Title : An improved device to measure viscosity, phase transformation and
crystallization in liquid melts at a temperature up to 1450°C.
FIELD OF INVENTION
The present invention relates to an improved ultrasonic viscometer to
transmit and receive ultrasonic normal incidence shear including
longitudinal waves in molten fluxes/slags/metals/polymers at temperature
up to 1450°C. More particularly, the invention relates to an improved
device for measuring viscosity, phase transformation and crystallization in
molten solids at temperatures up to 1450°C.
BACKGROUND OF THE INVENTION
The ultrasonic viscometer can be used to measure physical and thermo
physical properties of liquids such as viscosity (η), density (p), at both
room temperature and elevated temperatures.
The basic underlined principle of the current invention is the sensitiveness
of ultrasonic shear waves to the variations of the properties like viscosity
(η), density (ρ) of a liquid medium. The product of viscosity (Η) and
density (ρ) is correlated with the reflection coefficient of these waves. The
longitudinal ultrasonic waves are also related with density of the liquid. If
the density of the liquid is obtained using the longitudinal waves, the
viscosity of the liquid can be determined.

The presently available conventional high temperature viscometers comprise a
number of rotating components which are prone to frequent damage under high
temperature conditions. Due to absence of the rotating parts in the proposed
ultrasonic viscometer such problems have been eliminated. However the main
constraint in determination of viscosity in molten fluxes/slags/glasses using the
proposed ultrasonic viscometer is their high melting temperature which poses
problem in transmitting ultrasonic waves in the hot liquid medium. This high
temperature problem for transmitting ultrasonic waves has been solved by applying
a cooling system near the end of the buffer rod where ultrasonic transducer has
been positioned.
The special feature of the proposed viscometer is the design of a port made at the
other end of the buffer rod to hold the powdered sample. Using this viscometer the
ultrasonic waves can be transmitted in the hot liquid (molten fluxes/slags/glasses)
through buffer rods made of materials capable to withstand the temperature of
1500°C
The main feature of this viscosity measuring device is that there is no rotating part
like that in conventional HAAKE viscometer used for this purpose.
OBJECTIVE OF THE INVENTION
The objective of the present invention is to propose an improved ultrasonic device to
determine viscosity of molten fluxes/slags/glasses and low melting metals and alloys
such as Pb, Zn etc.

SUMMARY OF THE INVENTION
The improved ultrasonic device comprises of a melting unit, a buffer rod/sample
holder, a cooling unit, and an ultrasonic testing system. The buffer rod/sample
holder can be configured as a vertical rod with a port on the top to hold the sample
positioned inside a vertical tubular furnace. A sample is kept in a port/chamber at
top end of the buffer rod/sample holder, which can be inserted into the furnace from
the bottom. The bottom end of the buffer rod/sample holder is water cooled at
which the ultrasonic transducers are kept for ultrasonic measurements.
In an alternative embodiment, the sample will be inserted through a buffer rod with
a port at its first end through the side walls of a box type or through one end of a
horizontal tubular furnace. The second end accommodating transducers at which the
ultrasonic measurements are to be taken will be water cooled.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The invention can now be described in detail with the help of the figures of the
accompanying drawings in which:
Figure 1 shows schematic diagram of an improved ultrasonic device with a vertical
buffer rod/sample holder inside a vertical tubular furnace with a cooling means,
probe positioning and display of interfacial echoes, according to a first embodiment
of the invention.
Figure 2 shows the details of the furnace and the buffer rod/sample holder as shown
in Figure 1.

Figure 3 shows an alternate embodiment box type furnace and a buffer rod/sample
holder inserted through the side walls of the furnace.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF
THE INVENTION
Figure 1 is a schematic diagram of a proposed device showing a tubular vertical
furnace (1) with at least two heating elements (2) in the refractory walls (3). A
buffer rod (4) holding a powdered sample (S) has been inserted from the bottom
(5) of the furnace (1). The filling of the powdered sample in a port (6) of the buffer
rod (4) should be such that the sample after melting, the molten slag touches a
reflector's surface (RS). When the furnace (1) is on, the temperature of the powder
(S) rises, it melts and in molten condition at a desired temperature (that is 1300°C
for mold fluxes for continuous casting of steel) the ultrasonic parameters like
reflection coefficient or shear waves and ultrasonic velocity of longitudinal waves in
molten slag is measured. The bottom part of the buffer rod (4) is water cooled by
means of a water jacket (7) as shown in Figure 1. As shown in Figure 1, the
reflection coefficient of shear waves is measured from the amplitude of the echo
from the buffer rod/molten slag interface (RS), whereas the ultrasonic velocity of the
longitudinal waves is measured from the transit time between the echo from the
buffer rod/molten slag interface (RS) and that from molten slag/reflector interface
(SS). The interfacial echoes can be displayed in an ultrasonic display means (14).
The transducers (8) are placed at the bottom end of the buffer rod/sample holder
(4). The furnace (1) will have thermocouple (11). The water jacket (7) provided with
water inlet (12) and a water outlet (13).

Figure 2 shows the dimensional details of the vertical tubular furnace along with the
position of the buffer rod/sample holder (4) in a device. The dimensional details of
the furnace (1) details are given in Table 1.

The heating elements (2) are made of silicon carbide or graphite and positioned
in the vertical walls of the furnace. The furnace body (9) including the support
members (10) for the furnace (1) and the buffer rod/sample holder (4) can be made
of stainless steel.
Table 2 shows the dimensional details of the buffer rod/sample holder (4), reflector
and the port (6) in the buffer rod (4) in the case of vertical tubular furnace.


Length of the buffer rod/sample holder (4) outside the furnace (1) = 200 mm
Figure 3 shows the dimensional details of a box type furnace (2) along with the
position of the buffer rod/sample holder (4) in the device.
Table 1. Dimensional Details of Box type furnace (2).

Refractory (3) thickness in top, bottom cover and side alls = 50 mm Height of the
bottom stands (10) = 400 mm. The heating elements (2) are silicon carbide or
graphite placed on the three vertical walls and on the roof.
Dimensional details of the buffer rod/sample holder (4) are
Cross section = 50 x 50 mm; Length = 300 mm;
Material of the buffer rod/sample holder;
Alumina AD-94 or Direct Sintered Silicon Carbide DS-SC or Mo or W or Ti
Dimension of the port made in buffer rod/sample holder;
Length = 70m; Width = 30 mm; Height = 30 mm.
ADVANTAGES OF THE PRESENT INVENTION
1. Unlike conventional viscometers (HAKEE VISCOMETER), due to the absence
of rotating parts at high temperature, the frequent material damage problems
are eliminated.

2. Unique design of a port made at the end of a buffer rod/sample holder allows
the ultrasonic measurement by positioning the ultrasonic probes at one end
only rather positioning at both the ends.
3. The buffer rod/sample holder with a port made at one end (which remains
inside the furnace during measurement) serves both as a sample holder as
well as transmitter of ultrasonic waves in liquid at temperatures up to 1450°C.
4. Careful selection of advanced ceramic materials like Alumina AD-94 or Direct
Sintered Silicon carbide (DS-SC) or Mo, W or Ti for making buffer rod/sample
holder. This allows easy transmission of ultrasonic waves into the molten
materials at temperature upto 1450°C through the buffer rod/sample holder.
5. The use of the above buffer rod/sample holder allows to measure reflection
coefficients of ultrasonic transverse waves and transmit time of ultrasonic
longitudinal
waves in the liquid at high temperature. From reflection coefficient viscosity
and from transmit time density of the liquid is determined.
6. During cooling, crystallization and phase transformations can be indicated by
abrupt change in the ultrasonic velocity or attenuation.
7. The presence of a box type cooling chamber near the measuring end
(projected outside furnace) allows the probe position to cool down and avoids
the probe damage due to high temperature.
8. The dimensional details of tubular vertical furnace and box type furnace to
suit the ultrasonic measurements.

We claim:
1. An improved device adaptable to furnaces, to measure viscosity, phase
transformation and crystallization in liquid melts at temperatures upto 1450°C,
the furnace can be selected as a vertical tubular furnace or a box type
furnace, comprising at least two heating elements (2) in its refractory walls
(3), and a thermocouple (11), the furnace (1) being disposed on stainiess
steel support (10) and encased in stainless steel casing (9), the device
comprising :-
- A buffer rod / sample holder (4) having a port (6) at a first end to hold
a powdered sample (S) which when inserted into the furnace (1) from
a bottom (5) for allowing the powdered material to produce molten
slag which touches the surface of a reflector (RS) of the rod (4);
- At least one transducer (8) attached at a second end of the buffer rod /
sample holder (4) being projected out of the furnace and disposed in a
cooling unit (7) having one each water inlet (12) and water outlet (13)
wherein the transducer (8) is disposed for measuring reflection co-
efficient of shear waves from the data received from buffer rod /
molten slag interface (SS) and transit time between the echo from the
buffer rod / molten slag interface (SS) and that from the molten slag /
reflector interface (RS) for determining the ultrasonic velocity of the
longitudinal waves; and
- An ultrasonic display device (14) for displaying the interfacial echoes
generated by the transducer (8).

Characterized in that the liquid phase of slag being generated in the buffer
rod subjected to an ultrasonic testing from the lower part by means of
transducer (8) wherein the reflection co-efficient of shear waves are
measured from the amplitude of the echo from the buffer rod / molten
slag interface (SS) and the
ultrasonic velocity of the longitudinal waves are measured from the transit
time between the echo from the buffer rod / molten slag interface (SS)
and that from the molten slag / reflector interface (RS) wherein interfacial
echoes are displayed in an ultrasonic display means (14).
2. The device as claimed in claim 1, wherein the buffer rod/ sample holder (4)
comprises ceramic materials for example, Alumina AD 94 or Direct Sintered
Silicon Carbide SC-DS or Mo or W or Ti selectively chosen for high
temperature application upto 1450°C.
3. The device as claimed in claim 1, wherein the vertical tubular furnace can be
selected to have a dimensional relationship of H:ID:OD=5:1:4
Where,
H = Height, ID= Internal diameter, and OD = outside diameter.
4. The device as claimed in claim 1 or 3, wherein the buffer rod / sample holder
(4) is correspondingly configured to have a dimensional relationship of Length
(L) and diameter (D), for example, L = H, and D = 0.5 ID.
5. The device as claimed in claim 1, 3 or 4, wherein the port (6) of the buffer rod
/ sample holder (4) is configured to have diameter (D1) and height (H1)
relationship as D1 = 0.6D, H1 = 0.2H.

6. The device as claimed in claim 1, wherein the box type furnace (1) can be
selected to have dimensional relationship between length (L'), width (W) and
Height (H1) at a ratio of 1:1:1.25.
7. The device as claimed in claim 1 or 6, wherein the buffer rod / sample holder
(4) is correspondingly configured to have a cross-section (CS) and Length (L1)
for example, L1= 0.75W, and CS = 0.125 W x 0.125 W.
8. The device as claimed in claim 6 or 7, wherein the port (6) of the buffer rod /
sample holder (40 is correspondingly configured to have a dimensional ratio
relationship of width (W') = 0.075W, Length (L') = 0.175L', height (H'') =
0.06 H'.

ABSTRACT

Title : An improved device to measure viscosity, phase
transformation and crystallization in liquid melts at
a temperature up to 1450°C.
There is provided an improved device adaptable to furnace to measure viscosity,
phase transformation and crystallization in liquid melts at a temperature up to
1450°C, the furnace can be selected as vertical tubular furnace or a box type
furnace comprising at least two heating elements (2), the refractory walls (3) a
thermocouple (11), the furnace (1) being disposed on stainless steel support
(10), a buffer rod / sample holder (4), having a port (6) at a first end to hold a
powdered sample (S) when inserted from a bottom (5) to allow the powdered
material to produce molten slag which touches the surface of reflector (RS) of the
port, wherein the transducer (8) attached at the second end of the buffer rod (4),
disposed in a cooling unit (7) acquires data to measure reflection co-efficient of
shear waves and the transit time between the echoes from the molten slag /
reflector surface (RS) interface (RS) and that from the buffer rod / molten slag
interface (SS) to determine the ultrasonic velocity of the longitudinal waves, the
ultrasonic display device (14) display the interfacial echoes.