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Nickel-Boron Depositions
Nickel boron (NiB) has already been rapidly embraced by the aerospace, automotive and defense
industries because it is harder than hard chrome and has higher corrosion protection. NiB is a highly
unique coating that outperforms both hard chrome and electroless nickel-phosphorous in hardness
and wear resistance. In recent years, the EU’s End of Live Vehicle (ELV) directive and its Restriction
of Hazardous Substance (RoHS) Directive banned the use of hexavalent chromium. NiB coated via an
autocatalytic process that has multiple advantages over electroplating, high velocity oxygen-fuel (HVOF)
thermal spray and physical vapor deposition (PVD).

Figure 2. Gun barrel application, surface and cross sectional structures
of Ni-B and Ni-B composite depositions.

SAU electrochemical and thin film coating team has been working on the new deposition materials
especially for defense applications, consistent with the SAU’s defense industry research vision. Starting
from 2004 an interdisciplinary team has been established on the electrochemical depositions of Ni,
Cu and nanocomposite coatings on steel, aluminum, copper etc. and polymeric materials. SAU team
specifically concentrated on the automotive and defense materials surface modification and coatings to
develop surface stability, tribological properties, corrosion resistance and load bearing for gun barrels
and machine parts, alternative to conventional hard chromium depositions. SAU NiB based depositions
is an advanced, electroless NiB alloy and NiB nanocomposite coatings that is environmentally friendly
and an ideal hard chrome replacement that provide superior hardness, wear resistant, and low co-
efficient of friction. NiB has a columnar morphology due to the growth mechanism of the deposit (Fig.
2). The columnar grain growth of the NiB deposits formed the surface of the coating a nodular (semi-
hemispherical) structure. This type of surface retains lubricants under conditions of adhesive wear.
The nodular structure reduces surface contact providing a low-friction surface and increased wear
resistance. BN, CeO2, TiN and Al2O3 particles co-deposited in with electroless NiB alloy and it has been
detected that the second phase particles are continually exposed as NiB composite coatings wear down.
This ensures superior hardness lubricity and longevity. Especially extreme self-lubrication, superior
wear, corrosion and friction resistance has been provided due to load bearing and lubrication effect
of the inorganic co-deposited particles. Alternative NiB and NiB composite coatings can withstand
temperatures up to 1430 °C, provides good corrosion resistance, homogeneous coating with excellent
hardness up to 1400 HV. NiB depositions has a friction coefficient as low as 0.08-0.2 according to ASTM
test standards.

Figure 3. Representative results from ballistic tests and finite element modeling

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