How long a furnace, 1 cm, 10 cm or 100 cm?
This is perhaps important in the design.
Do you have any needs for rapid heating or cooling? This too is
important to the design. Really rapid heating requirements would tend to
influence the thermal mass of the furnace.
So, unbutton that lip and talk some more about this mysterious furnace.
At this stage, if you were a prospective consulting customer, I might
otherwise determine that someone else would be far better suited to your
needs than myself.
I am assigned to design a very small furnace (5 - 6 cm, diameter
doesn't matter, temperature 1000 Celcius). I am looking for suitable
heating methods. Please share if you have any idea.
ps. somebody told me to try 'halogen lamp heater' but there is not
much information about it in the internet. So idea about this 'halogen
lamp heater' will help me much too.
Thanks in advance
You did not specify whether you wanted a box or tube type furance
which significant changes your design parameter. However, you should
be able to buy commercial nichrome or kanthal embedded heating
elements for this purpose or just buy the wire and make your own
(Zircar would be a good place to start). You can even buy ceramic
potting compound to embed the elements. One method I have used for
making my own small custom furnaces is gas furnace hot surface
ignitors made out of silicon carbide, available at most appliance
shops for $20 or so. They are quite cheap and the width of the units
ranges from 1 - 2 cm or more. They can even be run off a variac if
you want quick and dirty heating then you can just monitor temp with
an external thermocouple. I have reached temps of 1400C with these
units. Quartz or halogen lamps can be effective but the geometry of
the sample can cause issues and you either need reflectors to direct
the heat or some sort of susceptor since most oxide are not effective
in this area. Silicon carbide should work as a susceptor for your
You have a difficult problem in getting meaningful results.
There will be gigantic thermal gradients along the length of the fiber
from the grips to the middle of the hot zone and then down to the grips
Maybe you can attribute the maximum temperature of this with the
fracture event or approximately so.... So you have in effect some
temperature uncertainty because of the large gradient.
If anyone asks you the gauge length of the test specimen you have a
IF you are asked to try to make some claims as to the fracture strain,
you have a problem.
I would begin to devise a tiny furnace, tiny in ID so that the aspect
ratio of the hot zone is as large as possible so as to try to get a
reasonable uniform hot zone.
I might heat it directly with current flow. In this case, the heating
element could be disposable and there would be standard heating elements
fabricated (or bought) for these single use short term thermal heatings.
So, in effect, you would be assembling a disposable furnace during the
mounting of the specimen using water cooled grips, perhaps, or grips
that can take quite a few heating cycles before needing replacement.
Now, I stop.
It is your project and part of the project and your education is to
wrestle with these things to work them out.
There are, of course, many more clever things that other high
temperature researchers have developed, used and evaluated.
A day is the library is often worth a week playing around in the lab.
An evening sucking ideas out of newsgroups can be even better than a day
in the library...... unless the suckee avoids getting too involved.
Well the furnace is for high temperature tension test of less than 8
cm long oxide fibres. So far I am expecting to design a furnace which
is less than 5 cm long because I am expecting only to heat the sample
(not the whole or parts of the testing apparatus) up to 1000 C. Rapid
heating or cooling is not that necessary in this experiment.
(Waiting for help)