Thermo-electric characteristics of carbides

Thermo-electric characteristics of carbides

Citation for published version (APA):

Bus, C., Touwen, N. A. L., Veenstra, P. C., & van der Wolf, A. C. H. (1971). Thermo-electric characteristics of carbides. (TH Eindhoven. Afd. Werktuigbouwkunde, Laboratorium voor mechanische technologie en

werkplaatstechniek : WT rapporten; Vol. WT0267). Technische Hogeschool Eindhoven.

Document status and date: Published: 01/01/1971

Document Version:

Publisher’s PDF, also known as Version of Record (includes final page, issue and volume numbers)

Please check the document version of this publication:

• A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.

• The final author version and the galley proof are versions of the publication after peer review.

• The final published version features the final layout of the paper including the volume, issue and page numbers.

Link to publication

General rights

Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain

• You may freely distribute the URL identifying the publication in the public portal.

If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license above, please follow below link for the End User Agreement:

www.tue.nl/taverne

Take down policy

If you believe that this document breaches copyright please contact us at:

openaccess@tue.nl

providing details and we will investigate your claim.

VJT-RAPPORT No .0267 Code: C.4.a.

THERMO-ELECTRIC CHARACTERISTICS OF CARBIDES

eHR. BUS N.A.L. TOUWEN

P.C. VEENSTRA A.C.H. VAN DER WOLF

~lARCH 1971

Eindhoven, University of Technology the Netherlands

io.rport no.0267

SUMMARY.

-1-Thermo-electric characteristics from 00 up to 10000C are determined for several grades of carbide versus Pt.

The characteristic of Pt versus C45N-steel is obtained too.

From these, the thermo-electric characteristics of the carbides versus C45N-steel can be derived.

The calibrations are carried out in a radiation furnace set-up.

The specimen consists of a bar with a square cross-section of 12.5 mm2 and a length of approximately 300 rom.

RESlJM£.

Des caracteristiques thermoelectriques de 00 jus qu'aUKIOOOoC sont terminees pour des especes de carbure differentes contre Pt. La caracteristique de Pt contre acier C4SN est realisee de merne. De ces grandeurs les caracteristiques thermoelectriques des carbures contre acier C4SN peuvent etre inferees.

Les calibrages sont faits a l'aide d'un equipementa fourneau rayonnant. Le specimen est compose d'une barre d'une coupe carree de 12,5 mm2 et unelongueur de 300 mm approximativement.

ZUSAMMENFASSUNG.

Fur den Temperaturbereich von 0° bis 100aoC, sind die thermoelektrischen Spannungen verschiedener Hartmetallsorten und Stahl C45N gegen Platin experimentell bestimmt worden.

Die aufgefuhrten Daten ermoglichen die Ermittlung der jeweiligen Hartmetall - Thermospannung gegen Stahl C4SN.

Die Eichungen wurden durchgefuhrt mit Rilfe eines speziellen elektrisch geheizten Strahlungsofens und Proben mit einem quadratischen Querschnitt

12 5 2 . ..

R.0267

INTROPUCTION.

-2-The aim of this investigation is to obtain numerical data for the relationship between thermo-electromotive forces and temperatures for several grades of carbide and workpiecematerial (C45N).

For reasons of proper calibration, we carried out every experiment versus platinum (Pt). This metal has many advantages, such as:

high melting point,

great stability as far as corrosion is concerned, no transformation points.

METHOD OF TEST.

The calibration set-up consists among others of a radiation furnace and a cooling device, as can be seen in Fig. 1. One end of the test bar is placed in the furnace, the other end in the cooling device.

Both ends of the bar are connected with a platinum wire. The temperatures of the hot and cold junctions are measured by Chr /Al thermocouples and are put on paper-tape by means of a datalogger.

At the same time the emf voltage between the hot and the cold junctions of the calibration bar is put on this tape.

A good contact at the junctions is assured by the weight of the furnace. The hot end of the calibration bar is protected against corrosion by means of an inert gas.

The cooling device operates by means of water and keeps the cold junctions approximately at 130C.

TEST MATERIALS.

As mentioned before the Lests are carried out for several grades of carbides and the workpiece material C45N. The carbides used are Sandvik grades SI, S2, 84, 86, HOS, Hlp, HIO, HI3, H20 and FOZ.

NUMERICAL ELABORATION. (see Fig. 2.)

Starting data: A paper-tape with ~n preset-time on two channels data-logged non-scaled measured values of the hot junction temperature

R.0267

-3-(emf voltage of the Chr fAl thermocouple) and the emf voltage between the hot and the cold junction of the calibration bar in-volved (= difference voltage).

For a qualitative control and a counting of the couples of the measurements the tape is read through (program A - 327 - 14a). Next, the measurements are mutually adjusted in order to eliminate

the influence of the preset-time-interval (the difference voltage belonging to the hot junction is found as the arithmetic mean of the preceding and next measurement) and to introduce the scaling

(program A - 3948 - 5).

At the same time the adjusted measurements are represented on paper-tape in two ways:

CD

All measurements at the hot junction with matched difference voltages, and

CD

equidistant chosen hot junction values with matched difference voltages (interpolated).

Wi th the aid of series

CD

a graph is made:

Along the horizontal axis the Chr fAl thermoelectric voltage of the hot junction, along the vertical axis the difference voltage of the calibration bar involved (A - 3943 - 11).

In order to get the final data of the calibration curve, the following two corrections are necessary. First: a correction for the increasing temperature of the cold junction of the calibration bar during the experiment. Second: a correction for the translation of the coordinates to a common starting point (in accordance with the zero-point of the Celsius-scale).

With the aid of the well-known data on the Chr fAl thermocouple, the graph already made with tape

CD,

and the measured temperatures of the cold junction, the corrections mentioned above are carried out on the adjusted measurements of tape <%> (program A - 4571 - 3).

Furthermore, in this program the voltage of the hot junction In mV Chr fAl is converted into degrees Celsius.

With a regression-program (A - 2080 - 6) the polynomial coefficients of the calibration curve are calculated (used model: calibration bar voltage versus Pt = a.T + b.T2 + c.T3) (1).

-4-For plotting the graph of the calibration curve in correspondence

with the calculated formula (with program A - 3943 - 11) the coordinates are first made with a sub-program (A - 1908 - 3).

At choice, it is also possible to plot the underlying measurements (tape

a»

in the same graph.

In Fig. 3. the calibration curve with the measurements of the carbide grade 52 versus Pt is given.

RESULTS.

The results of all measurements are listed in Table 1.

In this table the coefficients a, b, and c are given for the carbides mentioned and the workpiece material C45N. Moreover, the 2a-value

(0

=

standard deviation) of every coefficient as calculated by the regression-program is given.

DISCUSSION OF RESULTS.

In general, the shape of the calibration curves are parabolic.

It is possible to obtain the emf -relationship between one of these carbides and C45N-steel.

Therefore, the emf of S2 versus c45N is: emf S2_C45

₌

_{emf c45 - emf}Pt S2

Pt In numerical values it will be:

Pt emf - - = C45 emf - =S2 Pt emf - - =S2 c45 -1 -5 2 -8 3 + 0.129 x 10 x T - 0.644 x 10 x T + 0.549 x 10 x T -2 -6 2 -8 3 0.949 x 10 x T - 0.34 x 10 x T + 0.497 x 10 x T -1 -5 2 -8 3 + 0.224 x 10 x T - 0.610 x 10 x T + 0.052 x 10 x T (see Fig. 4.)

The carbide grade F02 and the C45N-steel have a positive emf versus Pt; this can be seen from the coefficient a in Table 1.

-5-The heating-process calibrations are less stable and they do not reproduce so well as far as the materials with a negative emf are concerned.

The data of Table 1. are obtained from three or more well reproducible calibrations of the cooling-process.

As already mentioned the calibration curves of the materials having a negative emf are parabolic.

The formula

emf

=

a.T + b.T2 + c.T3

describes a curve through all the measuring-points of the calibration series with a very good technical accuracy (see Fig. 3.).

The c45/Pt calibration possesses in the upper range of the curve a loop. This loop is caused by the A

1,2,3 transformation energy. The A transformations absorb energy. During the A transformations

c r

the absorbed energy is released.

If no transformation should occur, the calibration curve should be

~n the middle of the loop mentioned before, because the absorbed energy and the released energy are of the same quantity (see Fig. 5.).

The coefficients of the calibration curve are determined to the average value of the A

c and Ar curve.

At the moment, research is going on in our laboratory into the back-grounds of being less stable of the carbide calibration curves in the heating-process.

REFERENCES.

Veenstra, P.C., Bus, Chr., Zweekhorst, E.T.W.:

Preliminary report on the measurement of cutting tool temperature (WI-0072), on behalf of CIRP-conference, Cincinnati 1963. Also published in Dutch in "Metaalbewerking",

r----~A~M.~EijL-.

} THERMOCOUPLE

H T JUNCH N

L. eTRIC fURNACE

COLD JUNCTIONS COOLING DEVICE

Cli ~L. THYMOC UPLE

z

a

....

-«

C' ctl PLATINUM INERT GAS WillES

____ -.J

DATA LOGGER

L

_

1

~

I

I

I

I

I

I

I I

I

,__

E.M.F. VOLTAGE E.M.F. VOLTAGE

TAPE HOT JUNCTION TEMPERATURE

COLD.

"

"

FlG.1.

CALIBRATION SET-UP

n.0267 Starting Data datalogged non-scaled measurements remaining measurements qualitative control counting of couples (A 327 - 14a) elimination influence time-base, scaling (A 3948 - 5) paper-tape with all measurements

o

rough calibration graph carbide/Pt - Chr/Al (A 3943 - 1 I) paper-tape with equidistant chosen measurements corrections for: increasing temperature cooling watercircuit translation to a common startingpoint (A 4571 - 3) calculation polynomial coefficients calibration curve (A 2080 - 6) coordinates calibration curve (A 1908 - 3) calibration curve wi th/wi thout underlying measurements (Fig. 3.)

(J ~---.- L..-. .. ... L ...L.--. ._..L..- .l 200 400 600 800 1000 ~ _':l "-CL

"""'-1sl

CO

I

tJ OJ _I

en

-4

~

2nd

colo

0

3rd

co I

_a LL

4lh

colo

0

I

V L 0

w

-6

L

> E

Temperature

f O("'~1 l G) Fig. 3. E.M.:F. 82

n.o267

18

S2/C4S -

1

C4S/Pl

-

2 C:'J/P1 - 3 ....Je l l -16 14 12 10 8 6

/

4

E.M.F. (1) = E.M.F. (2) - E.M.F. (3)

2

/

600

400 200

o

~

----"-

--l-. . _ - - - L L...-.-_~ ---.J

600

1000

> E -2

Temperalure

G

-4

LL (J L (J w -6

Fig. 4. E.M.F. c45 ' E.M.F. ---82 C45 and E.M.F. - - as a function of the82

Pt Pt

14 12 10 B >

6

E ~ 4 CL ~ lJ) ~ u 2 ~ i.J :L~ a W

4lh

cola

0 5lhcola~

6lh cola

h.

o

L - -L.. L -_ _. ...L . L - ~___l

o

200 400 600 BOO 1000

T

.empero ure

t' (

°el

Fig. 5. E.M.F. --- as a function of the temperature.C45

Pt

The curve through the plotted loop determines the average value of the A_{, c} and A_r energy.

.,., ,....

...

•

R.0267

Materials

versus emf coefficients with 20--values Pt

20-a 20- b 20- c

carbide grade SI -O.349xlO~ -2 O.3xlO-4 -O.198xlO-5 O.8xIO-7 +O.479xlO-8 O.6xlO- 1O

-2 -4 -6 -6 -8

O.7xlO- 1O carbide grade S2 -O.949xIO O.4xlO -O.343xIO O. 1OOxl 0 +O.497xIO

carbide grade S4 -O.729xlO-2 O.4xIO-4 +O.746xIO-6 O.I1IxIO

-6

+O.387xlO-8 O.8X10- IO carbide grade 86 -O.I015xlO-I O.5xlO

-4

-O.426xlO-5 O.15xIO-6 +O.830xlO-8 O.llxlO-9 carbide grade H05 -O.I090xIO-1 O.9xIO

-4

+O.807xlO-6 O.260xlOE+O.475xIO-8 O.19xlO-9 carbide grade HIP -O.866xlO-2 O.5xl0-4 +O.164xlO-5 O. l6xI 0-6 +O.374xlO-8 O.llxlO-9 carbide grade HIO -0.9l4xIO-2 O.8xIO-4 -O.569xlO-5 O.23xlO-6 +O.865xlO-8 O. 19x1 0-9 carbide grade H13 -O.84lxlO-2 O.7xIO-4 +O.571xIO-7 O.22xlO-6 +O.493xlO-8 O.16xlO-9 carbide grade H2O -O.997xIO-2 0.1 OxI 0-3 -O.496xlO-5 O.30xIO-6 +O.849xIO-8 0.22xlO-9

1--- - - ---

_---=2-

- ---'4

- - - -

_{-- ---=6}

....

---

---carbide grade F02 +0.430xlO O.5xIO +O.454xlO-5 O.I6xlO -O.106xlO-8 O. 12xl 0-9

steel C45N +0.129xlO-I 0.1 xIO-3 -O.644xIO-5 O.42xlO-6 +O.549xlO-8 O.30xlO-9

Table 1. Coefficients of Eq. 1. for several grades of carbide and steel C45N .