# US 6,296,385 B1 · Apparatus and method for high temperature viscosity and temperature measurements

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- Number: US 6,296,385 B1
- Document ID: US6296385B1
- Status: Granted
- Kind: B1
- Application number: 09/075,922
- Filed: 1998-05-12
- Granted: 2001-10-02
- Earliest claimed: 1997-05-12
- Assignees: Mississippi State University
- Inventors: Krishnan Balasubramaniam; Vimal Shah; R. Daniel Costley; Jagdish P. Singh
- Web page: https://patentgrep.com/patent/US6296385B1

## CPC

- G01N 11/16: by measuring damping effect upon oscillatory body
- G01K 11/22: using measurement of acoustic effects
- G01N 29/024: by measuring propagation velocity or propagation time of acoustic waves
- G01N 29/22: Details {, e.g. general constructional or apparatus details}
- G01N 29/228: {related to high temperature conditions}
- G01N 29/2462: {Probes with waveguides, e.g. SAW devices}
- G01N 33/205: in liquid state, e.g. molten metals
- G01N 2291/015: Attenuation, scattering
- G01N 2291/0252: Melting, molten solids
- G01N 2291/02818: Density, viscosity
- G01N 2291/02881: Temperature
- G01N 2291/0422: Shear waves, transverse waves, horizontally polarised waves
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- G01K: MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR (radiation pyrometry G01J5/00)

## Abstract

A probe for measuring the viscosity and/or temperature of high temperature liquids, such as molten metals, glass and similar materials comprises a rod which is an acoustical waveguide through which a transducer emits an ultrasonic signal through one end of the probe, and which is reflected from (a) a notch or slit or an interface between two materials of the probe and (b) from the other end of the probe which is in contact with the hot liquid or hot melt, and is detected by the same transducer at the signal emission end. To avoid the harmful effects of introducing a thermally conductive heat sink into the melt, the probe is made of relatively thermally insulative (non-heat-conductive) refractory material. The time between signal emission and reflection, and the amplitude of reflections, are compared against calibration curves to obtain temperature and viscosity values.

## Claims

### Claim 1

A probe for simultaneously measuring viscosity and temperature of a hot liquid, comprising:
(a) a buffer rod comprising a refractory material acoustical waveguide comprising a first inner refractory material encased in a second outer refractory material, said buffer rod having a first and second end, said second end comprising a buffer rod probe surface, wherein the inner refractory material is a high temperature resistant, reduced heat sink material selected from the group consisting of alumina, silicon carbide and mixtures thereof; and
(b) an ultrasonic shear wave generating transducer at the first end of the buffer rod;
wherein said ultrasonic shear wave generating transducer emits shear waves that are in part transmitted and in part reflected at the interface between the two refractory materials; and
wherein the shear waves reflected at the interface between the two refractory materials provide a reference signal that can be used to measure time differences.

### Claim 2 (depends on 1)

The probe of claim 1, wherein said first end is provided with a means for cooling said transducer.

### Claim 3 (depends on 1)

The probe of claim 1, wherein the transducer is piezoelectric.

### Claim 4 (depends on 1)

The probe of claim 1, wherein said probe measures the temperature and viscosity of said hot liquid at the buffer rod probe surface.

### Claim 5 (depends on 1)

The probe of claim 1, wherein said liquids are at a temperature of 500° Celsius to 1600° Celsius.

### Claim 6 (depends on 1)

The probe of claim 1, wherein said probe can measure viscosities from 0-2000 poise.

### Claim 7 (depends on 1)

The probe of claim 1, wherein said transducer, has a frequency range of from 1-25 MHZ.

### Claim 8 (depends on 1)

The probe of claim 1, wherein said buffer rod dimension is 0.1-25 inches long and 0.2-5 inches wide.

### Claim 9 (depends on 1)

The probe of claim 1, wherein said outer refractory material is a high temperature material selected from the group consisting of molybdenum, inconel and tantalum.

### Claim 10 (depends on 1)

A method for simultaneously determining viscosity and temperature of a molten material, comprising:
(1) inserting the second end of the probe of claim 1 into said molten material;
(2) causing said shear wave generating transducer to emit shear waves through said waveguide to said molten material, wherein said shear waves shear a surface of said molten material and are reflected;
(3) detecting reflections of said shear waves through said transducer, and determining said viscosity and temperature of said molten material by comparing a time difference between said shear waves emission and reflection detection to determine temperature and by comparing amplitude of said reflection to determine viscosity.