Laser-based powder process with tribologically modified PEEK powder

The spe­cial­ty chem­i­cals com­pa­ny Evonik is devel­op­ing new tri­bo­log­i­cal­ly mod­i­fied plas­tic pow­ders based on VESTAKEEP® PEEK (poly­etherether­ke­tone) for laser-based pow­der process­es as part of a research project fund­ed by the state gov­ern­ment of North Rhine-West­phalia and the Euro­pean Union.

The over­all objec­tive of the project under the name “ENLAPRO” is to devel­op an ener­gy-effi­cient, laser-based pro­duc­tion process for PEEK-based tri­bo­log­i­cal coat­ings. This can be used to coat metal­lic com­po­nents that are sub­ject­ed to high mechan­i­cal loads — such as pis­tons or bear­ing shells in inter­nal com­bus­tion engines or met­al com­po­nents in air-con­di­tion­ing compressors.

By devel­op­ing new high-per­for­mance mate­ri­als based on VESTAKEEP® PEEK, the com­pa­ny is lay­ing the foun­da­tions for the project work, which is sched­uled for com­ple­tion at the end of 2021. In doing so, the spe­cial­ty chem­i­cals com­pa­ny is draw­ing on more than 50 years of expe­ri­ence in poly­mer chem­istry at its largest pro­duc­tion site world­wide in the Marl Chem­i­cal Park.

Greater efficiency through less friction

A large num­ber of appli­ca­tions, par­tic­u­lar­ly in mechan­i­cal and auto­mo­tive engi­neer­ing, are char­ac­ter­ized by fric­tion­al and wear stress­es com­bined with the high­est require­ments in terms of tem­per­a­ture stress and cor­ro­sion resis­tance. This often requires the use of spe­cial coat­ings. In terms of mate­r­i­al prop­er­ties, high-per­for­mance poly­mers in par­tic­u­lar are pre­des­tined for such appli­ca­tions. Due to its excel­lent mate­r­i­al prop­er­ties and very high mechan­i­cal, ther­mal and chem­i­cal resis­tance, VESTAKEEP® PEEK occu­pies a spe­cial position.

Con­ven­tion­al coat­ing process­es typ­i­cal­ly involve sev­er­al steps: chem­i­cal com­po­nent clean­ing and pre­treat­ment of the com­po­nent using blast­ing media, coat­ing in pow­der form with a mate­r­i­al loss of up to 70 per­cent, and a sub­se­quent, ener­gy-inten­sive oven process. In this, the com­plete com­po­nent is heat­ed to typ­i­cal­ly 400 °C to melt the coat­ing mate­r­i­al and thus obtain an adhe­sive coating.

New coating process consumes less energy

The key inno­va­tion of the new process is the sig­nif­i­cant increase in ener­gy effi­cien­cy, since only the coat­ing mate­r­i­al and a thin edge lay­er of the com­po­nent are heat­ed by laser radi­a­tion. Accord­ing to ini­tial cal­cu­la­tions, the use of the laser-based coat­ing process could reduce ener­gy con­sump­tion by more than 90 per­cent com­pared with oven process­es. The new coat­ing process also promis­es a sus­tain­able reduc­tion in mate­r­i­al loss dur­ing coat­ing appli­ca­tion and the elim­i­na­tion of chem­i­cal clean­ing agents and blast­ing media thanks to laser pretreatment.

Oth­er project part­ners in the project, which is sup­port­ed by fund­ing from the Euro­pean Region­al Devel­op­ment Fund (ERDF), are the com­pa­nies Carl Bechem GmbH, Hagen (devel­op­ment of PEEK coat­ings), Clean-Laser­sys­teme GmbH, Her­zo­gen­rath (laser pre­treat­ment) and the Fraun­hofer Insti­tute for Laser Tech­nol­o­gy ILT, Aachen (laser process development).