Breakthrough coating technology

Citation

(2002), "Breakthrough coating technology", Aircraft Engineering and Aerospace Technology, Vol. 74 No. 2. https://doi.org/10.1108/aeat.2002.12774bad.013

Breakthrough coating technology

Keywords: Aerospace industry, Coatings, Technology

A breakthrough coating technology, which claims solutions to problems not solved by any existing process, is believed to be poised to have a major impact on the manutacture of parts and equipment for the aeronautics industry world-wide: with applications ranging from actuators to undercarriages.

Known as Hardide and originally developed in Russia, the gas phase process is thought to be a world first in that it is reportedly the only low temperature, super hard coating technology to be able to coat "out of sight" surfaces and complex shapes uniformly.

Hardide, the composition of which is based on tungsten carbide, is according to its manufacturer also able to challenge all existing coating methods such as PVD, thermal or plasma spraying due to a novel combination of credentials, these are reported to be –

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  Super hardness (up to 3500 HV) outperforming spray coatings, hard Chromium, nitriding and cementation by a ratio of three to one

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  An ultra low dry friction coefficient (from 0.1 to 0.2) offering enhanced self lubricating capabilities

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  Unrivalled chemical and corrosion resistance to water, salt and acids

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  A wear factor of between 40 and 100 times less than case hardened steel – and up to 10 times less than ceniented carbide hardmetal

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  Outstanding erosion resistance, outperforming steel by a factor of 10 when subjected to water/sand jet tests at a speed of 10 m/sec and by 100 when speed increased to 20 or 30 m/sec

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  Porosity of less than 0.04 per cent

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  Coating thickness with a variability range from 5 to 30 microns

Hardide technology produces a family of more than 20 coatings offering a variety of parameters meet specific application requirements. All these coatings can be produced at one plant, while the composition and structure of each is controlled by process conditions.

Hardide also informs us that its non-porous coating can also facilitate the release of any moulded product in that it has non-stick characteristics. It is also said to be inert and so does not interact with other materials.

Accelerated wear tests reprtedly show that five pairs of piston sleeve hydraulic parts coated with 30 microns of Hardide outperformed case hardened piston sleeves by a factor of seven when subjected to the rigours of oil with diamond abrasive grit. Other more common abrasives like sand would make the difference much more significant.

Hardide asserts that with the potential to dramatically reduce manufacturing and maintenance costs – Hardide coated parts can last up to 100 times longer – the process offers a major new technological weapon for industrial companies fighting cheap imports from China, Latin America and the Pacific Rim.

It has taken 20 years for Hardide to come to the coatings market after being extensively researched and developed, initially in Russia and more recently in Oxford, England, where the first application development centre in the West and only the second in the world – the other being in Moscow – has just been unveiled and from where samples can be obtained on request.

Heading up the team at the new UK centre of excellence are two leading Russian scientists. Professor Yuri Lakhotkin, technical director of Hardide Ltd, is one of the world's leading authorities on chemical vapour deposition used in the Hardide process; while Dr. Yuri Zhuk, Hardide Ltd's managing director, is not only a renowned academic but an expert in international technology transfer - and a prime mover in bringing Hardide's benefits to the West.

Hardide is believed to have the potential to provide major benefits for manufacturing and coating companies serving all industry sectors, with specific areas already pinpointed including aeronautical, automotive, construction and agricultural equipment.

In the aeronautics sector, Hardide claims advantages for manufacturers of equipment ranging from actuators to undercarriages. It is suggested that Hardide could mean smaller and lighter pumps, requiring less power to drive hydraulic systems because of lower friction. Fuel valves can be made more efficient because of Hardide's ability to coat internal surfaces.

The fact that Hardide provides a slippery low friction surface without lubrication will, it is thought, make it attractive to bearing manufacturers among others, and its extreme wearability makes it ideal for precision parts found in fuel injection systems where there are very strict tolerance issues.

The Hardide technology is also said to score heavily over hard chrome coating. Not only is the Hardide process claimed to be environmentally-friendly, it also claims a coating that is three to four times harder.

Hardide's composition, structure, coating method and applications have been protected by international patents covering 67 countries including the USA and Canada, the EU, Japan, China, Korea, Brazil and Mexico.

Details available from: Hardide Ltd. Tel: +44 (0) 1865 309677; Fax: +44 (0) 1865 309676; Website: http://www.hardide.com