Among other properties, carbon-fibre-reinforced thermoplastics exhibit high strengths at the same time as a low weight and good wear resistance characteristics. That is why these compounds are also used in components for which tribological properties are demanded. If the wear resistance and coefficient of friction do not meet the requirements, the materials undergo modification with lubricants. However, this reduces their strength. A compromise therefore has to be found between tribological and mechanical characteristics.
Combining conflicting properties does have its attractions; it is an area that can give rise to innovation! This was the result of cooperation between Lehmann&Voss&Co. and Impreglon Oberflächentechnik GmbH. Injection moulding and electrostatic powder coating are combined so that components made of polymers such as PA 6 or PEEK can be coated with other thermoplastic tribopolymers such as POM.
The material of the injection-moulded part (substrate) is optimally adapted to the coating system. The latter consists of a primer and a thermoplastic layer with a thickness of 100 micrometres. High-strength components with optimally lubricated surfaces are the result. The lubricant-modified POM surface exhibits a coefficient of friction of 0.06 against steel (measured on an interfacial corrosion testing apparatus). No running-in effects were observed during the process. Unlike injection-moulded parts, the POM layer is not “frozen” by a cold tool surface. Instead, a highly crystalline morphology forms on the surface. These tightly packed crystals ensure high wear resistance and a matt surface. In the Taber test, 27.3 cycles are required to abrade one micrometre. Apart from POM, other coating systems are available such as those based on PBT.
Layer thicknesses of 100 to 200 µm can be applied with uniform layer thickness distribution. Impreglon also offers the coating service from and with LUVOCOM® materials for large series with continuously operating automatic processes.
Dr Marcus Rechberger
Phone: +49 40 44197 411
Fax: +49 40 44198 411