The effect of metallic inter-layers on multilayer ceramic/metal coatings properties

Wear resistant coatings are used to protect surface of industrial components working under high and constant wear loads. Within this group the ceramic hard coatings like titanium nitride (TiN) are of special interest in a number of technological fields due to their corrosion resistance and mechanical properties [1, 2]. The wear of hard coatings can change dramatically with adjustment of parameters like load, sliding speed, contact geometry and humidity. Cracks initiation and propagation are often responsible for wear. Nowadays it is a tendency to connect the properties of different type of materials, like for example combination of hard and soft phases in composite like coating or application of multilayer systems where soft (metallic Ti) and hard (ceramic TiN) interlayers are deposited in a sequence way [3÷5]. The Ti layers would allow extensive plastic deformation at crack tip and also, due to a lower elastic modulus compared to TiN, deflect the cracks. Consequently, multilayered Ti/TiN coatings display an improved fracture resistance as compared to homogenous TiN [6]. On one side the presence of plastically deformed metallic layers play an important role in cracks propagation mechanisms. Their presents can stop crack propagation, on the other side the decrease of the amount of this, metallic phase may have an influence on mechanical properties like for example hardness. The current work is focused on how the change of the ratio of ceramic phase to metallic one influence on the microstructure and mechanical properties of coating. Experimental The hybrid PLD (Pulsed Laser Deposition + magnetron sputtering) system equipped with high purity titanium target (99.9 at. % Ti) was used for deposition of Ti/TiN multilayered coatings.