Measuring and testing – Liquid analysis or analysis of the suspension of solids in a... – Viscosity
Reexamination Certificate
2002-07-02
2003-06-24
Larkin, Daniel S. (Department: 2856)
Measuring and testing
Liquid analysis or analysis of the suspension of solids in a...
Viscosity
C073S054390
Reexamination Certificate
active
06581439
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for measuring the viscosity of a green compact formed by compaction molding of crystallized glass powdered and the like, an apparatus for measuring the viscosity of the green compact sample, and a computer readable recording medium for storing the method for measuring the viscosity of the green compact sample.
Furthermore, the present invention relates further to a method for measuring the viscosity of a green compact sample formed by compaction molding of amorphous glass powder and the like.
2. Description of the Related Art
Recently, in the electronics industry, various researches and developments have been made on ceramic multilayered substrates and thick-film materials which can meet higher densities for mounting components and circuit conductors, higher signal frequencies, etc. In particular, ceramic multilayered substrates which are formed by firing composite materials containing amorphous glass powder and crystallized glass can satisfactorily meet the higher density and higher frequency requirements because they have small relative dielectric constants and can be fired simultaneously with Ag conductive materials having small resistivity.
In such ceramic multilayered substrates and thick-film materials, physical properties of inorganic oxide powder, such as amorphous glass powder and crystallized glass powder, strongly affect the substrate characteristics and thick-film characteristics. In particular, the viscosity characteristics thereof greatly affect the sintering process of the inorganic oxide powder, the diffusion behavior of Ag conductive materials, and so on, thus being significantly important parameters in material design and process design.
In general, in order to measure the viscosity of such glass powders, an extended fiber viscometer is used in the high viscosity region of approximately 10
10
Pa·s or more, and a rotary viscometer (draw sphere viscometer) is used in the low viscosity region of approximately 10
4
Pa·s or less. The viscosity is measured by a parallel plate viscometer in the intermediate viscosity region of 10
4
to 10
9
Pa·s, which is particularly important in the sintering process of such glass powders.
A method for measuring viscosity &eegr; by a parallel plate viscometer will be described below.
First, as shown in
FIG. 31
, a test piece (sample)
1
in which the height H and the volume V have been accurately measured is placed on a quartz plate
2
a
which is fixed on a support
3
. The test piece
1
is then sandwiched between the quartz plate
2
a
and a quartz plate
2
b
which is fixed to a quartz rod
4
, and while a certain load M is applied to the quartz rod
4
and the apparatus
6
is heated by a heater
5
, the displacement (height H) of the test piece
1
is detected by a differential transducer (not shown in the drawing) interlocking the quartz rod
4
. By extracting the displacement over time, a sample deformation rate dh/dt of the test piece
1
is calculated.
Next, the sample volume V, the load M, and the sample deformation rate dh/dt are substituted into the Gent equation below to calculate the viscosity &eegr; of the test piece
1
(refer to A. N. Gent, British Journal of Applied Physics, Vol. 11, February 1960).
&eegr;=2&pgr;
MGH
5
/{3
V
(
dh/dt
)(2&pgr;
H
3
+V
)}
where M is the load, H is the height of the sample, G is the gravitational acceleration, V is the sample volume, and dh/dt is the sample deformation rate.
By performing the above for each temperature, and a variation of viscosity &eegr; with temperature, that is a viscosity-temperature curve is derived.
However, in the measurement of viscosity by the parallel plate viscometer described above, a bulk sample must be used as the test piece
1
. That is, the Gent equation is only applicable in a case where the test piece
1
can be assumed to be an incompressible fluid. For example, when the viscosity of glass powder is measured, a bulk sample in which the glass powder is melted, quenched, and formed into a bulk material must be used.
That is, in the method described above, although the viscosity of glass which in formed into a bulk can be measured, it is difficult to measure the viscosity of glass in the powder state, in particular, the viscosity of crystallized glass powder. This is because of the fact that in the crystallized glass powder which tends to be crystallized, crystals may be precipitated during the formation of a bulk sample. Even if a bulk sample is formed, since the crystallization behavior is essentially different between the bulk sample and the powder sample, the viscous behavior differs between the bulk sample and the powder sample even with respect to the same type of glass powder.
However, as described above, in most of the ceramic multilayered substrates and thick-film materials, crystallized glass, amorphous glass, and the like are used as powders samples. That is, in view of material design and process design, evaluation of viscosity characteristics as powder samples must be performed with respect to crystallized glass, amorphous glass, and the like.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a method for measuring the viscosity of a green compact sample formed by compaction molding of inorganic powder with high accuracy. It is another object of the present invention to provide an apparatus for efficiently measuring the viscosity of a green compact sample. It is another object of the present invention to provide a computer readable recording medium for storing the method for measuring the viscosity of the green compact sample.
In one aspect of the present invention, in a method for measuring the viscosity of a green compact sample, the viscosity &eegr; of a green compact sample formed by compaction molding of inorganic powder is measured in accordance with the Gent equation:
&eegr;=2&pgr;
MGH
5
/{3
V
(
dh/dt
)(2&pgr;
H
3
+V
)}
where M is the load, H is the height of the sample, G is the gravitational acceleration, V is the sample volume, and dh/dt is the sample deformation rate.
The method includes the steps of:
(A) finding a corrected value V′ of the sample volume of the green compact sample, where the corrected value V′ of the sample volume is a volume occupied by the inorganic powder in the green compact sample;
(B) finding a corrected value (dh/dt)′ of the sample deformation rate of the green compact sample, where the corrected value (dh/dt)′ of the sample deformation rate is the difference between the apparent sample deformation rate and the sample deformation rate due to sintering shrinkage;
(C) separating a temperature range X in which sintering shrinkage dominates and a temperature range Y in which plastic deformation dominates with respect to the displacement of the green compact sample;
(D) substituting the corrected value V′ of the sample volume for the sample volume V and substituting the corrected value (dh/dt)′ of the sample deformation rate for the sample deformation rate dh/dt in the Gent equation with respect to the temperature range X in which sintering shrinkage dominates; and
(E) substituting the corrected value V′ of the sample volume for the sample volume V in the Gent equation with respect to the temperature range Y in which plastic deformation dominates.
In the method for measuring the viscosity of the green compact sample in the present invention, with respect to the measurement of viscosity which has been conventionally applied only to an incompressible fluid, such as a bulk sample, by executing (A) a step of extracting the corrected value V′ of the sample volume by correcting the sample volume, (B) a step of extracting the corrected value (dh/dt)′ of the sample deformation rate by correcting the sample deformation rate, and (C) a step of separating the temperature range X in which sintering shrinkage dominates and the temperature range Y in which plastic deformation dominates w
Niwa Yoshihito
Takagi Hiroshi
Keating & Bennett LLP
Larkin Daniel S.
Murata Manufacturing Co. Ltd.
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