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Whiteware VII testing and measurement 1
Testing and Measurement of Ceramic Bodies
Testing and Testing and Measurement of Measurement of Ceramic BodiesCeramic Bodies
Part VIIPart VII
Whiteware VII testing and measurement 2
Testing
• ก����ก������ ����������ก�����������������
• �������� �� !�"��!��#�ก �����$��
• %� �%����� �� ��"�� &��'��� ()����
• ������ก��!���#�'��� () ��*���� ����+�!��!�"���,*��ก��'��� ��ก��-.!�#
Whiteware VII testing and measurement 3
ก������� �/����
• ก���������ก�# ��(Physical Testing)
• ก���������!��� (Chemical Testing)
• ก������������ (Mineral Testing)
Whiteware VII testing and measurement 4
� 0������ก������
1.���� ��#���
2.����� �/����ก���!'�
3.����� �/������ �!'�
4.����'��� ()
Whiteware VII testing and measurement 5
ก������ ��#����*�# cone and quarter
Whiteware VII testing and measurement 6
การหาความชื้น (Moisture content)
������-%: �����!7����ก)
Whiteware VII testing and measurement 7
ก������������8!��#� (Particle size analysis)
• Sieve test -about 30 micron diameter
• Sedimentation Methods
• Hydrometer Method for 10 µm
• Andreasen Pipette for 2 µm
• Centrifuge – down to 0.1 µm
Whiteware VII testing and measurement 8
Sieve test
• Mesh numbers: no. of apertures per linear inch
• British Standard Sieves: BS410:1976
• Institute of Mining and Metallurgy (IMM): UK diameter of wire should be equal to the width of the screen opening
• Tyler Standard Screens and US Standard
Whiteware VII testing and measurement 9
Sieves and Aperture sizes
--53300
657475200
105-105150
107125125120
127149150100
21025025060
8001190100016
1600238020008
USS(µm)
IMM(µm)
BSS(µm)
Sieve No.
Whiteware VII testing and measurement 10
��9�ก������������8!��#�:�#�,*�8�ก������!��#�
• � �/����~500 g ;%����*����110 °c %�8�� 4 ,�.• , ���.�.� �/������*�• �+������'�ก ��0+���*!%<��0+����!���� ������1: 3 � 0���0�;�*24,�.• ก����0+����'����8�ก���8!��#� !,�� 100 Mesh• �+��8�ก��;%'�����ก=�ก�0+���*;�����!��>�*��!�������ก �+��8�ก��;%����*� , ��
�.�.����*���8�ก��
����%����� �/�������'����8�ก��(%)
= ����0+��� ก��*� – � �/�����*���8�ก�� ×100����0+��� ก��*�
Whiteware VII testing and measurement 11
ก������������8!��#�:�#ก������'����8�ก�����!%?#ก
• �����*�100 g. ����0+� 300 cc. ก�� 30 ���� � 0���0�;�*%�8�� 30 ����
• ก����0+����'����8�ก�� ��8!�"�� !���) #60,120,200��8300 /������ �� �/�����*������
• �+��8�ก��;%'���ก=�ก;�����!��> ��*��+�;%����*�!�� �/�����*���8�ก������8����;%, ��
• �+���%�������� �/�������'����8�ก������8����
Whiteware VII testing and measurement 12
Sedimentation Methods• Depend on setting of particles from a dilute aqueous
suspension under the influence of gravity →Stokes' Law.• Hydrometer and Andresen pipette (<10µm, non-plastic) (2µm,
clays)
Stokes' Law
r = radius of particlesν =velocity of fluidη =coefficient of viscosityρ1=specific gravity of solidρ2 = specific gravity of fluidg = acceleration due to gravity
grr )(3
46 21
3 ρρπηνπ −=
Whiteware VII testing and measurement 13
grw 13)
3
4( ρπ=
gr 23)
3
4( ρπ=
W = downwards due to the weight of the particle B = upward thrust due to the buoyancy effect of the fluid displacedV = the viscous drag created in an upwards direction as it opposes the downwards motion of the particle
W=B+ VForce= Mass × Acceleration
= Volume × Density × Acceleration
Buoyancy effect
Viscous drag,
w = B + V
ηυπrV 6=
grr )(3
46 21
3 ρρπηυπ −=
2212
9
)(2kr
gr=
−=
ηρρ
υ
Whiteware VII testing and measurement 14
Assumtions in deriving Stokes’ Law
• Equivalent sphere• Terminal velocity → this short acceleration period
can be ignored• Restriction of containing vessel: >3 cm. in
diameter, restriction imposed by the walls of the container on the free flow of particles is negligible.
• Turbulence: setting velocity must be low no turbulence occurs.
• Dispersion: Type and amount �,* Hydrometer: highest reading indicates the maximum dispersion for a given deflocculant.
Whiteware VII testing and measurement 15
Deflocculants
• Flint,Feldspar,Alumina → Water,Calgon or Sodium Oxalate Dispex,SodiumCarbonate,Sodium Silicate.
• Colours: Water, Potassium Citrate• Chalk: Isopropanal or Acetone• Silimanite: Methyl Alcohol• Clay: Water: Sodium Hydroxide, Calgon,
Dispex and Sodium Silicate.
Whiteware VII testing and measurement 16
Andreasen Pipette
Theory d = 14.29 %( By Weight) of particles less than a given diameter = (CT/C0) ×100
When d = diameter of particles (µm) L = effective depth (cm)T= settling time (min)CT = concentration after timeC0 = original concentration
• Spherical particles falling freely in a liquid, settle at a rate given by Stokes ' Law
grr )(3
46 21
3 ρρπηυπ −=
Whiteware VII testing and measurement 17
Whiteware VII testing and measurement 18
“equivalent spherical diameter ”(d)
For conditions of the Andreasen test the following values are used:
d = diameter of particles (µm)
η = viscosity of water 0.01002 poise at 20 °cρ1 = density of particles 2.5 g/cm3 (assumed for ceramic powder)
ρ2 = density of water 1.0 g/ cm3
gd
)(
18
21 ρρηυ−
=
Whiteware VII testing and measurement 19
V = L/T = depth (cm)/time (min)g = 980.7 cm/s2
at 20 °c, d = 14.29
• At given depth, at a given settling time (T) is associated with a given concentration (CT) and a given diameter then:
%(wt) of particles less than a given diameter = (CT/C0) x 100
To measure the size of the particles a sample of the suspension is taken by a specially designed pipette from a depth L (cm) after settling time T (min)
xTxx
xLxxd
607.9805.1
1001002.018 8
=
T
L
Whiteware VII testing and measurement 20
Test Procedure (Variable position Apparatus)
• 25 g. of sample powder is weighed + 100 ml of H2O in 600 ml beaker.
• Boil → Stirred → # 200 → Dried →
1 l Cylinder + 40 ml of 4 % Calgon →Stirred → Pipette
Whiteware VII testing and measurement 21
Calculation of results: example
Deflocculation correction; 40 ml of 4% calgon in 1 l. of suspension
1000 ml contains 1.6 g calgon i.e. 20 ml contains 0.032 g calgond = 10 µm at 10 cm → settling time = 20 min 25 sec
Average original conc. 0.5771Less deflocculant correction 0.0320
C0 = 0.5451
At 10 cm depth 0.2698Less 0.0320
Ct= 0.2378At 20 cm depth 0.4418Less 0.0320
Ct= 0.4018• (0.2378/0.5451) ×100 = 43.6 % less than 10 µm• (0.4098/0.5451) ×100 = 75.2 % less than 20
Whiteware VII testing and measurement 22
Andreasen Pipette Test: Fixed Position
• 10 ml pipette, working at 20 cm sampling depth, with a two way stop-clock.
• d = 20 µm at 20 cm depth, the settling time is 10 min 13 sec
Whiteware VII testing and measurement 23
Calculation of Results: Example using a slop sample
• Temp = 20 °c• Specific gravity of dry material = 2.5
• Vol. of sedimentation vessel = 630 ml.
• Deflocculant correction per 10 ml. pipette = 0.0127
0.10370.11641038-2318.8
0.17010.1828209-4819.2
0.21110.2238-019.6
0.21000.2227-020.0
�0+��� ก���/-ก�*��
(g)�0+��� ก�� ���
(g)Particle(µm)
T(min.)
SamplingDepth (cm)
C0 = average 0.2100, 0.2111 → = 0.2106% less than 20 µm = (0.1701/0.2106)×100 = 80.8 %% less than 10 µm = (0.1037/0.2106)×100 = 49.2 %
Whiteware VII testing and measurement 24
Hydrometer methodCalibration Procedure:��ก�� calibration ��� ���ก���������������������������������� ��ก Hydrometer (R) � ���� Effective depth (L, cm) �����ก����!
L = H +(h/2)–(V/2A) – M• H+(h/2) �"��������� �+���;�*��ก Hydrometer
• V/2A �"� Displacement correction ������;�*��กก�������� Hydrometer ��ก�8��ก��� (V �"�%��������� hydrometer, A �"� �"0������*�� ����ก�8��ก���)
• M = meniscus correction ~ 0.2 cm.
Whiteware VII testing and measurement 25
Note 1: Displacement correction (V/2A)
• %����������0+���� /-ก�������������*�# Hydrometer 7���!%<�]̂�ก), ����%��������� hydrometer ����"0������*�� ����ก�8��ก��� � �� 0�������/-ก�*���"� V/2A ���8� �������ก����>
Whiteware VII testing and measurement 26
Note 2: Meniscus correction (M)
• ������%�8��!�"����*����������;�*��ก Hydrometer /-ก�*����ก#�����0� !�"�����ก�0+�����������+���*ก���������'������;%;�* ���%�8������'��������0%�8�� 0.2 cm
Whiteware VII testing and measurement 27
Hydrometer calibration
h/2 = 16.6/2 = 8.3 cm, V/2A = 66.38/(2x30.58) = 1.08 cmM = 0.2 L = H + (h/2) – (V/2A)- M = 7.02
Whiteware VII testing and measurement 28
Graph of effective depth (L,cm) & observed reading (R)
Whiteware VII testing and measurement 29
Hydrometer method
Test Procedure
BS 1377 (Calgon – T. as deflocculant)
• Sample of dry material
50 g of sample powder (dry wt) → 200 ml of distilled H2O → Stirred → sieve '��� 200 !�, � �+��0+����;%����ก�8��ก��� � !��� 4% calgon ��;% 40 ml � ก��'�ก � � � 0���0�;�*���!������ก+���� (16,25,36 min.) ��*�����������!ก���� Hydrometer (reading)
Whiteware VII testing and measurement 30
Sample of Slop Material ���!����ก"��#���������• �,*��� pycnometer• , ���0+��� ก �0+���� + ���• , ���0+��� ก�0+�!%��� + ���
(Bottle + Slip) – (Bottle + Water) = Z Z ≈ 28~32 g. !�"����*;�*����!�*��*�����0+�������!���8���ก��� �ก��ก�8��#���� S = Specific gravity of solid
Z×(S/S-1) = W
Hydrometer method
Whiteware VII testing and measurement 31
Calculation of Results��ก����������;�*��ก hydrometer ���!�������> �+�;%������� L ��กก��] ��8�+�������� d ��"����������� ��:�#�,* Stokes' Law
d = 14.29 • ��!%��)!7a��) (by wt) ���'����������!�aกก������� d � 0�> =• ����� Rc ��ก�ก�� Rc = R+Cc-CD
!�"�� R = ����������;�*��ก hydrometer
Rc = corrected hydrometer readingCC = composite correction = 0.0022CD = deflocculation correction = �0+��� ก�����,��#ก�8��#� � !,��
/*��,* 4% calgon %������ 40 ml �8�� calgon = 40*4/100 = 0.0016
T
L
Z
xRc 000,100)1( −
Whiteware VII testing and measurement 32
52.31.01579.0614.471.015136
58.71.017610.5813.71.017025
67.71.020112.7312.71.019516
%< d(µm)Rcd(µm)LRT(min)
��ก calibration graph ��� R = 1.0195 �������� L (cm) = 12.70��ก Stokes' Law
d = 14.29 = 14.29 √(12.70/16) = 12.73 µm����� composite correction = CC = 0.0022 � ��� deflocculation correction = CD = 0.0016
Then Rc = 1.0195+0.0022-0.0016 = 1.0201W = 50 g, s = 2.5 g/ml
= % undersize
��� �����!�aกก���12.73 µm �� = (1.0201 -1)100,000/(50x0.6) = 67 %
T
L
S
SWx
xRc
)1(000,100)1(
−−
Whiteware VII testing and measurement 33
Proof that “% (by wt) of particles < given diameter”=
Z
xRc 000,100)1( −
Brongniart's formula
W = (D-1) / (S/S-1)Where W = weight of dry material in 1 ml
D = density of suspension = Rc
S = specific gravity of dry material Weight in 1 ml = (Rc-1)(S/S-1)Weight in g/l = 1000 (Rc-1)(S/S-1)(CT/Co)x100 = % (wt) of particles less than a given diameterCo �"�����!�*��*���������a� ����#!%<� g/l ก���ก��� 0���0�;�* Since the concentration is g/l is calculated from hydrometer reading after time (T)Then CT = 1000 (Rc-1)(S/S-1) and C0 = Z x (S/S-1)
Z = Weight (bottle + slip) – Weight (bottle + H2O) (CT/C0)x 100 = 1000 (Rc-1) (S/S-1) x 100 = (Rc-1) 100,000
Z (S/S-1) Z
Whiteware VII testing and measurement 34
CentrifugeTheory: force acting on a particle = mass × acceleration
Centifuge = mass x Rω2
where R = distance from centre of rotationω= angular velocity
Stokes'Law
Integrating between R2 and R1 where R1= distance from center of rotation to suspension surfaceR2= distance from center of rotation to the bottom of centrifuge
tube
221
3 )(3
46 ωρρπηπ Rr
dt
dRr −=
ηρρω
9
)(21. 21
22 −=
r
Rdt
dR
Whiteware VII testing and measurement 35
ηρρω
9
)(2ln
1 2122
1
2 −=
r
R
R
t
221
221
2
)(2
ln9
r
k
r
R
R
t =−
=ρρω
η
• Radius = calculated size of particle which is just completely sedimented under the given conditions.
Plot % sedimented + critical radius��� ������ก�8ก�������8!%<���� �������������.�ก��� critical radius• The cumulation size distribution (% undersize) ��;�*:�#��กก��]��0:�#ก����ก!*����������:�*���ก��� r ��8��ก!*������0������� �������"� 3/2r :�#��ก!*������ก��� 3/2r ;%��8:%�!�����ก� y �8;�*��� P
Whiteware VII testing and measurement 36
Test procedure• ���� ��#�������'����8�ก�� 100 ��8 200 !�, • �+�����������'�����!���#�!%<��0+���� ��8!กa�� ��#������:�#�,*%e!%��-��� 25 ml• �+��0+���� 25 ml ��������������� (�����8 25 ml)• �+��0+���������������;%!�*�!��"���!����#� ���!��� ��8����!�a���ก����������*��ก��• !�"��;�*!������ก+���� �+��0+������ก����ก!��"��� �#ก������;��;�*�ก�8ก����ก • �+��������ก�8ก��;%�� ��*�, �����0+��� ก����������� ��� �0+��� ก����8ก�����;�* ��กก ��0+��� ก���'�����#-������������# ����8!���ก ��0+��� ก��������a�����#-����0+���� 25 ml
• �+�'�ก����������+������������ ��
Whiteware VII testing and measurement 37
Calculation of Results
-------------------------------------0.1941�������ก�8ก��
32.210.60260.63010.4360������������#
% �������ก�8ก��
�0+��� ก���/-ก�*���.�. '�� ��#���� 0����
�0+��� ก�� ���
25 ml of 4% calgon25 ml of 0.1 M NaOH 1 litre, 25 ml suspension = 0.0250 g calgon
+0.0025 g NaOH
%���������,��#ก�8��#� ����0+����� ��#��� 0.0275 g
% �������ก�8ก�� = (0.1941 x100)/0.6026 = 32.21%��กก��%������� % sediment & Critical radius (micron)
P = % over size at r of 0.4 µm = 34%100-P = 66% is less than 0.4 µm
Whiteware VII testing and measurement 38
Graph of % sediment and critical radius
Whiteware VII testing and measurement 39
Modern Methods
• Micromeritics Sedigraph Particle size Analyser: !%<�ก��� �� ���ก���ก�8ก�������� �� ��8���'���ก��!%<� cumulative
undersize distribution curve. ( ���������� �� (d) & % %������� �����������!�aกก������ ��� 0�> ):�#ก���,* x-ray ������!�*��*������� �����ก�8��#� ���� �ก������������ก����> !%<�]^�ก), ����!��� ��� Logarithm of the transmitted X-ray intensity /-ก�+�����ก����8%�8���'���ก��!%<� “ Cumulative Mass Percent Finer”.
Whiteware VII testing and measurement 40
Whiteware VII testing and measurement 41
Whiteware VII testing and measurement 42
Laser Diffraction Particle Size Analysis
• !�"���+���ก�8��ก ���� ���������������> �8!ก��ก��ก�8!�������ก�� ��ก� 0�� ������ �ก��ก�8!����8����� ���8��'�!�*�-�������!���)!�"��%�8���'���ก��!%<�ก��ก�8��#����
Whiteware VII testing and measurement 43
���ก�����ก�����!ก����กก�8!��������!�"���กก�8��ก ���� ��
Whiteware VII testing and measurement 44
Cation exchange capacity
CationCation exchange exchange capacitycapacity
Whiteware VII testing and measurement 45
Cation Exchange Capacity of Clays
• %�8�������%�8��!%<���!�"�����กก��!ก��ก��������������������� charge/size ratio �ก�*!��#�ก �
Ex. Al3+ for Si4+ � some distortion and reduced stability of the structure��"�!ก����กก����ก� �98�+���*!ก���*�����!%<�%�8����ก��8�����������:����*��'��ก�����������"�!ก����กก���-�7 ���"�ก����ก!%���#������ก �����!�a�:��;��)�"��>
M clay + NA = N clay + MANa clay + HCl = H clay + NaCl
��������/��ก����ก!%���#������������!%<�� ก�8!g��8������ 7�����'�������� ���*���"��>�������*�#!,��
• Plasticity• Drying shrinkage• Viscosity • Deflocculated/flocculated
Whiteware VII testing and measurement 46
• Cation (or base) exchange capacity: ���%�����������ก
(milliequivalents) ������ 100 g �������/�8!ก��ก���-�7 �;�*
• /*��������� CEC -� ���������,���� 0�����������/��ก���-�7 ������;�*�� 7���� 0��"�:����*��������� 0��8;��!%<��8!��#���ก
• ��ก��� CEC �8�+���*!������������� ���*������>������ ���� 0�%������,��#ก�8��#� �����*���,*�*�#
Ex. China clay: � �!%<���������:����*�����!%<��8!��#� ����� CEC = 3-6 meq/100 g
Ball clay, Fireclays: !%<� Disordered kaolinite ����� CEC = 15-40 meq/100 g Smectite: Highly disorder, montmorillonite ����� CEC = 70-150 meq/100 g
Whiteware VII testing and measurement 47
The determination of CEC and individual exchangable cations
Whiteware VII testing and measurement 48
Test Procedure and Calculation of CEC
(ammonium acetate)%h�ก���#�!��� Z clay + NH4Ac = NH4 Clay + ZAc
ก������&����� cec
• NH4 Clay: ammonium borate in excess boric acid solution after the distillation stage.
(NH4 )3 BO3 + 3HCl = H3BO3 + 3 NH4Cl
• %������� HCl ����,*��ก��;�!���!���ก �%������� ammonium ion ���/-ก������
!,�� 10 g of clay + 15 ml of 0.107 N HCl (107 milli-equivalents HCl ������� ��"� 0.107 milli-equivalents �����.7�.)
� �� 0� 1.605 milli-equivalents (���#/��ก�� 1 milli-equivalents �+�%h�ก���#�ก � 1 milli-equivalents ��� (NH4 )3 BO3
� ��� 100 g �8�-�7 � ;�* 16.05 milli-equivalents.
• � �� 0� CEC = 16.05 milli-equivalents ��� 100 g.��������*�
Whiteware VII testing and measurement 49
PlasticityPlasticityPlasticity
Whiteware VII testing and measurement 50
����!���#� (Plasticity)
• !�"����*���ก�8�+�ก ���� ����8!%���#��-%����;% /*����������!���#���ก���กa�8# ����-%�����#-�;�* � ���"�����/%^i���"���0��-%;�* ��8;��!ก��ก����ก�#ก��ก��กก �
• �������#��� plasticity �����ก����#/��• Stress = Force/Area in Tensile,
Compressive, Shear force• Strain = Deformation of the body = dL/L• K = stress/strain = Modulus of elasticity
or Young's modulus
Whiteware VII testing and measurement 51
The yield point: ������!����!ก�� plastic deformation.Max Deformation or Total Stress: ก��!%���#��-%��ก�����ก����������8!ก��ก���#ก ��"���ก��ก��กก �Max Stress: ���-�������,*��ก����0��-%���� 0�>
Whiteware VII testing and measurement 52
%̂�� #�����'��������!���#�
• ���� �'����"��'�(!��)� �)��������� �'������ก ��'�������ก � �� ��ก��*�)��&�!���ก'�(���� �)�'����������+",!���*�� � �����-���*�)��&�!�ก� ��ก������ ��ก��'�(���� �)�������'�����
Whiteware VII testing and measurement 53
• *�)��&�!������.�/����%�����0+�����-�7 ��#-��8!%<�]e��)�#-����'����� ����� 7����8�+���*!ก��ก���"�� � �� 0�����+���*����!���#�!������0�
• # "���)�������0������� �ก �!%<�ก*�� ��"� Flocculated clay: ��� ������ �� �ก ��8�+���*!ก��ก��!��#�� �ก ��#�������> �+���*!ก��,��������8�������� ����ก � �� 0��8�*��ก��%�����0+���ก��ก��!��������!���#� �-�������!ก����0���0�8�+���*������a����ก���!'������#�����ก� �� 0������0�8�� Moisture Content-�
Plasticity Index -�Stiffness Index -�Unfired Strength ��+�
Whiteware VII testing and measurement 54
��9�����,*����������!���#�
• ������+����� 0���%̂i�!%<�����#��> ��*��+�����!%<��� �,*�����-*�ก��ก��� �����������0;����ก��ก��กก �
• � �������a��������������ก���!'� /*������-� ����!���#�������� 0��8-��*�#• � �����!���#�:�#ก���-� ก�8ก��!ก�8ก ������� Measurement of
Binding: :�#ก��'����ก ����# ��8�-���/*�%����������#����,*��ก����0��-%��ก กa���������� 0�������!���#���ก
• �+�ก������:�#ก��� �%��������,"0� �� Flocculation �8�+���*���������!���#�!������0�;�* !���8������!%<� flocculation �8�*��ก���0+�%������ก��ก���+���*���������!���#�!������0�
Whiteware VII testing and measurement 55
ก��� �ก����� �ก��� �ก����� �ก��� �ก����� �
Whiteware VII testing and measurement 56
ก����� �• Wet-to-Dry
• Dry-to-Fired
• Wet-to-Fired
• Linear or volume
Whiteware VII testing and measurement 57
Plot of volume against moisture content for a plastic body during drying
!�"�����!������*� �0+��8�8!�#��ก;% �+���*������ ����� ������ C ��ก��] �����*!�a������� ������8��� ���� �' ก � �0+�# ����#-���,��������8�������� ��� 0�Critical Moisture Content (CMC) “leather-hard condition”
�����0��0��#-�ก �� ��������� clay / non-plastic, ������� ��, �-%���������� ����8ก��ก�8��#����. �������,"0�������-�ก������ CMC�0+��8�8!�#��ก;%�*�#� �������� !��#ก���,��� constant rate period
Whiteware VII testing and measurement 58
• Wet-to-Dry linear shrinkage (wet basis)= (Wet length – Dry length)/ Wet length x 100
• Dry-to-Fired Contraction: variation of body composition % dry-to-fired linear shrinkage (dry basis) = (Dry length – Fired length)/ Dry length x 100
• Wet-to-Fired ShrinkageDetermine the size of the fired article, since the
wet size of the product will be fixed and governed by the size of mould. Variation in size of the finished product.
• Wet-to-fired linear shrinkage (wet basis)= (Wet length – Fired length)/ Wet length x 100
Whiteware VII testing and measurement 59
Test procedure
Sieve (#120, #80)
เกรอะในปูนพลาสเตอร นวดดวยมือ
ทําแผนทดสอบ, ทําเครื่องหมายบนชิ้นงานตัวอยาง
% Wet-to-Dry linear shrinkage (Wet basis)
Firing
% linear dry-to-fired shrinkage (dry basis)
Clay + Water
Whiteware VII testing and measurement 60
ก��� �������a�������'��� ()ก��� �������a�������'��� ()ก��� �������a�������'��� ()
Whiteware VII testing and measurement 61
Modulus of rupture
• Clays: ��0��#-�ก �,���������
• Body (Unfired): ��0��#-�ก �����!���#���8%�������� �/��������,*!%<����'�
• Body (Fired): ��0��#-�ก ���������� � ����ก����ก���� ก��!���#��0+���� ��8��� -������,*!'�,�0����
Whiteware VII testing and measurement 62
Test Procedures
• '�������������'��(��ก����)��ก��# )�• ����&�������ก���"��������/ก �, ���'� ����
MOR = , kg/cm2
L = แรงทีก่ระทําใหชิ้นงานหัก; kgD = ระยะระหวาง support; cmb = ����ก� ��"���#�����/; cmd = �������"���#�����/��(�'� �#��1����ก ��"��-)!����/; cm
• ����&�����'2 �����ก�����/ 10 ��������
3
8
d
LD
π 22
3
bd
LD
Whiteware VII testing and measurement 63
• '��,�0����!��#�;������#��ก ��#�*��• � ������ length/diameter ratio ����8�������กก�����"�!���ก � 6/1 !�"�����ก!���#�����'������!�"�������ก�������,�0�� ��#���
/*���� length/diameter ratio �������ก ก��!%���#��%��������a�������,�0�����8��'��*�# ���8���/*����� ��������0������*�#�8��'�������������a�������,�0������ก � ��-%• ��ก������*�,�0���� /*�����*�!�a�!ก��;%�8�+���*!ก��ก��:�*��� ��"�����8!ก����#��ก �*��!�"�����กก����� �!�a���ก!ก��;% ��8�8;%�+���*���������a�������� �;�*���������• ���� ������ก���ก �8�+���*�����������a�������,�0������ก • ��ก������������a�������,�0����ก���!'� ����8!���#�,�0������*!��"��ก �,�0��������,*������� !,�� /*���ก����,�0������:��������� �+�ก������� 80 % relative humidity 7������������a�������� �;�*�8�������กก���,�0������������ 110°c
Whiteware VII testing and measurement 64
ก���������� ������������)ก���������� ������������)ก���������� ������������)
Whiteware VII testing and measurement 65
Tests on Plaster of Paris
• Blending time• Setting time• Strength (modulus of rupture)• Porosity (water absorption)• Hardness, loss on heating to 200°c
(degree of calcination). Abrasion test (surface texture and mould life)
Whiteware VII testing and measurement 66
Test Procedure• Plaster is added to the water• Blending time: ,���!������'�%��!���)
• Setting time: !������� �� 0�������%��!���)��-������ก�8� ��!����!7a�� �
Whiteware VII testing and measurement 67
ก������'��� ()�� �!'�ก������'��� ()�� �!'�ก������'��� ()�� �!'�
Whiteware VII testing and measurement 68
����������;]���!�"0������ �!'� (Softening point)
• ตรวจสอบชวงการเผา• ทดสอบหาคาการยุบตัว• สามารถเปรียบเทียบคาการทนไฟของดินตาง ๆ ได
Whiteware VII testing and measurement 69
����ก�������8��#��8ก���ก� � (Vitrification)
Density , Porosity , and water absorption• “ Vitreous ” : ��ก�����.,��!�� ��ก��� 1 % • “ Porous ” : �����ก�����.,��!�������-��� 1 % - 15% • “ open pores ” : ����3��//'*4� ���!���(�"��'� �
5����ก�����+.,�#����� • “ Sealed pores or close pores ” : ����3�
�//*4� ��'ก)���ก%��ก6�.��'ก)�",!�"&�'#� '�(��'ก)�ก6�.",!�� �'ก)�ก��'�7����'*8�'�(!��ก ���� 'ก)�'*8�������ก�1����5����
Whiteware VII testing and measurement 70
Density of SolidsDensity = Mass /Vol
• For a vitreous object there : Mass / Vol.For a porous solid :Apparent Volume ( Bulk Volume ) = *�)��&"��"���"7����������3�
�//'*4�� ��//*4�� �� �����+���� ��ก • � ����� �����ก�# �����,�0�� ��#���• �,*ก��� �:�#ก��������%��� (a mercury displacement method) ,
e.g. a Volumeter• � ���ก������ก�����8������0+��� ก���,�0������������ �;%�*�#�0+� ��8�0+��� ก���,�0����
������#���0+�
True Volume = %������������a��#���!��#�!���� 0� �����%h�� ���+�;�*:�#ก����� �������a���*!%<���� ��!�aก>!�"���+���#�-��������> � �;�*:�#�,*���%������ ��"� pycnometer
Whiteware VII testing and measurement 71
Apparent solid Volume = *�)����"��"���"7�� �����3��//*4� = the difference between dry weight ( D ) and the immersed weight ( I ) of piece.
• S – I = volume of open pores + sealed pores + solid• S – D = Vol. open pores• D – I = Vol. of sealed pore + solid
Apparent ( or bulk ) densityWeight = D
App. Vol. S –I
True density = WeightTrue Vol.
Apparent solid density = Weight = DApp. – solid Vol D –I
Where D = wt. Of dry piece ( g )S = wt. Of soaked piece ( g )I = wt. Of soaked immersed piece ( g )
Whiteware VII testing and measurement 72
Porosity
�-����!%<����!%��#�!��#�%����������-�����*�#%��������"��0+��� ก���,�0�� ��#���!��
Apparent Porosity = Ratio of open pore volume to total volume% App. Porosity = open pore vol. x 100
Total vol.= S – D x 100
S – I
Water absorption = Ratio of open poer vol . to weight of the test piece% Water absorption= open pore vol. x 100
wt.= S – D x 100
D
Whiteware VII testing and measurement 73
ExampleThe difference between absorption per unit volume ( App. Porosity ) and absorption per unit weight (Water absorption )A trial piece weight 210 g ; after soaking in water it weight 250 g ; and when suspended in water its weight is 150 g
Ans: % App. Porosity = S – D x 100 = 250 – 210 x 100S – I 250 – 150
= 40 %% Water absorption = S – D x 100 = 250 – 210 x 100
D 210= 19%
For most whiteware materials , the apparent porosity is approximately twice the value of the water absorption
(Based on)Apparent porosity apparent volumeWater absorption wt. Of material
Apparent porosity : Value of the “open pores per unit volume “� glaze “ pick up “
Whiteware VII testing and measurement 74
ExampleAn earthenware body and high alumina tableware body both have the same water absorption but the apparent porosities are entirely different
• Both have water absorption of 8 %• Bulk density of earthenware = 2.05 g / ml • Alumina body = 3.25 g / ml
%Apparent porosity : consider 100 g sample in each case For earthenware body : Density = M
VV = M = 100 = 48.8 ml
D 2.05Thus 48.8 ml vol. will have an absorption of 8 ml volume of water Thus, 100 ml volume of earthenware body has an absorption of :
8 x100 = 16.4 ml H2O48.8
= 16.4 % Apparent porosity Similarly for the high alumina body :
100 = 30.8 ml volume3.25
and 8 x 100 = 26.0 % App. Porosity 30.8
Whiteware VII testing and measurement 75
True porosity: All the pores ( open and sealed )
% True Porosity = Volume of all pores x 100Total vol. of the test piece= App. Vol – True vol. x 100
App. Vol.
= 1 - True Vol. x 100 App. Vol.
True Vol./App. Vol. = =
where Da = Apparent density = weight App. Vol.
Dt = True density = weight True. Vol.
% True porosity = 1 - Sa x 100• St• Sa = Apparent specific gravity• St = True specific gravity
t
a
a
t
D
D
D
weightD
weight
= 100)1( xD
D
t
a−
Whiteware VII testing and measurement 76
Sealed Pores% Sealed Pores = %true porosity - % App. Porosity Volume
True Density Powder � a specific gravity bottle
• constant Vol.• no bubbles• weight at constant temp.m1 = weight of bottlem2 = weight of bottle and solidm3 = weight of bottle and solid and waterm4 = weight of bottle and waterP0 = density of water ( at 20 o C is 1 g / ml )
Density = MassVolume
X = weight of water required of fill the bottle = (m4 - m1 )Y = weight of water required of fill the bottle above the powder solid = (m3 - m2 )( X - Y) = weight of water occupying the same volume as the solid sample
Whiteware VII testing and measurement 77
True density (g/ml) =
=
0
12
/1)()(
P
yx
mm
−−
)(
)( 012
yx
Pmm
−
−
Apparent density or bulk density = mass/ App. Vol. = D/S-I
Whiteware VII testing and measurement 78
การทดสอบ (หลังเผา)1. Vary firing Temp.2. วัดขนาดของแผนทดสอบหลังเผา3. ชัง่น้ําหนักแผนทดสอบเมื่อแหง อบที่ 110 o C4. ชัง่น้ําหนักเปยก � ตม 2-3 ชม. แชน้ําไว 24 ชม. ซับน้ําที่ผวิ5. นน. แผนทดสอบเปยกโดยวัดคาการลอยตัวของน้ํา6. คํานวณ หาอัตราสวนการดูดซึมน้ํา =
น.น. เปยก – น.น. แหง x 100น.น. แหง
7. คํานวณ หาอัตราสวนการหดตวั =ความยาวเดมิ - ความยาวใหม x 100
ความยาวเดิม8. Apparent solid density (����-�������!%e�!���� 0�)= น.น. แหง
น.น. แหง - น.น. ในน้ํา9. Bulk density(����-����� 0����)= น.น. แหง
น.น. เปยก - น.น. ในน้ํา10. Apparent Porosity = น.น. เปยก - น.น. แหง x 100
น.น. เปยก - น.น. ในน้ํา
Whiteware VII testing and measurement 79
ตัวอยางการทดสอบแรดินเซอริไซทหลังการเผาในอุณหภูมิตางๆ (ศูนยพัฒนาอุตสาหกรรมเครื่องเคลือบดินเผา ภาคเหนือ)
Whiteware VII testing and measurement 80
����!�*�ก �;�*�8�����!��"����8!�"0�'��� ()
����!�*�ก �;�*�8�����!��"����8����!�*�ก �;�*�8�����!��"����8!�"0�'��� ()!�"0�'��� ()
ก����*!ก���+����ก����*!ก���+���� !,��ก����ก���!,��ก����ก��� !��"����������!��"���������� ��"�!ก�8ก ���"�!ก�8ก � '��;��'��;����+�!����+�!�� ��8!%<�ก���������� ��������������!��"��!�"����8!%<�ก���������� ��������������!��"��!�"��
�+�;%�,*!%<�'��� ()�����������+�;%�,*!%<�'��� ()����������
Whiteware VII testing and measurement 81
����!�*�ก �;�*�8�����!�"0������8!��"��Body-glaze fit
• Thermal expansion Tests !%<�ก������ก���#�#� �!�"��;�*� ������*�����,�0�� ��#����#กก � �"� ����� ��#���!�"0������8����� ��#���!��"��
• Autoclave Test '*8�ก���������'" �ก���� ��ก�/'� (�/� �'�(!��)�������/��ก-)!�����������#���ก��'� (�/��� � � ����/���� ������������� 50 lb / in 2
( 0.34 MN/ m 2)
Whiteware VII testing and measurement 82
Determination of stresses between bodies and glaze
• Deflection of glazed bars : Stager Glazing one side of a bar and heating it to 800 o C. The stresses resulting from differences in expansion of glaze and bar cause the bar to deflect.
• Flat Plate Test : SchofieldFlat plate or tile 4 x 2 x 3 / 16 inch . /*��*�����!��"����ก��:�*��� :�#!%<����!�*�!�*��*���� (concave) !��"���8!%<������� (tension) ��8����8!ก��ก����ก���;�* (crazing) /*��*�����!��"��!ก��!%<�:�*���ก (convex) !��"���8�#-� �#��*���ก� �+���*!ก��ก��ก8!��8��������;�* (shiver or peel)
Whiteware VII testing and measurement 83
Thermal expansion of body and glaze
• The glaze has a higher expansion than the body glaze will contract more than the body Tensile stress craze
• The glaze and body have equal thermal expansion�����ก������ “ moisture expansion “ steam pressure of 50 lb / in2for 1 hourIf the ware withstands about 10 cycles not craze in everyday use.
• The glaze has a lower expansion than the bodyOn cooling, body contracts more than the glaze and puts it into compression � peel
Whiteware VII testing and measurement 84
Expansion of earthenware body and glaze
At 500°C, the expansion is 0.38% for Body and 0.32% for glaze. The difference of expansion of 0.06% is found suitability in practice for most earthenware products.
Whiteware VII testing and measurement 85
Dilatometer
Whiteware VII testing and measurement 86
Calculation of Results
lT = l0 (1+αT)
α = (lT-l0)/l0T
Where l0 = original length of test piece
lT = length of test piece at temp. (T)
α = Coefficient of linear expansion
T = rise in Temperature (°C)
• The Coefficient of fused silica = 0.55 x 10 –6
• The silica correction = lo x 0.55 x 10 –6 x T
Whiteware VII testing and measurement 87
Length of test piece = 3.104 inSilica expansion between 20°°°°C and 50 °°°°C= 3.104 x 0.55 x 10-6 x 30 = 0.000051Thus, the silica expansion = 0.000051 for each 30°°°° increment in Temp.
Whiteware VII testing and measurement 88
Calculation of the thermal Expansion Coefficient
% Expansion = Total expansion/ Length of test piece x 100
If expansion from 20°C to 500°C = 0.418%
( 0.418/100) * (1/480) = 8.7 x 10-6
Then coefficient of expansion = 8.7 x 10-6
Note: %expansion and coefficient of expansion should always be quoted with reference to the temperature range over which they were measured.
Whiteware VII testing and measurement 89
• Thermal expansion of body must be higher than that of the glaze.
• Bruce and Wilkinson suggest that the difference should be 0.4 to 1.0 x 10-6 at 500°C.
• Ex. %expansion = 0.4x 10-6 x100x480 = 0.02% at 20 to 500°C
• Ware with a high porosity (ex. 8 % water absorption) would require a glaze with an expansion of 0.04% to 0.06% less than that of body.
• Vitreous ware (low moisture expansion) could use a glaze with differential expansion of 0.02.
Thermal expansion values of body and glaze
Whiteware VII testing and measurement 90
Assessment of Body/Glaze Compatibility using a Glaze Fit Instrument
• Based on the differential curvature measurement between bisque and glazed bars.
• Bar tests 18.7 x 2.4x0.43 cm• After measuring the curvature of the
bisque bars, glaze is applied to one surface only and fired glost.
• Note. The bisque side of bar contacts the shaft of the dial gauge.
Whiteware VII testing and measurement 91
Malkin’s body/glaze fit instrument
Zero reading on the glaze fit instrument
Whiteware VII testing and measurement 92
Measurement of body/glaze fit using an earthenware body and three glazes of different expansions
A = curvature of cast bisque bars fired to 1160°CB= glost bar fired to 1080°C using glaze with a thermal expansion of 0.283% at 500°CA-B = differential curvature
Whiteware VII testing and measurement 93
ก������!��"�����ก������!��"�����ก������!��"�����
Whiteware VII testing and measurement 94
• Particle size: hydrometer (ex. Sanitary ware glaze maybe ground to a specification of 73-77% less than 10 micron)
• Inclined Flow Test• Glaze thickness: penetrometer (unfired glaze
thickness are 0.02 to 0.03 in for sanitary and 0.006-0.008 in for tableware
Tests on unfired glazed
Whiteware VII testing and measurement 95
Inclined Flow plane
Whiteware VII testing and measurement 96
Measurement of glaze thickness by penetrometer
Whiteware VII testing and measurement 97
ก�������"��>+��� �'��� ();��)���)ก�������"��>+��� �'��� ();��)���)ก�������"��>+��� �'��� ();��)���)
Whiteware VII testing and measurement 98
Metal Release
• Lead in glazes and colors
• Lead release in colored glazed
• Atomic Absorption Spectrophotometer
Whiteware VII testing and measurement 99
Thermal shock resistance• When specimens are exposed to sudden temperature
changes a sharp thermal gradient results, which introduces volume changes producing large stresses within specimen
• Low thermal expansion high thermal shock resistance• Modulus of elasticity• Strength• Thermal diffusivity
• Thermal shock resistance α ST/Eαwhere S = strength
E = Modulus of elasticityT = Temperature of diffusivityα = Coef. Thermal expansion
Whiteware VII testing and measurement 100
Strength and elasticity
• Strength Thermal shock resistance
• Elasticity Thermal shock resistance
( low Modulus of elasticity )
Whiteware VII testing and measurement 101
Test Procedure• quenching cylindrical rods from a given temp. and subsequently
examining for cracks after immersion in a suitable dye.Temperature on quenching is quoted as the thermal shock result ,when the modulus of rupture decreases to half its original value.
Cylindrical Rod test12 rods 1 / 2 inch diameter and 6 inch long no. crack
100 o C for 30 min cold water ( 15 oC )
aniline blue dye increased by 10 oC
cold water visible signs of fracture
No crack
crack
Whiteware VII testing and measurement 102
The mean temp. of failure = temp. x no. of rods failed at that temp.
The sum of products is divided by the total no. of rods used in the experiment
For earthenware160°°°° C 4 rods 160 x 4 = 640170°°°° C 6 rods 170 x 6 = 1020180 °°°°C 2 rods 180 x 2 = 360
= 20202020 / 12 = 168 ( Thermal shock resistance )
ASTM:C 554-88 Glazed whitewaresC 385-58 (1986) Porcelain enamels utensilsC 484-66(1981) Glazed ceramic tile
Whiteware VII testing and measurement 103
Any Questions ?Any Questions ?Any Questions ?