Internal treatment of tubes and hollow objects

Treating the inside of thin tubes or hollow objects requires a specialized approach to overcome access constraints and ensure uniform coating along the entire length. Materia Nova has two complementary plasma deposition systems (PVD/PECVD), covering a wide range of diameters, on metal or glass tubes:

• Regular cathode: diameter from 4 cm
• **Mini-cathode (patented technology)**: diameter from 5 mm to 4 cm

In both cases, the plasma is generated directly inside the tube: the process is therefore free of the line-of-sight constraints typical of conventional PVD coating, with excellent control over coating thickness and uniformity across the entire inner surface. The process is dry, under vacuum, with no bath or liquid effluent.

A flagship, ready-to-market product

Based on the mini-cathode, Materia Nova offers a chrome-type plasma PVD coating on the inner wall of tubes with a diameter of 4 to 10 mm, over a length of up to approximately 50 cm — a readily available alternative to hexavalent chromium plating, which is now subject to REACH restrictions. Compared to hard chrome plating, this coating provides functional equivalence — surface hardness, friction, corrosion resistance — with a thickness of only a few microns, versus several tens of microns for traditional chrome plating.

The same installation can also deposit other materials (metals, oxides, nitrides, carbides) and produce multilayer stacks, opening the way to additional functionalities.

Solutions tailored to every application

Thanks to the various coatings available at Materia Nova, we treat the inside of tubes according to the specific needs of each sector:

• Corrosion protection, for metal tubes used in corrosive environments (water, oil, or chemical pipelines)
• Wear resistance, for applications involving abrasive materials or high-speed fluids
• Friction reduction, improving the efficiency of fluid or gas flow
• Thermal resistance and thermal or electrical insulation, for applications at extreme temperatures
• Antimicrobial properties, for medical or food applications
• Chemical resistance, for transporting reactive substances in industrial settings
• Ease of cleaning, through non-stick coatings, useful in the food and pharmaceutical industries
• Barrier properties, limiting permeability to gases or volatile liquids

Custom process development

Beyond these standard ranges, our expertise in plasma processes allows us to develop, on request and for a specific customer need, configurations adapted to other geometries or pressure conditions — by extending current systems or via a dedicated treatment architecture (magnetron).