CoatMat

In this work, a nanocomposite (Cr,Al)xN1−x/Si3N4 coating system was deposited on H11 hot work tool steel, using the Lateral Arc Rotating Cathodes (LARC®) deposition system and modulating the chemical composition of the chromium and aluminium–silicon content. Structural characterizations were performed using scanning electron microscopy, equipped with energy dispersive spectroscopy probe, and applying x-ray diffraction, for the evaluation of phase constitution and crystallite size.

In heavy loaded mating components, such as sliders and sliding bearings, guaranteeing the efficiency of lubricant films for long times during severe service conditions is very complicated. In this work, the benefits deriving from the use of fiber laser sources for surface texturing of very thin TiN coatings in severe wear working conditions were demonstrated. Evaluations of the laser textured dimples shape, geometry and density are given. Wear performance of the fiber laser textured surfaces was evaluated in discontinuous oil lubricated conditions with a flat contact.

Under various working conditions, rolling elements may suffer from different types of damage behaviour, including fractures in the coatings and bonding interfaces, and plastic deformation in the substrate materials. The present paper reports research into the prediction of the critical load of a metal-rolling system (metal-rolling system) by considering the damage of the coated surface based on a novel FE simulation-procedure developed by the present authors.

La tecnologia laser texturing (LST) è una delle tecniche più promettenti nel campo delle microlavorazioni superficiali in quanto consente di ottenere un eccellente controllo della forma e delle dimensioni dei microfori prodotti ed è estremamente veloce e senza ricadute dannose per l'ambiente. Recentemente si è assistito allo sviluppo di diversi lavori nei quali il laser è stato impiegato per migliorare il comportamento tribologico di componenti meccanici in materiale metallico.

In this work, the scratch resistance of laser surface textured TiN coatings is studied to discriminate laser conditions in terms of coating adhesion and integrity in view of future wear tests. Laser surface texturing (LST) is performed on TiN coating ,3 mm thick using a pulsed active fibre laser working in nanosecond pulse regime. Laser process parameters are varied to obtain several patterns with different dimple diameter, depth and pitch, all of which are essential for controlling tribological behaviour.

Thermal fatigue (TF) is a common problem in many tool steel components. It is caused by thermal cycling in presence of internal constraints. The resulting thermomechanical stresses induce thermal cracking (heat checking). A laboratory test was developed to reproduce TF damage on a laboratory scale, under oxidizing conditions. Two different test configurations were used to induce unidirectional and bidirectional cracking. Nitriding impairs TF resistance of plain steel due to the easier propagation of cracks through the diffusion layer.

This paper deals with a study of the failure mode of thin PVD coatings in alternated contact with molten aluminum alloy. CrN and ZrN monolayer coatings deposited through cathodic arc evaporation were used. The coatings morphology was assessed by SEM and their mechanical properties evaluated by nanohardness test performed at room temperature. An experimental test rig which cyclically immerses coated steel samples in molten Al-alloy and in a cooling bath was applied.