New thermal spray PTFE composite coating gives less friction and less wear

Citation

(1998), "New thermal spray PTFE composite coating gives less friction and less wear", Industrial Lubrication and Tribology, Vol. 50 No. 6. https://doi.org/10.1108/ilt.1998.01850fab.019

New thermal spray PTFE composite coating gives less friction and less wear

New thermal spray PTFE composite coating gives less friction and less wear

Keywords: Coatings, PTFE

Following an intensive research and development programme, Plasma & Thermal Coatings Ltd, one of the leading UK surface technology companies, this month launches a brand new PTFE coatings technology.

The company's new Plasmod® range of coatings represent a significant advance in the use of PTFE's very low coefficient of friction. Whilst having an enormous number of benefits, historically PTFE has offered little wear resistance in aggressive, erosive and abrasive service environments. Currently thermal sprayed metallic coatings are used as an undercoat to reinforce and protect the PTFE surface layer (Figure 1). However, once the metallic peaks have worn, PTFE is removed and the surface loses its non-stick, non-wettable and low friction properties often with catastrophic consequences. Although this two step method has benefits regarding service life, compared with a simple PTFE coating (Figure 2), it is significantly more expensive and requires longer processing time. Also the protection provided by the peaks of the metallic bond coat extends to a depth of less than 0.1 mm.

However, with the development of the Plasmod® coatings, for the first time a one-step process has been created for thermal spraying of ceramic and metal composite coatings containing fluoropolymer uniformly distributed throughout the entire coating (Figure 3). These new coatings combine the properties of the metal, ceramic or carbides with the inherent benefits of PTFE, and retain low friction, low wear and non-stick, non-wettable properties throughout the much extended life of the coating.

Figure 1 Metal reinforced coating system

Figure 2 Simple PTFE coating

Figure 3 New Plasmod PTFE coating system

The new composite coating can be deposited to thicknesses over 0.5 mm and thereby greatly extending the surface life of the coating. Compared with other typical thermal spray coatings these composites with embedded particles of PTFE have demonstrated 50 per cent less friction and 20 per cent longer wear.

Plasmod® coatings have been developed by Plasma & Thermal Coatings Ltd using proprietary patented materials which comprise particles clad with ceramic and other materials. The cladding provides a thermal barrier that protects the fluoropolymer against destruction by the extreme heat of the thermal spraying process.

This clever encapsulation of PTFE particles within the thermal coating means that the inherent properties of wear resistance and low friction continue through the full depth of the coating.

The new Plasmod® coating also has an environmental benefit ­ PTFE can give off toxic fumes under heat, but by encapsulating the PTFE within the thermal coating, this is to a large extent prevented.

Plasma & Thermal Coatings Ltd sees an enormous array of applications for the Plasmod® coatings across a range of industries. These will mainly include the paper, textile and packaging industries where the coating will prevent material sticking to rolls and drums; the food and chemical processing industries which will benefit from the almost frictionless coating surface; and the plastics and moulding industry where the low friction coating will benefit rolls, guides and moulds.

Other applications are likely to include copier rolls, heat exchangers, and machine element components, bearings and seals providing wear resistance and low coefficient of friction.

Having developed this new thermal spray process, Plasma & Thermal Coatings Ltd are able to offer industrial users a number of services. The company is able to provide a Plasmod® coating service; supply the equipment for in-house application of coatings; and supply materials in conjunction with the licensing of the technology. Plasma & Thermal Coatings Ltd also has research facilities for application and coating development to meet customers' specific requirements.

Further details from: Helen Manley, Plasma and Thermal Coatings Ltd, Maesglas Industrial Estate, Newport, South Wales NP9 2NN. Tel: +44 (0)1633 211148; E-mail: sales@plasmacoat.co.uk