results of studying the arc contraction in various media showed
that by varying a medium composition it was possible to efficiently
govern the power characteristics of the arc. It enabled to improve
the known methods and to develop new ones for microplasma welding.
The microplasma welding of the most of metals is performed by the
direct polarity arc burning between tungsten electrode of the plasmatron
and a workpiece in a stream of plasma forming inert gas (argon)
The microplasma is used for high quality welding of thin-walled
workpieces and precision structures of various non-ferrous and ferrous
metals and their alloys (steel, nickel, titanium, Fernico, copper,
brass, etc.); for precision hard-surfacing to eliminate microcracks
and microdefects in finished products; for soldering, cutting and
for other processes of heat treatment of thin materials, requiring
a concentrated heat source.
The microplasma at direct polarity, however, cannot be used for
welding aluminium and aluminium based alloys, having refractory
oxide films on their surface. On the basis of the studied cathode
processes and features of reversed polarity arc burning, the a.c.
welding process of sheet aluminium and its alloys has been developed.
The developed methods of microplasma welding of aluminium and its
alloys were performed at E.O.Paton Electric Welding Institute in
1968, the first being used in domestic and foreign practice. They
were widely introduced into national economy
of our country and patented in France, Italy, Germany, United Kingdom,
Switzerland and Japan.