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Within the physical vapor deposition (PVD) high power pulse magnetron sputtering (HPPMS) or high power impulse magnetron sputtering (HiPIMS) is a frequently studied technology in the last years. HPPMS offers the possibility to produce coatings with lower roughness, denser microstructure and better mechanical properties in comparison to direct current magnetron sputtering (dcMS). However, HPPMS is known to have much lower deposition rate due to the low duty cycle compared to dcMS. Therefore, from an economic point of view, dcMS is more effective compared to the HPPMS technology. An approach to overcome this issue is the dcMS/HPPMS hybrid technology, whereby dcMS and HPPMS cathodes are used simultaneously to combine the benefits of both technologies. In hybrid processes, the influence of dcMS and HPPMS on the plasma and coating properties is of crucial interest. Therefore, in the present work measurements on plasma properties as well as on coating properties using dcMS, dcMS/HPPMS hybrid and HPPMS (Cr,Al)N processes were carried out. The (Cr,Al)N coating system as well as the utilized steel substrates were chosen to address the application in plastics processing. In the first step of this work the plasmas of dcMS, dcMS/HPPMS hybrid and HPPMS processes were analyzed. Dependancies of the plasma properties on the type of the process as well as the pulse parameters such as the pulse length t on and the frequency f were investigated. The most significant influence was identified depending on the process type. In the second step (Cr,Al)N coatings were produced using the same process parameters. A similar behavior as with the plasma properties was observed for the coating properties. In the third step the measurements of the plasma and coating properties were correlated. It was proven that changes in the plasma and coating properties correlate significantly. Therefore, the coating development can be simplified through prediction of the coating properties with the more efficient plasma diagnostics. [ABSTRACT FROM AUTHOR]

In plastics industry molding tools are subjected to adhesive and abrasive wear as well as to corrosion. In this regard, (Cr, Al)N hard coatings deposited by physical vapor deposition (PVD) have a high potential to be used as protective coatings. The high power pulse magnetron sputtering (HPPMS) technology offers several advantages with regard to the deposition of hard coatings. Variation of the pulse length has a significant influence on the current–voltage-characteristic (I–U) of the cathodes, the chemical composition and the mechanical properties of the (Cr, Al)N coatings as well as on the reaction layer on the coating surface, which affect the interactions between the coated tool and the plastic melt in terms of adhesion. The present work deals with investigations of the influence of HPPMS pulse length at constant pulse frequency on the reactive gas N 2 in the deposition process and on the adhesion behavior of (Cr, Al)N coatings towards plastic melt. For this reason, the HPPMS plasma was analyzed at the substrate side via a retarding field energy analyzer (RFEA) and energy resolved mass spectrometer (MS). The RFEA was used to determine ion current densities at different HPPMS pulse length of t on = 40 μs, 80 μs and 200 μs. The MS was used to analyze the intensities of Cr + , Al + , N + and N 2 + in the HPPMS plasma. The results revealed that a decrease of the pulse length leads to an increased ion current density as well as an increased dissociation of molecular nitrogen, which has a significant influence on the chemical composition of the coating. Furthermore the adhesion behavior between coating and plastic melt is influenced by the pulse parameters via the changed chemical composition of the reaction layer on the coating surface. Based on these results, coatings with desirable mechanical properties with regard to wear resistance in plastics processing and a passive layer designed to ensure low adhesion of the plastic melt shall be developed. [ABSTRACT FROM AUTHOR]