Hybrid magnetron sputtering of ceramic superlattices for application in a next generation of combustion engines

Abstract

A hybrid magnetron sputtering process (dcMS/HiPIMS) was developed to manufacture nanostructured CrN/Cr1-xAlxN multilayers, motivated by improving the low-emission efficiency when applied on gas-nitrided diesel piston rings of a next-generation of combustion engines. In order to improve the mechanical, tribological, and corrosion behavior of the multilayers, the hybrid dcMS/HiPIMS process was designed by selecting the optimal sputtering procedure applied to AISI 440 base steel. The effect of substrate bias and carousel rotational speed on the phase composition, crystallographic texture, residual stresses, surface roughness, coating periodicity and densification, instrumented hardness, elastic modulus, as well as wear and corrosion resistance was determined. The results have demonstrated that hybrid magnetron sputtering produces multilayers with a superlattice structure, which outperforms commercial PVD coatings of CrN for diesel piston rings manufactured by cathodic arc evaporation. Also, multilayer periodicities in the range of 5 to 10 nm yield the best tribological performance under bench tests for the piston ring/cylinder liner system.

Tailoring the Hybrid Magnetron Sputtering Process (HiPIMS and dcMS) to Manufacture Ceramic Multilayers: Powering Conditions, Target Materials, and Base Layers

“…Furthermore, the detailed view of the base layer (inset of Figure 3) shows a layered structure of Cr (light contrast) and CrAl (dark contrast), while some of the grains can be observed by electron channeling contrast (ECCI). The periodicity of the CrN/CrAlN multilayer (20.7 nm) can be measured from the BSE image and matches the prediction given by Equation (4) (20.8 nm) [17].…”

“…The periodicity of the CrN/CrAlN multilayer (20.7 nm) can be measured from the BSE image and matches the prediction given by Equation (4) (20.8 nm) [ 17 ]. …”

“…All diffracted peaks corresponded to the face centered cubic (fcc) CrN phase. The absence of peaks related to Cr 2 N or AlN phases showed that aluminum occurs as a substitutional element without phase segregation or AlN precipitation [ 17 , 25 , 26 ]. In addition, all the peaks presented a slight shift to the left (i.e., toward smaller 2θ angles).…”

“…All ceramic multilayer depositions were performed in a Plasma-HiPIMS-250 (PLASMA LIITS, Campinas, Brazil) vacuum chamber equipped with three different target positions and connected to HiPIMS and DC power supplies. The vacuum chamber schematic with three targets used in this work is published elsewhere [ 17 ]. The depositions of the coatings were carried out on piston rings made of AISI440 martensitic stainless steel produced for a diesel engine application and supplied by MAHLE Metal Leve, Jundiai, Brazil.…”

“…HiPIMS produces dense coatings with a few defects and enhanced hardness; however, it is associated with a low deposition rate [14,15]. Some studies have shown that it is possible to combine both techniques and develop a hybrid process that allows for a higher deposition rate (than HiPIMS) and increased hardness (than DC) [16,17]. Furthermore, if different materials are grown on each other, a multilayered architecture will be produced and a superlattice structure may be generated, if the crystal lattices are of the same nature and the periodicity of the sub-layers is small enough.…”