Jacques P. Tardif

Technical direction

NEAR ZERO-QUANTUM FRICTION  

When you combine several materials that are not miscible with each other to obtain a result with properties that each component alone cannot achieve, you are making a composite.

Composite materials have existed for many years. Reinforced concrete has been around since 1848; glass-fibre reinforced liquid polyester since 1950.

Today, the most familiar composites are made with an epoxy, polyester or polyurethane matrix, but they also exist with metallic matrices. The SAFRAN Group has 16,000 patents, obtained at the rate of 450 per year. It has filed a patent for an invention using phosphorus, nickel and talc (known since ancient times) for aeronautical fasteners, and another for a Ni-Ag-MoS2 coating that is resistant to liquid hydrogen at -253°C.

Fluid mechanics usually involves striving for the lowest possible drag coefficients in water or air, but in the field of tribology, formulators look for lubricants with coefficients of friction as close to 0 as possible, whatever the substrate, speed, load, temperature, or environment.

Solid lubricants enter into this picture, but none of them have the performance characteristics needed to satisfy every possible scenario on their own. The structure, adsorption (their affinity with surfaces), and the physical-chemical properties all play an essential, but not decisive, role.

A few examples:

Boron nitride

Cubic Boron Nitride (CBN). Alongside diamond, it is known as an excellent abrasive material used to manufacture wheels for grinding.

In its hexagonal form (h-BN), it is a solid lubricant. It has a mediocre coefficient of static or kinetic friction, starting from 0.4.

Both forms of boron nitride have a very high temperature resistance: 900°C in oxidising atmospheres, 1200°C in neutral atmospheres.

Mos²

With its remarkable affinity for metals, its use boomed in the 1960s. In laminar form, with an initial coefficient of friction of 0.04 (a factor of 10 lower than that of h-BN), temperature resistant from -180°C to +450°C in air, it degrades in the presence of chlorine, bases, or oxidants, and may corrode surfaces.

PTFE

Its coefficient of friction is very mediocre at 0.2. It has exceptional chemical inertia, but relatively poor resistance to high temperatures. At 260°C and above, it releases hydrofluoric acid. This limits its use to medium-temperature applications.

Note that graphite has an initial coef of 0.1, that of graphite fluoride (Cfxn) is 0.01, and that of tungsten disulphide (WS2) is 0.03.

A lower coefficient of friction, wear, and energy are constantly being sought.

Much research is being conducted into the high-tech applications of new solid lubricants such as fullerenes C60, C540, NDPs, graphene nanoscroll, and DLC (diamond-like carbon with a COF of 0.001).The SHELL marathon holds the record of 1017 km for 1 L of fuel equivalent, and a reduced coefficient of friction is one factor in this success. This initiative has driven, and continues to drive research. The many teachers and students who participate in it deserve to be congratulated. There are Luddites who will say that these advances are not marketable, but let's not forget that Eric Tabarly's many inventions (I have the greatest admiration for him because we share a passion for the sea) are now a part of our everyday lives.

High content of sub-micronized technical ceramic particles and solid lubricants

44 %

Optimum reduction in friction coefficient

Very strong anti-welding properties

High film strength

Anti-oxidation  

Anti-Fretting  

Anti-pitting

Eliminates catalytic coupling problems
on ferrous/non-ferrous contacts.

Low thermal and electrical conductivity

Non-flammable in use

Improved cleanliness for industrial maintenance
and in a machine environment

-25°C +900°C

in oxydizing atmospheres

-25°C +1200°C

in neutral atsmospheres

Assembly - disassembly of screws subject to repetitive impacts and critical vibratory phenomena

CERAM 900 has very high resistance to extreme heat

limited to the ductility (malleability) point of metals, including stainless steel

Tower 101 Taipei 509.2 m

Assembling the clamping plates of cable plies (Hertzian micro-contacts) that suspend the tuned mass damper (a sphere weighing 660 tonnes) which absorbs and reduces the movement of the tower from 30 to 40% in case of typhoons or earthquakes

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