Effect of CrAl interlayer on adhesion strength of CrAlN coating

Abstract

CrAlN coating is widely used to prevent Ti alloy from wear nowadays, however, the poor adhesion between the coating and substrate is an urgent problem to resolve. In this paper, CrAlN coating with CrAl intermediate layer is prepared on Ti alloy by RF magnetron sputtering technique. The adhesion strength of the coating is measured by automatic scratch tester. The results show that the adhesion strength of CrAl/CrAlN coating is much higher than that of mono-layer CrAlN coating. The CrAl layer with thickness of 5.07 μm displays an excellent adhesion strength, which is 84.2 N. The nano-hardness and elastic modulus are 26.45 and 215.33 GPa, respectively. The improvement of adhesion strength can be attributed to the two reasons: (1) the elastic modulus of the CrAl layer is between the Ti alloy and the CrAlN coating, playing a role of stress transition. (2) The intermediate layer inhibits the columnar growth of CrAlN.

The effect of duty cycle on the mechanical and electrochemical corrosion properties of multilayer CrN/CrAlN coatings produced by cathodic arc evaporation

“…The layered structure of the CrN/CrAlN films could disrupt the growth of the columns, close the porosity and voids, and thus impede the penetration of the corrosive solution. A similar mechanism was reported by Zhao et al [22] in CrAl/CrAlN coatings deposited by the RF magnetron sputtering method. CrAl intermediate layer disrupts the columnar structure of the CrAlN layer which leads to a decrease in diffusion path and an increase in the adhesion strength of layers.…”

“…Generation of MPS on the coating surface or inserted in the deposited films could disrupt the uniform structure and create defects, pinholes, and voided boundaries. These internal imperfections could provide through-film paths for the electrolyte to accede to the film/substrate interface and result in the formation of galvanic cells and localized galvanic corrosion in the substrate [2,22,30]. Better corrosion resistance in the deposited films could be obtained with the higher thickness and the denser microstructure of multilayer CrN/CrAlN coatings.…”

“…The effect of the CrAl intermediate layer on the adhesion properties of CrAlN films was investigated by Zilong et al [22]. They reported that CrAl interlayer with high elastic modulus acts as a stress transition layer between CrAlN coating and the substrate.…”

Substantial electrode life enhancement in resistance spot welding of galvanised steels through nanolayered multi-layer CrN/(Cr,Al)N coating

“…However, the electrode degradation mechanism has been less studied in detail, calling for more investigations. Moreover, the previous studies have focused on single-layer coatings, while multi-layer coatings have many advantages over their single-layer counterparts, such as high strength [18-22], greater adhesion [22,23], less residual stress[24], better mechanical and typological properties [23,25-32], and more desirable corrosion resistance [20].…”

Effect of bilayer number on mechanical and wear behaviours of the AlCrN/AlCrMoN coatings by AIP method

“…In recent years, the CrAlN multilayer coatings with high adhesion, hardness [11], outstanding thermal stability [12] and oxidation resistance [13] have been extensively used as protective coatings in metal cutting and numerous industrial applications. Many AlCrN-based multilayer coatings such as AlCrN/AlCrON, Cr/CrN/CrAlN, and CrAlN/VN [14] showed low coefficient of friction and wear rate as compared with a monolayer CrAlN coating.…”