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To comply with the need to provide sliding mating surfaces with greater resistance to corrosion and wear, the surfaces that come into contact are often coated with hard chromium and with nickel-phosphorus
alloys.
They are both very hard materials with a low coefficient of
friction; despite this, if lubrication is faulty or missing completely, it will lead to the wear and seizure of the mated
surface.
In the case of dry
lubrication, substances such as graphite, molybdenum bisulphide and Teflon (PTFE) are often
used.
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The metallographic section of the ELNIFLON process shows how the particles of Teflon are evenly blended in the NI-P matrix.
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The latter material, which is of interest for its particular
qualities, is widely used for sliding mating surfaces.
Therefore, the idea came to mind of using nickel-phosphorus which is very suitable as PTFE incorporating
matrix, thus achieving a hard surface with a high level self-lubricating power. This gave rise to the ELNIFLON
process.
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ELNIFLON is a composite system of chemical nickel-plating which, while maintaining the same characteristics of ELNIP 13, enables a sliding non-stick surface to be produced thanks to the particles of Teflon (PTFE).
In fact, with the ELNIFLON process the Nickel matrix is provided with a suitable percentage of particles of Teflon, a chemically inert material in the presence of corrosive substances with a relatively high softening point (approx. 330 °C) and, when applied to a hard substrate, it has the lowest coefficient of friction of any polymer.
ELNIFLON contains from 20 to 30% in volume of particles of Teflon of less than 1 micron in size. The matrix is an alloy containing 87-90% of nickel and 10-13% of
phosphorus..
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Right from the start, the ELNIFLON coating has aroused considerable interest in many different industrial sectors.
In fact the possible applications are countless.
These include several that have already been widely experimented such as:
parts of automatic gears
carburetor parts
aluminium cylinders for dry compressors
shafts, gears, pistons, etc.
valves
rails and guides for transport and movement
moulds for foodstuffs (pasta,
bread, cakes, etc.)
rubber and plastic moulds
butterfly and ball valves etc.
screws, tie rods, bolts
carburetor parts |
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craft motor components |
- AERONAUTIC
- AEROSPACE
- SHIPPING
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The particles of Teflon used to lower the coefficients of friction and to give the surface a self-lubricating capacity are evenly blended in the NI-P matrix.
In this way, when they come into contact with a sliding surface the particles, supported by the matrix itself, are not removed but gradually wear away as the thickness of the coating gets thinner. Therefore, the solid PTFE on the whole of the surface enables a low coefficient of friction to be maintained for a very long working period.
Thanks to the ELNIFLON coating, abrasion is considerably reduced even when the coating is provided on just one of the mating surfaces.
The mechanical properties of the ELNIFLON coating are a mixture between those of NI-P and those of Teflon.
The average hardness read with a micro-durometer is about 250 HV, which following a heat treatment at approx. 320 ° increases to 400 HV. However, to have an idea of the resistance to wear and/or the duration of this process, these values are not sufficient.
In fact, the very low coefficient of friction should also be added to the qualities as it preserves against wear and the nickel-phosphorus agglomerating alloy which has a hardness of at least 500 HV increases to 1000 HV following a heat treatment.
Here below are the tables showing the values given after three different tests; the speed of wear and the coefficient of friction have been calculated using a rotating ring and a drill pressed against the
same.
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Material of the drill:
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ELNIP 13 without heat treatment |
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Material of the ring:
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Chromium-plated steel |
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Hardness of the ELNIP 13:
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550 HV |
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Specific consumption: (-10-6mm3/m)
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35 |
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Coefficient of friction:
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0,6 ÷ 0,7 |
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Material of the drill:
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ELNIFLON |
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Material of the ring:
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Chromium-plated steel |
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Hardness of the ELNIFLON:
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250
HV |
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Specific consumption: (-10-6mm3/m)
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Steel 40 |
| ELNIFLON
1 |
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Coefficients of friction:
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Steel 0,2
÷ 0,3 |
| ELNIFLON 0,1 ÷ 0,2 |
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Material of the drill:
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ELNIFLON |
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Material of the ring:
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Chromium-plated steel |
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Hardness of the ELNIFLON:
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400 HV |
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Specific consumption: (-10-6mm3/m)
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Steel 20 |
| ELNIFLON
2 |
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Coefficients of friction:
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Steel 0,2
÷ 0,5 |
| ELNIFLON 0,1 ÷ 0,7
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