Properties And Optimization Of Rf-Bias-Sputtered Tin For The Wear Reduction Of Plastic Manufacturing Tools And Components

TiN was reactively sputtered using RF magnetron sputtering with RF-biased substrates for the purpose of wear protection of parts working under plastic manufacturing conditions. A complete optimization procedure is described starting with the investigation of fundamental coating properties such as structure, adhesion, hardness and their dependence on the deposition process and concluding with the evaluation of the tribological properties. These were investigated using the unlubricated Timken test (plate on cylinder) and a special model wear test for the simulation of the conditions of plastic manufacturing. The RF bias allows deposition with low bias voltages. Highest hardness values and best adhesion are obtained at -20 V and -50 V respectively. In both tribological model wear tests the optimized coatings showed excellent wear behaviour. For use under the corrosive and abrasive conditions of plastic manufacturing, the important role of coating structure could be demonstrated. Using these results in a practical application, the coating of a plastic forming mould with RF-bias-sputtered TiN resulted in a marked improvement in the lifetime under production conditions by a factor of more than four.