14 Nov 2001
High Performance PEEK™ Polymer combined with PTFE in New Cylinder Head Gasket Coating for Increased Wear Resistance
German manufacturer STE has developed a new cylinder head gasket using a powder coating process that combines VICTREX® PEEK™ polymer and PTFE. The development of this highly durable plastic coating also opens up important opportunities for other applications in which low friction and low wear must be ensured at high temperatures and under load.
The gasket, sold under the trade name of Monomet®, is a solid steel stamping with a predefined thickness distribution. The coating, which is applied in a secondary step, has to meet a range of demanding requirements and is of key importance to the overall function of the product.
An engine’s cylinder head places extreme demands on all surrounding components, in particular on the cylinder head gasket. The temperatures in this environment vary between 30°C and 250°C, (85°F and 480°F), and can be even higher in the short-term. The aggressive mix of hot water and steam from the cooling circuit with glycol, and hot engine oil and gasses from the combustion compartment represents an extreme challenge to the sealing materials. Furthermore, due to the distortion of the cylinder head, the gasket is subjected to compression forces of up to 200 N/mm2, which demands high strength over a wide temperature range. In addition, the micro-movement of the aluminium cylinder block resulting from temperature variations and engine vibration must be absorbed by the gasket at the lowest possible coefficient of friction.
Applied using the multislide® coating process, STE’s tailor-made compound based on PEEK™ polymer and PFTE meets these critical requirements for temperature, wear and chemical resistance. The innovative coating prevents the risk of contact corrosion and “welding” of the cylinder head on the cylinder block. This means that the parts can be easily disassembled and replaced, if necessary, during servicing. In fact, the gasket can be repeatedly reinstalled without any significant effect on cylinder head performance.
One of STE’s most difficult tasks was to ensure a good permanent adhesion of the coating to the metal gasket. By using a special bonding agent, STE perfected the coating technology so that an overall coat of only 20 µm, (less than 0.8 mil), passed 2,000 hours of hot water testing at 120°C (248°F). In the meantime, the coated head gasket has been proven in both OEM tests, (including 900 hrs of thermal shock), and in 30 months of operation in vehicles on the road.
Reader enquiries
Helen SwarbrickVictrex plc
Victrex Technology Centre
Hillhouse International
Thornton Cleveleys
Lancashire FY5 4QD
United Kingdom
Tel +44 1253 897700
Fax +44 1253 897701
United Kingdom
Notes for editors
Victrex plc, which has its sales, technical and production headquarters at Thornton Cleveleys in Lancashire, UK, had a turnover of more than £58m in the last financial year. The company exports 98 percent of its VICTREX® PEEK™ polymer output to OEMs in the automotive, industrial, medical, food and electronics market sectors in Europe, North America and Asia Pacific.
Information on products, technical support services and sales and distribution contacts worldwide, can be accessed through the company’s web site: www.victrex.com
The PEEK™ Trademark
For many years Victrex plc has been using the PEEK™ trademark to refer to its brand of Polyaryletherketone. Victrex plc is the sole manufacturer and supplier of the PEEK™ brand polymer world-wide. PEEK™ is a trademark of Victrex plc.
Related images
Photo caption
High Performance VICTREX® PEEK™ polymer combined with PTFE in new cylinder head gasket developed by STE of Wilhelmshaven, Germany.
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