Objectives and content
A new type of instrument for mechanical testing, the
Nanoindenter, was developed in the late 80's, as a spinoff of the scanning tunnelling microscope. This
instrument allows high precision measurements of the
penetration depth of a diamond indenter into the test
material as function of the load, usually two curves for
the loading and the unloading cycles are recorded, from
which hardness, elastic modulus, toughness and many other
properties can be derived. The demand of this new type
of mechanical testing on industrial products is strongly
increasing. However, its use is limited due to the fact,
that only samples of restricted size can be tested.
Larger samples from industrial equipment have to be cut
in small pieces, which fit into the instrument. The
instrument, as it exists to-day, is extremely sensitive
to vibrations, and has to be mounted in vibrationally
The goal of this project is to develop a portable
instrument for testing metallic and other electrically
conductive materials. In contrast to the classical
nanoindenter, the new instrument will determine the depth
of penetration by measuring the electrical resistivity
between the indenter and the testpiece. For this purpose
the surface of the indenter will be coated with a thin
doped diamond layer, or an electrically conductive ultrahard ceramic coating. Due to its measuring principle,
the instrument will not be influenced by vibrations and
can be built as a hand-held device allowing measurements
to be performed on large test pieces and on sites which
are not accessible by conventional instruments.
Mechanical testing on site is especially important for
pieces which are relevant for the safety of industrial
installations as power plants and chemical plants, and in
the public transport as for example in aeroplanes.
The feasibility of the new measuring principle has been
recently demonstrated by the prime partner of the
project, using a diamond indenter whose surface had been
rendered conductive by ion implantation. However, due to
the resulting surface degradation of the indenter the
service life time was too limited for industrial use.
The deposition of boron-doped epitaxial diamond layers
has recently been demonstrated by another partner of the
project. The deposition of ultra-hard, electrically
conductive ceramic coatings is an alternative process
which might contribute to considerable cost reduction.
Coatings of the envisaged type have been intensively
investigated by another partner and can be found in the
ternary Ti-B-n system.
The consortium includes a manufacturer of hardness
testers, a producer of dedicated electronic equipment, a
diamond tool factory, an institute for the production of
semiconducting layers, an institute for the production of
low conductivity ceramic layers and for the calibration
of the indenters, and three industries, which are users
of the instrument, and which will develop its application
under specific conditions.
Funding SchemeCSC - Cost-sharing contracts
Venecono Superiore Varese
7521 RB Enschede