than l/10?
Red = Results obtained Blue = Ongoing
Studies of bond tensile strength vs. chemical
composition of solution
• Aqueous solutions studied:
– sodium silicate (as used in aLIGO)
C-plane
• contains pre-dissolved SiO2 ; aids formation of
polymer-like chains in bond
– sodium hydroxide and potassium hydroxide
• absence of SiO2 may allow thinner bonds
– sodium aluminate
• of interest for optical purposes – better index
match to sapphire?
• All solutions were prepared with de-ionised water
to have a pH of 12 – (to match the pH obtained
when using a ratio of commercial sodium silicate
solution to water of 1:6 as used in aLIGO)
• The samples were bonded, cured and broken at
room temperature to assess their tensile strength
Bonding
surface
Tensile strength (MPa)
Bond tensile strength at room T as a
function of solution used
For comparison:
• GEO and aLIGO: K. Haughian
Thesis (2012): Silica jointed
using sodium silicate solution
(Tensile strengths ~16 MPa)
•
Suzuki et al (2006):
Sapphire-sapphire jointed
using potassium hydroxide
solution
(Shear strengths of ~7 MPa)
•
Dari et al (2010):
Sapphire-sapphire bonds
jointed using potassium
hydroxide solution (Shear
strengths of ~1.5 MPa)
•
For KAGRA strengths of ~10
MPa will be sufficient.
Bonds tensile strength at cryogenic temperature, and
after thermal cycling
Tensile strength (MPa)
Two further sets of
sodium silicate
bonds created:
• One set were
broken in a liquid
nitrogen bath
• One set were
thermally cycled –
cooled to 10 K and
then increased
back to room T
three times
Re-bonding sapphire
• Almost all sapphire pieces survive strength testing intact – of
order 15% are damaged when the bonds are broken
• Re-bonding the pieces could provide information about ability
to repair breakages in bonded sections of a suspension
Example of undamaged surfaces
after strength testing
Example of damaged surfaces after
strength testing
• Samples already used once in bonding experiments were
cleaned and re-bonded using sodium silicate solution
Tensile strength (MPa)
Tensile strength of bonded
sapphire after re-bonding
Slightly lower than
those made with
pristine samples;
however the
strengths are still
good (and are
strong enough for
use in typical
detector
suspensions)
Strength of bonds between different
crystalline axes
• Bonds for KAGRA will
be C-to-A or C-to-M
due to the crystal
orientation of the
mirror and the fibres
• A new set of bonds
were created to
measure the effects of
bonding different
crystal axes together
Are we able to bond at all if parts
aren’t as flat as hoped?
• Generally samples are used which have
surfaces to be jointed with flatness of
<λ/10 (λ=633 nm)
• Unfortunately, sapphire is difficult to
polish and most of the samples
procured by ICRR for the study of the
effect of crystal axis/plane on bond
strength had poorer flatness than λ/10
• For the initial set of experiments the
best samples were chosen, Allowing 9
bonds each of C-to-A, C-to-M and C-toC type samples to be produced. These
each had a flatness of <λ/4
Bonding surface and
plane of interest
Shear strength of bonds between different
crystalline axes tested at KEK at 10 K (Preliminary)
• C-to-M appears to
be the most
promising of the
available options
• Both the C-to-A
and C-to-M bonds
are strong enough
for KAGRA
• The red point in
the C-to-C set
could not be
broken, and may
have a strength
even greater than
119 MPa
Are we able to bond at all if parts
aren’t as flat as hoped?
• A new set of experiments was devised, using the
remaining samples which had flatnesses ranging from
~ λ/4 to ~λ
To determine the
effect on bond
strength if one
surface is significantly
flatter than the other
1. C-to-A with samples with flatnesses of
~λ/4 bonded to samples with flatnesses of >λ/4.
To determine the effect on bond strength if one
surface is significantly flatter than the other
2. A-to-A with samples with flatnesses of >λ/4;
half using the 0.4 μl/cm2 of solution and half
using 0.8 μl/cm2 of solution.
To determine whether
increasing the volume
3. M-to-M the same way as experiment 2
• These bonds have been created and their strengths
will be measured at by somebody at the ICRR in the
New Year, when they will be fully cured
of solution will
improve strength
when bonding with
surfaces of poor
flatness
Thermal conductivity of bonds
• Sapphire was jointed using
sodium silicate solution to
allow studies of bond
thermal conductivity
(Glasgow)
• Typical bond brought to the
ICRR where an experiment
was set up to test its
thermal conductivity
– Work ongoing
Thermal
conductivity
set-up at IGR
Thermal
conductivity
set-up at
ICRR
Summary - Sapphire
• Sodium silicate solution produces the strongest bonds
• Breaking bonds at liquid nitrogen temperatures appears to have
no detrimental effect on the measured strength compared to
breaking them at room temperature
• Thermally cycling bonds appears to reduce the average bond
strength; after 3 cycles average strength still ~40MPa
• Re-bonding samples reduces average bond strength; however
re-bonded samples still have average strength >40MPa
• C-to-M bonds initially appear to be stronger than C-to-A at 10 K.
Alternative bonding techniques:
• Work in Glasgow in mid-90s considered range of techniques for
jointing fused silica to use in GEO600 suspensions at room T:
– Optical contacting (rejected due to poor reliability and possibility
for substrate damage)
– Direct welding of fibres to silica test masses (rejected due to
likelihood of damaging test masses due to relaxation of thermal
stresses)
– Indium bonding (well known as a technique to joint glasses)
In addition to:
– Hydroxide catalysis bonding
• Reported in PhD thesis of S. Twyford.
Fused quartz test mass suspended by silica
fibres jointed using different techniques
•
•
•
•
Comparison of loss measurements
were made of internal modes of test
mass when:
– slung by wires
– suspended via an indium bond:
– suspended via a hydroxide
catalysis bond
To form indium joint: the samples
were heated to 140 °C (just below the
melting temperature of indium)
An ultrasonic soldering iron was used
to deposit indium on surfaces to be
jointed - breaks the thin oxide later
that forms on the surface of the
indium
Bond ~50 µm thick formed
(estimated from measuring the mass
of the indium used)
Fused silica
fibres welded
to T-piece
fused quartz
T-piece, stub
and cylinder
post jointed to
mass using
Indium bond
15 mm wide flat
polished along
the mass
64 mm diameter by
70 mm long fused
quartz test mass
Measured Mechanical Losses of Test mass modes:
Bond Type
39.7 kHz
49.5 kHz
50.6 kHz
60.1 kHz
Weld
(5.5 ± 0.2) × 10-7
(6.2 ± 0.1) × 10-7
(1.9 ± 0.1) × 10-6
(7.1 ± 1.1) × 10-7
Indium
(1.4 ± 0.2) × 10-5
(2.1 ± 0.2) × 10-6
(4.3 ± 0.3) × 10-5
(3.0 ± 0.2) × 10-5
Hydroxide
catalysis
(1.8 ± 0.1) × 10-5
(7.7 ± 1.8) × 10-7
(2.9 ± 1.2) × 10-7
(4.8 ± 0.6) × 10-6
Wire-slung
7.3 × 10-7
-
-
-
Initial Results
• Concluded
– mechanical losses associated with using indium
jointing were tolerable when scaled to use in fullsize suspensions
– low melting point meant it was not practical for
use in Room T suspensions (e.g: suspensions are
heat treated for cleaning purposes)
– of interest for cryogenic suspensions?
Recent studies
•
•
•
•
•
Kelvin Nanotechnology Ltd in (Glasgow)
fabricated silicon cantilevers: 35 mm
long, 5 mm wide and 54.5 µm thick
Thin layer of indium (tIndium = 530 ± 30
nm) evaporated onto one face of the
cantilever at Univ. of Jena
Mechanical losses measured between
10 K and 80 K with and without indium
applied
Mechanical loss of indium calculated
Nb :
– exposed surface layer of indium
oxidised
– Indium coating rather than a joint or
bond
Clamped cantilever
with indium layer
applied
Loss of indium film at cryogenic
temperature
-4
14
2222.3 Hz
x 10
• Loss of approximately
5 x 10-4 at a few 10’s of K
• Broadly consistent with
values from Liu et al (1999)
13
Coating Loss
12
11
10
9
8
7
6
5
4
0
10
20
30
40
50
Temperature (K)
Mode 4 at f = 2222 Hz
60
70
• FEA models of thermal
noise from indium bonds
used in an Advanced
detector-like suspension
geometry at 40K suggest
noise would be ~x10 lower
80
than sensitivity of ET.
Summary – indium bonding
• Not ideal for use at room temperature when suspensions
may be heated for e.g. cleaning purposes
• Loss at low (10’s of K) temperatures makes it of potential
interest for use in construction of cryogenic suspensions
• Further work: construction of small prototype sapphire
suspensions using indium bonding.
Thank you for your attention
References:
[1] A. Dari et al. Breaking strength tests on silicon and sapphire bonding for
gravitational wave detectors. Classical and Quantum Gravity, 27(4): 045010, 2010
[2] T. Suzuki et al. Application of sapphire bonding for suspension of cryogenic
mirrors. Journal of Physics: Conference series, 32, pp 309, 2006
[3] K. Haughian. PhD Thesis. University of Glasgow, 2013
[4] A. A. van Veggel et al. Strength testing and SEM imaging of hydroxide-catalysis
bonds between silicon. Classical and Quantum Gravity, 26(17): 175007, 2009
[5] X. Liu et al. Low-temperature internal friction in metal films and in plastically
deformed bulk aluminium. Physical Review B, 59(18), 1999