 About
1930 the investigation of the failure of a railway tyre in service
led to the discovery by C. Sykes of 'order-disorder transformation',
which aroused considerable interest in academic circles. This phenomenon,
which is quite common in alloy systems, is a rearrangement of the
atoms within the solid solution: in an ironaluminium alloy, for
instance, either the aluminium atoms may be distributed at random
among the iron atoms, or they may alternate on the cube corners of
the body-centred lattice giving an ordered structure. The rearrangement
is caused by heat treatment and was first detected by the change in
the electrical resistance of an iron-aluminium alloy containing 25
per cent of aluminium by atoms; its cause was confirmed by x-ray work.
This discovery appears to have escaped notice because the sensitive
physical methods of examination—x-ray analysis, electrical resistivity
and specific heat measurement—were not normally used.
Work
on refractory materials was of practical value for the tips of cutting
tools, where an alternative was desired to the sintered tungsten
carbide obtainable from the Continent. Research work on titanium
carbide began in 1931, and in the following year sintered carbides
were being made on a modest scale in the research department under
P. P. Starling. By 1938 a range of these hard metals, later known
as Cutanit, were available in the quality and consistency required
and were being sold in an increasing volume, mainly for tool tips.
Further research by Sykes and T. Raine on the basic powders used
rendered this country independent of continental supplies before
the war began, and manufacturing methods were rapidly developed
and plant installed, mostly employing new and superior processes.
This work had invaluable results in war-time.
Sykes,
who had been in charge of the physics laboratory, left in 1940 to
be superintendent of the metallurgy department of the National Physical
Laboratory. He became an F.R.S. in 1943 and is now director of research
at Thos. Firth and John Brown Limited.
Another
development in new materials was Metrosil, the resistance of which
exhibits a remarkable departure from Ohm's Law: by doubling the
voltage applied to it the current is increased twentyfold. In 1937
a small manufacturing section was set up in a laboratory for the
production of this material under controlled conditions. As a non-ohmic
resistance Metrosil had an obvious field in lightning protection,
and this application was rapidly developed. Gradually its uses were
extended, and they now cover a wide range from 132-kV surge diverters
to telephone and radar equipment.
Research
on electrical insulating materials was directed in 1937 towards
better heat-resisting qualities, and the use of glass insulation
on high-duty machines was investigated, both alone and also impregnated
with a synthetic resin such as glyptal. In the following year the
laboratories began to manufacture, on a small scale, a range of
insulating varnishes and impregnants and also a wide range of special
priming and finishing paints.
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