A network of contacts built up over 30 years between eastern
and western Europe led to three highly successful steel surface-treatment
projects under the Copernicus programme. Key players Plasmaterm and
the University of Birmingham worked together with universities and
research organisations in Hungary, Poland and Romania as well as Germany
and the UK to develop new test methods and novel solutions for improving
surface wear and corrosion resistance. The resulting technologies
are already being applied extensively to make machine parts for the
automotive, chemicals and precision engineering industries.
New generation plasma surface engineered
sewing machine parts.
Romanian surface-treatment specialist Plasmaterm
is a survivor of the complete shutdown of its local textile industry
which employed 10,000 people in Tîrgu Mures, Transylvania - about
midway between Budapest and Bucharest. Originally a state-funded research
institution, it provided R&D support for precision-engineered textile
machinery used in spinning, weaving, sewing and knitting.
Founded in the mid-1960s, to meet a burgeoning need for new technology
in Romania, it established an international reputation in surface
treatment, with several patents in low-temperature nitrocarburising.
However, the political turmoils of the early 1990s paralysed operations
and funding dried up. So its director, Dr Zoltán Kolozsváry, proposed
a workers' buyout of the unit from the state - a gamble which has
EU RTD support through the Copernicus programme played a crucial
role in the company's rebirth. "The programme should not be used
to replace vanished state subsidies for research," says Dr Kolozsváry,
now managing director of Plasmaterm. "But what it can do is allow
valuable laboratories to survive the transition into viable business-oriented
units. Taking part in the Copernicus programme was the turning point
Plasmaterm inherited a unique expertise
in surface treatment, along with a wonderful array of measuring
and testing equipment, much of it home-made.
The company had a valuable inheritance. Sewing machines run at very
high speeds - up to 10,000 cycles per minute - and intermittently,
so parts must be extremely resistant to wear. Plasmaterm had therefore
developed unique expertise in surface treatment and testing. It
has used this to build up a business in contract materials testing
and analysis, failure analysis, and of course surface treatment,
especially plasma nitrocarburising. This high-tech surface technology
causes nitrogen and carbon molecules to diffuse into the surface
of the steel, creating a hard layer composed largely of iron carbonitride.
Traditionally, this has been achieved by immersing the steel in
a cyanide bath or an equivalent gaseous medium. However, the toxicity
of these media can result in undesirable side effects.
Plasma nitrocarburising offers a more environmentally sound approach.
It involves applying an electric charge to the objects to be hardened
while they are immersed in an atmosphere containing nitrogen, hydrogen
and carbon. The gases' atoms become excited and react with the surface
of the charged engineering components.
Treatment is normally carried out by hanging parts from a stainless
steel cathode in the centre of a cylindrical stainless steel chamber
at around 750 volts and 590°C. Depending on customer requirements,
each batch may be treated for up to 12 hours, resulting in a carbonitride
diffusion layer up to half a millimetre deep. A hardness of up to
1000 Vickers units can be obtained on stainless steels, coupled
with a reduced friction coefficient.
From steel to polymers
The company is now embarking on its third European collaborative
project within the Copernicus programme. All of them have been led
by Professor Tom Bell of the University of Birmingham, and have
involved partners in Hungary, Poland and Romania as well as Germany
and the UK.
From Professor Bell's perspective, the collaboration is natural:
"I've known Zoltán Kolozsváry for 30 years, and we are both world
experts in surface treatment. He is the current president of the
International Federation of Heat Treatment and Surface Engineering
(IFHT); I was president 15 years ago and will be the 'millennium'
president. Through my involvement with the IFHT, I have an extensive
network of contacts in both eastern and western Europe. So when
Copernicus came along, it was possible to take quick action for
three projects. The results have been very beneficial, considering
the very small amounts of money that have been invested, and the
economic potential is tremendous."
The first project ran from 1994 to 1996. It investigated how to
increase the wear and fatigue resistance of machine parts by optimising
process parameters for plasma nitrocarburising. The work covered
plain carbon and low-alloy steels as well as special nitriding steels.
Results included a new test method for improving the ductility of
surfaces and led to an improved industrial process. The latter has
since been applied in Romania, where three plasma units now work
almost round the clock to carry out nitriding and nitrocarburising.
Improved corrosion resistance for chromium steels - keeping stainless
steel stainless - was the objective of the second project, which
started in 1995 and finished in 1998. Two approaches were examined,
and both were successful. Professor Flis at the Institute of Physical
Chemistry of the Polish Academy of Sciences investigated surface
passivation techniques, while Dr Bell at the University of Birmingham
carried out innovative studies on phase structure. Both processes
are now in use in Romania for components applied in the chemical
industry and for food machinery.
The third project is in its start-up phase and runs until early
2000. It applies an ion-beam technique to improve the friction and
wear properties of polymers, and will have practical application
in improving orthopaedic implants such as hip- and finger-joints.
Fundamental in-situ studies are being carried out in Hungary using
advanced analytical techniques, while tribological properties are
being investigated in Germany. Nano-scale surface properties after
treatment are being measured in the UK by the SME partner Micro-Materials,
and Plasmaterm is building a small robot for testing prostheses.