Pre-Paint Treatment
April 2007
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Bonderite NanoTech (NT), a nanoceramic conversion coating, is an industrial metal pretreatment using nanotechnology for improved paint adhesion and corrosion protection that reduces energy costs, speeds up processing and generates no waste requiring disposal.

According to its developer, Henkel KGaA, the coating is suitable for surface pretreatment for all conventional powder and wet paint coatings. It can be applied by dipping or spraying and creates a cohesive, inorganic, high-density layer incorporating nanoparticles. The coatings are also reported to increase the surface area and offer the paint a larger surface to adhere to than iron phosphating.

The process is said to offer numerous economic benefits. No bath heating is required. The coating can be applied at room temperature, which helps save energy. Speed is also accelerated, the supplier says, because throughput time for parts being treated is about 20 seconds and is said to make passivation unnecessary, which eliminates an entire process step.

According to the supplier, it also offers environmental advantages. In addition to low energy needs, the coating is distinguished by its entire lack of organic ingredients. Neither phosphates nor toxic heavy metals have to be disposed of, so far less sludge is generated in production. The positive environmental profile is said to pay economically because it means outlay on wastewater treatment, waste disposal and plant cleaning and maintenance is significantly reduced.

The coating can be used on existing equipment with minimal modifications and is said to be ideal for steel, zinc and aluminum surfaces. With a thickness of only 20 to 30 nm, it is thinner than the coating achievable with conventional iron phosphating, but the corrosion protection and paint adhesion performance are said to be substantially better. The supplier reports that corrosion protection was tested with a salt spray test to ISO 9227 and the paint adhesion using the Cross-Hatch Test to ISO 2409. On all substrates, the nanoceramic coating showed minimal rust creep at the scribe and achieved better results in the salt spray test. On steel substrates, corrosion creep was reduced up to one-ninth of the creep with iron phosphating (1.5 mm compared to 14.0 mm). www.bonderiteNT.com


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